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YARD College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois Newsletter No. 8 • May 23, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Scale Crawlers Home, Yard, and Garden Pest Newsletter No. 3 discussed and described scale species that may be present on trees and shrubs. This article discusses the immature or crawler stage of some important scale insects. The oystershell scale overwinters in the egg stage beneath the female scale covering. Their egg hatch is in May or early June in the northern part of the state. The brownish red crawlers will move onto new shoots and leaves. Euonymus scale crawlers will also begin to hatch in late May and in June. The yellow- or orange-colored nymphs move out from the adult female covering to new green fo- liage and stems. Pine needle scale nymphs ap- pear on new needles in June. There could be additional generations for some scale species. Oystershell scale can have another generation in the southern part of the state. There could be two or three more generations of the euony- mus and pine needle species. Oak lecanium, if present, will appear as crawlers in late June or early July. Control: All these scale crawlers can be controlled with an insecticide labeled for use on the host plant. Malathion, diazinon, Dursban, and Orthene are commonly used for scale crawler control. Striped Cucumber Beetles Striped cucumber beetles are now a problem on cucumber, melon, and squash seedlings and young plants. The beetles do not really damage the young plants, but they can infect them with bacterial wilt, causing the leaves to wilt until the whole plant dies. No cucumber or melon varieties are resistant to bacterial wilt. Control: To prevent this disease, you must strictly control the cucumber beetles the first few weeks after your plants emerge. Apply Sevin or rotenone three times at five-day inter- vals, treating new growth as it appears. If good control is achieved during the first month, the beetles often are not a problem the rest of the season. If the plants are in bloom, apply the in- secticide in the evening to avoid interfering with pollination by bees. Tree Borers Borers that attack the trunks or stems of lilac, dogwood, viburnum, flowering peach, plum, fruit trees, and ash have similar life cycles and are controlled in the same manner. The adults of the borer species that attack these ornamen- tal plants are wasp-like, clear-winged moths. They lay their eggs in the cracks of bark in May and June. The young tunnel into the wood and remain there until the next spring. There is only one generation per year. In central Illinois, borer moths begin to emerge from infested trees and shrubs in late May and peak in early June. Control: Pheromone traps are available to determine the adult emergence of ash, lilac, and peach borers. The traps are baited with the scent of a female moth and attract male moths of the same species. To be successful, insecti- cides should be applied when eggs are hatching and before the young borers have tunneled be- neath the bark. Dursban, an insecticide, is ef- fective on this borer species. Mosquitoes Heavy rains last week, combined with warm temperatures, will likely produce large numbers of mosquitoes during Memorial Day weekend (and several before and after). Inland flood- water mosquitoes, Aedes vexans, lay their eggs on low-lying land. Heavy rains flood these low- lying areas and the eggs hatch into larvae, months to years after they were laid. In warm water, the larval mosquitoes will develop to pupae and emerge as adults in 2 weeks. These female floodwater mosquitoes will easily fly 15 miles and can fly 30 miles to obtain a blood meal. (These mosquitoes bite primarily during the evening hours.) Control: Repellents containing DEET will protect against mosquito bites. But even with AGRICULTURE LIBRARY State • County • Local Groups • U.S. Department of Agriculture Cooperating OCT 1 No. 8 • May 23, 1990 repellents, you may wish to restrict outdoor evening activities to avoid these nuisance pests. LAWNS Turfgrass: Diseases Necrotic ring spot was formerly part of the di- sease called Fusarium blight, probably the most serious and widespread disease of established Kentucky bluegrass turfs that are intensively managed. The causal fungus is favored by slightly cool temperatures from spring to au- tumn and is most severe in late spring and early autumn. The disease starts as light green patches, about 2 to 6 inches in diameter. In warm to hot weather, the patches enlarge and rapidly progress from a dull reddish brown to light tan Necrotic ring spot and finally become straw colored. The patches enlarge each year and commonly become sunk- en, roughly circular, doughnut-shaped areas of dead or stunted grass, up to 2 to 3 feet in diameter. Tufts of "healthy" grass commonly appear in the center, giving a "frogeye" pattern. Serious turf damage occurs when the blighted areas are numerous and overlap. Control: The soil should be fertile, well prepared, and well drained and have a soil re- action (pH) of 6 to 7. Grow locally adapted, disease-resistant grasses in blends or mixtures. Avoid pure stands of very susceptible grass cul- tivars such as Fylking, Glade, Merion, Monop- oly, Nugget, Park, South Dakota Common or Certified, and Victa. Maintain adequate to high balanced fertility based on soil tests, the recom- mended fertilization program for your area, and the grass or grasses being grown. Mow frequently at the maximum height (1 1/2 to 3 inches) for upright, lawn-type grasses. Remove no more than one-fourth to one-third of the leaf height at one cutting. Remove thatch now if it has accumulated to 1/2 inch or more. Water established turf thoroughly at each irrigation (soil should be moist at least 6 inches deep). Avoid overwatering and frequent sprink- lings in late afternoon or evening. Reduce soil compaction by core aerifying now, repeating the operation until there are 18 to 36 holes per square foot, 1 1/2 to 2 1/2 or 3 inches deep. Preventive fungicide sprays may be needed where disease has been increasing for the past several years. The two fungicides that give ex- cellent control (when applied according to man- ufacturer's directions and drenched into the top 3 to 4 inches of soil) are Rubigan and Banner. The first application should go on before dis- ease is evident or when night temperatures do not drop below 70 degrees F for the first time. Banner and Rubigan also control several other turf disease including summer patch, dollar spot, Rhizoctonia brown patch, rusts, anthrac- nose, leaf smuts, and powdery mildew. Dollar spot attacks all turfgrasses when temperatures are warm (60 to 85 degrees F) and the weather is wet or humid, particularly if the turf is deficient in nitrogen. Look for more-or-less round, straw- colored, somewhat sunken spots up to 4 to 8 inches in Dollar spot attacking diameter. Kentucky bluegrass. Infected J b leaves show bleached white to light tan girdling lesions with a dark brown, reddish brown, or purplish border. If serious, many patches merge to pro- duce large, irregular, sunken areas of straw- colored dead turf. Control: Maintain adequate to high fertility (see under necrotic ring spot above) and avoid overwatering and frequent sprinkling in late afternoon or evening. Do what you can to in- crease air movement over the turf. You can choose from a number of tolerant or moderately resistant Kentucky bluegrass cultlvars, fine-leaf fescues, and perennial grasses. Mow at the maximum height. If dollar spot has been se- rious in the past, start fungicide applications when the disease is first evident. In addition to • i ~ * - \ * , '- No. 8 • May 23, 1990 Banner and Rublgan, some excellent fungicides include Chipco 26019, Daconil, Duosan, Dy- rene, and Vorlan. Always carefully follow the manufacturer's directions. Apply the fungicide in 3 to 5 gallons of water per 1 ,000 square feet and apply it uniformly to the turfgrass area. Red thread is most serious in cool, exces- sively wet weather in spring and fall on fine-leaf fescues, Kentucky bluegrass, and perennial rye- grass. It is an important disease on slow- growing, nitrogen-deficient turf, where thatch is over 1/2 inch thick, calcium levels in the soil are low, there is a sudden drop in temperature, herbicides have been misused, or the turf is otherwise under stress. The most conspicuous sign is the appearance of pale to bright coral pink, orange, or red mycelial masses on the grass blades. In moisture-saturated air, the gelatinous masses may completely cover the grass leaves binding the blades and leaf sheaths together. Diseased patches fade when dry, and the turf appears bleached tan, yellow, or "scorched" in roughly circular- to irregular- shaped areas from 1 inch to more than 2 feet in diameter. The spots may be scattered, or a number of patches may merge to form large, ir- regular areas of blighted turfgrass with a red- dish brown to tan cast. Control: Follow the same cultural practices as outlined for dollar spot and necrotic ring spot. Several improved perennial ryegrasses, fineleaf fescues, hard fescues, and Kentucky bluegrass cultivars are resistant to red thread. The same fungicides that control dollar spot will also control red thread. Applications should start when the disease is first evident. Separate well-illustrated Reports on Plant Diseases cover the importance, symptoms, dis- ease cycle, and control measures of these three diseases: Report on Plant Diseases No. 408, Summer Patch and Necrotic Ring Spot of Lawns and Fine Turfgrasses; Report on Plant Diseases No. 407, Dollar Spot of Turfgrasses; and Report on Plant Diseases No. 413, Red Thread and Pink Patch of Turfgrasses. PLANT DISEASES Many Herbaceous and Woody Plants: Pythium and Phytophthora Root and Crown Rots Species of the soil-bome fungi Pythium and Phytophthora are common soil inhabitants that are commonly called "water molds." One or more of these fungi attack essentially all plants when the soil is saturated with water, poorly drained, and high in clay. The primary problem caused by Pythium species is the damping-off of seedlings and basal rot of cuttings; but they are also com- monly associated with root rots of established plants. Pythium. root rot is favored by cool, wet, poorly-drained soils and by an excess of water. Pythium infects the younger feeding roots, caus- ing a wet, odorless rot. The rot later takes on a light brown to black coloration. The soft to slimy, rotted outer portion of the root (cortex) can usually be easily separated from the inner core (stele). Affected plants are commonly stunted; they wilt easily and often die in hot, dry weather. Phytophthora species are usually associated with root and crown or stem (trunk or collar) rots of established plants, but they may be a cause of damping-off and basal rot of cuttings. Like Pythium, species of Phytophthora enter the root tips and cause a water-soaked, odorless, reddish brown to dark brown or black rot. Species of Phytophthora cause a serious collar rot of apples, pears, stone fruits, raspberries, strawberries, rhododendrons, azaleas, beech, birches, pines, yews, junipers, dogwoods, elms, lilacs, lindens, oaks, sweet gum, willows, and many other plants. Foliar symptoms include chlorosis (yellowing), marked stunting, wilting, and death. Wilting occurs just prior to plant death and causes leaves to drop even when wa- ter is applied. Phytophthora collar and root rot are primarily a problem on sites that are poorly drained. High soil moisture is essential for the survival, movement of, and infection by species of both Phytophthora and Pythium. Control: Avoid heavy, wet soils, low-lying sites, and standing water around the bases of plants. Plant shallow or on ridges; avoid winter injury; provide support for young trees by a stake, several stakes, or a trellis; and fertilize and prune properly to keep plants as vigorous as possible. Buy disease-free vigorous plants from a reputable nursery, florist, or commercial propagator. If damping-off, root rot, or collar rot occurs, diagnose the problem promptly and apply a fungicide to protect other plants in the area. Some excellent fungicides against Pythium and Phytophthora diseases include Aliette, Truban or Terrazole, Subdue, and Banol. Carefully fol- low the manufacturer's directions and check label registrations, since none of these fungi- cides are registered for use on all susceptible plants. No. 8 • May 23, 1990 With fruit trees, it is often helpful to remove soil around the base of a recently infected tree to expose the entire cankered area. Cut away all diseased tissues (which are usually brown) and leave the trunk area open to permit drying of the infected area and to prevent further dis- ease development. Refill the area around the trunk with good fresh soil in late autumn. Reports on Plant Diseases that cover prob- lems caused by species of Pythium and/or Phy- tophihora include: Report on Plant Diseases No. 615, Damping-ojf and Root Rots of House Plants and Garden Flowers; Report on Plant Diseases No. 636, Canker and Dieback Diseases of Wood Plants, Report on Plant Diseases No. 701, Strawberry Red Stele Root Rot, and Report on Plant Diseases No.812, Phytophthora Collar Rot of Apple. These well- illustrated leaflets provide much more detailed information on symptoms, disease cycles, and control measures. Many Herbaceous Plants: Sclerotinia Disease, White Mold or Watery Soft Rot This common disease is caused by three com- mon soil-bome fungi that attack over 370 species of plants in 64 plant families. Plants grown outdoors and in greenhouses are com- monly infected during cool, excessively wet periods where the plant population is high, veg- etative growth is dense, and air movement is restricted. Characteristic symptoms and signs include a fluffy, white growth of the fungus on infected plant parts in which globular, flattened, elongated or irregular sclerotia are produced. The sclerotia are white at first, but later be- come hard and black. Sclerotinia causes damping- off or bed rot; stem and crown (collar) rot; wilt; leaf and petiole rot; flower or blossom blight; and fruit rot (depending on the vege- table, flower, or fruit plant infected). Control: The soil in greenhouses and plant beds should be steam-pasteurized. Plant in well-prepared, well-drained soil in raised ridges or beds. If mulching with an organic material, avoid contact with the stems; the same is true of manure. You can lighten heavy, clayey top- soil by blending in generous amounts of sand, peat moss, or well- decomposed organic matter. Removing the infested soil and replacing it with new soil before seeding or setting out other plants in the vacant spot is another alternative. Sanitation is important— collect and remove all diseased plant material promptly when infec- tion is first detected and before sclerotia have formed that will later contaminate the soil. All refuse should be burned immediately as far away as possible from growing plants. Do NOT place this refuse in a refuse dump or compost pile, because the sclerotia can remain viable for several years. Keep infested soils as weed-free as possible. Follow the best cultural practices to promote vigorous growth and drying of the soil and plant surfaces. Place root and other crops in a clean, cool, and dry storage immediately after harvest. The humidity in storage should be 90 to 95 percent to prevent shriveling and shrinking, but there should be no free moisture on the walls, ceiling, or floor. Fungicides are beneficial if applied be- fore infection occurs, at the time of planting, or to the base of established plants. Protection is most needed during extended cool and rainy periods in spring and early summer. Suggested fungicides are listed in University of Illinois Cooperative Extension Service Circulars 1 184, 1259, and 1260, which should be available at your county Extension office. The timing and placement of applications will vary with the crop. For more information on this disease, a listing of host plants, pictures of the various diseases caused, disease cycle, and a full dis- cussion of control measures, read Report on Plant Diseases No. 1008, Sclerotinia Disease, White Mold or Watery Soft Rot To obtain copies of any of the Reports on Plant Diseases mentioned in this or other newsletters, send a check, made out to the University of Illinois, to Extension Plant Pathology, N-533 Turner Hall 1 102 South Goodwin Avenue, Urbana, IL 61801. There is a 50 cents charge for each Report on Plant Disease. Home, Yard & Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Permanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engi- neering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. ^uU fiz^/fetf Roscoe Randell Extension specialist Entomology G3S Illinois Cooperative Extension Service Helping You Put Knowledge to Work College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois a. 2 OME. YARD ^ GARDEN PEST Newsletter No. 9 • May 30, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Leafminers Leafminers are insects that live as larvae inside the leaf. More specifically, they feed on the spongy and palisade mesophyll that contain most of the chlorophyll-bearing chloroplasts. They live between the upper and lower epider- mis, or top and bottom covering of the leaf. Several groups of insects, including sawflies, flies, moths, and beetles, have developed the ability to live as leafminers. This lifestyle pro- tects the larvae from drying out and protects them from many kinds of predators and parasites. However, many predators and para- sites can attack leafminers, and some feed only on leafminers. Life cycles are similar for most leafminers. They normally overwinter as pupae in the soil or debris at the base of the plant. In the spring, the adults emerge to lay eggs on or in the leaves. These eggs hatch into larvae that feed within the leaf. Leafminers usually leave the leaf as fully grown larvae, dropping to the ground to pupate. They frequently have several generations per year. Mines start out whitish or light green in color, turning brown as the epidermis over the mine dies. Black specks are often seen in the mine— these are usually the feces of the leaf- miner. If held up to the light, the leafminer larva can usually be seen as a silhouette in the mine. Damage to the leaf is normally limited to the mine itself, since the unmined part of the leaf is apparently able to continue producing food for the plant. Consequently, all but the most severe leafminer attacks do not affect the plant's health, causing only aesthetic damage. Leafminers commonly attack columbine, chrysanthemum, beet, spinach, birch, alder, elm, honeysuckle, holly, and oak leaves. Birch leafminers are probably the most serious, but they can be controlled when Cygon is applied to control bronze birch borers. Chrysanthemum leafminers are serious problems to the green- house industry, and holly leafminer is a serious problem in more southern states. Control: Most leafminers can be controlled by either spraying the plants when mines are still small or picking off and destroying mined leaves. Both methods rely on reducing early generations of leafminers so that later gener- ations are not produced that will cause more noticeable damage. Plants that are heavily at- tacked tend to be heavily attacked year after year. Because leafminer damage is mostly aes- thetic, only heavily attacked plants or plants with very obvious damage should be treated. Bird Mites Bird mites are now being found in homes and will be more of a problem over the next few weeks. Bird mites feed on birds, becoming par- ticularly numerous on, and sometimes killing, young birds in the nest. Many of the mites live in the nest itself, only getting on the birds while feeding. When the young birds leave the nest, some mites are carried away with them; but a large number of mites is usually left behind. Within a few days, these mites become hungry and start looking for a meal. Mites in nests that are under eaves, on windowsills, under air conditioners, and elsewhere on build- ings will crawl into the building through cracks around windows. These mites will feed on people and pets, frequently causing a rash and itching sensation. (Scratching will cause sores to develop.) Although mites feed on people and other mammals, they are unable to reproduce and die within several weeks. Control: Bird mites in a building can be killed by washing surfaces with soapy water. Spray pyrethroid aerosols (such as flying and crawling, household or indoor-outdoor insect sprays) in cracks and crevices and along win- dow casements. Remove abandoned nests and wash the area with soapy water or spray the area with insecticidal soap. Prevent bird mites by removing bird nests as soon as they are empty or cover areas where nests are built with screening to prevent future nesting. AGRICULTURE LIBRARY State • County • Local Groups • U.S. Department of Agriculture Cooperating U L I i / 1990 No. 0 • May 30, 1990 Millipedes Millipedes, or "thousand leggers," are close rel- atives of insects; they are black or brown, hard- shelled, and have many tiny legs. These slow- moving animals are usually about 1 inch long and curl into a coil when disturbed or when they die. They feed on decaying plant material in damp areas. The recent rams in Illinois have increased the number of millipedes that are coming into houses. Once inside the house- usually the basement— they die within a few hours from lack of moisture. Control: Millipedes can be controlled by caulking cracks and crevices in the foundation to keep them from coming indoors. Remove plant debris, such as fallen leaves and bark mulch, and reduce moisture next to the foun- dation. Spraying the outside foundation and adjacent soil with diazinon is also somewhat effective against the millipedes, although there are no pesticides that are very effective in controlling millipedes. LAWNS Managing Landscape Waste Here are basic recommendations for reducing the need to collect lawn clippings. Further information is contained in the fact sheet Turfgrass Management Strategies for Reducing Landscape Waste. 1 . Return clippings to the turf whenever possible. When lawns are healthy and the existing thatch is thin, short clippings do not contribute to thatch. 2. Mow when turf is dry, removing no more than one-third of the grass blades at any one mowing. For example, for a desired height of 2 inches, mow when turf reaches 3 inches. Do not mow turf too short. Keep mower blades sharp. 3. Fertilize and water with care. Over- fertilizing and overwatering lead to rapid turf growth, which often leads to increased mowing and thatch production. 4. In most lawns, maintain thatch layer at 1/2 inch or less through proper irrigation, fer- tilization, and cultivation (through core aerify- ing, power raking, or vertical mowing). 5. Use good turf management as a first defense against turf pests. Use pesticides only when good management will not solve turf pest problems. PLANT DISEASES Blackberries, Black and Purple Raspberries: Orange Rust Orange rust is the most common and serious of the several rust diseases that infect bramble fruits. It is most serious on wild blackberries. You can see the rust now on weak, pale green to yellowish canes that lack spines. The leaves on such canes are stunted or misshapen and covered with bright orange, powdery pustules. These plants are systemically infected, and the fungus grows throughout the roots, canes, and leaves. Control: Grub out and burn all wild brambles now, including the roots. Include any cultivated plants that are rust infected. The best time to dig up and burn infested plants is early in the spring before the orange pustules break open and discharge their spores (which are airborne and infect healthy plants). Next spring, set out only certified, disease-free plant- ing stock from a reputable nursery. For more information, read Report on Plant Diseases No. 708, Orange Rust of Brambles. Trees and Shrubs: Leaf Tatter This noninfectious problem appears in leaves of C maple, oak, sycamore, and other woody plants. Symptoms are round to irregular holes that look as if they have been chewed out by in- sects. The damage is actually caused by winter injury to the buds. Heavy rains and hail may produce similar damage, but torn leaves usually indicate this latter type of injury. There is no control for leaf tatter. Hackberry: Witches' Broom Witches' broom is a very common disfiguring and unsightly disease of hackberry that is be- lieved to be caused by the combined activity of a powdery mildew fungus and a minute erioph- yid mite. A large common hackberry tree may have from a few to hundreds of brooms without obvious loss of vigor. Each "broom" consists of numerous thin, short, stubby twigs that arise close together, often at a swelling or knot on a branch. Control: Pruning out and burning or other- wise destroying witches' brooms is of limited value. Where feasible, purchase broom-free trees of resistant species such as Celtis sinensis and Celtis jessoensis. Avoid planting the com- mon hackberry if the presence of witches' broom is aesthetically unpleasant. For more No. 9 • May 30, 1990 information, write for a copy of Report on Plant Diseases No. 662, Witches' Broom of Hackberry. Spruce: Cytospora Canker Colorado blue spruce and Norway spruce are most commonly affected by Cytospora canker in Illinois. Occasionally you can find the disease in other spruces (Koster's blue, red. Oriental, and white), white pine, balsam fir, and eastern hemlock. The first symptom is the appearance of brown needle tufts at the tips of branches followed by death of the lower limbs. Occasion- ally, branches in the center or top of a tree are attacked first. The needles may drop early from affected branches or remain attached for months, leaving dry, brittle twigs. Conspicuous patches of white resin commonly form on bark in cankered areas and drop on lower branches, or the resin may flow down the trunk. Control: Plant healthy, vigorous young spruce on sites favorable for their growth. Avoid shallow or excessively drained soils, crowding with other trees or buildings, un- necessary bark wounds, and planting on ex- posed sites such as a southfacing slope. A thick organic mulch helps maintain good soil moisture and prevents deep freezing as well as alternate freezing and thawing. Water thor- oughly during extended dry periods, moistening the soil to a depth of 12 to 14 inches. Every few years, have a soil test made and apply fer- tilizer. The Cytospora fungus attacks spruce that are under stress. Proper planting, water- ing, and mulching will largely prevent this dis- ease. Severely cankered trees cannot be re- stored to good health. These trees should be cut down and burned to prevent them from in- fecting other trees. For additional information concerning Cytospora canker, write for a copy of Report on Plant Diseases No. 604, Cytospora Canker of Spruce. Landscape Trees, Especially Elms and Poplars: Bacterial Wetwood and Slime Flux Bacterial wetwood occurs in the trunk, branches, and roots of many shade and orna- mental trees, but is usually not obvious in trees less than 10 years old. Wetwood can be found in virtually all older elm and poplar trees as a chronic disease. It may contribute to a general decline in tree vigor, especially in older trees growing under stressful conditions. The most obvious symptom is the appearance of light and dark streaks where liquid seeps out of cracks and wounds and flows down the bark. As the liquid dries, it leaves a light gray to white incrustation. The liquid is toxic and commonly kills the cambium at the base of pruning cuts and around trunk cracks. Liquid on the bark surface is colonized by various bacteria, yeasts, and filamentous fungi that give it a slimy tex- ture and often a foul odor. The gray to brown, foamlike liquid is called slime flux. Foliage in the tops of trees severely affected by bacterial wetwood sometimes curls, scorches, droops, turns yellow, and defoliates early. Scattered branches may wilt and die back, or the entire crown may gradually decline over several years. Wilting is much more common in younger trees. Control: There is no cure or preventive treatment. The following practices may be of some help: (1) fertilize stressed trees to stim- ulate vigorous growth; (2) where feasible, have an arborist install perforated iron or plastic drain tubes to relieve gas pressure within the tree; (3) remove dead and weak branches, dis- infecting tools by swabbing or dipping them in 70 percent rubbing alcohol before pruning an- other tree; (4) promptly prune and shape bark wounds. Remove diseased bark and underlying wood around infected pruning cuts. Then ap- ply a coating of shellac as a disinfectant. For more information, read Report on Plant Dis- eases No. 656, Bacterial Wetwood and Slime Flux of Landscape Trees. Iris: Leaf Spot Leaf spot is a common disease, especially of rhizometous species of iris. The disease weak- ens plants and makes them unsightly. Re- peated severe attacks reduce blooming and may kill plants after several years. Leaf spot is most severe in mild, very damp weather, espe- cially in sites where air movement is poor and diseased iris debris has been allowed to accu- mulate. The lesions are green to yellow and at first water-soaked, but they soon turn brown and dry, becoming surrounded by a water- soaked margin that later turns yellow. When severe, large dead areas (where the lesions en- large and merge) may cause the leaves to turn yellow, die back from the tip, and curl. Control: Collect and burn all leaf and flower stalks in the fall or early spring before the new fan leaves appear. Cut off and destroy infected parts of leaves. Plant iris in full sun in a rich, well-drained soil. Space plants, keep down weeds, and avoid sprinkling the foliage when watering. Do not work among plants when the foliage is wet. Plant more resistant species and cultivars of iris. The Siberian iris, the parent species of many forms and hybrids. No. 0 • May 30, 1990 is remarkably resistant. The commonly grown bearded or German iris is very susceptible. Fungicide sprays are effective where cultural practices fail to check the development and spread of the disease. Apply a fine, misty spray at 7- to 10-day intervals to keep the young, susceptible growth protected. Adding a spreader-sticker or surfactant to the spray ensures better wetting and coverage. Onfy about a teaspoonful is needed per gallon to lower the surface tension and get good cov- erage. Suggested fungicides include Daconil, maneb or mancozeb, Benlate, Bayleton, Chipco 26019, and Topsin M. Junipers: Phomopsis Blight Phomopsis blight is the most common and se- rious disease of junipers, especially in pro- longed, warm wet periods (April through early June) and again in late August and September. Look for a progressive dieback of new shoot growth that changes from light yellow to red- brown and finally an ash gray. Entire branches may gradually die. Control: Plant only resistant species, varieties, and cultivars. An extensive list is given in Report on Plant Diseases No. 622, Phomopsis Twig Blight of Juniper. Where prac- tical, prune out and burn all blighted parts as PLANT CLINIC HIGHLIGHTS May 14 to 24, 1990 HOST DIAGNOSIS COUNTY Allium Fusarium basal rot Winnebago Azalea Cercospora leaf spot Kane Clematis Pythium root rot Winnebago Elm Dutch elm disease White Euonymus Aphids Champaign Phomopsis twig blight Cook Exacum Sclerotium rolfsii Champaign Geranium Bacterial blight Out of State Botrytis blight Out of State Botrytis blight Winnebago Yellow net virus Winnebago Impatiens Tomato spotted wilt virus Grundy, Kane Ivy Anthracnose Cook Maple Spring leaf tatter Peoria Verticillium wilt Knox Petunia Botrytis blight McHenry Tulip Botrytis blight Champaign Rock island Vinca Phoma stem blight Kane Rhizoctonia root rot Winnebago they appear. Prune in dry weather. Fungicides give effective control when correctly timed. Since only new growth is susceptible, apply sprays at budbreak and repeat at 10- to 14-day intervals until the new growth has changed to dark green. Spray also when new flushes of growth appear in the summer and early fall or in response to pruning and shearing. Effective fungicides include Benlate, Zyban or Duosan, Cleary 3336, and mancozeb. Carefully follow the manufacturer's directions. Color Picture Sheets on Plant Diseases Sixty-two sheets, each covering fifteen to nine- teen diseases in color, are available from the Vocational Agriculture Service, University of Illinois, 1401 South Maryland Drive, Urbana, IL 61801. Each sheet gives information on the name and cause of the problem, symptoms, im- portance, overwintering, etc. At present, there are six sheets on flower and house plant dis- eases, four on trees and woody ornamentals, one on turf diseases, eleven on fruit problems, and four on vegetable diseases. More sheets are planned for the future. Over 500,000 of these color picture sheets have been sold world- wide. For more information, including the cost, contact the Vocational Agriculture Service (217)333-3870. To obtain copies of any of the Reports on Plant Diseases mentioned in this or other newsletters, send a check, made out to the University of Illinois, to Extension Plant Pathology, N-533 Turner Hall 1 102 South Goodwin Avenue, Urbana, IL 61801. There is a 50 cent charge for each RPD. Home, Yard Si. Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineer- ing, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. /is0t<#S fa«d££{ Roscoe Randell Extension specialist Entomology G£5 HI 5 Helping You cjw^.J Put Knowledge to Work Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME, YARD c GARDEN PEST No. 10 • June 6, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Periodical Cicadas Periodical cicadas started emerging in northern Illinois on Thursday, May 24, and have con- tinued to emerge in even larger numbers. These cicadas typically sing for about two weeks before egg-laying occurs. If the cicadas are numerous in an area where there are trees with a trunk diameter of 1 1/2 inches or less, protection from egg-laying damage is necessary. Control: Protect the trees with mesh bags, such as onion bags, or netting around the tree. Tie the netting or bag low on the trunk to keep the cicadas from walking under the netting and up the trunk. Sprays of Talstar or Tempo will give about 10 days of control, which may be a better option for you. Ambush or Pounce will give a similar length of control but can only be used in nurseries. Sevin is the only insecticide that is effective and available to homeowners. It will probably keep the cicadas away from sprayed trees for about three days. Eastern Tent Caterpillars Eastern tent caterpillars have finished feeding in most areas of the state and are coming down from trees to pupate. At this time, when the caterpillars are crawling on the sidewalk and house foundations, people usually request control. Control: The only effective control of the caterpillars at this stage of their life cycle is to step on them. Insecticides will not be effective enough to warrant their application. Since the caterpillars are done feeding for this year, con- trolling the insects serves no purpose anyway. Moths, however, will be emerging soon to lay their eggs on pencil-sized and smaller twigs for next year. The eggs should all be laid by the Newsletter end of June. Homeowners can rub eggs off twigs between the end of June and next spring to eliminate next year's population on the tree. Dispose of eggs that are rubbed off— do not drop them on the ground under the tree. Euonymous Scale We have received reports of Euonymous scale crawlers on leaves in central Illinois. Control: Acephate (Orthene), dimethoate (Cygon), malathion, or diazinon can be applied as a crawler spray to provide control. Four ap- plications should be made that are 10 to 12 days apart for the best control. Pirate Bugs Tiny insects that give a painful bite when you are working outside are probably pirate bugs. These insects are about 1/16-inch long and white and black in color when fully grown. If you are working in and around plants, the nymphs may get on your arms and bite as well. The nymphs are smaller and yellowish-brown. Pirate bugs feed on other insects and are effective predators of mites, aphids, and other small insects. They appear to be attracted to perspiration, but will commonly bite people that are not perspiring heavily. Control: Repellents containing DEET will help reduce the problem as will mowing tall grass and other vegetation in the area where bugs are numerous. For those who are working in vegetation and perspiring enough to wash off the insect repellent, there is little that can be done for protection. Honey Bee Swarms A honey bee swarm consists of thousands of bees that leave a hive to start a new colony. Swarming tends to occur in the spring when a successfully overwintered colony builds up its numbers on early spring nectar flows from flowering fruit and other trees. The swarm forms a mass of bees on a tree branch, porch railing, or other elevated spot while a few of the bees scout for a permanent location, such as a hollow tree, for the new colony. This location is usually found within a AGRICULTURE LIBRARY State • f.niintv • I nral firm ins -llfi Denartmfint nf Anrinultum Coorjerat fl£T 1 7 1990 No. 10 • June 6, 1990 few days, and the swarm will then leave and occupy their new, permanent home. Control: Although you may be alarmed by a swarm of honey bees, stings are unlikely unless the swarm is disturbed. If you cannot wait the few days for the swarm to leave on its own, it can be removed by an exterminator or a beekeeper. Many county Extension offices, po- lice, and fire departments maintain lists of beekeepers willing to remove swarms, but there is usually a fee for this service. PLANT DISEASES Bacterial Diseases of Vegetables The frequent rains we have been receiving have made conditions favorable for many bacterial diseases that occur on vegetable crops. Bacteria are often spread from plant to plant by splash- ing water. They require a film of water on the plant surface to infect. If the rainfall continues as temperatures increase, then we can expect to see epidemic levels of many bacterial diseases. Bacterial diseases are common on beans, tomatoes, peppers, the cucurbit crops such as cucumber and muskmelon, and many other vegetable crops. Common blight, halo blight, and bacterial brown spot are several bacterial diseases of snap beans that attack the leaves and pods. They produce similar symptoms that can be difficult to distinguish. Leaf lesions of common blight and halo blight start as small, water- soaked spots that turn brown and necrotic and become surrounded by a chlorotic or yellow halo. With common blight, the lesions can become quite large, killing most of the leaf tissue, and the yellow halo is fairly narrow. Halo blight lesions stay fairly small, but the chlorotic halo can be broad. Brown spot starts as chlorotic flecks of various sizes that have turned brown. These are not water-soaked and do not have a halo. Control: These bacterial diseases are most often introduced into a planting on infected seeds, as the bacteria can survive on and in seeds produced by infected plants. The bacteria can also survive on infected bean debris. Therefore, control measures include a combi- nation of planting disease-free, western-grown seed and a two- to three-year crop rotation. Also, avoid touching plants when they are wet. Bacterial spot. Bacterial speck, and Bacterial canker are diseases that are common on toma- toes and peppers. Tomatoes are susceptible to Bacterial spot of tomato all three. Bacterial spot is also a problem on peppers, causing dark raised dots on the leaves and fruit. On peppers, bacterial spot can cause severe de- foliation which leads to plant stunting and fruit sunburn. Bacterial speck attacks tomato leaves and fruit, with young, green fruit being more susceptible than maturing fruit. As the name implies, the super- ficial, black lesions are very small— usually less than l/16th of an inch in diameter. Bacterial canker of tomato is a systemic disease that spreads through the vascular system of the plant. Infected plants show signs of wilting, are less vigorous, and develop a brown discolor- ation of the vascular system. Bacterial canker can also produce spots on the leaves and fruit. Control: These diseases can be seed-borne and may survive in infected debris, but are usually introduced each year on infected transplants. The best control is to plant only certified, disease-free transplants, or start your own plants directly from seed. Avoid touching plants when they are wet, because any bacteria present can be easily spread from plant to plant in drops of water. Water plants in the morning or early afternoon so they can dry before sunset. Bacterial wilt is the most devastating disease of cucumbers and muskmelon in the Midwest. Unlike the bacterial diseases mention- ed so far, bacterial wilt survives in and is spread by the striped and spotted cucumber beetles. The bacteria enter the plant through the wounds created by the beetle feeding. The bacteria then enter the vascular system and spread rapidly throughout the plant. Wilting of leaves, vines, and eventually the entire plant is caused by bacteria clogging the vascular system and preventing water flow. The disease is less common on other cucurbits such as squash, pumpkin, and watermelon. Control: Control measures are aimed at stopping the disease before it starts by controlling the cucumber beetle and by using resistant varieties. Several insecticide sprays are usually required, although trap crops and insect screening may provide some protection in small plantings. Angular leaf spot is another bacterial disease of cucurbit crops. Symptoms vary on different crops, but usually show up as water- No. 10 • June 6, 1990 soaked spots on the leaves. The size of the spots Is limited by the leaf veins, giving them an angular shape. The spots become light brown and necrotic, and the tissue may fall out. giving the leaves a tattered appearance. The disease can also attack stems, blossoms, and fruit. Under moist conditions, bacteria may ooze from infected tissue. Control: Because the bacterium can overwinter in infected seed and possibly in infected crop debris, the use of disease-free seed and a one- to two-year crop rotation are the primary methods of control. Copper fungi- cides may be useful in limiting the spread of the disease, but should be used with care because they can injure plants if used repeat- edly or at high rates. Elm Diseases Dutch ebn disease (DED) has eliminated millions of elms in the United States, and the disease is still killing elms in Illinois. Leaves wilt, turn dull green to yellow, brown to red- brown, curl, and usually drop early on one or more branches. Twig tips often curl downward to form "crooks," and then branches die back. Entire trees may die in one to two months- others survive for a year or longer. A brown to black discoloration occurs in the white sapwood just under the bark in wilting branches. Posi- tive identification is only possible through culturing in the University of Illinois Plant Clinic or another credited laboratory. Control: A community-wide program is needed that includes removing and burning (or burying) all dead, weak, and dying elms when first found. You should clean up and burn all injured, weak, and dead elm wood (with tight bark) in the trees or on the ground— preferably before trees leaf out. Remove bark from stumps and firewood. The elm bark beetles that spread the DED fungus breed in weak and dead elm wood with tight bark. Repair and paint tree wounds promptly. Keep trees vigorous by proper watering, fertilization, and pruning. Prevent the transmission of the DED fungus by severing root grafts of elms growing within 35 to 50 feet of one another using Vapam Soil Fumigant. Injections of a systemic fungicide into the root flare or lower trunk using Arbotect 20-S or a MBC-phosphate-carbendazin com- pound provides some protection for highly prized elms, but is the least effective and most expensive method of control. Treatment must be applied before a tree becomes infected or when less than five percent of the crown shows symptoms. For more information concerning control, symptoms, diagnosis, and disease cycle for this deadly disease, obtain a copy of Report on Plant Diseases 647, Dutch Elm Disease and Its Control Elm yellows, or phloem necrosis, is actually killing more elms now in Illinois than Dutch elm disease. Elm yellows occurs throughout Illinois, but is more common in the southern two-thirds of the state. The first noticeable foliar symptoms are usually seen in mid- summer and include a rapid, general decline. Leaves droop, curl upward at the margins, turn yellowish green then bright yellow, and finally turn brown and drop off within a few weeks. Branches then die, followed by the entire tree within one growing season. Elms that exhibit leaf symptoms after early August usually leaf out normally. These leaves wilt, turn yellow, and drop in late June or July. Usually, American elms show symptoms throughout the entire crown at the same time. The innermost bark of infected trees turns yellow then butterscotch or tan, sometimes flecked with dark brown before finally turning totally dark brown. When several pieces of the inner bark are chiseled out of dying trees and placed in a small, clean jar for five minutes, they have a faint odor of oil of wintergreen. Control: An infected tree cannot be saved. All dead and diseased trees should be promptly removed, then burned or buried. There are elms resistant to the mycoplasma-like (MLO) bacter- ium that causes elm yellows. These include Ulmus carpinifolia, U. glabra, U. laevis, U. parvifolia, and U. pumila. For additional infor- mation on elm yellows, read the new Report on Plant Diseases 660, Elm Yellows or Phloem Necrosis and its Control. Roses: Virus and Viruslike Diseases Virus diseases are common but often go undetected because the symptoms are usually mild and easily overlooked. Some of these diseases cause serious damage— others only retard normal growth. The causal agents appear to be spread only by budding and grafting (except rosette or witches' broom discussed in an earlier Home, Yard, & Garden Pest News- letter, No.9). Viruses are systemic and there is no cure. Foliar symptoms include overall yellowing or mottling; yellowing (chlorosis), or clearing of the veins; yellowish green to bright yellow spots and blotches; and various wavy "oakleaf," "watermark," or ring patterns. The leaves may also be misshapen, puckered, recurved, cupped, twisted, brittle, and smaller than normal. Affected canes are often stunted No. 10 • June 6, 1990 to dwarfed or the new terminal growth is rosetted. Only one or a few canes of a plant may show symptoms. Any one disease may exhibit a broad range of symptoms. Control: Commercial nursery growers have a responsibility to provide healthy rootstocks and disease-free budwood or cuttings taken only from properly indexed, virus-free mother plants. All rose plants showing symptoms in nurseries should be tagged by the propagator or commercial grower when symptoms are first evident. Infected mother plants should be de- stroyed. For symptoms, pictures, and other information, write for a copy of Report on Plant Diseases 632, Virus and Viruslike Diseases of Roses. Geraniums: Diseases Botrytis blight is very common now following all the damp weather, affecting the blossoms and leaves, as discussed in Home, Yard, & Garden Pest Newsletter, No. 6. Bacterial blight or wilt is also a major problem in warm, humid weather. Leaves show two types of symptoms: (1) Small, round, water- soaked spots appear on the under-leaf surface and then become angular, sunken, and often surrounded by a diffuse yellow halo. The lesions finally turn dark brown to black and become hard and dry. (2) Wilting of the leaf margin results in large V-shaped yellow or dead areas bounded by the veins. Such leaves soon wither and hang on or drop. The stem rot phase is often called "black rot," when the stem and roots rapidly turn a dull gray to blackish brown. Plants gradually become defo- liated except for a few dwarfed leaves at the shoot tips. The stems and branches rapidly blacken and shrivel into a dry rot. Control: Purchase disease-free cuttings or plants from a reputable nursery or garden supply store. Florists should buy only CVI (culture-virus-indexed) cuttings from a com- mercial propagator. All infected plants should be promptly removed and destroyed including all old leaf and plant debris. There is no cure for infected plants. For more information concerning this highly infectious disease and other bacterial diseases, read Report on Plant Diseases 607, Bacterial Diseases of Geranium. Sycamores, Maples, and Ashes: Anthracnose Diseases As predicted in earlier pest newsletters, anthracnose is very common all over Illinois. These diseases have "run their course" for this year. Trees are dropping infected leaves in large numbers. Control: There is no fungicide control now. Fertilizing to increase tree vigor is the only suggested control measure at this time. Read Report on Plant Diseases 621, Anthracnose Diseases of Shade Trees for good pictures, symptoms, disease cycle, and control measures. White Ash: Flower Gall Clusters of very irregular, bunchy (1/4 to 3/4 inch in diameter) brown galls are evident on male (staminate) flowers, especially on trees being defoliated by anthracnose. The galls are caused by minute mites and are most conspic- uous on trees during the winter months. Control: Since the galls do little harm, no control measures are usually recommended. Extension entomologists suggest using a miti- cide, applied after the buds swell and before new growth emerges in the spring. To obtain copies of any of the Reports on Plant Diseases mentioned in this or other newsletters, send a check made out to the University of Illinois to Extension Plant Pathology, N-533 Turner Hall, 1 1 02 South Goodwin Avenue, Urbana, IL 61801. There is a 50 cent charge for each Report on Plant Disease. Home, Yard 8l Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology Helping You cG>p>^. ■ Put Knowledge to Work Illinois Cooperative Extension Service GS5 College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME, YARD c GARDEN PEST Newsletter No. 11 • June 13, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Turfjgrass Grubs At this time of year it is not unusual to observe grub activity on home lawns or golf courses. The annual white grub is pupating and will emerge as a 1/2-inch long, tan beetle. These beetles will soon be observed around yard lights or on window screens. They will mate and lay eggs in late June in the southern section of the state, in early-to mid- July in the central area, and in late July in northern Illinois. Ataenius turfgrass beetles migrate from outside the golf course to the fairways. Egg laying occurred when spirea (bridlewreath) was in full bloom. The grubs, which are only a damaging problem in the northern half of the state, have hatched and if they are numerous enough to cause wilting, they should be present now in the central part of the state, after June 20 in the north central part, and about July 1 to 10 in the lake shore area on the north side of Chicago. Fifty or more ataenius grubs per square foot will cause damage. This grub is rarely a problem on home lawns. If there are large grubs in the turfgrass root zone, check the underside of the last segment for two rows of setae or spines that are parallel to the body. These are true white grubs with a three-year life cycle. These pests will remain in the root zone and cause damage during the growing season. Control: Grub insecticides include Dylox, Proxol, Turcam, diazinon, Oftanol, and Tri- umph. Dylox, Turcam, diazinon, and Oftanol can be applied as granules or as sprays. Proxol and Triumph are applied as sprays. Do not apply diazinon to golf courses and follow in- structions on the Triumph label. Cicadas - Request to Advisers We would like to obtain information from county Extension advisers on where periodical cicadas are occurring in their counties and where the cicadas are particularly numerous. Please give Phil Nixon or Roscoe Randell a call at (217)333-6650 or drop them a note mention- ing where they are being found. If landscapers or others would like to provide this information, it would also be welcome. This information will be stored for use when the cicadas emerge again in 2007. Thanks for your help. Aphids Probably due to the cool weather and heavy rains that we've had so far this spring, aphids have not been as numerous as usual earlier in the spring. Recent warmer temperatures have caused aphids to occur in large numbers dur- ing the past week. Roses, poplar, and honey- suckle have been reported as being highly in- fested, but almost any plant is likely to have an aphid problem, particularly on young leaves and shoots. Potato Leafhopper on Trees Potato leafhopper numbers have greatly in- creased in the last few days. Samples of damage to redbud and red maple have been submitted to the plant clinic. Last year, potato leafhoppers were very numerous in late sum- mer, creating considerable damage on these two trees as well as black locust trees. Newly emerged leaves on red maple will be red and distorted, with leaves on redbud and black locust also being distorted with brown edges and V-marked brown areas near the edges. In the nursery, many types of woody plants will show distorted leaves from potato leafhopper injury. Control: Potato leafhoppers are about 1/8- inch long, green, slender insects that tend to walk sideways to the other side of the leaf when disturbed. They can be controlled with pyrethroid insecticides such as bifenthrin (Talstar), cyfluthrin (Tempo), or permethrin (Ambush, Pounce). Ambush and Pounce can only be used in the nursery. APICULTURE r iC* Qtptp • nnnntv/ • I nral f^rminc • I I Q nonartmont nf Anriri ilti iro P.nnnoratinn 1 7 JS90 No. 11 • June 13, 1990 Cabbageworms Cabbage and related crops, such as broccoli and cauliflower, are often damaged by one or more species of worms. At this time of year the most noticeable one is the velvety green import- ed cabbageworm. It feeds on the leaves around the new, forming head. Later in the growing season cabbage loopers may appear and be a problem in July and August. Diamondback moth larvae are small, green worms which are less important because of their size. Control: All three worms are controlled by the bacterial agent. Bacillus thuringiensis. It can be purchased under the trade names Dipel, Thuricide, Worm Attack, and others. The worms have to eat the applied B. thuringiensis material and will die in a day or two. This product does not affect predator or parasitic insects and is non toxic to warm-blooded animals, including people. Follow label directions when applying to infected plants. Carpenter Bees Carpenter bees look like bumblebees with black abdomens. These large bees primarily attack unfinished wood to build their nests. A 1/2- inch diameter hole is bored in the wood with the tunnel running up the board with the grain. Control: These insects can be controlled by shooting a small amount of carbaryl (Sevin) dust into the hole. Most attacks can be pre- vented by finishing the wood with paint or varnish. Rove Beetles Small, black, elongate insects about 1/8-inch long that crawl on your skin and bite are probably rove beetles. These insects are excel- lent fliers, being particularly active during cloudy conditions and in the evening. Their bite is usually not very painful, but more of a nuisance. They develop in decaying vegetation such as thatch, fallen leaves, and mulches. Control: Insect repellents help reduce the problem. PLANT DISEASES Strawberry: Leaf Variegation or June Yellows Leaves on certain plants became irregularly mottled, streaked, or spotted with golden yellow to white and pale green areas. Variegation is most common when temperatures are cool. Seemingly healthy plants may become varie- gated at any stage. Affected plants never recover and usually die within two or three years. Control: Do not propagate from variegated mother plants. Destroy affected plants when first detected and replace with nonvariegated, "yellows-resistant," certified, virus-free plants. Never accept plants that show leaf variegation. There is no cure for leaf variegation and the disorder appears to be noninfectious. For more information read Report on Plant Diseases 706, Leaf Variegation in Strawberries. Strawberry: Gray Mold or Botrytis Blight This is the most common and serious disease of strawberries. It is especially severe in wet, cloudy seasons when plants are not protected by fungicides. The fungus attacks the blossoms and the developing fruit. Blossoms turn brown, die, and become covered by a dense, gray mold. Most commonly attacked are berries resting on damp soil; on mulch; touching a decayed berry, or dead leaves in lush, dense foliage. Fruit in- fections are soft, light brown, and enlarge rapidly. The berry soon dries out, turns a darker brown, "mummifies," and is covered with a gray, dusty mass of botrytis spores. Pickers > handling infected fruits spread infection to ^ healthy fruit, causing the good berries to turn into a rotted mass within 48 hours of being picked. Control: The cultivars Canoga, Guardian, and Honeoye are partially resistant to gray mold. The best cultural controls include: (a) planting in a sunny site with good air and soil drainage; (b) properly spacing plants and fertilizer applications; (c) avoiding wide, matted rows and mulching plants with dry, organic matter or applying black polyethylene sheeting to keep fruit from contacting soil; (d) keeping weeds down; (e) picking fruit frequently and early in the day when plants have dried off; (f) culling out all diseased berries and removing them from the field; (g) always handling berries carefully to avoid bruising and refrigerating promptly. Fungicide sprays are usually needed using a mixture of captan (3 pounds per acre or 4 level tablespoons per 1,000 square feet of bed) plus benomyl (Benlate) at the rate of 1/2 pound per acre or 1 level tablespoon per 1,000 square feet. Other good fungicides include a captan- Ronilan combination. Repeat sprays at 7- to 10- day intervals from just before the first blossoms appear through the fruit harvesting period. * Always read and follow label directions when ( No. 11 • June 13, 1990 applying any fungicides. The spray interval will need to be shortened if more than 1-1/2 inches of rain falls in 7 days. Captan and benomyl have no restrictions on use and they can be applied throughout the harvest period. Ronilan can be used until harvest and during the picking season if applied immediately after a picking. For further information read Report on Plant Diseases 704, Gray Mold of Strawberries. Blackberries: Sterility Blackberry plants often appear healthy, flower- ing profusely, but then fail to set fruit or only set some misshapen berries. This condition may be caused by a virus, fungus, insect damage, a hereditary abnormality, or a combination of these. There are several viruses that cause sterility. Diseased plants produce new, more vigorous canes with rounder and glossier leaf- lets than normal. These leaves turn a pre- mature, brilliant red in autumn. The virus(es) spread in a planting. Control: Purchase only certified, virus-free plants from nursery producers who will certify that their plants come from fruitful stock. If at all possible, destroy all neglected and wild brambles within 500 feet of new plantings. Rogue out plants that fail to set fruit— dig out as much of the root system as possible— and immediately destroy these plants. Remove and destroy old canes right after harvest, since anthracnose and insects may injure fruit. Fol- low the spray program for bramble fruits as outlined in University of Illinois Cooperative Extension Circular 1145, Home Fruit Pest Control A mixture of ferbam plus Sevin or malathion is suggested. Azalea: Leaf and Flower Gall This unsightly disease is rarely damaging to greenhouse- or outdoor-grown azaleas and other rhododendrons. The disease, caused by a fungus, results in severe distortion, swelling, and thickening of leaves, flowers, stems, and seedpods. The white-to-pink galls are fleshy and bladderlike. All or only part of a leaf may be affected. Sometimes a fleshy rosette of leaves forms at a shoot tip. Flower infections appear as hard, waxy, irregular galls. Affected parts usually turn red, pale green, or whitish. As the galls mature, they turn white or pink with a smooth, shining surface. In humid weather the galls are covered with a chalk-white, velvety bloom of fungus spores. The galls then rapidly shrivel, turn brown, and become hard. Control: Purchase and plant only hardy, disease-free plants from a reputable nursery. If only a few galls are present, pick off and de- stroy them (burn or haul away with the trash) when first evident— before they turn white and spores are formed. Fungicides that control fungal leaf spots (e.g., captan, mancozeb, maneb, ferban, zineb or Daconil) also control leaf and flower gall. Add a commercial sticker to the spray mix to ensure good coverage. For more information read Report on Plant Diseases 639, Azalea Leaf and Flower Gall Many Flowers and Vegetables: Aster Yellows Aster yellows is caused by one or more strains of a minute bacterium that is transmitted from plant to plant by the aster or six-spotted leaf- hopper, as the insect feeds. Over 300 kinds of plants in 48 families are affected by this bac- terium. Symptoms are highly variable. The most common is a general yellowing, stunting of the plant, and rosetting of leaves. The older and outer leaves are usually normal, while the inner and younger leaves are usually dwarfed and yellowed. The tight rosette or "witches' broom" is common on many plants. Carrot and other root crops develop excessively pale, hairy roots with a bitter taste. Infected ornamental plants are usually yellowish, stunted, stiff, and erect with numerous spindly shoots. The flow-ers on such plants are often a sickly yellow-green wholly or in part, dwarfed or lacking. Control: This disease is very difficult to control because of the wide host range and because the leafhoppers can transmit the bacterium as long as they live— 70 days or longer. It helps to eradicate all susceptible overwintering weeds. Destroy infected plants when first found. Do not plant a susceptible crop next to a yellows-infected crop. Applying a suggested insecticide is often beneficial. Sug- gestions are given in University of Illinois Cooperative Extension Circular 897, Insect Pest Management for Commercial Vegetable and Greenhouse Growers. Spray before removing infected plants. Placing aluminum foil strips as a mulch between rows increases control by dis- orienting the leafhoppers. There are no resistant or immune crop varieties. For much more infor- mation on symptoms, disease cycle, a listing of susceptible plants, and other controls read Report on Plant Diseases 903, Aster Yellows. (Huge swarms of aster leafhoppers have been noted flying from the south and covering much of the upper Midwest.) Raspberries, Blackberries: Virus Diseases Raspberry yields may be reduced 50 percent or more by a virus or combination of viruses. Once infected, a plant remains diseased for life. The viruses are spread by the feeding of aphids— not by pruning or otherwise mechan- ically injuring plants. Symptoms are most evident in cool weather and are often confused with other problems. Leaf curl appears as a down-curling of the tip leaves; later the leaflets appear rounded, dwarfed, and crinkled with the margins curled tightly downward and inward. Common mosaic causes the greatest loss of any bramble virus. Canes are short and weak with mottled and puckered leaves showing large, irregular green "blisters" that arch upward. In hot weather such leaves may be symptomless or show only a faint mosaic pattern. In late summer the leaves show a fine, yellowish, speckled mottling. Affected plants become more stunted each year with dwarfed, yellow mottled and sometimes deformed leaves. On black and purple raspberries the tips of PLANT CLINIC HIGHLIGHTS May 25 to June 7, 1990 HOST DIAGNOSIS COUNTY Ash Verticillium wilt Ford Barberry Botryosphaeria canker Macon, White Bluegrass Brown patch Champaign Crabapple Apple scab Champaign McDonough Dogwood Septoria leaf spot Champaign Elm Dutch elm disease Champaign Gardenia Iron chlorosis Peoria Ginseng Sclerotinia white rot Pike Honeysuckle Honeysuckle aphid Woodford Iris Fungal leaf spot Douglas Juniper Ice injury Kane Maple Anthracnose Carroll Champaign Spring leaf tatter Iroquois Grundy Maple vein gall Coles Melons Pythium root rot Will Oak Anthracnose McDonough Vermilion Peach Peach leaf curl Tazewell Peony Root rots Winnebago Pine Pine wilt Ford Rose Winter injury Champaign Sycamore Anthracnose Vermilion No. 11 • June 13, 1990 young canes often curl downward, turn black, and die. Leaves formed in cool weather are faintly to severely mottled and puckered. Fruit on mosaic-infected plants tends to be small, dry, and seedy. Other viruses that attack bramble fruits in Illinois include black rasp- berry streak, red raspberry ringspot, and raspberry bushy dwarf. Control: Destroy all wild and neglected brambles, if possible, within 600 to 1,000 feet before planting only certified, virus-free plants. Separate black and red raspberries (if possible) by 150 feet or more to reduce virus cross- infection. Destroy infected plants when first seen— symptoms are most evident during cool, cloudy weather in mid-to-late spring. Check again in early summer and again in early to mid-fall. Spray plants a day or two before their removal with malathion (2 tablespoons of 25 percent wettable powder) to kill any aphids that may be virus carriers. Maintain strict aphid control at all times— especially in late spring and early summer when aphid populations are likely to be high. For more information on virus diseases of bramble fruits obtain a copy of Report on Plant Diseases 710, Virus Diseases of Brambles in the Midwest To obtain copies of any of the Reports on Plant Diseases mentioned in this or other newsletters, send a check, made out to the University of Illinois, to Extension Plant Pathology, N-533 Turner Hall, 1 1 02 South Goodwin Avenue, Urbana, IL 61801. There is a 50 cent charge for each report. Home, Yard &. Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. a < Roscoe Randell Extension Specialist Entomology G5S Helping You Cc^^J C\ Put Knowledge to Work tHi^2^. =>*- — • Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOWIE, YARD r GARDEN PEST Newsletter No. 12 »June 20, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Periodical Cicada Update Cicadas are now in the potentially damaging phase of their life. The only damage done by these very visible insects in the northeastern section of the state is done during egg- laying. Slits are cut into twigs by the female cicada ovipositor or egg-layer. This L^jH ^-^55^ activity will *^*jg^%S^ .,*?£iKgP produce "flag- ging" or dead Periodical cicada twigs on older forest trees, but it can damage young trees in the landscape. Egg-laying will last about seven to ten days and adult cicadas will begin disappearing as they die. Control: Homeowners can control cicadas on small trees and shrubs with a spray con- taining Sevin. Repeat every four or five days if necessary. Do not use Sevin on blooming plants because of the possibility of bee kill. Elm Leaf Beetles Adult elm leaf beetles have now left their overwintering sites in northern Illinois to lay eggs on tree foliage. In southern Illinois, the first generation is ending, producing adults for the next generation. The adults eat holes in the foliage and the newly hatching larvae skeletonize the leaves by feeding on the under- sides, leaving the netting of veins and the upper leaf surfaces to turn brown. Adult elm leaf beetles are yellowish to dull green and approximately 1/4-inch long. They feed on elms, especially the Chinese or Siber- ian type. The larvae are sluglike and almost black. Control: Elm leaf beetles will not severely injure the host tree, but skeletonizing does reduce the attractiveness of shade trees. Sevin or malathion will control this insect when it is present. However, since there are two or more generations each year, sprays will have to be repeated. Spruce Spider Mite Spruce spider mites attack most conifers and related evergreens in the spring, becoming more of a problem as summer approaches. Samples have been reported recently on juniper and spruce. Damage can be so severe that part or all of the infested plant may die. Damage appears as a darker, dull color; lighter color; or brown-colored foliage, depending on how severe the infestation has become. Close inspection will reveal tiny, light spots on the needles and occasionally fine, silk webbing. The mites are easy to see with a microscope, but almost too small to be seen with the naked eye. One method of detecting the mites is to hold white paper under a branch and strike it several times. The mites will be more easily seen on the paper; they usually produce a red streak if squashed. During the hot, dry days of summer, the mites stay in the egg stage, occasionally hatch- ing and causing more feeding damage in the late summer and fall when temperatures moderate. Control: Sprays of dicofol, sold as Kelthane, fenbutatin oxide, sold as Vendex, or insecticidal soap will kill the mites. Because these pesti- cides only kill hatched mites, two or three applications should be made weekly to elim- inate hatching eggs. Dimethoate, sold as Cygon, should also be effective. Because Cygon lasts longer, one application should be adequate for most hosts of the spruce spider mite. AGRICULTURE LIBRARY OCT 1 7 State . r.nuntv • I nnal firouos • U.S. Deoartment of Aariculture Coooeratinq No. 12 • June 20, 1990 Ash, Lilac Borer Lilac borer lays its eggs at this time of year on lilac and ash. This borer primarily attacks stems that are at least 1-inch in diameter. Control: On lilac, control is achieved by pruning out the older, larger stems, leaving the younger, smaller ones. It is more difficult to control in ash. Particularly young, recently transplanted trees are attacked, so newly transplanted ashes that are adapting to site and replacing roots that were damaged during transplanting are very susceptible. The lilac borer adult is a moth that relies on tree wounds to lay its eggs. Storm breakage and pruning wounds usually provide these egg- laying sites. Prevention of borer attack involves reduced pruning for the first few years after transplanting and promoting vigorous growth through proper watering, fertilizing, and other cultural practices. Control of lilac borer in ash includes the application of chlorpyrifos (Dursban) at full to late bloom of bridal wreath spirea or Zabeli honeysuckle with another application four weeks later. This will correspond roughly to this week in northern Illinois with the second spray being applied at this time in southern Illinois. Young Ticks Are Active The three most important ticks that attack people in Illinois are the American Dog Tick, Lone Star Tick, and Deer Tick. Only the adult of the American dog tick attacks people and these 3/16-inch long ticks are usually easily found when they attach to people. The other two ticks attack people in all three active stages; larva, nymph, and adult, but the larva does not attack people as often as the nymph and the nymph of the deer tick is the most common stage that transmits Lyme Disease to people. Nymphs of the lone star and deer tick are easily missed when they feed on people. Each is only slightly bigger than a period printed on this page, and the larvae are slightly smaller than a period. Nymphs of both of these ticks are now being found on people and will be present for the next couple of months. If you are out in wooded or other areas where tick attacks are likely, check yourself and each other every few hours for ticks. If a tick is found, grasp it with tweezers where the head enters the skin and pull out with gradual pressure. Treat the bite with an antiseptic. Control: Tuck pant legs into boots and apply a repellent containing DEET. Wear light- colored clothing so that ticks can be easily found before they reach your skin. Since ticks must be attached for at least 24 hours to transmit Lyme Disease or Rocky Mountain spotted fever, these diseases can be avoided with occasional inspections. Midge Galls on Trees Tree galls caused by the larvae of tiny flies called midges are becoming numerous. Recent examples that we have seen include linden twig gall, oak twig midge, and gouty vein gall. Linden twig gall on little leaf linden was sent in by Sandy Mason, horticulture adviser in Macon County. This gall appears as 1/2-inch, woody swellings on twigs. Oak twig midge forms an enlargement on white oak twigs. The gall is thicker on one side of the twig than the other, causing the twig to bend into a shepherd's crook. Gouty vein gall appears as enlarged veins on sugar maple leaves. There is little known information about the life cycle of these galls. Most galls start in the early spring due to feeding by newly hatched larvae at about the same time as bud break. Control: The appearance of these galls can be disturbing to homeowners, but little can be j done once the galls have formed. Insecticide ( sprays at or shortly after bud break may be somewhat effective in preventing gall formation. Since galls rarely reduce tree growth, control is usually not necessary. Galls on small trees that are in conspicuous locations can be removed by hand. PLANT DISEASES Turfgrass: Summer Diseases Now that hot weather has arrived, night tem- peratures commonly stay above 68 to 70° F. Since showers or high humidity are common, we can expect Rhizoctonia brown patch and Pythium blight Brown patch appears on higher cut turf found in lawns, parks, athletic fields, and golf course fairways as roughly circular, light brown, matted down patches up to about 2 feet in diameter. The patches sometimes devel- op green centers and may resemble the "frog- eyes" of summer patch and necrotic ring spot. (See Report on Plant Diseases No. 408, Summer Patch and Necrotic Ring Spot of Lawns £ and Fine Turfgrasses.) Diseased patches of m grass, however, often appear to be sunken. In No. 12 • June 20, 1990 light Infections of brown patch, the affected turf generally recovers in two or three weeks. When the attack is severe, the crown, rhiz- omes, and stolons may turn brown and rot, killing or thinning the turf in large areas. Irregular, watersoaked spots that turn a straw or ash brown color, and often surrounded by a dark border, are common on the leaves and leaf sheaths. Disease is worst in lush, succu- lent turf that has been both highly fertilized with nitrogen and watered, especially at night. Control: Good surface and subsurface drainage is important. The soil pH should be between six and seven. Fertilize based on a soil test. Avoid over-fertilizing with a quickly available, high-nitrogen fertilizer during the summer months. Increase light penetration, air movement, and drying of the grass surface by pruning or removing dense trees and shrubs and wider spacing of landscape plants. Keep the thatch below 1/2-inch by dethatching in early spring or mid-autumn. When the above cultural practices do not control brown patch, a preventive fungicide may be needed. Sug- gested chemicals are listed in University of Illinois Cooperative Extension Service Circular 1076-90, 1990 Turfgrass Pest Control and include Banner, Chipco 26019, Daconil, Duosan, Dyrene, Fungo, Rubigan, Tersan 1991. For more information read Report on Plant Diseases No. 411, Rhizoctonia Diseases of Turfgrasses. Pythium blight is caused by a number of common soilbome fungi that can cause seed- ling blight, root rot, and foliar blight from just above freezing to about 95° F. In hot, wet, or very humid weather, when the grass is dense and lush and there is little air movement, pythium blight can be devastating. Look for small, distinct, round to irregularly shaped, sunken spots up to 6 or 12 inches in diameter. These patches suddenly appear in wet, calm weather. At first, the grass is watersoaked, slimy, and dark. As the sun dries, the grass the leaves quickly fade from a reddish brown to a light tan. The leaves shrivel, twist, and may collapse. Clusters of blighted plants may merge to form streaks or irregular areas due to the fungus (or fungi) being spread by surface- drainage water or mowing when the grass is wet. At night or early in the morning, when the air is moisture-saturated, the leaves collapse and are matted together by a fluffy, white mold. Control: Follow the same cultural practices as outlined for brown patch and avoid mowing when the grass is wet. Preventive fungicides are listed in University of Illinois Cooperative Extension Circular 1076-90 and include Banol, Koban, Subdue, Terrazole, Terremec or Terraneb, and Chipco Aliette. The first application, carefully following the manu- facturer's directions, should be made as night temperatures stay above 68° F, when daytime air temperatures are 80° F or higher, and the forecast is for continued wet or very humid weather. The fungicides suggested for control of pythium blight may be alternated with another fungicide to control brown patch, dollar spot, and other diseases to give broad spectrum disease control. For more information read Report on Plant Diseases No. 410, Pythium Blight of Turfgrasses. Iris: Mosaic There are a number of viruses that affect iris. Look for fine, light yellow-green, or yellowish green, mosaic-like mottling and streaking on the leaves, flower stalk, and bud sheath. The symptoms become more pronounced as plants mature. When severe, plants show wide, pale green and yellowish -green stripes, and the entire plant may be stunted to dwarfed. Such plants produce inferior blooms which in yellow flowers may show clear, feather-like markings. Flowers may be reduced in size and are often twisted to one side. Symptoms are most ob- vious under cool conditions. The viruses are transmitted by aphids and soilborne nematodes. Control: Dig up and destroy infected plants when first discovered; they will not recover. Purchase only large, healthy bulbs or rhizomes from a commercial grower who has "cleaned up" his stock. Virus-free plants, started in tissue culture by meristem propagation, are available. Keep weeds down- -a wide variety of weeds harbor both viruses and aphids. Spray regularly with an insecticide to control aphids, following suggestions of University of Illinois Extension entomologists. For more information read Report on Plant Diseases No. 654, Mosaic Diseases of Iris. Pines: Needle and Gall Rusts These diseases are worse following cool moist springs. Needle rusts are evident as cream colored, yellow, orange -yellow, reddish, or bright orange to brown, dusty pustules on the needles. The needles often turn brown and may drop off. The disease(s) is most serious on nursery seedlings and young trees. The rust spores are No. 12 • June 20, 1990 blown onto pines from a wide range of weeds and garden plants Including amsonia, asters, azalea, blueberry, campanula, erigeron, ferns, fireweed, flowering currant, gayfeather, goldenrod, gooseberry, groundsel, gumweed, heliopsis, hydrangea, ironweed, Jerusalem- artichoke, Laborador-tea, leatherleaf or cassandra, loosestrife, marigold, Michaelmas daisy, morning-glory, oaks, poplars, pyrola, ragwort, silphium, sowthistle, sunflower, tick- seed, willows, and wood-nymph among others. Control: Destroy worthless alternate hosts (for example; goldenrod, sowthistle, fireweed, ragwort) within 900 feet of valuable pine plantings. This breaks the life cycle between pines and the alternate hosts of the needle rust fungi. Gall rust appears as perennial, more or less spherical galls on the branches or trunk, up to a foot or more in diameter. Witches' brooms or Eastern gall rust on a pine stem deep cankers may form instead. Foliage beyond the canker or gall is discolored, and later wilts and dies. The surface of galls appears whitish, yellow- orange, or bright orange and blister-like to spring. Alternate hosts include oaks, chest- nut, sweetfern, sweetgale, Indian paintbrush, peregrina, lousewort, toadflax, buckleya, birds- beak, owlclover, cow-wheat, and myriagale. Control: Where practical, remove galls by annual pruning. Destroy nearby alternate hosts. Start with rust-free nursery stock. Many Ornamentals: Fusarium Wilt Fusarium wilt, or yellows, is caused by a number of very specialized forms and races of the common soilbome fungus Fusarium oxysporum. Many popular garden and green- house flowers are attacked. The wilt is most serious and widespread in Illinois on aster (China-aster), carnation, chrysanthemum, gladiolus, lily, and narcissus. Once the fungus is introduced into soil it can live indefinitely, independent of any host plant. This makes general sanitation and any normal rotation program ineffective methods of control. Symptoms of fusarium wilt are commonly confused with root and crown rots, stem cankers, insect injury, drought, compacted or poor soil, and verticillium wilt. Overall symp- toms include a wilting, yellowing, withering, and dying of the foliage. Fusarium wilts are most severe at 75° to 90° or 95° F. Affected plants are commonly stunted with symptoms starting at the plant base and progressing upward, often starting on one side of the plant. When infected stems are split, brown to black streaks are evident in the vascular system. Plants started from bulbs, corms, or tuberous roots (for example, crocus, dahlia, freesia, gladiolus, iris, ixia, lily, narcissus, and tulip) show a dark discoloration within underground parts that may extend into the leaf bases. Control: Disinfest greenhouse, seedbed, and m potting soil before planting with steam or fumigate the soil with Vapam Soil Fumigant or Vorlex. These soil fumigants must be used sev- eral weeks before planting and will also control other pathogens, weeds, insects, and nema- todes in the soil. Also treat all containers, tools, and work surfaces that come into contact with plants or soil. Carefully follow the manufacturer's directions when using a soil fumigant because they are highly toxic. Do not grow susceptible plants in fusarium-infested soil where the same or closely related plants have grown within the past 10 years. Buy only healthy, top-quality, disease-free planting material. Fusarium wilt- resistant varieties and cultivars are available for some plants (aster/ China-aster, carnation, chrysanthemum, gladi-olus, lily, marigold, narcissus, sunflower, tulip, and zinnia) for growing in wilt-infested soil. For other controls, disease cycle, pictures, and a listing of ornamental plants susceptible to fusarium wilt (including vegetables, fruits, field crops, trees, and shrubs) read Report on Plant Diseases No. 650, Fusarium Wilt Diseases of Herbaceous Ornamentals. No. 12 • June 20, 1990 Diseases of Pepper Pepper Viruses: Now is a good time to check for signs of virus infection on young pepper plants, especially on purchased transplants. There are many viruses that can infect pepper, but only a few of these are important in Illinois. The most common viral disease of pepper in Illinois is caused by the Tobacco Etch Virus (TEV). The symptoms are a mild chlorotic mottling and distortion of the leaves. Concentric ring patterns may form on the leaves and fruit. Infected plants are often stunted and bushy, especially if infected early in the season, and usually produce misshapen fruit. TEV is transmitted by aphids, most commonly the green peach aphid. The virus can overwinter in weeds, but more commonly comes on transplants. Tobacco Mosaic Virus (TMV) causes symptoms that are similar to those of the TEV, but the mosaic patterns are usually more pronounced, and there may be some clearing of the leaf veins. Leaves may also be puckered and distorted, and the fruit are small and misshapen. TMV is moved from plant to plant by mechanical transmission— that is, by infected sap carried on garden tools or hands. No insect vector is known. Control: It is important to identify and remove infected plants early to reduce the risk of spreading the disease to neighboring healthy plants. After removing infected plants, wash tools and hands before touching the healthy plants. Insecticide sprays aimed at controlling the aphid vectors of TEV are usually not an effective method for controlling the disease. Phytophthora blight of peppers: Warm, wet conditions favor the development of this blight All parts of the plant may be affected. If infected in the seedling stage, the plants are often killed. On older plants symptoms may appear on the stems, leaves, and fruit. Stem lesions start as dark green, watersoaked areas which later dry and become brown. Stem lesions can start at any level on the plant, but occur most commonly near the soil line. Leaf symptoms include small spots, circular to irregular in shape, and appear scalded. The spots enlarge, and the leaf tissue dries to a papery texture, becoming white to light tan in color. Fruit usually becomes infected through the stem. The fungus grows into the fruit and initially causes the tissue to become dark green and watersoaked. Later the fruit rots and shrivels, but remains attached to the plant. The pathogen can overwinter in soil or on and in seed. Disease development is favored by moderately warm temperatures, high humidity, and films of water on plaint surfaces from rain, dew, or sprinkler irrigation. Control: Plant in well-drained soils, provide good weed control, and follow a two- to three- year crop rotation schedule. Plant only high- quality, disease-free seed. Collar rot can be reduced by planting on ridges or raised beds. Fruit rot can be reduced by staking or mulch- ing to keep the fruit off the ground. Some varieties of pepper are resistant to the disease. RMzoctonia Stem Canker of Potato Cool, wet soils favor the development of Rhizoctonia stem canker. Plants are most susceptible when young. Rhizoctonia attacks newly emerging and underground sprouts, causing delayed emergence and damping off. Well-defined, reddish-brown lesions develop just below the soil line. These lesions can expand and girdle the shoot or stolon. Sometimes a white fungal growth will develop on the stems just above the soil line. Rhizoctonia also produces small, hard, black structures, called sclerotia, on tubers. Control: Good cultural practices and growing conditions that favor rapid germination and growth are the principle means for controlling rhizoctonia stem canker. Avoid planting seed tubers that have rhizoctonia sclerotia on their surface. Plant in warm, well- drained soils. Form hills after sprouts have emerged. Tree Tips for Buyers of New Homes 1. Be sure that root flares are evident at the tree base and that they show an outward spread at the soil line. If not, the tree may be planted too deeply. 2. Dead twigs and branches could indicate root injuries, cankers, wood decay, or other infections. 3. Pale and thinning foliage or small leaves that may be discolored could mean root rot, verticillium wilt, gas injury, nutrient deficiency, or other problems. 4. Multiple trunk scars could indicate careless construction. Was the house built as care- lessly? Were the tree wounds properly shaped into a vertical ellipse with rounded ends and cared for? No. 12 • June 20. 1990 5. If the house is built close to a tree, root damage probably resulted. In five years, you may have a severely crippled tree or no tree at all. 6. Plaster, bricks, concrete, lime, scraps of wood, and other trash beneath foundation shrubbery breed termites and wood decay, and make it difficult to establish and maintain foundation plantings. Trash is also an indication of a sloppy contractor. 7. Rapid twig dieback indicates recent root injuries. 8. Look for new, large, multiple pruning scars on the trunk or large branches. Why were they cut? Are you in for future trouble? 9. Any constriction around the trunk (from a wire, chain, fence, or girdling tree roots) strangles the tree, leading to reduced growth, dieback, or even death. 10. Loose bark at the tree base often indicates a mower, herbicide, or other damage; wood decay \ probably has already occurred. 1 1 . New pavement or other construction over the root zone (which extends far beyond the outer drip line) cuts off air and water from the roots, killing them. Construction damage is also an invitation for infection by the verticillium wilt fungus and root rots. 12. Standing water in grass near the tree indicates poor drainage. The soil water level changes with construction. Root rot commonly results. To obtain copies of any of the Reports on Plant Diseases mentioned in this or other newsletters, send a check, made out to the University of Illinois, to Extension Plant Pathology, N-533 Turner Hall 1102 South Goodwin Avenue, Urbana, IL 61801. There is a 50 cent charge for each report PLANT CLINIC HIGHLIGHTS June 8 to June 14, 1990 HOST DIAGNOSIS COUNTY Apple Fire blight Champaign Arborvitae Pestalotia needle blight Cook Ash Ash flower gall Champaign Azalea Azalea leaf and flower gall Wabash Barberry Winter injury Edgar Boxwood Pseudonectria canker Peoria Crabapple Apple scab Out of state Exacum Botrytis Champaign Japanese Maple Canker DuPage Maple Spring leaf Tatter Potato leafhopper/ Champaign Wind tatter Champaign Verticillium wilt Vermilion Oak Anthracnose Champaign Peony Botrytis blight Champaign Redbud Potato leafhopper/ Wind tatter Champaign Spruce Cytospora canker Cook Out of state Sweetgum Winter injury McDonough Home, Yard & Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engi- neering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service .778 t^Z/ dtt£f Roscoe Randell Extension Specialist Entomology (J G3S Helping You Put Knowledge to Work cfi^?>< - linois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • C HOME, YARD r GARDEN PEST W Newsletter No. 13 • June 27, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Black Vine Weevil The black vine weevil feeds on more than 100 different kinds of plants, including flowers, weeds, trees, and woody ornamentals. The in- jury is severe on taxus (yew), the roots of which are destroyed by the larvae feeding. Taxus capitata seems to be very susceptible. Heavily infested plants turn yellow and eventually die if the injury continues. Damage has also been observed on rhododendrons and azaleas but has consisted primarily of foliage injury caused by the adult weevils feeding. Injury to taxus has appeared throughout northern Illinois. The importance of this pest as an economic insect has increased with the popularity of various taxus species for orna- mental purposes and the corresponding increase in the size and number of taxus plantings in nurseries. Occasionally, hundreds of plants are killed with dramatic suddenness after growing to the salable stage. Only one generation of black vine weevil occurs outdoors annually. The adults appear during June and early July. They feed on the foliage at night but hide during the day, pri- marily in debris and loose soil under plants. During July and August egg- laying occurs on the soil under the plants that the adults feed on. As the eggs hatch, the larvae burrow into the soil and feed on the roots. They overwinter in the soil as larvae and change to pupae in late May or early June. The beetles of this genus are unusual in that no male has been observed. Eggs are de- posited without fertilization and only produce females. The beetles cannot fly, so infestations spread slowly from one area to another, al- though they may spread rapidly in a specific area. Adult weevils feed on the foliage but rarely eat enough leaves to create a problem. The typical crescent-shaped feeding wound is useful in detecting the presence of an infest- ation. Damage and destruction of plants are caused by the larvae consuming smaller roots and stripping bark from the larger ones. Control: Black vine weevils were controlled in the 1960s by drenching infested plants with a residual insecticide such as chlordane. How- ever, the weevils became resistant to chlordane and it is no longer available. Now, when adult feeding appears on the foliage, drench with either Orthene or Turcam. Wet the soil surface under the shrubs to control weevil grubs hatching from eggs. Repeat one or two times at two- to three-week intervals until there is no fresh, adult feeding damage. Iris Borer Control: Iris borers are best controlled by drenching plants and root zones with a mixture of 4 teaspoons of Cygon 2E in a gallon of water. Treat when the first blossoms appear. Sod or Lawn Webworm Adult webworm moths, if present, should be emerging at this time from infested lawns. (So far the webworm activity seems to be low with very few moths being observed.) The buff-colored webworm moths have a wing span of about 1 inch. At rest, they look tubular because their wings wrap around their body. The moths are flushed from hiding places when grass is mowed or shrubbery is disturbed. They fly in a jerky fashion, a few feet at a time before diving down to rest on grass. The moths are attracted to lights at night. The elongate, oval eggs are dropped among in the grass by the females. The eggs are tiny, dry, and nearly impossible to find. The larva, about an inch long when mature, is gray to dusky green with a dark brown head and brown spots over its body. The larvae often hide in a silk-lined tunnel in the thatch of the lawn. Their excrement appears as clusters of small pellets that are pale to dark green — some the size of a pinhead. The resting stage between the larva and adult is a brown, torpedo-shaped pupa about half an i i r*,~, .~,- . C nooor+mant nf Anriri ilti irp Dnnnfi QCI 1 7 No. 13 • June 27, 1990 inch long. When empty, the pupa case looks like a dark-brown piece of cellophane. The sod webworm passes the winter as a larva, tightly coiled in a closely woven silk case covered with soil particles. In the spring, the larva resumes feeding, grows rapidly, and pupates in the cell. The webworm moths emerge in the early evening and mate shortly afterward. About a day after emerging, the female moths begin to lay eggs a few inches above the lawn, usually during the early even- ing. Each female lays about 500 eggs. In hot weather, the eggs hatch in six days. The larvae require four to five weeks to complete their development. The pupal stage lasts eight to ten days. The entire life cycle thus usually requires six to eight weeks. So, under normal conditions, two generations occur each year. Sod webworm larvae feed on bluegrass. They clip the blades of grass just above the sod. Brown spots appear in the turf where the larvae are numerous. These brown areas will usually recover, whereas similar spots caused by grubs will not. Control: Webworm control is often too late since it is usually applied after most of the damage has been done and about the time the worms are ready to stop feeding and pupate. The larva eats about 70 percent of its total food supply in the last ten days of its devel- opment. This is why severe damage can occur within a few days. EARLY DETECTION IS IMPORTANT FOR SUCCESSFUL CONTROL. Large numbers of moths flying zigzag just above the grass at dusk and collecting on doors and windows and around outside lights mean that the caution sign should be out. In central Illinois, moth flights occur between the first week of June and the middle of August. They are heaviest when the second-generation moths emerge in late July and August. Nor- mally, that is when lawns are damaged the most and treatment is required. However, additional moth flights continue well into September. Careful inspections are the only positive way of finding early infestations. A good time for this is two weeks after a heavy moth flight. The presence of unusual numbers of birds, especially robins and starlings, may indicate an infestation of webworms. By the time the birds invade the lawn, however, the damage is usu- ally extensive. Furthermore, the webworm larvae are nearly mature, and it is too late to apply chemical control measures. Brown spots are another late indicator of probable webworm infestations, although many other things can cause brown spots in lawns. A well-kept, properly fertilized and watered lawn will support a considerable webworm pop- ulation without serious damage. On the other hand, a lawn in poor condition will be affected more seriously by an equal number of web- worms. A lawn that is kept mowed will be somewhat less attractive for egg-laying than one where the grass is permitted to grow tall. To determine whether control is needed, inspect the lawn frequently in June, July, and August. If two or more larvae are found per square foot, treat immediately. For lawns with a history of webworm problems, or as a pre- ventive measure, apply treatments two weeks after a heavy moth flight (usually in late July or early August in central Illinois). Occasion- ally, overwintering larvae (in May) or first- generation larvae (in June) become numerous enough to cause damage and require control. Most chemical controls are applied as sprays, which are intended to stick to the grass blades where the webworms feed. Sprays applied in 3 gallons of water per 1 ,000 square feet of lawn area, or as granules, will control webworms. The insecticides effective for sod webworm control include Sevin, diazinon, Dursban, trichlorfon (Proxol, Dylox), or Turcam. PLANT DISEASES Diseases Now Active Many of the diseases covered in past news- letters are still active. These include anthracnose diseases of maple, oak, ash, sycamore, and other trees; black spot and powdery mildew of roses; necrotic ring spot, dollar spot, red thread, leaf spot, brown patch, and Pythium blight of turfgrasses; Botrytis blight or gray mold on a wide range of orna- mentals and vegetables; Phomopsis blight of junipers; apple and crabapple scab and fire blight; iron chlorosis on pin and other oaks, certain maples, sweet gum, gardenia, blueberry, rhododendrons and azaleas; Dutch elm disease and elm yellows; oak wilt; crown and root rots caused by Rhizoctonia, Fusarium, Pythium, and Phytophthora; pine wilt, needle blights, and rust diseases of pines; leaf curl and plum pockets of peach, plum, cherry, apricot, and May-day tree; iris leaf spot and mosaic; Sclerotinia white rot of many plants; spotted wilt of impatiens, cineraria, and other green- house ornamentals; aster yellows on many plants; virus diseases of geraniums and No. 13 • June 27, 1990 bramble fruits; crown gall of euonymus and other plants; Verticillium wilt of many plants; Volutella blight of pachyandra; Vinca (periwinkle) dieback; Cytospora canker of spruce; and powdery mildew of a growing number of plants. Control: Plant disease is almost entirely preventive if control management practices start before symptoms become evident. Once disease is obvious, very little can be done "until next year." We suggest homeowners and growers keep a log or diary of when diseases appear. Read over past newsletters and Reports on Plant Diseases that cover these disease problems and make plans to start control measures at the proper time. In home gardens, simply pick or snip off infected or insect- infested parts, place them in a paper bag and then in the trash every couple of days. Sani- tation is still an excellent control measure to reduce inoculum, thus helping to prevent future disease attacks. Boxwood: Canker, Dieback, Decline Infected branches often start growth later in the spring than normal ones. Leaves on such branches curl upward close to the stem and turn grayish green to bronze before finally becoming straw-colored. Leaves may wither and drop early, leaving bare twigs. This fungal disease often follows winter or drought injury, nematodes, root rots, nutrient imbalance, and poor soil drainage. Twigs, branches, and main stems die back. Small, waxy, pinkish to black mounds often develop on affected parts. The bark at the base of larger branches may die and slough off. Control: Good sanitation is essential in early spring before growth starts and whenever infected parts are evident. Cut out cankers on larger branches and cover the wounds with shellac. The following spray program, using a copper or liquid lime-sulfur fungicide, is effective: (1) spray while plants are dormant in late winter or early spring after old leaves have been removed and before new growth starts; (2) spray 10 to 14 days later; (3) spray when new growth is half complete; and (4) spray in autumn when fall growth has ceased. Carefully follow the manufacturer's directions when using any fungicide. Black Leg of Potato Black leg of potato, also known as bacterial stem rot, is caused by the bacterium Erwinia carotovora. Symptoms can appear on plants at any time. On older plants, the disease shows up as interveinal yellowing and upward curling of leaves. Infected plants may wilt during hot weather. The internal stem tissues of these plants will be gray-brown in color, and with time may turn inky black and become soft and mushy. Infections on younger plants cause stunting and erratic growth. If soils are extremely wet or cold and dry at planting, infected seed pieces may decay before shoot emergence. The bacterium can also infect tubers, causing them to decay in the field or later in storage. Tuber symptoms range from slight vascular discoloration to complete soft rot. Young tubers are more susceptible to infection than those with fully developed skins. The bacterium enters the plant through wounds on leaves, stems, tubers, or seed pieces. The disease is commonly spread to noninfected seed pieces during cutting, but the bacterium can also survive in the soil and infect seed pieces that have not had time to heal. Tuber infection is favored by wet soil conditions. Control: Planting whole tubers or disease- free seed pieces is an important part of managing black leg. Also, plant in warm, moist but well-drained soils that promote rapid wound healing and growth. Planting on raised beds can increase soil temperatures and improve drainage. Maintain good sanitation practices during seed piece cutting and planting. Rogue out infected plants early in the season. Although no potato varieties are truly resistant, some cultivars, such as Norgold and Kennebec are more susceptible. To minimize postharvest disease, allow tubers to mature before harvest and hold them at 50° to 55°F and 95 percent relative humidity for 10 to 14 days to promote proper suberization. Disease-Resistant Apple Varieties The loss of mancozeb (Dithane M-45, Dikar, Manzate 200) and the possibility of new restrictions or loss of other fungicides for apples will make disease control on apples more difficult and probably more expensive. Growers should give serious consideration to planting disease-resistant apples. All the disease -resistant varieties are highly resistant or immune to scab, the fungus disease that requires the greatest number of sprays in Illinois. They also have varying degrees of resistance to cedar rusts, mildew, sooty blotch, fly speck, and fire blight. Some fungicide sprays probably will be needed, but the number should be considerably less. No. 13 • June 27, 1990 Varieties worthy for trial are: William's Pride - dark-red skin with crisp, firm flesh ripening one week after Lodi and seven to eight weeks before Red Delicious. Requires several pickings. Redfree - good coloring red-skinned apple ripening three to four weeks before Red Delicious. Susceptible to cedar rust. Jonqfree - resembles Jonathan in appearance and somewhat resembles Jonathan in flavor. Ripens with Jonathan one week before Red Delicious. Susceptible to fire blight. Liberty - a "Mcintosh type" apple that ripens one to two weeks after Red Delicious. The flesh is firmer and stores better than Mcintosh. Many Woody Plants: Crown Gall This highly infectious bacterial disease infects at least 142 genera of plants in 61 widely separated families. The disease is economically important on apple, apricot, blackberry, cherries, cottonwood, crabapples, eunymous, grape, honeysuckle, nectarine and peach, pear, plum and prune, poplars, pyracantha, rasp- berry, rose, walnut, and willow. Plants affected by crown gall often grow poorly and are PLANT CLINIC HIGHLIGHTS June 15 to 21, 1990 PLANT DIAGNOSIS COUNTY Geranium Hibiscus Botrytis Anthracnose Madison Out of state Maple Leaf tatter Vermilion Oak Potato leafhoppers Anthracnose Champaign Champaign Cook Vermilion Oak twig midge Canker, dieback Winnebago Cook Cook Pachysandra Rhododendron Spruce Sycamore Vinca Volutella leaf stem blight Phytophthora rot Spider mites Anthracnose Rhizoctonia root rot Lake Champaign Clinton Champaign Madison Zoysia Rhizoctonia Madison stunted, weak, and more susceptible to winter injury. The crown gall bacterium only enters through fresh wounds (less than 24 hours old). The disease first appears as small overgrowths on the stem (trunk), crown, and roots, usually near the soil line or a graft or bud union. The gall or tumor is white or flesh-colored at first, more or less round, and quite soft and spongy. Tu-mors develop in the same places the following year, or part of the gall may decay and slough off, with new tumor tissue developing in other parts of the same gall. On some host plants, secondary tumors develop at points several inches from the primary gall. Control: Carefully dig up and dispose of all severely infected plants. Do not replant the same type of plant in the same spot for at least five years. Plant only certified, disease- free nursery stock with smooth graft union, free of suspicious overgrowths or enlargements on the roots or stems. Protect susceptible plants against winter injury. Avoid wounding while transplanting, cultivating, and moving. Pruning, budding, and grafting tools should be dipped in fresh liquid household bleach between cuts. Control chewing insects. Resist- ant rootstocks are available for apple, apricot, and peaches. For other control measures and additional information, obtain a copy of Crown Gall, Report on Plant Diseases 1006. To obtain copies of any of the Reports on Plant Diseases mentioned in this or other newsletters, send a check, made out to the University of Illinois, to Extension Plant Pathology, N-533 Turner Hall, 1102 South Goodwin Avenue, Urbana, IL 61801. There is a 50 cent charge Jor each report. Home, Yard & Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engi- neering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology OBS Helping You Put Knowledge to Work h Vj5 <-*??. A^ Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME, YARD c GARDEN PEST No. 14 • July 3, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Earwigs Jim Daugherty, agricultural Extension adviser, reports that earwigs are being found in Peoria County. They have also been reported in northeastern Illinois. Earwigs become active near the end of June as nymphs that develop into adults by early July. They do not disappear until late August, when they enter the soil to lay eggs. Earwigs feed primarily on decaying plant material at night, hiding in cracks and crevices during the day. They commonly enter houses but do not reproduce indoors. Control: Earwigs can be kept out of the home with foundation sprays of diazinon or chlorpyrifos (Dursban). They will also feed on some flowers, particularly marigolds, zinnias, and roses. Protect affected flowers with applications of carbaryl (Sevin) or rotenone. Be sure to keep the insecticide off blooms to reduce the chances of killing bees. Cicadas - Deformed and Diseased We have been receiving reports for the last month about deformed periodical cicadas in the northern third of Illinois where the cicadas have emerged this year. When any insect emerges as an adult, it has to crawl out of the old skin of the previous growth stage. The new stage that emerges is wet and soft but begins to harden immediately. If the insect is slow in shedding its skin, parts of the new skin may harden and stick, causing part of the insect to be deformed. These deformities include twisted or shortened wings, bent legs, or very small abdomens. Occasionally, the insect may dry while partly out of the old skin, which produces an insect that appears half adult, half immature. Newsletter Any time that large numbers of insects emerge in a short time period, such as the periodical cicada, many deformed insects are found even though the percentage is small. Insects are not very active at temperatures in the 50s and almost inactive in colder temperatures. This year, the periodical cicadas emerged in late May and early June, when nighttime temperatures were unseasonably cold. Since the cicadas emerge in the hours just before dawn — usually the coldest part of the day — these cold temperatures probably caused a larger proportion of deformed cicadas than would be found in a normal emergence. Pam Cater, Extension horticulture adviser in Lake County, sent in several periodical cicadas with white, cottony abdomens. These cicadas were infected with a fungus called Massospora, which only infects the genitalia of adult cicadas and commonly causes the abdomen to fall off. Bagworms Bagworms have hatched and are about 3/8- inch long in central Illinois. Bagworms commonly attack red cedar, and other junipers, arborvitae, and spruce, although many trees and shrubs, both evergreen and deciduous, may be attacked. Control: When less than an inch long, these insects can easily be controlled with many insecticides. When larger, Bacillus thuringiensis (Dipel, Thuricide), trichlorfon (Proxol, Dylox), and cyfluthrin (Tempo) are more effective than other insecticides. Annual White Grubs Annual white grub adults are 1/2-inch long, tan beetles. They have emerged in the southern two-thirds of Illinois. These grub adults are attracted to yard lights and other lights at night. In most turf areas, egg laying will peak in central Illinois about July 6 to 10, one week earlier in the southern third of the state, and one to two weeks later in the northern part. Daily flight activity for egg laying occurs soon after dark, peaks about 10:00 to 10:30 p.m., and ends about 1:00 a.m. This egg-laying AG" -E LIBRARY State • County • Local Groups • U.S.jDf partrpent q^griculture Cooperating No. 14 • July 3, 1990 Annual white grub activity can be observed along residential sidewalks and driveways. If you observe the lawn surfaces with car lights approaching, you may witness these adults with membranous wings unfolded from beneath their covers flying just above the lawn. Adequate soil moisture and a moderate number of beetles can add up to many eggs laid in many lawns with a low to moderate grub population in August and September. The first evidence of grub damage usually occurs about six to eight weeks after egg laying. Adequate soil moisture, the presence of beetles, and bluegrass turf add up to the potential for future annual white grub activity. However, the great number of lawns and other turf areas with optimum soil moisture this year may dilute the number of grubs in one particular lawn but may increase the total grub population for future years, which was greatly reduced in 1987 through 1989 by drought and high soil temperature in Jury and August of those years. Fall Webworm The first generation of fall webworm is active in southern and central Illinois. In the latter area they appear to be most common on mulberry. Last year they were most common on elms. In southern Illinois, this first generation tends to be most numerous on sweet gum and redbud. There will be a second generation in southern and central Illinois starting in late July. Northern Illinois has fall webworm for only one generation each year — first appearing in late July. PLANT DISEASES Woody Plants: Canker and Dieback Diseases Canker diseases are common, widespread, and destructive on all kinds of trees and shrubs, especially those under stress from transplant shock, an excess or deficiency of water (even going back to the drought of 1988!), or prolonged exposure to extreme temperatures. Sudden hard freezes in mid- to late fall or spring can also cause trees to be more susceptible to canker diseases. Other stress factors include summer or winter sunscald, frost cracks, nutritional imbalances, extensive defoliation from insects or disease, soil compaction, changes in the soil grade, mechanical injuries (such as hail, wind, a heavy ice or snow load, fire, lawn mowers, construction equipment or vehicles, or rodents), pruning wounds, root rot, insect borers, nematodes, dogs, or improper digging, storage, and shipping. Cankers are localized diseased areas in the bark that often cause an open wound. The lesion is often a definitely marked dead area, usually round to oval or elongate in shape, which may enlarge and girdle the twig, branch (limb), or trunk. The result is a gradual or rapid wilting, withering, and dying back starting at the shoot tip and progressing down the branch. The leaves on affected parts are often smaller than normal, first pale green, then yellow or brown, curled, and sparse. Control: Grow only well-adapted species and varieties or cultivars. Prune out affected plants in dry weather, including all dead and discolored wood. Make cuts several inches behind any sign of disease. Remove and burn or bury all affected parts when first noticed. Avoid leaving branch stubs. Make cuts as flush with the branch or trunk as possible, and sterilize pruning tools between cuts by swabbing them with 70 percent rubbing alcohol or freshly prepared liquid household bleach (1 part bleach in 9 parts clean water). All bark and wood injuries should be treated promptly. Cut away all loose or discolored and splintered wood. Clean, shape, and smooth the wound into a streamlined oval or ellipse with rounded ends and its long ax oriented vertically. Then paint the wound surface liberally with an antiseptic coating of shellac. Keep plants growing vigorously through proper application of fertilizer (in mid- to late autumn or early spring), soaking the soil to a 12 -inch depth every ten days during hot, dry periods (probably not this year!), pruning, and protecting in winter. For more information on other controls, many excellent pictures, disease cycles for annual and perennial cankers, and an alphabetical listing of principal canker and dieback-producing fungi on woody plants in the No. 14 • July 3, 1900 White break mosaic of gladiolus Midwest, refer to Report on Plant Diseases No. 636, Canker and Dieback Diseases of Woody Plants. Gladiolus: Virus Diseases There are a number of viruses that infect gladiolus. Identification of each virus based solely on symptoms is difficult because iihiiiiiiiii ■ ii nil ■ — — varieties often react differently to the same virus. The most common virus infections are caused by the cucumber mosaic or white break mosaic, and bean yellow mosaic, which occur worldwide on a range of cultivated and wild plants and are mainly trans- mitted by the feeding of aphids. Bean yellow mosaic (or mild mosaic) is also mechanically transmitted on contaminated tools. Other viruses that attack gladiolus include tobacco ringspot, which infects over 250 species in 54 plant families, tobacco rattle (notched leaf), and tomato ringspot (stunt). Symptoms of virus infection include conspicuous blotches in the flowers that are white, light gray, or yellowish (white break mosaic). Flowers may be crinkled or otherwise deformed. Foliar symptoms include blotches or squares between the leaf veins that may be gray, yellow, brown, or reddish. Plants may be stunted or have an overall yellow appearance. Leaves and flower stems often develop an angular, light- and dark-green mottling (mild mosaic) when temperatures are mild and plants are growing rapidly. The symptoms tend to be masked at high temper-atures (over 85°F). Leaves on affected plants develop brown or yellowish ringspot patterns when affected with tobacco ringspot virus. Control: Plant only certified, disease-free corms, preferably culture-virus-indexed from a reputable nursery. Remove and destroy all infected plants when symptoms first become evident — they will not recover and the virus(es) are passed on through the corms. Eradicate all nearby broadleaf weeds that serve as virus reservoirs or may harbor aphids that later move into gladiolus plantings. Avoid growing gladiolus near bean, clover, cucumber, melon, or tomato plants. For other controls, photos, and additional background on these diseases, read Report on Plant Diseases 612, Gladiolus Viruses. Melon and Cucumber Diseases Gummy stem blight occurs on all cucurbits, including cucumber, muskmelon, and watermelon. On squash and pumpkin, the disease is called black rot, but it is caused by the same fungus. Plants die quickly if infected in the seedling stage. On older plants, all above-ground parts can be affected. Leaf symptoms appear as tan, circular to irregular lesions and often begin at the leaf margins. Lesions can expand toward the center of the leaf, causing large areas of the leaf to become blighted. Small, black fruiting bodies, pycnidia and perithecia, usually develop on the necrotic tissue. Infection of the stem causes cankers or lesions that are initially oily green and later turn tan. Sap may exude from these lesions, which then dries to form drops of resin- colored gum (thus the name gummy stem blight). Lesions can expand to girdle the stem, causing wilt and dieback of entire vines or plants. Fruit symptoms vary on different crops but usually start as small, watersoaked, circular spots. These spots usually become dark colored with age, and gummy exudate and fruiting bodies may develop in the spots. The fungal pathogen overwinters in infected crop debris and can also be carried on infected seed. The disease is favored by rainy weather and moderate temperatures. Pruning, picking, and insect wounds can be infection sites, especially on older stems and leaves. Control: Two- to three-year crop rotation schedules, planting only disease-free seed, and good sanitation practices (removal of infected plant debris) are the best means for controlling gummy stem blight. Protecting plants with fungicide treatments may be necessary, especially when plants are young. Leaf diseases are caused by several pathogens, in addition to the gummy stem blight pathogen. Angular leaf spot, caused by the bacterium Pseudomonas syringae pv. lachrymans; Alternaria leaf spot, caused by the fungus Alternaria cucumerina; and anthracnose, caused by the fungus Colletotrichum orbiculare are the most common leaf diseases in Illinois. As the name implies, symptoms of angular leaf spot appear as necrotic areas on the leaves that are limited in size by the leaf veins; thus they take on an angular appearance. These spots start as small, watersoaked areas on the underside of the leaf. Later the spots turn tan to brown and may be surrounded by yellow haloes. Under humid conditions, a milky white bacterial ooze can be seen coming from the watersoaked lesions. The bacterium can also attack stems and fruit. Alternaria leaf blight and anthracnose, both caused by fungal pathogens, produce roughly circular tan to brown lesions on the leaves. Concentric rings develop on leaf spots caused by Alternaria, whereas small, black structures develop in the necrotic areas of anthracnose leaf spots. Both diseases can cause sunken circular lesions on fruit. Alternaria leaf blight is most common on muskmelon (cantaloupe) and less important on cucumber, watermelon, and squash. However, anthracnose commonly occurs on cucumber, muskmelon, and watermelon. All three of these diseases survive from season to season in infected plant debris, and two- to three-year crop rotation schedules can help control them. Angular leaf spot and anthracnose are spread from plant to plant by splashing water and thus are most likely to occur after periods of PLANT CLINIC HIGHLIGHTS June 22 to 28, 1990 PLANT DIAGNOSIS COUNTY Apple Arborvitae Fire blight Phomopsis Iroquois twig blight JoDaviess Barberry Winter injury Champaign Elm Dutch elm disease Livingston Evergreen Phomopsis twig blight Champaign Locust Leafhoppers/ plant bugs Kankakee Maple Anthracnose Bond Clinton Schuyler Winnebago Verticillium wilt Clinton Nectria canker Bond Oak Anthracnose Cook Pine Pine shoot moth injury Lawrence Pine needle scale. root injury Winnebago Rose Black spot Champaign Rose rosette McDonough Spruce Cytospora canker Vermilion Spider mites Adams Vinca Stem blight Lake No. 14 • July 3, 1990 rainfall. Wind is the mechanism for dispersal of the fungal spores of Alternaria. Warm, humid conditions and wet plant surfaces favor the development of all three diseases. Additional control measures include using resistant varieties (for angular leaf spot and anthracnose), using disease -free seed and protective copper sprays (for angular leaf spot), and using fungicide sprays for anthracnose and Alternaria leaf blight. To obtain copies of any of the Reports on Plant Diseases mentioned in this or other newsletters, send a check, made out to the University of Illinois, to Extension Plant Pathology, N-533 Turner Hall 1102 South Goodwin Avenue, Urbana, IL 61801. There is a 50 cent charge for each report Home, Yard 82, Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. ( ( /^^f Roscoe Randell Extension Specialist Entomology G3S linois Cooperative Extension Service Helping You Put Knowledge to Work College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD r GARDEN PEST Newsletter No. 15 • July 11, 1990 This newsletter Is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Giant Aphids Giant bark aphids are large, about 1/4-inch long. They have very long legs and are cream- colored with black spots. Their cornicles, tailpipe-like tubes off the back end of the body, are very short. This aphid's larger size and long legs cause many to identify them as spiders at first glance. They are found on oak, sycamore, linden, birch, hickory, pecan, wal- nut, and willow trees. When present in large numbers, giant bark aphids can kill branches from their feeding. These aphids are now being found on trees in central Illinois. Giant willow aphids were found in Grundy County by Bryon Kirwan, county agricultural Extension adviser. This aphid is found on vari- ous willows, particularly pussy willow. This aphid is nearly the same size and color as the giant bark. Unlike the giant bark though, it has long cornicles and a long spine. Pine Shoot Moths The dying of new shoot or "candle" growth on pines, especially Scotch, mugho, Austrian, and red varieties, usually indicates the presence of pine shoot moths. The Nantucket pine tip moth attacks pine terminals in southern Illinois, while the European pine shoot moth is more common in central and northern regions. Both insects tunnel inside the candle. The European pine shoot moth larva usually tun- nels almost the length of the candle. Terminals attacked by European pine shoot moth are usually light in color with the candle bent over like a shepherd's crook. They usually do not have accumulations of pitch. Terminals attacked by Nantucket pine tip moth will have died back with accumulations of white, dried pitch at the base of the needles. Usually this pitch is 1/8- to 1/4-inch thick. Nantucket pine moth larval tunneling is usually at in the candle base and nearby year- old wood. If the infestation of Nantucket pine tip moth is large, they will tunnel into the rest of the candle. Control: Dimethoate, sold as Cygon, is used to control both moth species. The Nantucket moth is controlled by sprays in southern Illinois in early April and mid-June. Due to the systemic action of Cygon, appli- cations now may still be effective. European pine shoot moth is controlled with a spray in late June in central Illinois and early July in northern Illinois. According to Don Orton in Coincide, (see Issue No. 4, April 25) appli- cations for European pine shoot moth coincide with the bloom of catalpa and Hills of Snow hydrangea. Cottony Maple Scale Common on Maples and Locusts Cottony maple scale, which appears as white, popcorn- like masses on the twigs of silver maple, honey locust, or other shade trees are beginning to show up in certain areas of northern Illinois, according to Fredric Miller, area Extension adviser in entomology in north- eastern Illinois. Cottony maple scales are brown, 1/4-inch diameter insects that feed on the sap of var- ious trees. They may also be found on other maples, linden, walnut, and other trees. In June, mated female scales produce white, cottony, 1/4-inch diameter egg sacs that make the scales' presence obvious. These eggs hatch into yellowish crawlers during the first two weeks of July that migrate to the foliage and settle down along veins under the leaf. Control: Once the crawlers settle on the leaves, they are resistant to most insecticide sprays, a feature that they keep for the rest of their lives. Before the leaves drop from the tree in autumn, the scales migrate to the twigs where development is completed through the following spring. Although the scales may cover most of the tree's branches, they are unlikely to kill the tree. Numbers of twice-stabbed lady beetles will AGRICULTURE LIBRARY State • County • Local Groups • U.S. Department of Agriculture Cooperatfrtcj ' ' ') increase on the tree, feeding on all stages of the cottony maple scale. Adult twice-stabbed lady beetles are about 1/8-inch in diameter and black with two red spots on the back. The larvae are whitish like the maple scale's egg cases, but they have legs. Control: Although insecticide sprays of malathion, diazinon, or acephate (Orthene) are effective against the crawlers when present in early July, these sprays may also kill twice - stabbed lady beetles. Spraying silver maple and honey locust trees with a dormant oil in the spring, before the leaves start to emerge, will kill overwintering scales, but will not harm the lady beetles that winter in protected areas beneath loose bark. Do not use a dormant oil spray on sugar, Norway, Japanese, or any other hard maple. Why Do Insect Outbreaks Come and Go? Every year we get calls about a "new" insect problem ("new" insect being one that has been around, but has been much more numerous for the last couple of years, and seems to be increasing in number every year with no end to the problem in sight). We also get calls about insects that can't be found— insects that were present for the last few years in large numbers, but are now almost unknown. Landscapers call to find out where huge numbers of insects are hiding and what can be done to keep them from suddenly appearing and severely injuring their plants. These variations in insect numbers are due to changes of the insect population in nature. We don't know all the reasons for the changes, but many are linked to climate, plant hosts, and natural enemies. This year is a good ex- ample of the effect of climate on insects. Last December, temperatures fell to about 20 degrees below zero, which may be responsible for the drop in elm leaf beetles in northern Illinois and of bagworms throughout the state. And the hot, dry weather of the summer of 1988 and 1989 in some areas of the state caused box elder bugs to be so numerous that it seemed like the world was turning red and black. But where are the box elder bugs this year? Similarly, where have all the annual white grubs been for the last two years? Research shows that at low moisture levels and with soil temperatures over 90°F, many white grub eggs never hatch. With heavy rainfall and early season low temperatures this year, the situation has been reversed. Almost every white No. 15 • July 11, 1990 grub egg laid this summer will probably survive. Damage to turf may not be too bad this year because the grubs will be spread over large areas, but this year's weather will probably cause large numbers of white grub adults next year. If we have typical rainfall next year, these large numbers will concentrate in watered turf areas, causing heavy damage. Some insect outbreaks in Illinois are apparently strongly linked to natural enemies. When pest numbers are low, the predators, parasites, and diseases that attack these pests are also low. When the climate is favorable enough for the pests to gradually increase in number, their natural enemies lag about two years behind in their buildup of numbers. This allows the pests to reach outbreak population levels for about three years before the natural enemies cause their numbers to drop. For instance, cottony maple scale in northern Illinois is apparently controlled by the twice-stabbed lady beetle in the third or fourth year of an outbreak. Similarly, there is a parasitic tachinid fly that appears to be a factor in the crash of Eastern tent caterpillar populations. There was an outbreak of tent caterpillars for the last three years in southern , Illinois, but this year the numbers are low. In I the northern third of the state, this was the third year of an outbreak of the same insect. So, we will probably not have many of these caterpillars in northern Illinois next year. There is also evidence that plants change their chemistry to combat insects. Even under the same weather conditions and without natural enemies, insects that have been on the same plant for more than one generation tend to drop in numbers. Research shows that plants increase the amount of some chemicals in their leaves and reduce others. The in- creased chemicals act as insecticides and anti- feedants. The reduced chemicals have been found to be nutrients and other compounds that the insects use to manufacture hormones that they need to survive. Chemicals mimicking insect growth hormones may also be produced. Some plants will grow tougher leaves that the insects cannot feed on as easily. It is interesting that these insect outbreaks rise and fall whether we use insecticides or not. Sprays are useful to reduce insect prob- lems in small areas such as specific land- scapes or towns, but nature controls the insect numbers on a grand scale and our efforts are pitiful in comparison. \ No. 15 • July 11, 1990 PLANT DISEASES Honeysuckle: Leaf Blight Leaf blight, caused by the fungus Insoli- basidium (Herpobasidium) deformans, is now widespread on honeysuckle following the rainy weather in May and June. Yellowish green blotches on the leaves turn tan and are now blackish brown. A whitish "bloom" of spores appears on underleaf surfaces in damp weather. The leaves roll, twist, wither, and drop early. Only young leaves are infected. Control: It is too late to spray this year, but fungicides containing copper, maneb, or mancozeb are effective when applied as new growth appears. Several applications at seven- to ten-day intervals are suggested. Many Ornamentals, Vegetables, and Fruits: Bacterial Soft Rot With bacterial soft rot, roots, fleshy stems, tubers, rhizomes, bulbs, buds, leaves, and fruit become soft, mushy, slimy, or pulpy—usually with a putrid odor. Foliage wilts, shrivels, and may collapse when the lower stem or under- ground parts decay. Infections occur through wounds (insect or nematode injuries, freezing or hail injury, harvest or cultivator wounds, etc.). Rot is most destructive in heavy, poorly drained soils in warm-to-hot, moist weather. Control: Avoid planting in poorly drained, infertile soil. Control soil insects following suggestions of Extension entomologists. Carefully dig up and destroy infected plants. Spray to control foliage -feeding insects. Control foliage blights and fruit rots. Avoid wounding plants when cultivating, digging, and handling at or after harvest. Store only dry, blemish- free vegetables and fruits in a dry, well- ventilated room at the recommended humidity and temperature. The storage area should be swept clean. Where possible, precool leafy vegetables to 45°F or below, then place in cold storage as soon after harvest as possible. For calla lily and iris, cut out rotted portions in the bulb, corm, or rhizome. Then dry thoroughly for a day or two before planting or placing in storage. Woody Plants: Wood Rots and Decays Wood rot diseases are caused by more than 1,100 different wound-infecting fungi. Nearly all woody plants are susceptible to decay of the trunk, large branches, and roots. Decay usually develops over several years and may not noticeably shorten the life of an affected tree or shrub. In living trees, most of the decay is confined to the older, central wood (heartwood). Once the tree is cut, however, the outer wood (sapwood) is colonized by the wood- decay fungi, as are the wood products made from the tree, if moisture and temperature conditions are favorable for fungi growth. Trees extensively invaded by a wood-decay fungus may show a gradual decline in vigor. Twigs and then branches die back. Affected trees become structurally weak and more susceptible to ice and wind damage. Most wood-rotting fungi produce fruiting structures of the bracket (shelf) or hoof type- called corms— or the mushroom type. These fruiting structures commonly do not appear until several years after decay is advanced. Decay fungi cause the colonized wood to become watersoaked, spongy, stringy, crumbly, or flaky. Such wood may also be discolored— usually brown, white, yellow, or some shade of red, for several feet or more above and below where the fruiting structures appear. Infection nearly always occurs through moist, unprotected breaks in the bark where the wood beneath is exposed. Entry wounds include branch stubs and pruning cuts; mowing cuts and bruises; cuts made by knives, bicycles, and vehicles; summer or winter sunscald; fire scars, lightning strikes, frost, or drought cracks; damaged roots, insect wounds, sapsucker punctures, or breaks due to ice or snow and windstorms. Control: Grow only species of shade, ornamental, and fruit trees and shrubs that are well-adapted to the area. Plant only vigorous, disease-free nursery stock. Keep plants vigorous through proper fertilizing and thorough watering during summer droughts and late in the fall. Wrap the trunks of newly transplanted, thin-barked trees, and prune periodically to remove all dead, dying, interfering, and broken branches. Prune broken stems below the damaged portion so that water will drain off and not collect on the wound surface. The severed ends of roots should be made blunt rather than left jagged. Pruning is best done in the dormant season when the weather is dry. Make as few changes as possible in the soil grade or drainage patterns in the vicinity of trees. Avoid compacting soil over the roots. Control wood-boring insects by following recommendations of Extension entomologists. Avoid all unnecessary bark wounds. Cut away all loose or discolored bark and remove splintered wood. Clean, shape, and smooth the wound into a streamlined oval or vertical ellipse. Then scrub the surface liberally with 70 percent alcohol or shellac. Tree wound dressing is of questionable value and is largely cosmetic. No. 15 • July 11, 1990 Raspberries: Winter Injury and Phytophthora Root Rot and Wilt We have received calls on the sudden dying of raspberries. Much of this can be attributed to winter injur}-, probably due to the severely cold weather in mid-December. Affected canes and laterals are weak, lack vigor, and usually die just before fruiting under other stresses. The leaves on these plants are mottled and lack good color. Phytophthora root rot and wilt starts in low areas in heavy, poorly drained soils and spreads rapidly within rows. Young canes wilt, wither, and die when they are 12 to 18 inches tall. New shoots keep emerging, then they too wilt and die. Roots on affected plants are dark and decayed. Heritage red raspberry is very susceptible to Phytophthora. Control: Drench with Ridomil. following label directions on rates, application, and harvest restrictions. Plant in well-drained soil with certified, virus-free plants. For winter protection suggestions, contact your county Extension office or Extension horticulturist. Russian Olive: Phomopsis Canker and Dieback Across the Midwest, Russian olive trees appear ragged, with dying or dead twigs and branches from a wound-infecting fungus called Phomopsis elaeagnL Although the fungus alone rarely kills trees, it can cause Russian olives to rapidly lose their attractive appearance and can weaken a plant enough to allow other patho- gens and pests to become established. This disease and verticillium wilt make Russian olive trees generally unsuitable for ornamental plantings. Cankers on affected trees are oval to elongate and depressed. The diseased bark on cankers varies from orange-brown to dark reddish -brown with the white sapwood beneath turning dark brown to black. The dead, withered leaves on cankered branches remain attached for some time. Control: Plant disease-free, vigorous nursery stock. Avoid trees with evidence of Phomopsis canker and dieback. Avoid all unnecessary bark wounds. Make pruning cuts flush with the branch to avoid leaving stubs. Sanitation is critical. Cut down and destroy all infected trees in ornamental plantings. Attempts to prune or surgically remove cankers on branches and trunks have largely proven unsuccessful. There are no effective fungicide controls. For more information, read Report on Plant Diseases No. 606, Phomopsis Canker and Dieback of Russian Olive. Rhododendrons: Phytophthora Wilt, Dieback and Root Rot This widespread disease is caused by many common species of the soilborne fungus Phytophthora. which thrives in heavy, wet soils. Leaves may be a dull, yellowish green or watersoaked before wilting and withering from a brown to black rot of the lower stem and roots, or terminal buds and leaves turn brown, roll up, and droop. Brown to black sunken, girdling cankers may form on the stems. Roots may decay and slough off easily. All parts above the canker or rot later wilt and die. Control: Grow varieties and species well adapted to your area. Plant in partial shade, sheltered from strong, dry, winter winds in a fertile, deep, well-drained soil. Keep soil well mulched (3 to 8 inches deep) with peat moss, well-rotted compost, pine needles, ground corn cobs, shredded bark, wood chips, or rotted sawdust. Renew the mulch annually. The soil pH should be 4.5 to 5.5 and high in organic matter. Avoid over-fertilizing and water thoroughly during summer droughts and late in the fall. Control insects (weevils and grubs, for example) following suggestions of Extension entomologists. Bud and twig blight and dieback can be controlled by spraying three times, seven to ten days apart, starting at budbreak using a copper, chlorothalonial (Daconil) or benomyl (Banlate) fungicide. To control root and crown rot, dieback and wilt, apply a fungicide as a drench around plants and then repeat at three- to twelve-week intervals in spring and autumn, or blend granules into the soil just before planting. The following fungicides are effective against soilborne species of Phytophthora when applied at the early onset of symptoms: etridiazole (Truban or Terrazole), Banrot, metalaxyl (Subdue), fosetyl- Al (Aliette) and propamocarb (Banol). Home, Yard 8l Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engin- eering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. ( \ ^f^U /&jf Roscoe Randell Extension Specialist Entomology i G3S Helping You /-^"/^ Put Knowledge to Work <^<^s/ • Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign. Illinois HOME, YARD c GARDEN PEST Newsletter No. 16 • July 18, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Fall Webworm Second generation fall webworm is present in southern Illinois and should appear next week in central Illinois. The only occurance of this insect in northern Illinois should begin in a week or two. Fall webworm feeds on a wide variety of trees, but is most common on crab- apple, walnut, pecan, and hickory. This caterpillar lives in colonies that spin silk tents over the ends of branches, enclosing the leaves. The hairy caterpillars feed on the leaves inside of this tent, enlarging the tent every few days to include more leaves. Fall webworm has two races; one race has a wide black stripe down the back, while the other race lacks the stripe, making the general color yellowish to orangish. Control is more effective on younger cater- pillars. Eliminating the caterpillars before they have eaten many leaves reduces the damage to the health and appearance of the tress. If in- secticides are used, smaller caterpillars are killed more easily than larger ones. The silk tent is waterproof, so to be effective insecticides must be sprayed with enough force to break up the tent. Bacillus thuringiensis (sold as Dipel, Thuricide, Sok-Bt, and Caterpillar Attack) is effective in controlling this insect, as are various chemical insecticides. Pruning out the silk tents removes the caterpillars and is an effective control. Many tents will be too high to be reached by this method, and those can be sprayed or ignored. Damage occurring this late in the summer is not very severe to the health of the tree, since the leaves that are eaten have already accom- plished most of their purpose for the tree. Twig prune r Twig Pruners and Girdlers Dean Carr, Extension agricultural adviser in Vermilion County, reports the appearance of twig pruner this year. The adult beetle lays its egg in the bark of a twig in the spring. The egg hatches into a larva that bores into the twig and feeds during the summer. Later in the summer, the borer severs the wood of the branch, leaving the bark intact. Winds blow the damaged branches out of the tree; the larva continues to de- velop in the fallen branch. The insect overwinters as a pupa and emerges from the branch in the spring as an adult. The twig girdler beetle also lays its eggs in twigs, but the beetle then girdles the twig by chewing a continuous notch around it. This damage occurs later in the summer, with the girdled branches blowing out of the tree with heavy winds. The eggs hatch in the fall, and the resulting young larva overwinters in the branches on the ground. In the spring and summer, the larva grows and develops in the branch, pupating and emerging as an adult in late summer. Control of both insects can be accom- plished by destroying fallen twigs and branches in the late summer and fall. Infested, fallen branches may be as long as 2 feet. Both insects cause relatively smooth breaks. The twig pruner leaves a smooth cut in the center of the twig, but the bark breakage will be more ragged. The twig girdler cut will be smooth in the bark and outer wood, but the pith and inner wood may have a more jagged break. Japanese Beetle Japanese beetles are feeding on ornamental plants in the eastern edge of Illinois. This insect occurs down the length of the state, but mainly in the easternmost counties. The insect is about 1/2 inch long, robust, and roundish in shape. It is metallic green and has coppery m fBRARY OC; 1 7 State • County • Local Groups • U.S. Department of Agriculture Cooperating The Illinois CooDerative Service Drovides eaual oooortunities in nrnnrams and emnlrti/r No. 16 • July 18, 1990 wing covers and white spots on the sides, just below the wing covers. The larva is one of the white grubs that feed on the roots of turfgrasses. The adults are active in the daytime and feed for about a month on a variety of plant leaves and flowers, including smartweed, rose, grape, raspberry, linden, and birch. Control is difficult, with handpicking as effective as insecticide sprays. Sprays of carbaryl (sold as Sevin) and acephate (sold as Orthene) are usually somewhat effective. Very valuable plants can be covered with nylon net- ting or mesh bags. Japanese beetle traps may also be effective. These traps have a pheromone and a floral lure so that both sexes of beetles are attracted. Place the traps at least 50 feet from the plants that you want to protect. A problem with these traps is that they may attract beetles to your yard from a long distance, ones that probably wouldn't have come to your yard if the trap wasn't present. List of Available Resources in Entomology Extension circulars, pesticide applicator training manuals, fact sheets, picture sheets, and slide sets covering a variety of insect pest manage- ment situations are available from the Univer- sity of Illinois. Some can be ordered from the Office of Agricultural Communications and Education, others from the Office of Agricultural Entomology, and still others from Vocational Agriculture Services. An extensive, up-to-date list of these resource materials, with infor- mation on their cost and how to order them, is available from the Office of Agricultural Entomology, 172 Natural Resources Building, 607 East Peabody Drive, Champaign. IL 61820. To receive a copy of this list, send a check for $1.00 payable to the University of Illinois. PLANT DISEASES Plums and Cherries: Black Knot Black knot is a widespread disease on wild plums and cherries and in home orchards where pruning and spraying are not practiced regularly. The disease will eventually stunt or kill infected trees unless effective control mea- sures are taken. Elongated, rough, girdling black swellings develop on twigs, branches, and even the trunk. The knots are a velvety olive green in spring. Gradually they become hard. brittle, and coal black by autumn. Affected parts may die back. Trees gradually weaken and die. Control: Purchase only disease-free nursery stock. Never buy trees with visible knots or abnormal swellings on the twigs and branches. Prune and bum (or bury) all infected wood in late winter or early spring before growth starts and as soon as new knots appear. Make cuts 4 to 8 inches behind any obvious, black knot swellings. Knots on the trunk or on large limbs should be carefully cut out with a knife and chisel, removing about an inch of healthy bark and wood beyond any visible gall tissue. Wounds over 1 1/2 to 2 inches in diameter should be painted with shellac. If possible, destroy (bum) all available wild, neglected, or worthless plum and cherry trees. Fungicide sprays should be applied (1) just before the buds break open, (2) at pink bud, (3) petalfall, and (4) at 2-week intervals until mid-June following the spray schedule for plums as given in University of Illinois Coopera- tive Extension Service Circular 1145, Home Fruit Pest Control For more information concerning control measures, resistant cultivars, and disease cycle, read Report on Plant Diseases No. 809, Black , Knot of Plums and Cherries. ' Peach: Perennial Canker This serious disease has several names includ- ing dieback, peach canker, Valsa canker and Cytospora canker. The disease may kill young trees, while older trees lose productivity and longevity. Cankers form on the fruit pedicels, twigs, scaffold limbs, and trunk. Wounds or dead areas in the bark must occur before the causal fungi can invade. Once established, gum is exuded at the point of infection. (The presence of gum or sap exudate on the scaffold limbs or trunks of peach trees may also be caused by insect borers, winter or mechanical injury, and other diseases. With perennial canker the in- ner bark tissue collapses. Older cankers are generally oval in shape with the outer bark generally broken and disorganized. The canker enlarges from year to year with callus rings forming around the canker as a defense mecha- nism. Limbs are gradually girdled and killed. Control: Destroy all wild and infected stone fruit trees before planting new, disease-free nursery stock. Choose winter-hardy rootstocks. Fertilize in late winter or early spring to avoid succulent, cold-tender growth in the fall. Prune ( peaches annually using the open center system. No. 16 • July 18, 1990 For details, read Illinois Extension Circular 1013, Growing Tree Fruits in the Home Orchard. Prune from late winter until just after bloom. Remove all weak and dead wood and all cank- ered branches that can be spared. Make cuts at least 4 Inches below a canker. Do not leave branch stubs. Paint the wounds as described for black knot. Clean out cankers on large limbs and trunks. Avoid mechanical injury to tree trunks. Control insects and other dis- eases. Follow the spray program outlined in Extension Circular 1145, Home Fruit Pest Con- trol For more information about this disease, read Report on Plant Diseases No. 806, Peren- nial Canker of Peach. Wet Feet: Many Plants Excessive rains in April, May, and June kept the soil in much of Illinois near field capacity. This killed plants such as yew (Taxus), white pine, Prunus species, roses, rhododendrons, and others. Roots require oxygen to grow. Satu- rated soil creates an anaerobic condition and also allows such soil-inhabiting fungi as Pyth- ium, Fusarium, and Rhizoctonia to attack the weakened rootlets, adding to the problem. Apple Diseases: Black Rot and Frogeye Leaf Spot; Sooty Blotch and Flyspeck Black rot and frogeye leaf spot are caused by the same fungus that also causes a serious canker and dieback disease of twigs, limbs, and trunk. Disease occurs from fruit rotting before harvest and in storage, a weakening of the tree from defoliation, and a blighting and dieback of twigs and limbs. Fruit develop a small, light brown spot that enlarges and forms concentric, brown or black rings. The rotted fruit turns black and shrinks into a wrinkled "mummy" that commonly hangs on the tree over winter. Frogeye leaf spot is a round to irregular lobed lesion with a light brown-to-gray center surrounded by one or more dark brown concen- tric rings and a purple margin. Black specks (pycnidia) develop in the rotted fruit, leaf spots, and slightly sunken, reddish brown cankers that form in the bark of old, stressed, or injured trees. The cankers slowly enlarge and darken. Larger cankers expand slightly each year. Control: Keep trees vigorous through annual pruning, thorough watering during extended droughts, and fertilizing. Good orchard sanitation is a primary control mea- sure. All mummified fruit and all dead, cank- Sooty blotch of apple ered, or infected twigs and limbs should be pruned out, removed from the orchard, and either burned or buried. Follow the suggested program for apples as given in Extension Circ- ular 1145, Home Fruit Pest Control. Handle fruit with care while picking, sorting, and packing to avoid bruises and cuts. For more information about this disease and its causal fungus that attacks many other woody plants, read Report on Plant Diseases No. 814, Black Rot and Frogeye Leaf Spot of Apple. Sooty blotch and flyspeck are caused by fungi that usually occur together on the same fruit. Both diseases are controlled in the same way. Sooty blotch appears as superficial, dull black spots or blotches up to 1/4 inch or larger and may merge to cover most of an apple. Flyspeck appears as clusters of 6 to 50 or more slightly raised, black, shiny round dots that resemble fly excreta. Like sooty blotch, they are superficial and can be re- moved by vigorous rubbing. The diseases are most prevalent in damp, low, more shaded areas of an orchard. Control: Keep trees well pruned to an open center for maximum air circulation and follow a full apple spray program as outlined in Exten- sion Circular 1145. Thorough coverage is es- sential; the most crucial period is during cool, wet weather in August and September. For more information, read Report on Plant Dis- eases No. 815, Sooty Blotch and Flyspeck of Apple. Rust of Sweet Corn Common rust is starting to show up on sweet corn in Illinois. This disease is named after the rust orange spores that form in the small pus- tules on leaves, husks, and tassels. Early in the season, these small pustules appear in bands across the leaf blade, but later occur in a more random pattern on the leaves. Late in the season, the rust-colored spores will grad- ually be replaced by dark brown to black spores. Severe infection can reduce yield if it occurs when the plant is young. However, if the plant remains relatively disease-free until silking, then even severe rust infections will not greatly affect yield or quality. This fungal path- No. 16 • July 18, 1990 ogen does not overwinter in Illinois, but is blown up from Central America and the south- ern United States by spring and summer winds. Thus, the disease cannot be controlled by crop rotation. Control this disease by using a hybrid that is resistant to rust. Resistant or moderately resistant hybrids include: Miracle, Honey and Pearl, Golden Glade, Gold Dust, Sugar Loaf, and Seneca Horizon. Hybrids with little or no rust resistance include Buttersweet, Candy Bar, Florida Staysweet, and Sweet Sue. Common Smut of Sweet Corn Common smut is one of the easiest diseases to recognize because of the large galls and masses of powdery black spores that can destroy an ear of com. Ear or kernel infections are the most noticeable and most destructive, but the fungus that causes corn smut, Ustalago maydis, can also infect and cause galls on PLANT CLINIC HIGHLIGHTS June 29- July 12, 1990 PLANT DIAGNOSIS COUNTY Amur maple Verticillium wilt Champaign Apple Diaporthe canker Winnebago Scorch, nitrogen Ogle deficiency, apple scab Fire blight Champaign, Dewitt Arborvitae Phomopsis twig blight Jo Daviess Bramble Spur blight, anthracnose Champaign Elm Dutch elm disease Madison. McHenry Ginseng Thielaviopsis root rot Pike Locust Phomopsis canker Kane Maple Anthracnose Lake Potato leafhopper damag< ; McDonough Oak Anthracnose Calhoun Leaf blister St. Clair Sphaeropsis canker Madison Vein pocket gall Calhoun Pine Pine needle scale Winnebago Raspberry Anthracnose Winnebago, Adams Spur blight Adams Strawberry Black root rot Bureau, Piatt Sweet gum Bleeding necrosis St. Clair Tomato Septoria leaf spot Marshall Tuberous begonia Pythium crown & stem rot Lake leaves, stalks, and tassels. Young galls are firm to spongy, with a semi-glossy, light exter- nal covering. As the galls mature they become more spongy, and the internal tissue turns into a mass of black, sooty spores. The pathogen overwinters in the soil, but spores are wind- dispersed, so crop rotation does little to reduce the incidence of smut. The only practical means of control is the use of resistant hybrids. Resistant hybrids include: Buttersweet, Calico Bell, Honey *n Frost, Melody, Miracle, and Snopak. Hybrids with moderate resistance include: Classic, Even Sweeter, Flavor King, Merlin Super Sweet, and Springdance. Suscep- tible hybrids include: Candy Bar II, Silver Bullet, Spartan, Springsweet, and Yankee Bell. Botrytis Leaf Blight of Onion Botrytis leaf blight shows up as small, whitish spots that may be surrounded by light green halos. Spot centers tend to become sunken and straw colored. Severe infection can cause tip dieback or a blasting of the entire leaf. For infection to occur, there must be free water on the leaf surfaces. Thus, the disease is most likely to develop following periods of persistent dew and high relative humidity. The disease is also favored by temperatures above 70 degrees F. Botrytis leaf blight frequently shows up after there have been high levels of atmospheric ozone. The ozone damages and may kill leaf cells, and the botrytis pathogen is able to colo- nize these weakened areas. Controls of this disease include destruction or disposal of onion debris and the regular use of fungicides. Home, Yard 8i Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. ^€Z/ /£L^ Roscoe Randell Extension specialist Entomology ces Illinois Cooperative Extension Service Helping You Put Knowledge to Work College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD ^GARDEN PEST No. 17 • July 25, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Deer Flies Deer flies are very numerous in many areas of Illinois this summer. These small relatives of horse flies are about 1/4 inch long and have clear wings with brown patterns on them. They may have yellowish or brown abdomens. They feed by slicing the skin with their mouthparts, making the bite very painful, and lapping up the blood that oozes out of the wound. They are more common in and near wooded areas and lay their eggs on vegetation near water. The larvae develop in damp soil in woodlands. Control is most effective through the use of repellents containing DEET, which is usually effective for 2 to 3 hours. Since these flies commonly bite exposed areas of the shoulders and neck, be sure to apply the repellent to these areas as well as other exposed skin areas. Because deer flies are strong fliers and tend to stay in wooded areas, sprays against the adults are not usually effective. Treatments against the larvae are not recommended. Japanese Beetle Japanese beetles appear to be expanding their range in several Illinois areas. Mike Hardiman, St. Clair County Extension Adviser, reports that this beetle is being commonly found in Collins- ville. Japanese beetles are being found in Urbana, and they seem to be expanding their infestation in northeastern Illinois, particularly in the Elmhurst area. Refer to last week's newsletter for information about their appear- ance, habits, and control. Cicada Killer Cicada killers are large wasps that appear in late summer, preying primarily on annual cicadas and other large insects such as AGRICULTURE LIBRARY Newsletter katydids. They are about 11/2 inches long and black with yellow markings; their wings are reddish. They live in groups, usually burrowing into a bare soil area such as flower garden areas, along house foundations, and under trees where it is too shady for grass to grow. Females burrow holes in the soil that are 1/4 to 1/2 inch in diameter, usually with a small pile of loose soil at one side of the hole. The tunnel goes down into the soil for about 6 inches and then turns and runs parallel to the soil surface for another 6 inches. At the end of the tunnel, one or more cells are constructed. Females find adult annual cicadas in the trees, attack, and sting them; the two usually fall to the ground together. The cicada killer climbs a tree while dragging the cicada. After climbing to a suitable height, the cicada killer can fly to her burrow with the dead cicada. The wasp apparently cannot get airborne with the cicada from the ground, since in areas where no trees are available, she drags the cicada along the ground to her burrow. One or two cicadas are placed in each cell in the burrow, and one egg is laid per cell. The larval wasp hatches in a few days and feeds on the living, paralyzed cicadas. The resulting adult cicada killer emerges the following summer. Female cicada killers are capable of stinging people but rarely do, even if provoked. Most stings result from someone grabbing the wasp by the hand or stepping on it barefooted. Fe- males normally ignore people. Where females have nesting burrows, male cicada killers will also be present. The males are usually numer- ous and spend much of their time flying in the area. Anything or anyone entering the area is normally inspected by these flying male wasps. People commonly get upset by these large wasps buzzing around them; but these males cannot sting because only the females have stingers, which are modified egg-laying structures. Control of cicada killers is normally unnecessary since people are rarely stung. Nesting areas near doorways where visitors will feel threatened by these wasps can be elim- inated by treating the soil with diazinon. Es- tablishing grass or other groundcovers in this OCT 1 7 I! UNIVERSITY ! i State • County • Local Groups • U.S. Department of Agriculture Cooperating The Illinois CooDerative Service Drovides eaual ODDortunities in oroarams and employment. No. 17 • July 25, 1990 area will usually reduce the number of nests in following years. Green June Beetle Green June beetles are 1 inch long, robust, metallic green beetles with yellowish wing cover margins; they are very active during sunny periods. They feed as adults on several kinds of fruit including peaches, nectarines, plums, apples, and various berries. They will also feed on corn and some vegetables. The biggest problem is that they fly about without regard to what is in their path. Large beetles flying around, making a loud buzzing sound, and crashing into people are very dis- turbing. They lay their eggs in organic debris with the larval stage being a white grub that feeds on decaying material such as piles of grass clippings, hay, or straw, the edges of compost piles, and the heavy thatch in poorly managed turf areas. The grubs rarely cause damage by their feeding habits; but they have been known to destroy turf areas since in the process of feeding on thatch, they can loosen the sod until the roots dry out and die. Control against the larvae to prevent subsequent adults can be accomplished by re- moving the decaying material that is their food source or by drenches of carbaryl (sold as Sevin). Adults can be controlled with Sevin sprays or dusts if you can locate their food source. Be sure to observe restrictions on harvest intervals for fruits and vegetables. Strawberry Root Weevil These are being found in southern Illinois and will likely appear throughout the state in the next few weeks. It is a very hard-shelled, black, roundish weevil with a broad, short snout. These adult weevils feed on a wide variety of plants, with damage most severe on strawberry, yew, and hemlock. They enter the house for the winter where they usually do not feed, but occasionally they will eat some house plants. They eat the leaf margins until much of the leaf is removed. Control is difficult; sprays of acephate (sold as Orthene) are relatively effective against plant feeding. In the home, chemical control is usu- ally not effective; removal by hand or vacuum- ing are the most effective methods. Yellownecked Caterpillar Yellownecked caterpillars are being found on pecans, other hickories, and walnuts in the southern half of the state. These caterpillars are reddish brown when young with several whitish stripes. As they get older, they turn black, keeping the whitish stripes, and have a yellowish to orangish area behind the head that gives them their name. When fully grown, they are about 2 inches long. They feed in groups of about a hundred, eating the leaflets of their host trees. They do not live in a silk tent, but migrate down to the trunk of the tree to molt. Although each group may strip the leaves from several tree branches, this damage occurs late enough in the summer that it is not very harmful to the tree. Thus treatment is not usually necessary to preserve the health of the tree. If control is desired. Bacillus thuringtensis, (sold as Dipel or Thuricide), malathion, chlor- pyrifos (sold as Dursban), or acephate, (sold as Orthene) can be used. Walnut Caterpillar Walnut caterpillars are close relatives of yellownecked caterpillars and feed on the same trees in the same way. Young walnut cater- pillars are also reddish brown but do not have whitish stripes; older caterpillars are black with long white hairs. Decisions on control and con- trol options are the same as for yellownecked caterpillar. PLANT DISEASES Fire thorn [Pyracantha): Scab Scab is a widespread and unsightly disease that blackens the brilliantly colored orange-red fruits as well as the leaves and stems. It is worst when spring and summer are cool and moist. Velvety, sootlike lesions appear on the shiny green leaves. Affected leaves first turn yellow and then dark brown before dropping prematurely. Black lesions also form on the new shoots and may cause twig dieback. Young infected fruits shrivel and fail to mature. On older fruits the skin becomes black, rough, scabby, and unsightly. Control: In the southern half of Illinois, in protected locations, grow resistant varieties (such as Mojave, Shawnee, and Yunan). These varieties may not be winter hardy even in southern Illinois. The firethom cultivars Chadwick, Kasan, Lalandei, Monrovia, and Wyatti are very susceptible. Collect and burn or bury all diseased plants during autumn or winter. It will also be necessary to apply a fungicide four times: at budbreak, just before No. 17 • July 25, 1990 the blossoms open, at petal-fall, and again 10 to 14 days later. Adding a spreader- sticker to the spray will improve coverage. Suggested fungicides include benomyl, Daconil, mancozeb, Duosan, Zyban, Topsin M, or Cleary 3336. Carefully follow the manufacturer's directions when mixing and applying any fungicide. For more information, read Report on Plant Dis- eases No. 638, Firethorn (Pyracantha) Scab. Stone Fruits: Brown Rot This common and destructive disease affects all stone fruits including the blossoms, fruit spurs, twigs, small branches, and fruit. One to sev- eral small, round, light brown spots form on a fruit as it ripens. In warm, moist weather the rot spreads very rapidly. Within 2 or 3 days the entire fruit becomes semi-watery, decayed, and light brown. Tannish gray spore tufts break through the fruit skin, giving it a pow- dery appearance. Infected fruit continue to rot after harvest, turning into black, shriveled mummies, some of which remain on the tree over winter. Blossoms suddenly wilt, turn brown, and wither, and later they are covered with a tan-gray mold. Oval or elliptical, brown, sunken and definite cankers form on the fruit spurs, twigs, and small branches. Gum com- monly oozes out from the canker margins dur- ing wet periods. The result is a wilting of leaves, which turn dull green, then light brown, wither, and die. Control: Sanitation is critical. All dropped and rotted fruit should be promptly picked up and destroyed. Remove all mummies from trees. Prune out all cankers and blighted twigs after the last picking and during the dormant season. Prune trees annually to an open cen- ter. Remove and burn or bury all wild and neglected stone fruit trees. Follow a routine spray program for stone fruits as outlined in Illinois Extension Circular 1145, Home Fruit Pest Control Stone fruit cultivars differ in resistance. For more information about this serious disease, symptoms, disease cycle, and other control measures, read Report on Plant Diseases No. 804, Brown Rot of Stone Fruits. Lawn Diseases Helminthosporium leaf spot has progressed into the crown and root rot phase called melting- out. Fungicides applied now for this disease are worthless. Some lawn care companies are applying Chipco 26019 or other leaf spot fungi- cides or are recommending to home lawn own- ers that they spray now. For more information about leaf spot and its control, see Home, Yard, and Garden Pests Newsletter No. 3, April 18. Report on Plant Diseases No. 405 gives full details on the importance of the disease, symp- toms, disease cycle, and control measures. The best, long-term solution is to overseed next month with a blend or mixture of resistant grasses. Summer patch and necrotic ringspot are now very evident as straw-colored patches up to 2 to 3 feet in diameter, often doughnut-shaped and sunken with "healthy" grass in the centers. For more information, see Home, Yard, and Garden Pests Newsletter No. 8, May 23, and Report on Plant Diseases No. 408. Dollar spot is also active now. This disease and its control were also discussed in Home, Yard, and Garden Pest Newsletter No. 8, May 23, and Report on Plant Diseases No. 407. On lawn grasses, dollar spot and young summer patch or necrotic ringspot patches look alike. Rhizoctonia brown patch and Pythtum blight are active during wet periods when nighttime tem- peratures are 70 degrees F or more. For more information, see Home, Yard, and Garden Pests Newsletter No. 12, June 20, and Report on Plant Diseases Nos. 410 and 411. Anthracnose is a widespread but generally minor disease of all turfgrasses. Grass under stress from a variety of causes is most sus- ceptible. Water-soaked lesions occur on the leaves. These lesions later become bleached and girdle the tiller, and scattered individual or small patches of plants turn yellow and die. Older leaves are colonized and die. Occa- sionally, on individual grass blades round to oblong or elongated lesions are found that are reddish brown surrounded by a yellow halo. Anthracnose fungi commonly infect grass blades from the tip down. The best diagnostic feature is the appearance of small, raised, black fruiting bodies (acervuli) which are very com- mon on senescing leaves. With a hand lens you can see the acervuli are covered with long black bristles and resemble pin cushions. Control: Keep the turfgrass growing vigorously by good surface drainage, main- taining a soil reaction (pH) of 6 to 7, and by growing locally adapted, disease-resistant grasses in blends or mixtures. Purchase only top quality, certified seed, sod, sprigs, or plugs. Plant at the suggested rate in a fertile, well- prepared seedbed. Fertilize according to local No. 17 • July 25, 1990 recommendations and soil tests. Mow fre- quently at 1 1/2 to 2 1/2 inches for lawn-type grasses and remove no more than 1/3 of the leaf height at one cutting. Keep the mower blades sharp. Water thoroughly during droughts (soil should be moist 6 inches deep). Increase light penetration and air movement over the grass surface by pruning or removing dense trees, shrubs, and hedges. Remove excess thatch when grass is growing vigorously in the fall or early spring when it accumulates to 1/2 inch. Core aerify compacted areas one or more times each year. Follow suggested insect and weed control programs for the area and grasses grown. The cultural practices briefly described should keep anthracnose and most other turfgrass diseases well under control. Several fungicides that also have proven effective are listed in Extension Circular 1076, Turfgrass Pest Control For more infor- mation on anthracnose and its control, read Report on Plant Diseases No. 416, Anthracnose of Turfgrasses. PLANT CLINIC HIGHLIGHTS July 13-19, 1990 Bacterial Diseases The 1990 growing season has been a banner year for bacterially-caused plant disease. The repeated wetting periods (rains), ideal tem- peratures, and strong winds have elevated these relatively minor diseases into major, uncon- trolled outbreaks. The bacterial disease of the week is bacterial spot of stone fruits. This disease, caused by a Xanthomonas sp. is dam- aging all varieties of stone fruits (peach, nectarine, plum, apricots, etc.). Symptoms are most evident on the foliage of these trees and are manifested by the sudden and repeated defoliation of leaves (generally quite yellow). Infected fruit develop numerous, small, round, brown to black spots. These spots are usually on the "sunny side" of the fruit and can become so numerous as to coalesce— causing fruit to become misshapen and to crack, allowing secondary rotters (fungi) entrances. Control: Grow cultivars with resistance to bacterial spot. Plant trees in fertile, well- drained soils and prune trees annually to per- mit good air circulation and vigor. Although bactericidal sprays suppress development of this disease, the very best way to control the disease is through resistant cultivars and good cultural practices. For more information on this disease, obtain a copy of Report on Plant Diseases No. 810, Bacterial Spot of Stone Fruits. PLANT DIAGNOSIS COUNTY Amelanchier Lesser peach tree Lake borer Barberry Winter injury Vermilion Blackberry Aphids Jefferson Crabapple Apple scab Morgan Cyclamen Rhizoctonia, botrytis, bacterial soft rot Kane Magnolia Growth regulator herbicide injury Edwards Maple Anthracnose Knox, Peoria Richland Potato leafhopper Richland Oak Anthracnose Champaign jumping oak galls Kane wetwood Richland Peony Rhizoctonia stem blight Cook Pine Pine chafer injury Whiteside Zimmerman pine moth Champaign injury Spruce Spider mites McHenry Peoria Walnut Growth regulator injury Morgan Home, Yard & Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Rand ell and Philip Nixon. Horticulture, Thomas Permanlan, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. jd^tat /L^ Roscoe Randell Extension Specialist Entomology H~7S linois Cooperative Extension Service Helping You Put Knowledge to Work College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD ^GARDEN PEST Newsletter No. 18 • August 1, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. FIELD DAY Field Day Set for August 15 The 1990 University of Illinois Turfgrass, Nursery, Landscape, and Trial Garden Field Day will be held August 15, 1990 at the Uni- versity of Illinois Ornamental Horticulture Research Center on South Lincoln Avenue in Urbana, Illinois. Registration, with coffee and donuts, will be from 8:00 to 9:00 a.m. After some introductory remarks, research plot tours will be held from 9:30 to 11:55 a.m. After lunch, there will be workshops and classes from 1:15 to 3:00 p.m. Research plot tours will cover the areas of Turf Pathology, Turf Herbicides, Nursery Weed Control, Turf Cultivars, Turf Entomology, Orna- mental Grasses, Turf Fertility, and Nursery Fer- tility. There will be an insect and disease diagnosis table, so bring in samples that you want identified. Registration is $20.00. Those who pre- register will receive a box lunch. Those who register at the door will not be able to purchase lunch. Send in your registration to: Tom Voigt, 1011 Plant Science Lab, 1201 South Domer Drive, Urbana, Illinois 61801 (Phone: 217-333- 7847). INSECTS Potato Leafhoppers These green, wedge-shaped insects are flying about or hopping on many host plants in Illi- nois this summer. This insect does not over- winter in Illinois but is carried in on storm fronts. As the leafhopper sucks plant juices from the foliage of various plants, it injects a toxin with its saliva. This toxin causes a bronzing or pink color to the foliage of infested trees such as red maples, red bud, and others. Some shrubs have also been damaged. Nursery managers and commercial applicators can use Sevin, Tempo, or Talstar for leafhopper control. In home vegetable gardens, leafhoppers are also damaging snap and lima beans as well as potatoes, causing a curling or crinkling of the leaves. The toxin these hoppers secrete into vegetables causes a browning of the tips and edges of the leaf and the death of the entire leaf or plant. Sprays or dusts containing Sevin will control leafhoppers on the vegetables listed. Fall Webworm The second generation of fall webworm has emerged in southern Illinois and seems to be most common on walnut, hickory, and crab- apple. They should be showing up in the rest State • County • Local Groups • U.S. Department of Agriculture The Illinois Connective Servine nrrtviries enual nnnnrtiinities in nrnnrams and emnlnvment. Fall webworm of the state in the last few days of July and early August. Yellownecked Caterpillar Dave Robson, Sangamon County Horticulture Extension Adviser, reports that many backyard apple trees and crabapples are being defoliated by caterpillars in central Illinois. Additional host trees include flowering peach, cherry, almond, quince, elm, butternut, hickory, wal- nut, chestnut, beech, and linden. When young, the larvae are reddish in color with a yellow neck, hence their name. They have black AGRICULTURE LIBRARY Cooperatft^T \ 1 No. 18 • August 1, 1990 heads and four light stripes along each side of their body. Young larvae usually begin feeding in July and skeletonize the leaf, while older larvae consume everything but the petiole. They usually feed in groups. Control of the yellownecked caterpillar can be achieved by physically removing them or spraying with Orthene, Sevin, Dipel, Thuricide, or malathion when feeding damage is first noticed. Young larvae are much easier to kill, so try to spray as early as possible. Zimmerman Pine Moth Zimmerman pine moth can be controlled in August when its eggs are hatching. Adult moths emerge at this time of year, mate, and lay eggs back on the bark surface. When the eggs hatch, the young larvae wander around on the bark, eventually crawling under a loose piece of bark for the winter. In the spring, usually during April, they emerge from the bark, wander on the bark, and then bore into the tree. They attack many pines, especially Scotch pine. Control: While the larvae are under the bark or in the tree, they cannot be controlled with insecticides. Only when they are wander- ing on the bark can they be controlled. Timing spray applications in the spring is difficult due to "early" and "late" springs. Correct timing of August sprays is much easier, allowing more dependable control. Chlorpyrifos (Dursban) or dimethoate (Cygon) sprays in early August in southern Illinois, mid-August in central Illinois, and late August in northern Illinois should effectively control this insect. Because these insecticides should last for 3 to 4 weeks on the trunk of the tree, one application should be sufficient. New Tick Control Available in Illinois Permethrin, which is sold as Permanone, has recently received a 24(c) registration for use in Illinois. About 35 other states have similar state labels for this insecticide. This pyrethrin is applied to clothing, making it toxic to ticks and other biting pests. It should be used in combination with repellents containing DEET for maximum effectiveness. Permanone is particularly effective against deer tick and other ticks. If DEET is applied to the skin, particularly the lower legs, ticks that are picked up will be repelled from the treated skin to your clothing, where they will crawl until finding an area of skin to attach to that has not been treated with DEET. With Perma- none applied to your clothing, particularly to trousers, these ticks are killed while crawling across the clothing. Fleas Fleas seem to be particularly abundant this year, and many people are already experiencing flea problems in their homes. Although flea problems are more common in homes where pets are kept, homes without pets can also get fleas. Fleas can usually be prevented in homes by treating pets with a flea and tick powder monthly during the warm months of the year. In a home with pets, fleas can be eliminated by treating the pets with a flea and tick powder weekly for 2 or 3 months. Rub the powder into the skin to get effective control. Since fleas greatly prefer to bite dogs or cats instead of people, by treating the pets, you eliminate the adult fleas before eggs are laid. To get quicker control in homes with pets or to eliminate fleas in petless homes, applica- tion of a mixture of an insect growth regulator and another insecticide is effective. The insect growth regulator used against fleas is metho- prene (sold as Precor). This insecticide mimics an insect hormone that keeps the larval fleas from growing into adults. Since this insecticide is not effective against the biting adult fleas, another insecticide, usually a pyrethroid, is included to kill adults. These insecticides are applied as a light spray to carpets, the undersides of upholstered furniture, cracks and crevices along base- boards, and in other areas. Precor is effective for 90 days, eventually eliminating the fleas since no adults are produced. Since Precor is effective as an insect hormone that is not found in people or pets, its toxicity to mammals is very low. The pyrethroid included in these mix- tures is also low in toxicity and lasts for only a week or two. Annual Cicadas Annual or dogday cicadas have emerged, and their singing can be heard in the evening throughout Illinois. These cicadas are different from the periodical cicadas that have been dis- cussed frequently this summer in this news- letter. Annual cicadas are about 2 inches long and greenish or brownish in color. They live on tree roots as nymphs for 2 to 5 years, with some adults emerging every year. Males sing in the evening to attract females for mating. Females insert their eggs into the twigs and branches of trees, but are not nu- No. 18 • August 1, 1990 merous enough to cause significant egg-laying damage like the periodical cicadas. The eggs hatch in several weeks, and the nymphs drop to the ground where they burrow into the soil to feed on tree roots. Due to their relatively small numbers, control of annual cicada is not needed. PLANT DISEASES Hawthorn: Leaf Spot or Blight This serious disease affects mostly English hawthorn and Paul's scarlet thorn. Such hawthorns may defoliate by midsummer. In- fected nursery trees produce little new growth and commonly lose all their leaves. Small, angular to irregular, reddish brown or dark brown spots appear on the leaves. The centers of older lesions form small, raised, dark brown to black fungus fruiting bodies (acervuli). On dead or fallen leaves, lesions are uniformly dark brown or black. Elongated lesions develop on the petioles and the large veins on the underleaf surfaces. Control: Collect and burn or compost fall- en dead leaves. Grow only resistant hawthorns such as Washington and Cockspur. English types are very susceptible. Prevent leaf spot or blight by applications of a fungicide starting in early June. Three or four sprays are needed spaced 7 to 10 days apart. Suggested fungi- cides include benomyl, captan, Daconil, Cyprex, maneb, and mancozeb. Daconil, maneb, and mancozeb also control rust diseases. For more information on this disease, its disease cycle, and control, read Report on Plant Diseases No. 637. Leaf Spot or Blight of Hawthorn. This disease was also discussed in Home, Yard, and Garden Pests Newsletter No. 4, April 25. Gladiolus: Corm Rots Gladiolus is susceptible to a number of corm rots. When planted, shoots may fail to emerge or the foliage may turn yellow and die pre- maturely at any time during the growing sea- son. Fewer and smaller blooms are produced on plants grown from diseased corms. The most widespread and serious corm rots include Fusarium rot, Penicillium rot, Botrytis corm rot, Curvularia corm rot, Septoria hard rot, Stroma- tinia dry rot, Penicillium core rot, and Bacterial scab. The symptoms of these diseases closely resemble one another. Some of the pathogens cause leaf or flower lesions. Control: Purchase only large, top-quality, disease-free corms from a reputable nursery. Inspect the corms carefully and discard those with rot lesions. Soak the remaining healthy looking corms for 15 to 30 minutes in a warm water solution (80 to 85 degrees F) containing 2 tablespoons of benomyl (Benlate 150%WP), Mer- tect 360 F, TBZ, or ornalin. Plant in a sunny location in fertile, well- drained soil where air movement is good. Rotate to a non-host plant for 4 or 5 years before replanting gladiolus in the same location. Control Botrytis leaf and flower spot and other fungal leaf spots by spraying weekly during damp or rainy periods, starting when such diseases first appear. Suggested fungicides include Topsin M, benomyl, maneb, mancozeb, captan, Daconil, Chipco 26019, ornalin, or Botran. Adding a few drops per gallon of a commercial spreader- sticker (surfactant) will improve coverage. Spray cut flower spikes with benomyl before shipment. Ornalin also makes a good post- harvest cut flower or corm dip for Botrytis control. For good pictures, description of symp- tom, disease cycle information, and other con- trols, read Report on Plant Diseases No. 651, Gladiolws Corm Rots. Poplars and Willows: Cytospora Canker This disease has caused the decline and/or death of many thousands of valuable orna- mental trees in landscape, windbreak, and rec- reational areas. The disease commonly kills Lombardy pop- lars by the time they are 10 to 15 years old. The disease usually attacks woody plants grow- ing outside their normal range or un- der stressful con- ditions such as a poor site, frost damage, extended drought periods, ex- tremely cold winter weather, transplant shock, or severe pruning (pollarding). Circular to oval or elongate, brown, sunken cankers appear on the twigs, branches, and trunk. The cankers commonly enlarge and girdle the affected part causing the portion beyond the canker to die. Vertical cracks form in older cankers and along the margins. As the cankers enlarge, the dis- eased outer bark may become black, brown. Cytospora canker. No. 18 • August 1, 1990 gray, reddish brown, or yellow and sunken, de- pending on the tree species and stage of dis- ease development. The sapwood appears red- dish brown to black and water-soaked. The canker fungi usually invade wounds, branch stubs, or the base of dead twigs. Control: Grow varieties of poplars (includ- ing aspens and cottonwoods) and willows that are well adapted to the area and planting site. Select only vigorous, disease-free nursery stock; avoid planting such highly susceptible varieties such as Lombardy, Simon, and Siouxland pop- lars. Resistant varieties are now available. Black and peach willows are reported to be resistant. Pruning all dead and dying branches and surgical removal of cankers on trunks is often beneficial. This work is best done by a licensed and experienced arborist with the pro- per tools, which are sterilized between cuts. Treat all bark and wood injuries promptly and cover the wound with shellac or 70% alcohol. Keep trees vigorous through proper appli- cation of a balanced fertilizer based on a soil test, watering deep during hot, dry weather (soil should be moist 10 to 12 inches deep), proper pruning, and winter protection of young trees. Avoid all unnecessary bark wounds and chemi- cal injuries. For much more information con- cerning this serious disease, including many other hosts of Cytospora canker, read Report on Plant Diseases No. 661, Cytospora Canker of Poplars and Willows. English Ivy: Leaf Spot Diseases This popular ground cover is attacked by sev- eral common leaf spots: Bacterial leaf spot and stem canker is the most common disease. It is first seen as small, round, dark green, "oily" lesions that enlarge into roughly circular to angular areas with greenish brown, water-soaked margins and red- dish brown to black centers. A yellow halo sur- rounds older lesions. The centers eventually become dry and cracked. Black cankers may form on the stems and petioles, causing shoot growth to be dwarfed and unthrifty and the foliage to be yellowish green. Colletotrichum leaf spot appears as irregular, brown to reddish brown spots as large as about 3/4 inch in diameter. Black specks (fungus fruiting bodies or acervuli) commonly appear within the lesions on the upper leaf surface. Lesions on the petioles and stems may cause premature defoliation, stem dieback, and even death of plants in scattered patches. Scab is identified by the small, raised, round to irregular spots with reddish brown margins and grayish white, slightly depressed centers. The centers are later sprinkled with dark fungus fruiting bodies called sporodochia. The spots, if numerous, may merge to form irregular blotches on the leaves. Control: Remove and burn or compost dis- eased plant parts. Remove dead leaves, stems, and other plant debris very early in the spring before new growth starts. Thin the stand peri- odically to prevent dense growth. Water early in the day while the temperature is still rising. (All leaf spot pathogens require free water on the foliage for infection to occur). Avoid exces- sive splashing of water or sprinkling (syringing) while irrigating. Whenever possible, keep water off the foliage and space the plants well. Where leaf spots have been severe in the past, apply fungicide sprays starting when the new leaf growth begins in the spring. Suggested fungi- cides include benomyl (Benlate), fixed copper compounds, Duosan, Zyban, mancozeb, and Chipco 26019. Copper compounds are the only ones that will check bacterial leaf spot. Apply several sprays, 7 to 10 days apart, starting when disease first appears. Keep the foliage protected during rainy spring and early summer weather. When buying plants be sure they are vigorous and disease-free. Home, Yard Si Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. /^^^ Roscoe Randell Extension Specialist Entomology d£%i OBS linois Cooperative Extension Service Helping You Put Knowledge to Work College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD, GARDEN PEST Newsletter No. 19 • August 15, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. AGRONOMY DAY Agronomy Day September 13 The University of Illinois Agronomy Day will be on September 13, 1990 from 7:00 a.m. until about 1:00 p.m. All tours will leave from the Agronomy-Plant Pathology South Farm on Wright Street, south of Florida Avenue in Urbana. Tours will provide information on field crop tillage, weed control, plant pathology, and entomology. For additional information, call (217)333-4424. INSECTS White Grub Situation Annual white grubs have hatched in Illinois. If damage will occur, it should be visible in turfgrass areas now in the southern third of the state, and early symptoms should begin to ap- pear in central Illinois. Questions often asked about grub biology and management include the following: Where did the grubs come from? Tan, 1/2- inch long beetles laid eggs in turfgrass in late June and July. These beetles were visible around lights and on window screens at night. Peak egg laying took place from about 10:30 to 11:00 p.m. What conditions favor grub activity? Dry soils and high temperatures, such as occurred in 1988, discourage egg laying and reduce egg hatch. Moist soils favor egg laying, which is why egg laying occurs primarily in watered turf in most years. But this year, with many turf areas having optimum soil moisture, egg laying occurred in many areas, and the total popu- lation was diluted in any one home lawn. Open areas in lawns with partial light and warm soils next to driveways and sidewalks are favorite egg laying sites. How do I inspect for grub activity? Check areas where grub damage has been a problem in previous years and in partially lighted and warm soil areas. Cut out a square of turf, pull it back to check for grubs in the root zone, and then replace it and tamp it down. Also, look for wilted turf, which will be loosened from the soil if grubs are present. Grubs simply chew off the roots of turfgrass. These roots tend to regenerate; but if grub numbers are high, the roots will continue to be pruned or eaten. How many grubs does it take to cause damage? At least 10 to 12 grubs per square foot are required to cause damage. In wilted grass areas where the sod can be rolled back, the number can be as high as 50 to 60 per square foot. Very few, if any, grubs will be found under trees or shrubs. The highest counts are often between the sidewalk and street next to a driveway. If I find 10 grubs per square foot in a few spots, will these numbers increase? No, if it is late August or September, hatch is complete and what you can detect is all you will have. Scouting for grubs requires attempting to roll back sod in more than one area of the lawn, determining where the heaviest population is located, and treating the areas above the threshold of 10 to 12 grubs per square foot. How long is the season of potential grub damage? After the initial damage is observed in late August or September, grubs may be found feeding on the grass roots until the soil temperature drops to 50 degrees F or lower. This could be as late as Thanksgiving in southern and central Illinois. What can be used to control grubs in a home lawn? Diazinon applied as granules or as a spray will control annual white grubs during a three-week period after being drenched into the grub infested soil. Homeowners and lawn care companies may use & ^inon. Another product available to homeowners is Oftanol, but its de- pendability for control is suspect. Some lawn care companies are applying it with success, and others have ceased using it for grub con- trol. Turcam and Dylox are available for use by lawn care companies to be applied either as a OCT 17 1990 State • County • Local Groups • U.S. Department of Agriculture Cooperating The Illinois CooDerative Service nrnvidR?; finnal nnnnrtunitips in nrnnrsms and prVinl, No. 19 • August IS, 1990 spray or as granules. Proxol and Triumph can be applied by lawn care companies as sprays. All treatments need to be drenched into the soil to be effective. All treatments require two to three weeks to control the grubs present. What can a homeowner do to assure effec- tive grub control if it is needed? Apply an effective product such as diazinon and drench it in immediately. If the grub treatment is commercially applied, be prepared immediately to water it into the soil surface. Do animals search out grub infestations? Yes, both skunks and raccoons may visit a lawn at night using their noses to roll back infested sod to find grubs to eat. Skunks and raccoons can literally "plow" large areas of a home lawn, park, or golf course in order to feed on grubs. Birds sometimes find a grub infested area, but only do minor turf damage. Imported Willow Leaf Beetle These insects have been reported in Peoria and DuPage Counties. The adult beetles are about 1/4-inch long and metallic blue-black. The larvae are black and about 1/4-inch long when fully grown. The larvae feed on the epidermis and mesophyll of the leaf, leaving one epidermis intact, which turns brown. The adult beetles eat notches out of the leaves, and when numer- ous eat entire leaves. They have two gener- ations per year; the second generation of larvae is now present in northern Illinois. They are rarely seen outside the northern third of the state. Although these insects can eat much of the foliage of willows, they do not seem to harm the trees to a great extent. The biggest problem that they cause is dropping out of the trees onto people, getting into their hair and inside their clothing. Control includes avoiding trees that are heavily infested so that the beetles do not bother you. The larvae can be controlled with sprays of carbaryl (Sevin) or Bacillus thurin- giensis 'san diego* (M-One). M-One will not kill the adult beetles and many of the beetles will fly away when the Sevin is sprayed, reducing the amount of control needed. Sprayed trees are frequently reinfested with beetles from near- by unsprayed trees. Imported Long-horned Weevil Imported long-horned weevils are 3/16-inch long, tan beetles with brown spots and wide, short muzzles. As larvae, they feed on the roots of a variety of ornamental plants, emerg- ing in mid-summer as adult beetles. These beetles come into homes to spend the winter. They normally do not feed, so they do not cause any damage. Because they do not feed and are hard shelled, they are not easily killed with insecticides. Control these insects by caulking cracks and crevices in the foundation to keep them from entering the home and by vacuuming them up when found indoors. Syrphid Flies Yellow and black, 1/2-inch long insects that hover near your arms, particularly when you are perspiring, are usually syrphid flies. These insects have flattened abdomens and very short antennae. Syrphid flies do not sting or bite. Most people call them sweat bees, but sweat bees are usually about 3/16-inch long and bluish or black. Sweat bees do not do much hovering, preferring to land on the arm. If they are disturbed, they will sting. Another yellow and black insect that is attracted to perspiration is the yellow) acket. This 1/2-inch long wasp, which will sting, has a cylindrical abdomen and easily seen antennae. PLANT DISEASES Phlox: Blight, Leaf Drop Older leaves turn brown and die from the base of the stem upwards. Shoots may die. This disease is most severe on older clumps where soil nutrients or water are exhausted. Varieties differ in susceptibility. (Do not confuse with the white, flour- like growth of the cosmopolitan powdery mildew.) Control Divide old clumps; apply a com- plete fertilizer in spring based on a soil test; keep down weeds; control insects and mites; and destroy tops and fallen leaves in autumn. Sanitizing Agents and Disinfectants Sanitation is a basic disease control measure, which involves (1) cleaning up sources of infec- tion, including plant debris; (2) controlling weeds— which may harbor diseases; (3) steaming the soil in greenhouse beds and potted plants (See University of Illinois Cooperative Extension Service Circular 1213, Soil Disinfestation: Methods and Materials, for details); (4) dis- infecting tools, equipment, and plant-growing surfaces in greenhouses and other appropriate areas. Old plant containers, trowels, spades. No. 19 • August 15, 1990 cutting tools, walkways, bench tops, potting tables, and the like should be disinfected. To disinfect, preclean the items with tap water (you can add a little household detergent) to remove soil or salt buildup. Then spray or rinse with an appropriately diluted sanitizer. Some effective sanitizing agents include 38 to 40 percent commercial formaldehyde (dilute one part of formaldehyde to 18 to 20 parts of water) and a freshly prepared liquid household laun- dry bleach solution (one part of bleach to nine parts of clean water). Rubbing alcohol is also a good disinfectant. Some commercially available disinfectants include Amphyl (about one ounce in five gallons of water) and Physan-20 (about one ounce in two gallons of water). Because commercial sanitizing agents and the household bleach solution are quite reactive and break down rather quickly upon contact with air and especially with organic matter, precleaning prior to disinfection is important. Mix and use all disinfectant solutions promptly. Formaldehyde should not be used within a few feet of growing plants. Chrysanthemum: Late Season Diseases Septoria produces small, dark brown to black spots that appear first on the lower and inner leaves. The spots gradually enlarge and may emerge to blight large areas of the leaves. Speck-sized, dark fruiting bodies (pycnidia) of the Septoria fungus are visible in older spots. Affected leaves wither and drop early. Control: Spray the foliage at 5- to 10-day intervals starting when disease first appears. Suggested fungicides to control Septoria include maneb, mancozeb, Captan, Daconil, Duosan, Zyban, Chipco 26019, or Ziram. Benlate can be added to any of the other fungicides to give broad-spectrum control. Fungicide sprays also control Ascochyta stem, and ray blight, anthrac- nose, and other fungal leaf spots. Maneb, man- cozeb, Rubigan, and Bayleton will control rust If Botrytis flower blight is a problem later, the following fungicides will do a good job if prop- erly applied: maneb, mancozeb, Benlate, orna- lin, Daconil, Zyban, Duosan, Chipco 26019, Topsin M, and Botran. If powdery mildew is the problem, use Benlate, Karathane, Bayleton, Rubigan, or sulfur. You may need to add a small amount (one teaspoonful per gallon) of a commercial spreader-sticker to the spray mix to ensure the best coverage. After the season is over, collect and compost, bury, or burn crop debris. Getting Ready for Winter Trees and shrubs express winter injury by (1) frost cracks (a vertical separation of bark and wood on the south or southwest sides of the trunk that may extend to the center of the tree), (2) blackened sapwood and death of the entire plant, (3) death of twigs and branches, (4) discolored cankers on exposed limbs or at the trunk base (sun scald), (5) injured or dead taproot and side roots, and (6) death or injury to leaf and flower buds. Preventing winter injury to trees and shrubs will help prevent death from a number of can- ker, wood decay, and wilt diseases next year. Here are some tips to avoid winter injury: 1. Select only well-known, hardy species of plants. Grow plants with borderline hardiness in locations protected against winter sun and drying winds. Plant in well-drained soil. Yews, roses, Prunus species, rhododendrons, and other plants are very susceptible to "wet feet." 2. Plants growing in raised planters or containers are most susceptible to root killing from low temperatures. 3. Provide hardy plants, especially ever- greens, with adequate moisture in late summer and early fall. The soil should be moist 12 inches deep after watering. 4. Fertilize evergreens in the fall after the first killing frost with a slow-release nitrogen product; but do not apply to plants exhibiting fertilizer stress. 5. Apply a 2- to 6-inch lightweight organic mulch over evergreen, rose, and fruit tree roots to prevent deep freezing plus alternate thawing and freezing, which shears off feeding roots. 6. Shade exposed evergreens against mid- day and late afternoon sun and wind by erect- ing barriers of canvas, plastic, cheesecloth, bur- lap, or slat screens placed 2 feet away on the south or southwest sides. 7. Broadleaf and other evergreens can often avoid winter "leaf burn" or kill if you apply a special "no wilt" latex or plastic antitranspirant spray such as Wilt-Pruf NCF, Vapor Gard, Exhalt 4-10, D-Wax, Plant Shield, Stop-Wilt, or Plantcote. Apply the spray to the foliage in late fall and repeat during midwinter when the temperature is above 40 degree F. 8. Protect young thin-barked trees against frost cracks by wrapping the trunks with sisal- kraft paper or strips of burlap, tying a 6-inch board upright on the south-southwest side of the trunk, wrapping young trees with aluminum foil, or applying a coat of whitewash. Frost cracks may reopen each year, providing entry for wood decay fungi and insects. Trees that No. 19 • August 15, 1990 are very subject to frost crack, when growing in exposed locations, include apple, ash, beech, elm, horsechestnut, linden, London plane, maple, oak, poplar, sycamore, tuliptree, walnut, and willow. 9. Boxwood, junipers, yews, and other multiple- stemmed evergreens that tend to spread, split apart, and break under a load of ice or snow can be protected by tying the branches together this fall with strong cord. 10. Apply winter protection against mice, rabbits, and deer to apple, crabapple, blue- berries, bramble fruits, grapes, pines, and many other susceptible plants. Protect against mice chewing the bark off the crowns and roots of young and old trees PLANT CLINIC HIGHLIGHTS July 20 to August 2, 1990 PLANT DIAGNOSIS COUNTY Apple Apple Scab Ford Ash Suspect Ash Decline Madison Birch Anthracnose, Iron Chlorosis Champaign Bluegrass Helminthosporium Melting Out Winnebago Chrysanthe- Rhizoctonia Stem Rot Will mum Crabapple Apple Scab Mcdonough Cyclamen Rhizoctonia, Botrytis, Bacterial Soft Rot Kankakee Elm Dutch Elm Disease Cook Sangamon Geranium Blackleg Cook Grape Anthracnose McLean Lilac Powdery Mildew Champaign Linden Verticillium Wilt Champaign Maple Anthracnose Piatt Iron Chlorosis, Iroquois Nitrogen Deficiency Oak Actinopelte Leaf Spot Shelby. Piatt Anthracnose McLean Iron Chlorosis Champaign, Piatt. Winnebago Pear Fire Blight McDonough Raspberry Anthracnose McLean Rose Black Spot, Rose Rosette Monroe Common Rose Champaign Canker Spruce Cytospora Canker Richland Spider Mites Macoupin, Richland, Rock Island Strawberry Black Root Rot Douglas Walnut Bacterial Blight McDonough from late fall into early spring by keeping trunk bases free of grass, weeds, and debris within a foot of the trunk, leaving the ground bare; put anticoagulant poison baits (for example. War- farin) in holes and runways; and banking soil against the trunk. Protect against rabbits by erecting a cylinder of hardware cloth 3 feet or more high and a foot away from the trunk. For young trees you can wrap the trunk and lower branches with several layers of newspaper in early November and remove the papers in late March (southern Illinois) or April (in central and northern Illi- nois). To protect bramble fruits and blue- berries, erect an 18- to 36- inch high chicken wire fence surrounding the planting. Protect against mice, rabbits, and deer by using a repellent such as Gustafson 42-S or thiram 42-S plus indoor white latex paint or Wilt-Pruf NCF (1 pint of 42-S and 1 quart of latex paint or Wilt-Pruf in 2 gallons of water) that is sprayed, brushed, or rolled on the trunk and scaffold limbs. To repel deer, dip pieces (3/4 inches by 6 inches long) of felt weather stripping in creo- sote, let the strips drip dry, and hang one or two strips on each young tree in late fall. Freshly treated strips attached in the fall usually are effective all winter. Repeat the creosote treatment once a month during the growing season, using an oil can to treat the felt strips. Home, Yard 81 Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Ran dell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Mead or, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineer- ing, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. /te£f Roscoe Randell Extension Specialist Entomology G3S Illinois Cooperative Extension Service Helping You Put Knowledge to Work H75 College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD ^GARDEN PEST Newsletter No. 20 • August 29, 1990 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. LAST ISSUE This is the last issue of the Home, Yard, and Garden Pest Newsletter for 1990. Thanks go to those of you who let us know when various pests and pest problems occurred throughout the state. Your input helped make the news- letter more useful. Suggestions or criticisms concerning the newsletter are always welcome, but are espe- cially important as we reflect on this year's issues and start formulating ideas to make the 1991 newsletter as useful as possible. If you would care to comment on articles that you found particularly useful or useless, or have ideas on future directions for the newsletter, please send them to Roscoe Randell, 172 Natural Resources Building, 607 East Peabody Drive, Champaign, IL 61820. You can also make your comments to any of the contributors listed at the end of the newsletter. IF YOU DO NOT RECEIVE AN ORDER FORM THIS WINTER FOR NEXT YEAR'S NEWS- LETTER, PLEASE CONTACT YOUR COUNTY ADVISER. LAWNS Diseases of Turf Insects Reduced numbers of several turf insects this year are probably due to their being killed by diseases that are more common during wet weather. Sod webworms are killed by micro- sporidian diseases including Nosema and Thelo- hania. Infected larvae are sluggish, and both larvae and pupae are darker in color than healthy ones. Chinchbugs and billbugs are both killed by Beauveria; diseased insects will be covered with a whitish fungus. AGBICULT 'VT Greenbugs Greenbugs damaging turf have been reported by Don Meyer, Agriculture Extension Adviser in McLean County, and have also been found in areas of the state other than Bloomington. This summer's weather patterns and the lack of reports of this insect in many areas of the state indicate that these insects have probably not migrated in on storm fronts from the southern parts of the country; they are more likely the result of overwintering populations. Greenbug damage occurs as reddish brown turf that starts under tree canopies before moving out into other turf areas. Nematodes for Grub Control Nematodes are being marketed for the control of grubs in turf in Illinois. These nematodes have been found to be effective against Japa- nese beetle grubs; but the results of our re- search last fall, as well as that of other mid- western states, indicate that these nematodes are not effective in controlling annual white grubs. Because the Japanese beetle is common in only small areas of Illinois, and the annual white grub is the predominant turf damaging grub, applications of these nematodes are not likely to provide acceptable control in most areas of Illinois. INSECTS Bugs: 1990 in Review Although insects will continue to be a concern in Illinois for several more months, enough of the summer of 1990 has passed to assess the year's trends in insect populations. Usually, climate has the greatest effect on insect num- bers in any year. There were two major cli- matic factors this past year. One factor was the extremely cold tem- peratures in the last two weeks of December 1989. In much of the state, temperatures dip- ped as low as 20 degrees F below zero. At the same time, there was snow cover in most of the state that insulated the soil so that it barely froze. Insects whose natural distribution does not extend very far north of Illinois and that ■ •• i 7 1990 State • County • Local Groups • U.S. Department of Agriculture Cooperating ThP nriWrtk^<^hrtrtr^tn/pIRhr\/in£ nrnviries Gfiijal onnortunities in oroarams and emDlovment. No. 20 • August 29, 1990 overwintered above the snow line were greatly reduced in numbers in 1990. Examples in- clude bagworm, elm leaf beetle, and mimosa webworm. The other major climatic factor on insect numbers was rainfall. Particularly in the spring of 1990, rainfall was very high. Along with this rainfall, temperatures tended to be rather low. A major cause of death in insects is fungus disease. These fungus diseases tend to be more prevalent in cool, damp conditions. Insects whose numbers have probably been re- duced from fungus diseases include boxelder bug, chinch bug, sod webworm, billbug, and recently, potato leafhopper. Inland floodwater mosquitoes were very numerous in the spring of 1990 due to the heavy rainfalls that assisted egg hatch and larval development of these insects. Other insects were numerous in 1990 due to natural periods of abundance. The emer- gence of periodical cicadas in the northern third of Illinois was the most predictable of these. Eastern tent caterpillars were very numerous in the northern half of the state and are likely to be numerous again next spring. This insect has reached the end of a period of abundance in the southern half of the state and is likely to be low in numbers again in 1991. Fall web- worm numbers are high for the second year in a row in Illinois, and these numbers will likely be high again next year, before dropping in subsequent years. Cecropia Moth Green caterpillars that grow to 3 or 4 inches in length with red and yellow bumps on their backs are probably cecropia moth larvae. These caterpillars feed on many trees and shrubs— including cherry, birch, plum, maple, walnut, and willow. Although each larva eats many leaves, only a few larva will be on any one tree, so control is rarely needed. These caterpillars spin a cocoon on the branch of a tree and overwinter there. In late spring, reddish brown moths with a 6-inch wingspread and crescent markings on their wings will emerge, mate, and lay eggs for the next generation. Fall Webworm Fall webworms are numerous in central Illinois, particularly in the Springfield area. The cater- pillars live in large groups within silk tents that are spun on the ends of the branches of crab- apple, walnut, hickory, and many other trees. These insects are different from the eastern tent caterpillars that were very numerous in some of these same areas earlier in the spring. Eastern tent caterpillars spin a web in the branch crotch and move out of the tent to feed. Fall webworms feed on foliage within the web, ex- panding the web as leaves are eaten. ^a4-ua Qonnro nmi'irisc onnai nnnnrti initio in nrnnrams ar: ^ ^ % *& SS <5N No. 1 • March 27, 1991 for them to leave the building for the summer yet, so they enter the living area, becoming a nuisance. Vacuuming these insects as they appear is the most effective control. Insecticide sprays are usually not very effective. Once the weather is warm enough, these insects will leave the building for the summer. Cluster flies will lay eggs in the soil so that the hatching larvae can attack earthworms. The box-elder bugs will fly to box elder trees to lay eggs with the resulting nymphs feeding on the box elder seeds and leaves. Insect Identification Insect pests can be identified by sending them to Extension entomology. The insect should be sent in a crushproof container, like a pill bottle. Insects that are sent unprotected in an envelope are commonly smashed beyond recognition by the post office stamping machine. Even envel- opes that say "Please Hand Stamp" usually contain crushed insects. Please do not send the insects in tissue paper or cellophane tape. Include information on the date of collection, the name of the host plant or other location where it was found, what town it was found in or near, and the amount and type of damage that this insect appears to be causing. Include your name, address, and telephone number. Most specimens are identified by Extension entomologists that will phone or write you about the specimen within a couple of days to a week. Other specimens are sent to insect identification specialists at the Center for Biodiversity, Illinois Natural History Survey where responses may be very quick or take as long as two weeks due to extensive collecting and research trips that these scientists take during the summer. If the specialist is unavailable for several weeks, the specimen must be sent to the USDA lab at Beltsville, Maryland for identification. In that case, you should be contacted about the delay. Insect specimens may be sent to: Office of Agricultural Entomology, 172 Natural Resources Building, 607 E. Peabody Drive, Champaign, IL 61820. If you have a plant disease specimen, it can be sent to the Plant Clinic, 1401 W. St. Marys Rd., Urbana, IL 61801. PLANT DISEASES Winter Injury Many tree and shrub samples thought to have winter injury have arrived at the Plant Clinic over the past few weeks. Although trees and shrubs are dormant in the winter months, moisture loss does occur through the bark as well as through leaves of evergreens. Foliage and buds may become scorched if exposed to the winter sun and warm drying winds. The condition is most apparent on plants on the south and southwest sides of buildings or on plants growing in exposed sites. Mechanical injury from excessive loads of ice or snow and strong winds is also very common and may not be noticed until later this spring. Prune-out dead or injured branches, remove debris, and keep plants well watered. A spring application of fertilizer based on a soil test will help plants regain their vigor. Garden Cleanup There are only two principle sources of disease- causing organisms (fungi, bacteria, nematodes) and viruses— soil and plants. If not already done, an excellent method of disease control in the home, industrial park, cemetery, or other landscape is to do a thorough job of sanitation now. Collect and burn, compost, or bury old plant debris. Prune trees and shrubs to remove cankered or otherwise diseased and dead twigs and branches. Remove rubbing, crossing, and interfering branches to increase air movement and sunlight. Open center pruning of fruit and other trees and shrubs promotes more rapid | drying of foliage and stems, reducing infections " by fungi and bacteria that require free moisture for infection to occur. 1991 Illinois Pest Control Handbook Chemical control suggestions for insects, mites, weeds, and diseases for home, yard, and garden plants, vegetables, woody and nonwoody orna- mentals, and turfgrasses are now available in a 522-page book at your county Cooperative Extension office. For a copy of this valuable handbook make your check payable to the University of Illinois for $14.00 and mail it to the Office of Agricultural Entomology, 1 72 Natural Resources Building, 607 E. Peabody Drive, Champaign, IL 61820. Flowers and Vegetables: Seed Decay and Damping-Off of Transplants All flower and vegetable seeds will profit from treatment with a captan seed-protectant fungicide. The treatment will help protect the seed against infection by seed- and soilborne- fungi until the young seedlings are up and "on their own." Dust the seed lightly with the seed- protectant fungicide. If treating in a seed packet, tear open an upper corner of the packet 4 and add an amount of fungicide that fits on the ' No. 1 • March 27, 1991 1 /4-inch tip of a pocket knife. Close the corner of the packet and shake vigorously for a minute or two to thoroughly coat the seed. For larger amounts of seed such as peas, beans, and sweet corn, fill a Mason jar about half full of seed, add a teaspoon of captan, close the jar, and roll it on the floor for several minutes until the seed is thoroughly coated. Then sift out the excess fungicide. Follow suggestions on the seed packet or box for the proper time (soil temper- ature), depth, and spacing of seed. Seed protectant fungicides provide maximum protection in cool and wet or very dry soils. Peach, Plum, and Cherry Diseases The control for peach leaf curl and plurn pockets is to apply a DORMANT spray BEFORE the buds swell, not later. In many areas of Illinois it is already too late. Leaf curl will appear in several weeks as severely puckered, distorted, thickened, and curled leaves that lose their normal green color and turn red, yellow, and purple tints. Such leaves soon turn brown, wither, and drop. Peach leaf curl Leaf curl is a serious, tree-weakening disease of unsprayed trees. Infected plum fruits become much enlarged, hollow, and "bladderlike." Such fruits are reddish at first and later have a velvety gray appearance before turning dark brown or black and usually dropping pre- maturely. Almost any approved fungicide, applied as a strictly dormant spray is effective, such as captan, ferbam, lime-sulfur, chloro- thalonil (Bravo) and Bordeaux mixture. The spray may be applied any time after leaf drop but before buds begin to swell in early spring. Thorough coverage is essential. Cooperative Extension Circular No. 1145, Home Fruit Pest Control gives suggested spray programs for all kinds of fruits. Copies are available at your county Cooperative Extension office. Raspberry and Blackberry Diseases Anthracnose is the most important disease of brambles, especially black raspberries. Look for sunken, light-gray, crusty areas on old canes. Many of the canes may be cracked and winter- killed. In several weeks, purple spots will appear on the new canes. To control anthracnose in brambles, remove and destroy last year's fruiting canes (burn, if possible) and prune out all weak, short, spindly, and injured canes. A delayed dormant spray of lime-sulfur is suggested when new leaflets are 3/8-inch long. It may be too late now for this spray in southern Illinois. Additional sprays of ferbam or a multi-purpose fruit spray are needed when the new canes are 6 to 8 inches tall, just before bloom, and again just after blooming. These sprays also control spur blight, cane blight, leaf spot, and fruit rots. Details are given in Cooperative Extension Circular No. 1145, Home Fruit Pest Control. Sycamore, Oak, Maple, Ash, Hickory, and Horsechestnut Diseases Anthracnose is a major cause of leaf and twig blight following cool (temperatures below 60 degrees F.) and wet weather as the buds break open and the leaves expand. Look for buds and young expanding leaves to turn brown, die, and drop early. Older leaves develop small- to- large, irregular brown areas along and between the veins. These leaves also drop early leaving tufts of leaves only at the branch tips. Twigs may die back from girdling, sunken cankers. To control anthracnose, prune out and destroy cankered twigs and small branches. Fertilize weakened trees to increase their vigor. Sprays are needed just before the buds break open, at budbreak, and when the leaves have expanded. Suggested fungicides include Daconil, Benlate, a copper compound, mancozeb, maneb, dodine, Duosan, Zyban, and Topsin M. Thor- ough coverage is required. Check label directions. Revised/New Reports on Plant Diseases (RPDs) 402 Turfgrass Disease Control (5/90) 404 Snow Molds of Turfgrasses (5/90) 409 Leaf Smuts of Turfgrasses (7/90) 604 Cytospora Canker of Spruce (7/90) 607 Bacterial Diseases of Geraniums (4/90) 614 Common Viruses of Orchids (5/90) No. 1 • March 27, 1991 616 621 626 634 642 660 661 663 664 815 926 928 929 931 932 933 934 935 936 937 938 940 942 943 960 1105 Bacterial Diseases of Anthurium, Dieffenbachia, Philodendron, and Syngonium (5/90) Anthracnose Diseases of Shade Trees (7/90) Rose Cane Cankers (5/90) Tulip Breaking or Mosaic (9/90) Wood Rots and Decays (11/90) Elm Yellows or Phloem Necrosis and Its Control (New 5/90) Cytospora Canker of Poplars and Willows (New 5/90) Oak Leaf Blister (New 9/90) Phytophthora Root Rot or Wilt of Rhododendrons and Azaleas in the Midwest (New 1990) Sooty Blotch and Flyspeck of Apple (1/91) Mosaic Diseases of Cucurbits (2/91) Scab of Cucurbits (9/90) Fusarium Wilt or 'Yellows" of Tomato (6/90) Onion Leaf Blights (9/90) Onion Pink Root (9/90) Onion Smut (9/90) Asparagus Rust (6/90) Early Blight of Potato (9/90) Late Blight of Potato (7/90) Bacterial Ring Rot of Potato (6/90) Leaf Blights or Spots of Carrots (3/90) Anthracnose and Alternaria Fruit Rots of Pepper (2/91) Gray-mold Rot or Botrytis Blight of Vegetables (6/90) Bacterial Soft Rot of Vegetables, Fruits, and Ornamentals (7/90) White Rusts of Vegetables (9/90) Mycotoxins and Mycotoxicoses (6/90) Copies of these RPDs are 50 cents each; five copies or more are 25 cents each. Checks should be made payable to the University of Illinois and mailed to Extension Plant Pathology, N-533 Turner Hall, 1102 S. Goodwin Ave., Urbana, IL 61801. If you would like to have a copy of the complete listing of all 230 RPDs send a postcard or note to the same address. There is no charge for the list. Home, Yard & Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Permanian, Floyd Giles, James Schmidt, Tom Voigt , and David Williams. Plant Pathology, Nancy Pataky and Malcolm Shurtleff. Agricultural Engineering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. i ■^a/ ^Z^ Roscoe Randell Extension Specialist Entomology i 035 Illinois Cooperative Extension Service Helping You Put Knowledge to Work fe*^ College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME, YARD c GARDEN PEST Newsletter No. 2 • April 10, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Eastern Tent Caterpillar White silk tents in twig crotches of crabapple, hawthorne, mountain ash, flowering cherry, and fruit trees are the homes of eastern tent cater- pillar larvae. These insects have hatched in southern Illinois and will be hatching in central Illinois during the next two weeks, with hatch occurring in northern Illinois in late April. If not controlled, the caterpillars commonly eat all the leaves off an inhabited tree by late spring. Because the caterpillars stay in the silk tent at night and on rainy days, removing the tents at that time will also remove the cater- pillars. Sprays of Bacillus thuringiensis kwstaki, sold as Dipel, Thuricide, and Caterpillar Attack, are also effective and are not toxic to honey bees and other insects, pets, or people. Sapsucker Damage While migrating north for the summer, the yellow-bellied sapsucker, a woodpecker, damages trees in early spring. Previously damaged trees should be protected at this time to reduce further damage. Most woodpeckers rely on insects and tree sap as primary sources of food. Many wood- peckers feed almost entirely on insects, finding most of them beneath the bark on dead tree limbs and in other places where their feeding is considered beneficial. The yellow-bellied sapsucker, however, relies on tree sap for more than half of its food, with the balance of its diet consisting of insects, berries, and fruits. Sapsuckers overwinter in Central America and southern North America and spend the summer in Canada and the northern United States. These birds migrate through Illinois in April and May on their way north. During September and October, they again pass through Illinois, migrating south for the winter. Pines, SDruGe^rbirches, and fruit trees are most cp^trilority attacked; individual trees may \ U State • County • Local Groups • U.S t,?* be attacked year after year. The damage consists of evenly spaced horizontal or vertical rows of holes in tree trunks and branches. Rarely does the woodpecker kill a tree in Illinois; but damage may weaken the tree, making it more susceptible to secondary diseases and insect problems. Control: To reduce damage from these birds, hang objects that reflect light or make noise in the trees, such as pie tins and strips of aluminum foil. Previously damaged areas of the tree may be wrapped with burlap or other protective material during April, May, September, and October to prevent further damage. However, do not leave these wraps on the tree during the summer because the moisture that accumulates under them may encourage disease problems. Winged Termites Winged termites are produced by termite colonies in the spring and are being found throughout Illinois. They are black, with clear wings that are much longer than the body. Including wings, they are about 1/2-inch long. Winged ants appear similar except that they may be black, brown, red, or yellow and their bodies are almost as long as their wings. Winged ants have hourglass-shaped waists and elbowed antennae, whereas termites have thickened waists and curved antennae. The presence of winged termites, usually more than 100, in a building indicates that a termite colony is close enough to attack the building. Thus a termite inspection is recommended. Control: Proper termite control is rarely a do-it-yourself job; contact professional pest control operators. Holes in Lawns Again In one of last year's newsletters, there was a discussion of mysterious holes in lawns. Some causes included the activity of earthworms, cicada killer wasps, periodical cicadas, green June beetles, and crayfish. We do not expect any periodical cicada activity in Illinois in 1991, in fact, very little if any activity before the spring of 1997 in the state. The other possibilities are as follow: • Earthworm activity is usually observed in the spring and fall. Night crawlers emerge to Department of Agriculture Cooperating iol r\nrvnrti initioc in nrnnramc and pmnlnumpnt No. 2 • April 10, 1991 mate and pull decaying organic matter into the soil. The holes will be about 1/2-inch in diameter, with soil piled around the hole. • Cicada killer wasps dig holes during the summer to bury annual cicadas that have been paralyzed by their sting. It is too early in 1991 for this activity to be observed. • Green June beetles are large, 3/4-inch long, velvety green beetles. They emerge from the soil in July. Presently, the immature form resembles any other white grub (except they have the habit of crawling on their back). They live in burrows in soil with a great deal of surface-decaying organic matter. The grubs will emerge to the surface at night and crawl in the turfgrass. This burrowing activity can produce mounds of soil 2 to 4 inches in diameter. Vertical burrows beneath the mounds can be 6 to 12 inches deep. Green June beetle larvae feed primarily on decaying organic matter and can dry out soil areas by their burrowing. • Crayfish are sometimes a problem in wet areas. An exit hole with mud piled about it will be obvious. These are some of the possible causes of holes in lawns this spring, but the most common cause is activity of the green June beetle. Clover Mites Clover mites are tiny, dark red mites that feed on grass. In the early spring and late fall, they commonly enter buildings on the south and west sides where they hide in cracks and crevices. They do not bite or cause any damage indoors, but they can be a nuisance. Control: Vacuum surfaces indoors and spray cracks and crevices around windows with aerosol pyrethroids, sold as sprays for flying and crawling insects. Spraying the outside foundation and adjacent soil with dicofol, sold as Kelthane, will also reduce the problem. Yearly problems with clover mites can be reduced by creating a 12- to 18-inch wide flower bed of tilled, bare soil along the south and west foundations of the building to trap the mites before they reach the building. TURF Annual Grassy Weeds in Turf Many recently introduced turfgrasses are vastly superior to older types, especially in their tolerance to wide ranges of cultural and environmental conditions. Unfortunately, even superior turfgrass cultivars have toleration limits. In most cases, when cultural and/or environmental conditions surpass minimum turfgrass tolerance levels, problems arise. For example, the presence of annual grassy weeds such as crabgrass, goosegrass, barnyardgrass, fall panicum, and yellow foxtail indicate problem growing conditions that allow these weeds to be more competitive than the desirable turf. Management practices that encourage annual grassy weed growth at the expense of turfgrasses include: (1) fertilizing according to soil test recommendations, making sure adequate nutrients are available during periods of active turf growth; (2) watering deeply and infrequently, allowing the soil surface to dry between watering; (3) mowing at the proper height (2 to 2-1/2 inches for most cool-season turfgrasses); and (4) core cultivating, dethat- ching, or power raking, in areas where these weeds are problems during the fall when the turf is actively growing and weed seeds are less likely to germinate. Proper turf management is primary to a weed control program. In some cases, turf is grown in environments that favor weed growth and development. Many annual grassy weeds are more tolerant of wet or compacted soils than are turfgrasses. Altering the growing environ- ment to favor turfgrass can shift the competitive edge away from weeds. The bottom line is that turfgrass breeding, selection, and evaluation has greatly improved turfgrasses. However, even new and improved turf selections are incapable of competing with weeds when mismanaged or planted into unfavorable environments. Control: Maintaining a dense, vigorous turf is the best weed control. Occasionally, herbicide applications are mandated to reduce weed populations to tolerable levels. When annual grassy weeds become a problem, preventive pre- emergence herbicides are often used for control. Several preemergence herbicides are rec- ommended by the University of Illinois Coop- erative Extension Service in the 1991 Illinois Pest Control Handbook. When using pesticides, follow the label directions for the safest, most efficient pest control. Several general recommendations can be made for using these products: • For annual grass control, preemergence herbicides must be applied prior to germ- ination. The soil temperatures necessary for weed seed germination vary by species. For No. 2 • August 10, 1991 example, barnyardgrass germinates at soil temperatures between 72 and 90 degrees F. Crabgrass germinates when soil temperatures are greater than 55 to 60 degrees F. for 7 to 10 consecutive days and continue germinating in soil temperatures to 95 degrees F. The optimum soil temperature for fall panicum germination is 80 degrees F. Goosegrass begins germinating when soil temperatures are above 65 degrees F. for several weeks, and yellow foxtail germinates at soil temperatures of 68 to 92 degrees F. Monitor soil temperature and apply a preemergence herbicide prior to reaching the weed germination temperature. • Conduct any cultivation practices, such as core aerification or dethatching prior to herbicide application. • Water following application according to herbicide label directions. • To lengthen the period of weed control, apply herbicide again at a later date. Follow label directions for rates and timing. • Consult individual preemergence herbicide labels for the specific waiting period between herbicide application and overseeding or reestablishment. Spring seeding can produce stands of quality turf, provided weeds are controlled and adequate moisture is available for summer survival. Only one preemergence herbicide, siduron (Tupersan), is labelled for application to newly seeded areas for annual grass control. All other labelled preemergence herbicides have waiting periods between applications and seeding. Avoid applying a preemergence herbicide immediately before installing sod. PLANT DISEASES Recall of Benlate DuPont, the manufacturer of the fungicide Benlate, has issued a "stop sale and recall" of all DF formulations of Benlate, because some lots have been found to contain small amounts of the herbicide atrazine. Benlate is used to control a number of fungal diseases on many fruits, vegetables, and ornamental plants. DuPont is recalling all lots of Benlate 50 DF, Benlate 1991 DF, and Tersan 1991 DF, even those purchased prior to 1991, to avoid any possibility of the contaminated product being used. Products can be returned to the point of sale for full credit. The recall does not affect the WP formulations of Benlate. At this time it is not known when the fungicide will be available again. DuPont has established a special customer service group to answer questions about the recall. The phone number is (800)441-7515. Depending on the type of plant in question, there may be one or more alternative fungicides that can be used in place of Benlate DF. Bravo and Daconil (chlorothalonil) are broad spectrum fungicides registered for use on some vegetable crops, turfgrasses, and ornamentals. These products are usually more difficult for the home gardener to find. When using fungicides it is important that the specific crop and disease to be controlled are listed on the product label. Not all fungicides are effective against all plant pathogens. It is also important to carefully read and follow the label directions, especially the recommended rate and number of applications, and the interval between the last application and harvest (the days to harvest interval). Leaf Spot Blights and Anthracnose Diseases of Trees and Shrubs Warm weather has speeded up budbreak and leaf expansion in the last 10 days. Controlling these foliar diseases generally requires three sprays: (1) as buds are expanding and opening, (2) 7 to 10 days later, and (3) 7 to 10 days after the second spray. Suggested fungicides include maneb, mancozeb, Topsin M, triforine (Funginex), Duosan, Zyban, dodine, captan, Daconil, and Rubigan. Check label directions. Pachysandra: Leaf and Stem Blight This fungal disease can kill large patches of this popular ground cover especially in beds that are overcrowded, have a heavy mulch, and are mechanically bruised or under stress. Look for chocolate brown, often zoned blotches on the leaves and dark brown to black expanding cankers anywhere on the stem above or below the soil line. Infected stems wither causing the plants to die out in patches. Control: Select only disease-free plants. Plant in a spot that is relatively free of drying winter winds. In dry weather, carefully remove all severely infected plants and prune out all diseased parts of remaining plants. Burn or haul away all dead and infected plant material. Control scale insects and other pests by timely applications of insecticides suggested by Uni- versity of Illinois Extension entomologists. Periodically thin out pachysandra beds to in- crease light and promote better air circulation. No. 2 • April 10, 1991 Protective fungicides include Daconil, maneb, mancozeb, Duosan and Zyban. Five spray applications are needed at about 10- to 14-day intervals starting now when new growth begins. For more information about pachysandra leaf and stem blight write for a copy of Report on Plant Diseases No. 649. Pines, Douglas Fir, and Spruces: Sphaeropsis Blight or Diplodia Tipblight This is a major disfiguring disease of 2- and 3- needle pines and to a lesser degree, various spruces and Douglas fir. It mainly affects trees growing under stress. The most noticeable symptom is a browning, stunting, and twisting of the new shoots and needle growth. Usually the lower branches of a tree are infected first. Young candles that grow from infected buds are often short, bent, and soon die. Infected twigs exude resin, causing stunted, dead needles to stick to the twigs. Dead tissues contain minute black fungal fruiting bodies (pycnidia) in the bark of woody stems, fascicle sheaths, seed cones, and the outer bud scales. Control: Fungicide protection is needed from bud swell to when the needles are half grown. Three or four sprays are needed 10 to 14 days apart, starting just before budbreak. Effective fungicides include Daconil, mancozeb, and a copper fungicide. Follow label directions. For more information about Sphaeropsis blight or Diplodia tipblight write for Report on Plant Diseases No. 625. Rhododendrons and Azaleas: Phytophthora Root Rot, Wilt, and Dieback There are several species of the soilborne fungus Phytophthora that cause this disease. Symptoms include a dull yellowing and dwarfing of leaves and stunted shoot growth. Infected leaves usually roll downward and inward and eventually wilt. Shoot tips, even entire young and mature stems, may wilt and die back. Infected roots are reddish brown and brittle. Control measures include purchasing only disease-free plants from nurseries where strict sanitation and indexing procedures for prop- agation have been followed. The plants should have an abundance of white, healthy roots and good foliage color — free of leaf lesions. Plant in sites protected from wind and direct afternoon sun. Avoid southern exposures. The soil should be light, porous, well-drained, and acid (pH 4.5 to 5.5) with an abundance of organic matter to maintain a relatively constant supply of mois- ture to the roots. For more information on symptoms, disease cycle, and control measures, write for a copy of Report on Plant Diseases No. 664. Plant Clinic The University of Illinois Plant Clinic opens Wednesday, May 1, 1991. Send samples to: Plant Clinic. 1401 West Saint Mary's Road. Urbana, Illinois 61801. The Clinic will not be fully staffed, however, until June 1. Please call (217)333-0519 to make an appointment if you plan to visit the Clinic in May. Please include a check or money order made payable to the University of Illinois. The fees are as follows: Laboratory exam and culturing $5.00 Soybean Cyst Nematode Analysis $10.00 ELISA Viral tests/Fungal test kits $10.00 Pinewood Nematode Analysis $10.00 All other nematodes $20.00 A completed specimen data form should accompany each sample. These forms are avail- able from your county cooperative Extension office or the Plant Clinic. List as much infor- mation as possible on the background of the problem, your care of the plant(s), control measures attempted, symptoms, etc. Remember, the diagnosis can only be as accurate as the information and sample provided. We are more likely to spend time with a sample that has accompanying information. Samples are fre- quently examined by several specialists from different departments. If you have a specific concern, please state this on the data form so your sample can be processed more quickly. Questions on sample submission can be handled by your county Extension adviser. To obtain copies of Reports on Plant Diseases (RPDs), send a check made out to the University of Illinois, to Extension Plant Pathology, N-533 Turner Hall, 1 1 02 South Goodwin Avenue, Urbana, Illinois 61801. There is a 50 cent charge for each Report. Home, Yard fit Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, James Schmidt, and Tom Voigt. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineering, Loren Bode, and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. /Z^&Zf Roscoe Randell Extension Specialist Entomology ^^ OSS Helping You C-fr-z>>. Put Knowledge to V\/ork Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign. Illinois HOME, YARD ^ GARDEN PEST Newsletter No. 3 'April 17, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Black Vine Weevil The black vine weevil will feed on more than 100 different plants, including flowers, weeds, trees, and woody ornamentals. However, the injury has been most severe on Taxus (yew), the roots of which are destroyed by the feeding of the larvae. Taxus capitata seems to be particularly susceptible. Heavily infested plants turn yellow and eventually die if the injury continues. Damage has also been observed on rhododendrons and azaleas but has consisted primarily of foliage injury caused by the feeding of the adult weevils. Injury to Taxus has appeared through- out Illinois. The importance of this pest as an economic insect has increased with the rise in popularity of various Taxus species for ornamental purposes and the corresponding increase in the size and number of Taxus plantings in nurseries. Occasionally, hundreds of plants have been killed with dramatic suddenness after growing to where they are salable for landscaping purposes. Only one generation of black vine weevil occurs outdoors annually. The adults appear during June and early July. This year, insect activity is 14 to 20 days ahead of schedule. They feed on the foliage at night but hide during the day, primarily in debris and loose soil under plants. Egg-laying occurs during July and August on the soil under the plants that adults feed on. As the eggs hatch, the larvae burrow into the soil and feed on the roots. They overwinter in the soil as well-grown larvae and change to pupae in late May or early June. The beetles of this genus are unusual in that no male has been observed. Eggs are deposited without fertilization and only produce females. The beetles cannot fly, so infestations spread slowly from one area to another, although they may spread rather rapidly in a specific area. Adult weevils feed on the foliage but rarely eat enough leaves to create a problem. The typical crescent-shaped feeding wound on the leaf mar- gin is useful in detecting infestation. Plant damage and destruction is caused by larvae consuming smaller roots and strip bark from larger roots. Control: Black vine weevil was controlled in the 1960s by drenching infested plants with a residual insecticide like chlordane. However, the weevils became resistant to this insecticide and now chlordane is not available for plant use. When adult feeding first appears on the foliage, drench with either Orthene or Turcam. Allow spray to wet the soil surface under shrubs to control weevil grubs hatching from eggs. Repeat once or twice at 2- to 3- week intervals until there is no fresh, adult feeding damage. Aphids on Pine Trees Rows of black, shiny eggs on pine needles indicate overwintering aphids. These eggs are hatching or soon will be. The soft-bodied, slow- moving aphids will multiply and suck sap from the needles. Unless aphids are numerous and honeydew excreted by the feeding aphids is present, no control is needed. These aphids can be a pest of Christmas trees which are cut and taken inside. If trees are infested with numerous aphids in late summer or early fall, a spray application con- taining malathion will control them. Sprays containing Cygon applied now or in August will control both these aphids and Zimmerman pine moth on Scotch and Austrian pines. Larder Beetles Larder beetles are 1/4-inch long, black beetles with grayish to yellowish bands in the center of the body. Their larvae feed on the meat of dead animals in nature. In the spring, the adult beetles are active and fly to lights at night, and individuals are common indoors. Finding at least 10 beetles per day indoors usually indicates that the larvae are feeding on dead mice or birds in the walls and chimney. Other indoor food sources include dry or semi- moist pet food. Remove beetles as they are seen; insecticide treatments are rarely needed. Miticides for Use on Ornamentals in 1991 Spruce spider mites can damage evergreens such as junipers, arborvitae, and spruce during State • County • Local Groups • U.S. Department of Agriculture Cooperating The Illinois Coonerative Service ornviries eaual ODDortunities in Droarams and emDlovment. No. 3 • April 17, 1991 the spring months. Miticides available to professional applicators include Kelthane, Tal- star, Omite, Cygon, Morestan, Pentac, Vendex, and Vydate. Kelthane, Omite, Morestan, Pentac, and Vendex may be applied to home plantings or commercial areas (nurseries). Vydate is both an insecticide and miticide labeled for use only on commercial plantings (nurseries). Cygon is a systemic insecticide that is also labeled as a miticide for only a few ornamental crops. Be sure to READ THE LABEL to find out which trees and shrubs can be treated. Pine Sawfly European pine sawfly will be hatching over the next few weeks in Illinois. Larvae will be present when saucer magnolia is dropping its flower petals, when serviceberry is blooming, and when redbud is starting to bloom, according to Don Orton in his book, Coincide, Timing Pest Management with Ornamental Plant Develop- ment (available from the Illinois Arborist Association, Morton Arboretum, Lisle, IL 60532). Pine sawfly larvae are dark green and feed in groups of about 30. The larvae lie along the needles, and are difficult to see. If disturbed, they will raise their front and rear ends in uni- son. They feed on second and third year need- les, but not on needles produced by new candle growth. Finding and treating the larvae as early as possible is important to avoid severe damage. Control can be accomplished by pruning infested shoots if the sawfly numbers are small and found shortly after they hatch. Sprays of carbaryl (Sevin), chlorpyrifos (Dursban), diazinon, and cyfluthrin (Tempo) should be effective. PLANT DISEASES Decline and Dieback of Trees and Shrubs A slowing down of growth and vigor coupled with progressive death of twigs and often branches is a major problem, especially of urban trees and shrubs or others growing under stressful conditions. Symptoms may continue even when corrective practices (proper watering, fertilization, and pruning) are carried out. Decline and dieback may be caused by 19 or more factors and are usually progressive over several years or more. All types of trees and shrubs of any age may be infected by this disease complex, but it usually infects plants that have reached some size and maturity. For details on symptoms, causes, stress factors, identification and control, read Report on Plant Diseases No. 641. The key to control is early detection and prevention. English Ivy: Leaf Spot Diseases This common ground cover is attacked by several leaf spot diseases. The most common is bacterial leaf spot and stem canker. It appears as small, round, dark green, water-soaked (oily) spots on leaves that enlarge into roughly circular to angular lesions with greenish brown, water- soaked margins and reddish brown to black centers. With alternating wet and dry periods, the centers later become dry and cracked. Under warm, wet conditions black girdling cankers form on the stems and petioles. When stem cankers develop, the plant remains dwarfed with yellowish green foliage. The causal bacterium is most often spread by splashing water and people working among wet plants. Fungal leaf spots appear as dry, brown to reddish brown, or grayish white, round to irregular spots that later become sprinkled with dark fungus fruiting bodies (acervuli or spor- adochia). Fungal leaf spots may cause premature defoliation, stem dieback, or even death of plants in scattered patches. Control measures include (1) selecting and planting only vigorous, disease-free plants, (2) removing and burning or otherwise destroying diseased plant parts, (3) removing dead leaves, stems, and other accumulated dead plant debris now, (4) thinning the stand periodically to prevent dense growth, and (5) keeping water off the foliage and spacing plants well. Water early in the day when temperatures are rising so that drying occurs before evening, and avoid splashing water or spraying the plants. Fixed copper fungicides are effective where leaf spots have been severe in the past. Spray several times, 7 to 10 days apart during rainy spring and early summer weather, when new growth is beginning. Cabbage Diseases The early season crucifer crops (broccoli, cabbage, and cauliflower) may begin to show signs of common diseases. If transplanting, it is important to check the plants for disease before planting, as many problems begin on infected transplants. Black rot is a bacterial disease that can infect crucifers at any stage. If cotyledons are infected they turn water-soaked and black, and eventually shrivel and drop. On true leaves, infection often appears as yellow, V-shaped lesions at the leaf margins. As the leaves enlarge, the tissue in the center of the lesions dies and turns brown to black, but No. 3 • April 17, 1991 the margins of the lesions usually remain yellow. In some cases bacterium can enter the vascular system and spread throughout the plant, causing damage to heads or florets. The bacterium can overwinter on infected plant debris, so it is important to remove or destroy any infected plant material at the end of the season, and, if possible, practice a 2- to 3- year rotation schedule. If traces of black rot are found early, spraying plants with fixed copper compounds may help slow the spread of the disease, but it will not control infections that are already established. Avoid working around plants that are wet with rain or dew, because the bacterium that causes the disease can easily be spread in water. The best method for control on cabbage is to plant varieties that are resistant to black rot, including Bravo, Green Cap, Olympic, and Solid Blue No. 770. These varieties are also resistant to Fusarium yellows. For additional information, read Report on Plant Diseases No. 924, Black Rot of Cabbage and Other Crucifers. Crucifer transplants should be carefully scrutinized for swollen or distorted roots which may indicate a disease called clubrool Once established in soil, the fungus that causes clubroot can survive for more than 10 years, even without cruciferous plants, so all precautions should be taken to prevent the introduction of this pathogen. Once established, it is very difficult to control, but using lime to raise the soil pH to 7.2 may help slow development of the disease. For more information, read Report on Plant Diseases No. 923, Clubroot of Cabbage and Other Crucifers. Blackleg is another fungal disease that can infect most crucifers at any time during the season. All parts of the plant are susceptible, but leaf and stem lesions are the most con- spicuous. Early infection will often cause seedling death. Stem infections begin as elon- gated, light brown, sunken lesions at or near the soil line, which gradually spread both up and down the stem, and may eventually girdle the plant, causing the leaves to wilt. Infected areas turn brown to black and small, black, spore-producing structures (pycnidia) form on the dead tissue. The fungus can also attack the leaves, starting as small circular, brown to gray spots that enlarge and become well-defined. With time, numerous black pycnidia develop in the center of the spots. Blackleg may also be carried on transplants. The pathogen can survive on debris in the soil for several years. Control measures include using disease-free transplants, removing or destroying infected material, practicing 2- to 3-year crop rotations, and planting in well-drained soils. For more information, read Report on Plant Diseases No. 955, Blackleg of Cabbage and Other Crucifers. Apple, Crab apple, Pear, Mountain-ash, Firethorn: Scab Dull, smoky spots that change to velvety, olive- green lesions will soon appear on leaves. These spots later turn black and sooty, and are often scaly. Spots also occur on fruit, which may become deformed, cracked, and russeted. Many infected leaves and fruits will drop prematurely. Control: Resistant varieties of apples and crabapples are available. Foliage and fruit need to be protected with fungicide sprays applied at 7- to 10-day intervals starting when the buds first show green leaf tissue. For most of Illinois, this means that at least two sprays should already have been applied. Check Extension Circular 1145 for suggested spray programs. Effective fungicides to control scab on crabapples include triforine (Funginex), Zyban, Duosan, and Rubigan. For more details on apple scab and its control, read Report on Plant Diseases No. 803, Apple and Crabapple Scab. Junipers: Rust Galls The brown, round to kidney-shaped cedar-apple and cedar-hawthorn rust galls will produce conspicuous, orange to brown, jellylike masses in the next 5 to 6 weeks. The masses contain billions of microscopic spores, which blow and infect nearby apple, crabapple, hawthorn, mountain- ash, amelanchier, flowering quince, quince, and related plants. Juniper species, cultivars, and varieties differ greatly in their resistance and susceptibility to these rusts. Control: Hand pick the galls NOW before the spores are released. Starting in early July, spray susceptible junipers four times, 10 to 20 days apart with maneb, mancozeb, Duosan, Zyban, or Bayleton. Follow the manufacturer's directions on the container label. Apple, Crabapple, Hawthorn, Mountain-ash, Amelanchier, Flowering Quince, Quince: Rusts Cedar-rust fungi have been or soon will be ac- tive during rains. Yellow to orange, or orange- red spots (eventually speckled with black) will appear on the leaf surface with creamy white to orange "cluster cups" underleaf. Heavily spotted leaves will turn yellow-orange and drop early. Spray 4 or 5 times, 7 to 10 days apart, be- ginning when the buds open with ferbam (Car- bamate), thiram, Nova, Bayleton, or Rubigan. The last 3 fungicides only require 1 or 2 applications spaced 3 weeks apart. Maneb or mancozeb can be used on all but apples. No. 3 • April 17, 1991 Pines: Dothistroma Needle Blight This disease is common on 2- and 3-needle pines causing brown to reddish brown bands. Minute, black, football-shaped fungus fruiting bodies are later formed in these bands. Infection usually begins on older and lower branches and works upward in later years. Control: Sanitation is important. Spray twice with a copper-containing fungicide. The first spray should be applied when the new needles are just emerging, and the second spray 6 to 8 weeks later when the new needles are fully expanded. For more details, read Report on Plant Diseases No. 624, Needle Blights and Needle Casts of Pines. Pointers for Buyers of New Homes with Trees: • Be sure that root flares are evident at the tree base and show an outward spread at the soil line. If not, the tree may be planted too deep. • Dead twigs and/or branches may indicate root injuries, cankers, wood decay, or other infections. • Pale and thinning foliage or small leaves that may be discolored could mean root rot, Verticillium wilt, gas injury, nutrient deficiency, or other problems. • Multiple trunk scars could indicate careless construction or "aggressive lawnmowers." Was the house built as carelessly? Were the tree wounds properly shaped and cared for? • If the house is built close to a tree, there may be root damage. In less than 5 years you may have a severely crippled tree. • Plaster, bricks, concrete, lime, scraps of wood, and other trash in the soil breed termites and wood decay, and make it diffi- cult to establish and maintain foundation plantings; trash is also an indication of a sloppy contractor. • Rapid twig dieback indicates recent root injuries. • Look for new, large, multiple pruning scars on the trunk or large branches. Why were they cut? Are you in for future trouble? • Any constriction around the trunk (from a wire, chain, fence, or girdling tree roots) strangles the tree, leading to reduced growth, dieback, or even death. • Loose bark at the base of a tree often indicates mower, herbicide, or other damage; wood decay probably has already occurred. • New pavement or other construction over the root zone (which extends far beyond the outer drop line) cuts off air and water from the roots, killing them. Construction damage is also an invitation for infection by the Verticillium wilt fungi and root rots. • Standing water in grass near trees indicates poor drainage. Soil water level changes with construction sometimes causing root rot. Program for Tree Survival The worst problems with urban shade trees is People-Pressure-Disease (PPD). Arborists and urban foresters recommend the following: • Do not disturb the root zone under the branches. • Maintain proper moisture balance. Water thoroughly (the soil should be moist 12 inches deep) during summer and fall. • Maintain oxygen in the soil: avoid soil compaction, poor drainage, overwatering, etc. • Plant disease-free trees properly. Allow plenty of room for the roots to spread out naturally. • Adjust support systems on newly planted trees and remove them as soon as possible. • Provide trunk protection in high-use areas and on young thin-barked trees during the winter. • Prune properly. • Fertilize on the basis of a soil test. • Mulch properly with an organic mulch (leaves, bark chips, or shredded bark, etc.). For more information on PPDs that cause decline and dieback of trees and shrubs, write for a copy of Report on Plant Diseases No. 641, Decline and Dieback of Trees and Shrubs. Copies of Reports on Plant Diseases mentioned in this and other letters are 50 cents each; five copies or more are 25 cents each. Checks should be made payable to the University of Illinois and mailed to Extension Plant Pathology, N-533 Turner Hall, 1 102 South Goodwin Avenue, Urbana, IL 61801. If you would like to have a copy of the complete listing of all 230 Reports on Plant Diseases send a postcard or note to the same address. There is no charge for the list. Home, Yard &. Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, James Schmidt and Tom Voigt. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin East burn. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. /^l^f Roscoe Randell Extension Specialist Entomology Helping You l-t /<--' Gi^BlS ft^^P Put Knowledge to Work ^P Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD ^GARDEN PEST Newsletter No. 4 'April 24, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Oystershell Scale Reports of oystershell infestations have been frequent this spring. The overwintering eggs should hatch by early May in the southern third of the state and by mid-May in the central section. This insect is often found infesting lilac, maple, birch, cotoneaster, and other trees and shrubs. Applications of dormant oil have pro- vided less than satisfactory control. The sug- gested insecticides for control include mala- thion, diazinon, Dursban, and Orthene. Follow the label directions as to rate and mixing. Spray the trunk and limbs thoroughly when crawlers have hatched and are present on the new shoot growth. Iris Borer The iris borer can be a serious problem in home plantings. The insect not only hollows out the rhizomes, but also spreads the bacterium Erwinia carotova, which causes a foul-smelling soft rot. The adult is a moth with dark purplish forewings and yellow-brown hind wings. The insect overwinters as an egg on old iris leaves and debris, particularly at the base of old iris stalks. In the spring, when the iris leaves are 5 to 6 inches high, the eggs hatch and young caterpillars enter the leaves a few inches above the ground, making pinpoint holes as they en- ter. After feeding on the soft tissues between the leaf surfaces, the larvae enter the rhizome, leaving a water-soaked appearance. There is only one generation per year. The iris borer can be partially controlled by removing any old leaves and debris in the fall or early spring. Apply Cygon 2E (4 teaspoons per gallon of water) when irises begin to bloom, but not on the blooms themselves. Make only one application. Adding a small amount of liq- uid detergent to the spray mixture will help improve coverage. Russian Honeysuckle Aphid During spring cleanup, many homeowners are observing the past year's damage to their honeysuckle. The stunted and twisted growth sometimes referred to as "witches-brooming" can be easily observed on susceptible plants. Dam- age from the Russian honeysuckle aphid was first observed in Illinois in 1979 and has rapidly spread over the Midwest since then. This insect can be controlled with monthly sprays of ace- phate (Orthene) or dimethoate (Cygon), starting in late May or early June when leaf-folding is first observed, and continuing until early Au- gust. Although these sprays reduce the damage so that severe witches-brooming does not occur, bushes usually need to be sprayed every year. New plantings of large bush-type honey- suckle in the northern half of Illinois should utilize varieties that are resistant to this aphid. Some resistant varieties are: • Lonicera x notha • L. x muendeniensis • L. x amoena "Alba" • L. x xylosteoid.es • L. tatarica "Arnold Red" ,--- .A % ^ V Arnold Red honeysuckle is quite common in the nursery trade. Malathion Label Changes Many pesticide manufacturers are in the pro- cess of reregistering product labels with or with- out some of the uses of previous labels. A re- vised label for Malathion, a commonly used insecticide for the past 30 or more years, is in the process of being approved by the EPA The basic manufacturer, American Cyanamid, will probably drop many of the past uses of mala- thion for controlling Insects on some fruits and vegetables. Uses to be dropped include those on tree fruit, most brambles, cole crops, melons, squash, and pumpkins. More information on the final outcome of reregistration of malathion will appear later. Woodroaches Woodroaches are now active and coming into homes. These native cockroaches live in mulches and in damp areas with decaying plant material (such as under fallen logs). They mate in the spring and are attracted to lights. Adult males are about an inch long; they are dark brown with cream edging on the front part of State • County • Local Groups • U.S. Department of Agriculture Cooperating The Illinois Cooperative Service provides equal opportunities in programs and employment. No. 4 • April 24, 1991 the body. They have wings and can fly very well. Females are similar in appearance, but do not have cream markings or wings. Once in the home, they will be attracted to lights and eventually to water; in the morning they can be found in the sink or beneath potted plants. They will not reproduce indoors, prefer- ring the outdoors with its damp areas and changing seasons. Overall treatments are rarely needed; eliminate individuals as they are seen. Reducing outdoor lighting and keeping doors and windows shut as much as possible in the spring are good preventive measures. PLANT DISEASES Substitutes for Benlate 50 DF, Benlate 1991 DF, and Tersan 1991 DF 1. The wettable powder (WP) formulations of Benlate and Tersan 1991 may be used; they are not contaminated with atrazine. 2. Cleary's 3336 (liquid and WP formulations available) can be used for all ornamentals be- cause its label is very similar to the Benlate label. 3. Duosan and Zyban (Sierra Chemical) con- tain the systemic ingredient in Cleary's 3336 plus a protective contact fungicide (mancozeb) to give broad- spectrum control. These products are labeled for numerous diseases on 54 plants. House Plant Problems There are relatively few infectious diseases of indoor plants that are bottom-watered. Most problems develop from an excess or deficiency of light, water, or fertilizer as well as from leav- ing plants for too long a period of time in a small container, or in a container without drainage holes. Injury from excess salts appears as a marginal dieback of the leaves and a whitish crusting on the pot rim or soil surface. For control, flush out the salts with water, using six or seven times the soil volume. Re- potting with a fresh soil mix is probably a bet- ter idea. Fertilize house plants lightly and only when they are actively growing. Root and crown rots can develop on all types of indoor plants. When they do, the roots, crowns, and bases of cuttings decay and be- come discolored. Control measures are largely cultural: (1) plant at the proper depth in a light well-drained, pasteurized soil mix; (2) use only containers that exhibit proper drainage; (3) keep plants vigorous by providing the recommended amount of light, water, and fertilizer; and (4) avoid overwatering. If crown and root rots start to develop, apply a fungicide such as Ban- rot or Terraclor Super-X, or a mixture of Truban plus Benlate 50 WP. Full information on con- trolling damping- off and root and crown rots is given in Report on Plant Diseases No. 615, Damping-off and Root Rots of House Plants and Garden Flowers. Plums, Cherries, Mayday Trees: Black Knot Velvety, olive-green swellings on the twigs, branches, and even the trunk will later elongate to about a foot and become rough, coal black, and hard. Affected parts exhibit dieback. If un- controlled, black knot will weaken and kill the Plum black knot tree. If not already done, prune out and burn all diseased wood now. Make cuts 4 to 6 inches behind any signs of the disease. All prunings should be destroyed so that they will not serve as a further source of infection. See University of Illinois Cooperative Extension Service Circular No. 1145 for a plum spray schedule to control black knot, brown rot, and other diseases. For more information, read Report on Plant Dis- eases No. 809, Black Knot of Plums and Cher- ries. Peony: Botrytis Blight Emerging shoots may be dark brown and rotted. Older shoots can wither, collapse, and die from a dark decay both at and below the soil line. The buds turn dark brown, dry up, and fail to open, or the blooms may be spotted brown, watery, and matted. Large, irregular, dark brown blotches may develop on the leaves. Af- fected parts are covered with a dense, grayish brown mold in damp weather. For control, re- move all of the old tops (if you didn't already do so in the fall) and burn or compost the debris. Make cuts about an inch below the soil line. Spray the soil surface as the new shoots emerge. Thoroughly spray the developing shoots at 10-day intervals until just before the blooms open, using Benlate, mancozeb, zineb, Topsin- I M, Duosan, or Zyban. Add a commercial No. 4 • April 24, 1991 3 spreader-sticker (surfactant) to each spray to ensure wetting the foliage. Additional sprays at 2-week intervals after bloom may be needed if the weather is cool and wet. These sprays will also control leaf blotch, bud blast, and shoot blight. In the fall, remove all of the tops, mak- ing cuts about an inch below the soil surface and burn or compost the debris. Also, spray the soil surface in late fall. For additional infor- mation read Report on Plant Diseases No. 623, Botrytts Blight or Gray Mold of Ornamental Plants. Strawberry Leaf Diseases To keep plants vigorous and fruitful, it is impor- tant that the foliage be protected with a fun- gicide film. There are three common leaf dis- eases that weaken runner plants and reduce yields. All three diseases can occur on the same leaf. Leaf scorch develops as small, angular, or irregular dark purple spots on the leaves. Leaf spot resembles leaf scorch at first, but as the lesions enlarge and age, they develop whitish centers. The leaf spot fungus also produces "black-seed" on the fruit. Both leaf scorch and leaf spot develop early in the growing season. Similar spots or streaks may develop on the petioles, stolons, and fruit caps. Leaf blight appears as large, roundish to elongate, reddish purple to dark brown spots. It appears more commonly later as V-shaped blotches on the leaves; the blotches have red- dish or purple margins. Similar spots occur on the sepals or fruit caps. Older leaves are blight- ed and may later die in large numbers. Leaf blight is most common and damaging after the fruit harvest is complete. Grow strawberry plants in full sun in well- drained soil. Avoid spring applications of fertil- izer and matted, crowded beds. Strawberry vari- eties differ considerably in resistance to leaf scorch and leaf spot, and to a lesser extent in resistance to leaf blight. Protect strawberry foli- age from the time the first leaves begin to un- fold in the spring through the harvest period with captan or a mixture of captan and Benlate 50% WP. After harvest, renovate strawberry beds and apply one or more fungicide sprays at 10- to 14-day intervals to keep foliar diseases in check. Apply captan, captan plus Benlate WP, Dyrene, or a multipurpose fruit spray. For fur- ther information on strawberry leaf diseases, write for a copy of Report on Plant Diseases No. 702, Strawberry Leaf Diseases. This leaflet gives the disease resistance of 22 strawberry cultivars to leaf spot, leaf scorch, red stele, Verticillium wilt, and powdery mildew. Strawberry: Gray Mold This is the most serious disease of strawberries, especially during prolonged rainy and cloudy periods. One or several blossoms in a cluster may turn brown and die. Light gray masses of dusty Botrytis spores soon appear. Infections are most common in well-protected areas of the plant where humidity is high and air movement Gray mold on strawberries is poor. Berries resting on soil or touching an- other decayed berry or a dead leaf become soft and light brown with rapidly enlarging lesions. The berry soon dries out, becomes a dark brown "mummy," and is covered with the typi- cal gray, dusty powder. Berries become more susceptible to infection as they ripen. Control measures are the same as for leaf diseases. Avoid heavy applications of nitrogen fertilizer in the spring. Mulch plants and row middles with clean straw, hay, or other dry organic matter, or apply black polyethylene sheeting to keep berries from contacting the soil. Control weeds by applications of herbicides suggested by your Cooperative Extension ad- viser and the Extension pomologist. Pick fruit frequently and carefully early in the day after the plants are dry. Cull out all diseased berries — don't leave them in the field. Fungicide sprays are needed to protect the blossoms and ripening fruit. Suggested fungicides include captan, thiram, Ronilan, Dyrene, or captan plus Benlate 50% WP. Repeat sprays at 7- to 10-day inter- vals through the fruit-ripening period. Follow the manufacturer's directions when applying any pesticide. For more information, obtain a copy of Report on Plant Diseases No. 704, Gray Mold of Strawberries. Turfgrass Diseases Now Active "Helminthosporium" Leaf Spot - This disease can be seen on susceptible turfgrasses throughout the state. "Helminthosporium" appears on leaves and leaf sheaths as purplish black to reddish brown spots that become round or oval. The lesions enlarge and develop light-colored cen- ters. Older leaves or entire plants may later turn yellow, then brown, and die (melting-out) No. 4 • April 24, 1991 from June through August. Many bluegrasses are resistant to this disease. (For further infor- mation on the disease resistance of Kentucky bluegrass cultivars, see next week's newsletter.) Other Kentucky bluegrasses that are resistant to leaf spot include: Admiral, America, Aspen, Aquila, Banff, Birka, Bono, Bristol, Cello, Chal- lenger, Charlotte, Columbia, Eclipse, Escort, Farblue, Galaxy, Holiday, Kimono, Merion, Merit, Midnight, Mona, Mosa, Nassau, Pennstar, Ram II, Shasta, Somerset, Touchdown, Trenton, and Windsor. Five applications of a fungicide may be needed if the rest of April and May is cool and wet. Suggested fungicides include Ban- ner, Bromosan-F, Chipco 26019, Duosan, Dy- rene, Fore or Formec, PCNB (Terraclor 75 per- cent WP), Turficide 10 G and 21 percent EC, maneb, and mancozeb. For more information, read Report on Plant Diseases No. 405, "Hel- minthosporium" Leaf, Crown, and Root Diseases of Tar/grasses. Powdery Mildew - Kentucky bluegrass that grows in the shade is commonly infected with this disease, which appears as a flourlike dust on the leaves. Later, the leaves turn yellow and die, and the turf thins out. Suitable fungicides include Banner, Bayleton and Rubigan. Sprays should go on at 10- to 20-day intervals. A bet- ter means of control is to overseed Kentucky bluegrass in shady areas with a red fescue, which is much better adapted to moderate shade. If the shade is dense, consider growing a shade-tolerant ground cover such as Pachy- sandra, Vinca minor, or English ivy. For addi- tional information, read Report on Plant Dis- eases No. 406, Powdery Mildew of Turfgrasses. Leaf Smuts - Patches of diseased plants are stunted and yellow with long or short, dull gray stripes in the leaves. These leaves soon rupture and release black powdery masses of smut spores. Diseased leaves soon shred, twist, and die. During summer droughts, infected plants die and the turf becomes brown, thin, and re- sembles melting-out, drought, or a thick thatch. Control: Probably the most practical control is to let the patches of smutted plants die dur- ing the summer (do not water) and then over- seed in August or early September with a blend of resistant Kentucky bluegrasses. Another al- ternative is to apply a soil drench of a systemic fungicide such as Banner, Rubigan, Fungo, or Tersan 1991 WP plus PCNB (Terraclor 75% WP). Two applications, spaced two to three weeks apart, are needed in autumn (October or No- vember) just before the grass becomes dormant. The fungicide(s) must be drenched into the soil immediately after application with at least an inch of water (600 gallons of water per 1,000 square feet of turf). Carefully follow the manu- facturer's directions on the container(s). For 4 more details, read Report on Plant Diseases No. 1 409, Leaf Smuts of Turfgrasses. Yellow Patch - This disease is active during very moist weather when temperatures are cool (40° to 60°F). Yellow patch can infect all northern turfgrasses, but is most common in Kentucky bluegrass or perennial ryegrass with a thatch layer an inch or more thick. Look for sunken, light green to yellow green, yellow, tan, straw, or bronze-colored rings and crescent-shaped patches from a few inches to 2 feet or even more in diameter, often with green grass in the centers of the circles. No very effective cultural or chemical control practices have been found. Applications of a nitrogen fertilizer, especially a slow-release form of N fertilizer may be helpful, but reduce the use of nitrogen in the spring. Thatch, of course, should be removed if over 1/2 inch thick. Dethatching machines can be rented at many garden supply and equipment rental stores. For more information, read Report on Plant Diseases No. 411, Rhizoctonia Diseases of Turfgrasses. Reports on Plant Diseases Copies of any Report on Plant Diseases men- tioned in this or other newsletters are 50 cents [ each; five copies or more are 25 cents each. Checks should be made payable to the Univer- sity of Illinois and mailed to Extension Plant Pathology, N-533 Turner Hall, 1102 South Goodwin Ave., Urbana, IL 61801. If you would like to have a copy of the complete listing of all 230 Reports on Plant Diseases, send a postcard or note to the same address. There is no charge for the list. Home, Yard & Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineer- ing, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Ani- mal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology ^£{ res PiftKi Knowledge to Work Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD^ GARDEN PEST Newsletter No. 5 • May 1, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Lawn Grub Review We in Illinois are fortunate not to have some of the white grub species present in lawns in other areas of the United States, especially the North- east. Grubs such as asiatic garden beetle, euro- pean chafer, oriental beetle, and northern masked chafer are not insect pests of turfgrass in Illinois. We do occasionally encounter damage by the black turfgrass ataenius grub on golf courses in the northern third of the state. Japanese beetle grubs have damaged turf in Lake and Cook Counties, while the metallic green adult beetles with coppery brown wing covers can be observed in many locations along the east side of state, from the state's northern boundary to Clark County. Japanese beetle adults emerge from the soil in late June and early July to feed on flowers, shrubs, and some trees such as linden. Japanese beetle larvae or grubs, if a problem, will feed on grass roots in August and successive fall months. This feeding period coincides closely with the feeding damage caused by annual white grubs. The Japanese beetle grub can be identified by the V pattern of bristles on the underside of the tip of the abdo- men; there is simply a uniform pattern of bristles on the underside of the annual white grub. Occasionally, true white grubs can be found damaging patches of turf in June. The timing of this damage does not fit that of the annual white grub or the Japanese beetle grub. The raster pattern for true white grub will be two parallel rows of bristles on the underside of the last abdominal segment. If grub damage is ob- served in June and grubs are present, the con- trol alternatives are the same as for annual white grubs in August and later in the fall. Green June beetles can be mistaken for Jap- anese beetles because of the green color of the adults. From mid-June through August, you may notice large, bright, iridescent green beetles flying with a loud buzzing noise over lawns and around trees. These beetles are the adult green June beetles. The adults are 3/4 to 1 inch long, with a velvety green and yellow-margined upper surface and shiny metallic green below. Adults also have a distinct, small flat horn on the head. The adults often congregate around seep- ing tree wounds or ripening tree fruit. Mated females dig into the turf to lay a cluster of 10 to 30 eggs in a compacted ball of soil, about the size of a walnut. The eggs ab- sorb soil moisture and hatch in 2 to 3 weeks. The young grubs dig to the soil surface, where they feed on organic material, especially decay- ing thatch. The grubs are often active at night, feeding on decaying matter, especially after warm rains. The grubs have an unusual habit of crawling on their back rather than using their legs like other grubs. When the grubs reach 1 inch or larger, they dig temporary bur- rows up to 8 inches deep, and often cast out soil onto the turf surface. By late summer, the grubs are large enough to cause concern from their burrowing and nocturnal migrations. These grubs rarely eat enough turf roots to cause severe damage. However, their burrowing and mound building greatly reduce the aes- thetics of the turf. The grubs also cause con- cern through their nocturnal wanderings. After a rain, they may end up on sidewalks, in the garage, or in ground-level swimming pools. Control: These grubs are generally easy to control if they are feeding on thatch material. Chemical controls are most effective if applied after a rainfall or after a good irrigation followed by a warm night. The grubs can be detected by the mounds they burrow in late August through September. Spring controls are more difficult to time because of erratic migrations and feeding behavior. An application of Sevin will control them. The adult females are attracted to soils with high organic matter and to natural ma- nures or fertilizers when females are laying eggs. The major white grub species in Illinois is the southern masked chafer, which will be dis- cussed in a future newsletter. Indianmeal Moth . The indianmeal moth is one of the most 6$8n- mon pests of stored food products. Theunsect will feed on flour, meal, cereals, bd^^seed^e^ts, and many other similar food itg^$» State • County • Local Groups • U.S. Department of Agriculture Cooperating Tl-./-. lllin/-.ir- Pr.^noritiiio Con/if-o nrnviHoc onual nnnnrti initioc in nrnnramt; 3nH Amnlnvmfint. *' .* ss .**' & & * \N>> v^ No. 5 • May 1, 1991 The adult moth is approximately 3/8 inch in length, with a wing span of about 3/4 inch. The outer two-thirds of the front wings are copper colored, while the inner one-third appears gray. The larvae are dirty white and about 1/2 inch in length. The insect can complete its entire life cycle in 1 to 2 months. The adult moths are common around lights and may rest on the ceilings or walls of the kitchen and adjoining rooms. The larvae spin a silken web over the surface of the infested ma- terial, and the mature larvae generally leave their food source in order to pupate. The larvae are frequently seen around cupboards, walls, or ceilings. Control of the indianmeal moth can be achieved by discarding any infested packages. If food is to be stored for long periods, it should be transferred to airtight glass, metal, or plastic containers. Some products can be stored in the refrigerator, and nonhuman food (for example, bird seed) can be frozen for 3 to 4 days in order to kill the moth eggs and larvae. Remember to clean and vacuum food cabinets and shelves thoroughly and to clean up any spillage as soon as possible. Deer Tick Adult deer ticks are being found on people in northern Illinois this spring. They are about 1/8 inch in diameter and usually reddish in color. Both this stage and the nymph stage can trans- mit Lyme disease to humans. Nymphs will start appearing in May and will be present most of the summer. They are much smaller than the adults, being the size of a pinhead. As with all ticks, deer ticks are most likely to attach to the skin on the lower body. The nymph tends to attach in the groin area. Deer ticks are most likely to be picked up in the northwestern and northcentral portions of Illinois, although occasional ticks have been found in other parts of the state, particularly in the northern half. There is some evidence to suggest that other species of ticks can occa- sionally transmit Lyme disease, although this is very rare. To be on the safe side, precautions should be taken against ticks whenever one is out in natural areas, particularly wooded areas. Protect yourself from deer ticks and other ticks by wearing long pants and tucking your pantlegs into your socks so that the ticks can- not reach your skin easily. Wear light-colored clothing so that the ticks can be seen more easily. Apply an insect repellent containing DEET to your skin, particularly your lower legs and ankles. Clothing can be sprayed with Per- manone, an insecticide that will kill any ticks that get on the clothing. Every few hours, check yourself for ticks, particularly at the end of the day. Ticks need to be attached for at least 24 hours to transmit Lyme disease. If ticks are found, grasp the head where it enters the skin with tweezers and pull it out slowly and steadily. Apply an antiseptic to the bite. If tweezers are not available, pull the tick out with your fingers. Protect the skin of your fingers from any tick secretions by using a tissue. Other methods of removing ticks usually kill the tick, resulting in part of it remaining in the wound. You may wish to save the tick for identification by putting it in rubbing alcohol. Millipedes Millipedes are close relatives of insects. They are usually black or brown, wormlike, and hard shelled; they are slow moving with many short legs. Because they feed on moist, decaying, organic matter, they may be numerous in ac- cumulations of dead leaves and bark mulches along house foundations. They commonly enter the house, usually dying within a few hours from lack of moisture; but their dead, coiled bodies all over the basement floor can be a nuisance. Control millipedes by reducing the moisture and organic matter next to the house. Caulking cracks and crevices in the foundation will also help reduce their numbers indoors. If the base- ment is very damp, try to reduce the moisture through ventilation or a dehumidifier. Pesticides are not very effective against these pests. PLANT DISEASES Strawberry: Diseases In Home, Yard & Garden Newsletter No. 4 we discussed leaf diseases and Botrytis blight or gray mold. Other diseases are now active. Powdery Mildew. This disease can be seen now as a rolling upward of dull gray or purplish red leaflets that may be scorched at the mar- gins. Buds, flowers, fruit, fruit stems, and underleaf surfaces may be covered with a thin, whitish gray mold. Control: Strawberry cultivars differ in resis- tance (see Table 1). Damage by powdery mildew is usually not serious enough to warrant fun- gicide applications. Red Stele. This root disease, caused by a soilborne, water-mold fungus, is serious when- ever poorly drained soils are saturated with water in cool weather (conditions such as we had in April). Check now for wilting and dying plants with few new roots. The central core i No. 5 • May 1, 1991 Table 1. Disease Resistance of Strawberry Cultivars Commonly Grown in Illinois" Red Verticillium Leaf Leaf Powdery Cultivar stele wilt spot scorch mildew Allstar VR R R R R Canoga I I R R - Cardinal S S R R R Catskill S VR S R R Delite Rb R R S-R S Earliglow Rb T-R S-R R I Guardian Rb T-R S-R R S-R Honeoye S S R R - Jewel S S R R - Lester R R R R R Midway Rb S-I S S I Pocahontas S S S-R S-I R Raritan s S S S I Redchief Rb R S-R R S-R Scott R 9-R S-R R R Sparkle S-R S S S-I R Sunrise Rb R VS R R Surecrop Rb VR S-R S-R - Tennessee Beauty S R R S-R S Everbearing Tribute VR T-R T T R Tristar R R T T R aVS = very susceptible; S = susceptible; I = intermediate; T = tolerant; R = resistant; VR = very resistant; - = unknown. Resistant characteristics of the cultivar usually preclude the need for other controls. bResistant to several races of the red stele fungus. (stele) of roots in an infected plant will be brick red or brownish red instead of yellowish white as in a healthy plant. Later in the season, the red discoloration disappears as the rotted roots are replaced by new ones. Control: The only practical control is to grow certified, disease-free plants of resistant cultivars (see Table 1). Additional information is given in Report on Plant Diseases No. 701, Strawberry Red Stele Root Rot. Verticillium Wilt. This root disease is caused by a widespread, soilbome fungus that attacks about 300 cultivated plants. Older and outer leaves wilt, collapse, turn reddish yellow or dark brown, and often curl up along the midvein. Plants are often stunted, dry, and flattened and have small yellowish leaves. Brownish to bluish black streaks may form within decaying crowns and roots. Control: As for other root diseases, it is important to plant in fertile, light, well-drained soil. Set out certified, disease-free plants of tolerant or resistant cultivars (see Table 1). For more information, read Report on Plant Dis- eases No. 707, Verticillium Wilt of Strawberry. Leaf Variegation or June Yellows. This dis- order (of unknown cause) appears on young leaflets as irregularly mottled, streaked, golden or pale yellow-to-white and light green areas. Symptoms occur mostly in cool weather. All runners and daughter plants produced by dis- eased plants are also variegated. Seemingly healthy green plants may become variegated at any stage. As the disease progresses the symp- toms increase in intensity. The leaves become more mottled each year until they are complete- ly golden yellow-to-white and frequently puck- ered or otherwise distorted. Plants become dwarfed and unproductive. Affected plants never recover and usually die within 2 or 3 years. Control: DO NOT propagate from variegated mother plants. If there are only a few variegated plants in a new or established planting, remove and destroy them when first detected. Purchase only certified, virus- and other disease-free plants from a reputable nursery. For more infor- mation read Report on Plant Diseases No. 706, Leaf Variegation or June Yellows in Strawberries. No. 5 • May 1, 1991 Table 2. Modern Kentucky Bluegrass Cultivars Adapted to Illinois and Reported to Be Moderately to Highly Resistant (R)* to One or More Diseases1" Leaf Summer Kentucky Helmintho- and pate h or Septoria bluegrass sporium Leaf stem necrotic Dollar Typhula leaf Red cultivars diseases smuts rust ring spot spot blight spot thread A-20 R R R R R R A-34 (Bensun) R R R R Adelphi R R R R R R R R Baron R R R R R R R Bonnieblue R R R R R R R Brunswick R R R R R Cheri R R R R R R Enmundi R R R R R Enoble R Fylking R R R R Geronimo R R R R Glade R R R R Majestic R R R R R R R Monopoly R R R R R Nugget R R R R R R Parade R R R R R R Plush R R R R R Rugby R R R R R Sydsport R R R R R Touchdown R R R R R Vantage R R R Victa R R R R R aA resistant (R) rating does not mean that a particular cultivar will be resistant in all locations every year. Due to the presence of physiological races or strains of the various fungi that cause these diseases, a cultivar may be susceptible in one locality and highly resistant in another. This is especially true of powdery mildew and is the reason we omitted this disease from our ratings. bA blank under a given disease does not necessarily indicate susceptibility. In some cases it means that no data are available on which to evaluate the relative susceptibility or resistance to a particular disease. Kentucky Bluegrass Cultivars In last week's newsletter, we discussed various turfgrass diseases. Table 2 refers to these dis- eases and lists the relative resistance of sug- gested Kentucky bluegrass cultivars. Reports on Plant Diseases To obtain copies of Reports on Plant Diseases (RPDs), write to Extension Plant Pathology, N-533 Turner Hall, 1 102 South Goodwin Avenue, Urbana, IL 61801. There is a $.50 charge for each RPD, or $.25 each in orders of 5 or more (any variety). Please make checks payable to the University of Illinois. Home, Yard 8l Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineer- ing, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology Q» Helping You Put Knowledge to Work Co*.^ Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD ^GARDEN PEST Newsletter No. 6 • May 8, 1991 This newsletter is issued weekly to provide timely infor- mation on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe stor- age and disposal of pesticides, and other topics of interest are discussed. INSECTS Annual White Grub: Biology and Management In last week's newsletter, we discussed lawn grubs, but southern masked chafer, also called annual white grub, was not included. Most of the lawn grub problems in Illinois each year are caused by this species. Probably more than 90 percent of the grub damage in home lawns, golf course fairways, and other high-quality turf- grass areas is the result of annual white grubs feeding on the roots of the sod. Annual white grubs are now full-sized, C- shaped, white worms with legs and brown heads. Anyone spading in grass areas can ob- serve an occasional one in the soil. The full- grown grubs will move down 4 to 6 inches in the soil to pupate later this spring in formed cells. The pupa is a resting stage prior to trans- formation into an adult beetle. Tan, 1/2-inch beetles begin to appear in June and can be ob- served around lights, on window screens Annual white grubs or on sidewalks. The annual white grub adult < does not feed, but only mates; the adult female lays eggs in turfgrass areas. Egglaying is at its ; peak during the first two weeks of July. Eggs are most commonly laid between 9:00 p.m. and State • County • Local Groups • U The Illinois Cooperative Service provides 1:00 a.m., with the peak from 10:30 to 11:00. More eggs are deposited in warm soil areas, such as next to sidewalks, driveways, and streets. Open areas free of trees and shrubs are preferred, and moist soil is favored over dry soil in which to bury the eggs. Egghatch occurs in July. The earliest damage from a new generation of annual white grubs is approximately 5 weeks after egglaying, usually August 15 to 20. In summary, in central Illinois annual white grubs hatch from eggs laid in early July and increase in size and number to cause the first damage in mid- to late August. The biological cycle of annual white grubs occurs about 2 weeks earlier in the southern third of the state and two weeks later in the northern third. Annual white grub management is most suc- cessful when the biology of the grub is under- stood. There is no reason to treat a home lawn for annual white grubs in the spring. Adult egglaying can be easily observed in July; and grub feeding activity, if present, can be first ob- served in late August and September. Ten to twelve grubs per square foot will prune the roots of sod and cause it to wilt under heat and drought stress. Higher numbers can cause ac- tual damage to plants. Control: Insecticides containing milky dis- ease (sold as Japademic, Doom, and Grub At- tack), while effective on Japanese beetle grubs, do not control annual white grubs. Homeowners can purchase and apply diazinon. The granular formulation is preferred. Lawn care companies and other commercial applicators have several effective grub control materials available for their use. Triumph, Dylox, Proxol, Turcam, and diazinon are suggested. Regardless of who makes the application or which product is ap- plied, the material needs to be drenched into the soil surface so that the upper inch of soil is wet. There will be more information on grub management and outlook in future newsletters. Aphids on Pine Various kinds of aphids found on different spe- cies of pine are being reported around the state. These insects rarely cause much damage to the tree; although the honeydew, a clear, syrupy solution that they produce, can be a problem. Control these insects with sprays pJLmalathion, diazinon. or acephate t^flffi^toffiSF MAY 1 0 1991 S. Department of Agriculture Cooperating equal opportunities in programs and H«0^/CQC1TY OF ILLINOIS No. 6 • May 6, 1991 Spruce Galls Galls on spruce are usually caused by close relatives of aphids called adelgids. The Cooley spruce gall is about 1 inch long and occurs on the ends of branches. The closely related eastern spruce gall is about the same length but forms farther back on the twig, resulting in the end of the twig sticking out of the end of the gall. Usually the end of the twig is killed by the gall, making the gall and twig look like a long-necked bottle. These galls form in late spring out of stem tissue; they are green at first, turning brown later in the summer. They look similar to the cones of the tree, except that there are needles sticking out of them. When the galls turn brown during the sum- mer, holes open up along the needles, allowing the adelgids inside to escape. These insects lay eggs on spruce, and Cooley spruce gall adelgids may also fly to Douglas fir to lay eggs. The eggs hatch into nymphs that overwinter on the twigs. The following spring, the nymphs mature into adults that lay eggs for a spring generation. Nymphs that hatch on Douglas fir feed on the needles and develop into small, white cot- tony insects that never cause a gall to form. These insects can be controlled at any time during the summer with sprays of malathion, diazinon, acephate (sold as Orthene), or insec- ticidal soap. Nymphs that hatch on spruce feed on the stems, causing the stem tissue to swell and form a gall that encloses the insect. Once this gall forms, the only control is pruning off the green galls before they turn brown and split, releasing the adelgids. These insects can be controlled on spruce in the spring when the new growth is elongating before the insects have caused the gall to form. They can also be con- trolled in late September when the nymphs are feeding prior to overwintering. Sprays of mala- thion, diazinon, acephate (sold as Orthene), and insecticidal soap should be effective at these times. Oystershell Scale Oystershell scale is an elongate, 1/8-inch long scale that is wider at one end, giving it an oystershell shape. These insects are common pests on lilac, ash, maple, willow, and a variety of other trees and shrubs. They can build up to numbers large enough to kill twigs and branches. Scales that overwinter as nymphs or adults can usually be controlled with dormant oil sprays. Scales, such as oystershell scale, that overwinter as eggs are difficult to control with dormant oil. These scales can only be controlled with certainty with crawler sprays. The scale crawler is the first-stage nymph that hatches from the eggs. Crawlers have legs, a antennae, and eyes; they do not have the waxy f covering that will protect later stages from in- secticide sprays. After crawling around on the plant, the crawler settles down and molts into the next nymphal stage, producing a protective waxy covering and gradually losing its legs, eyes, and antennae over successive growth stages. Scale crawlers are susceptible to sprays of malathion, diazinon, acephate (sold as Orthene), insecticidal soap, and other insecticides for about 10 to 14 days. These crawlers were re- ported from central Illinois by Nancy Pataky at the Plant Clinic on May 2, and should be ap- pearing in northern Illinois within the next week or two. According to Don Orton in Coincide, the crawlers are present when Spirea x vanhouttei is in full to late bloom. On May 2 in central Illi- nois, this spirea was just entering full bloom. This is approximately one month earlier than we normally see crawlers of this scale insect in central Illinois, and illustrates the value of using the stage of plant development, or phenol- ogy, as described in Orton's book, particularly in a year like this one in which plant and insect development is earlier than normal. Honeylocust Plant Bug Distorted foliage on honey locust is usually caused by honeylocust plant bug in the spring. These insects hatch from eggs shortly after honey locust bud break. They feed for about 6 weeks on the foliage and stems of the tree, lay- ing eggs into the young stems of the honey lo- cust in late May and June. Fully grown honeylocust plant bugs are green and about 1/2 inch long. Nymphs are also green, but much smaller. Due to their small size, the nymphs are rarely controlled be- fore considerable leaf damage has occurred. Greg Smith of Arborsmith reports that these nymphs first appeared in Champaign during the first week of May. One or more nymphs per compound leaf is usually enough to cause damage. Sprays of ace- phate (sold as Orthene), cyfluthrin (sold as Tem- po), and bifenthrin (sold as Talstar) are effective controls. Pine Sawfly Pine sawfly larvae in central Illinois are about 1 inch long. Control of this insect may still be needed in central and northern Illinois. Refer to Home, Yard & Garden Newsletter No. 3, April 17, 1991, for the biology and control of this | insect. No. 6 • May 6, 1991 Ants Ants are frequently a problem indoors during the spring. Nests in the soil that are close to foundations are warmed by the heat of the building, causing ants in these nests to become active earlier than those in nests that are lo- cated away from buildings. The outside air tem- perature is usually too low for these ants to for- age much outdoors, so they follow the source of heat indoors, becoming a nuisance. The most common of the ants that come in- doors is aptly named the pavement ant, Tetra- morium caespitum. These ants commonly nest in the soil along foundations, and the workers come indoors. These workers are wingless, dark brown, and about 1/8 inch long. Control can be obtained in a variety of ways. Long-term control is possible by caulking cracks and crevices in the foundation. Sprays of diaz- inon or chlorpyrifos (sold as Dursban) on the outside foundation and adjacent soil are also effective. Indoor sprays of propoxur (sold as aerosol ant and roach sprays) or chlorpyrifos (sold as aerosol crack and crevice sprays) along baseboards and into other cracks and crevices are also effective. Recently, the development of slow acting baits that ants carry back to the colony have added another indoor control of ants. These in- clude ant traps containing hydramethylnon (sold as Combat) and sulfluramid (sold as Raid Max Ant Bait). Liquid ant baits, such as Terro ant bait, are also effective in poisoning the nest. Terro containing arsenic was available for many years, and has recently been replaced with a formulation that contains boric acid as an in- secticide. TURF Controlling Broadleaf Weeds in Turf The yellow dandelion flowers currently seen in large numbers are often welcomed by children as harbingers of spring. To turf managers, how- ever, actively growing dandelions and other broadleaf weeds signal the need for control. Weed invasions can be minimized through proper turfgrass management. Consider use, site, and budget when selecting an appropriate turfgrass for your conditions. Follow correct se- lection by appropriate mowing, watering, fertiliz- ing, and cultivating, which can produce a dense, healthy turf. Reduced weed populations result because weeds have difficulty becoming established in healthy, competitive turf. In areas where broadleaf weeds are already a problem, initiate controls. Mechanical removal of weeds by hand-pulling or hoeing can elimi- nate small numbers of weeds easily. Be sure to remove as much of the root system as possible to reduce regrowth of perennials. Postemergence herbicides can also provide effective control now during active weed growth (see the 1991 Illinois Pest Control Handbook for recommendations). Individual herbicides or combinations of these herbicides are available. Be sure to read and follow the label direc- tions for proper use of these chemicals. If mishandled or misapplied, these herbicides may damage or kill many desirable ornamental or edible plants in the landscape. Follow these general recommendations when using post- emergence broadleaf products: 1. Apply these herbicides when environmen- tal conditions are appropriate for control. • Watch wind speeds to avoid drift. Often, air is stiller in early morning than later in the day. • Apply these herbicides when air tempera- tures are between 65° and 85°F. • Adequate soil moisture is important to maintain growth and translocation of herbicide throughout the entire weed. • Do not apply when precipitation is ex- pected within 24 hours. 2. Do not mow for several days prior to or following application. This allows maximum leaf surface for interception and absorption of the herbicides. 3. To reduce unnecessary pesticide use, when possible make spot applications rather than treatments of large areas. 4. Apply these herbicides to new turfgrass seedlings only after they have been mowed four times. Wait at least 30 days following applica- tion before seeding into areas treated with post- emergence broadleaf herbicides. 5. Many broadleaf weeds can also be treated effectively during active growth in autumn. Do not ignore treatment during fall when broadleaf weeds are a turf problem. PLANT DISEASES Pine Problems Pine wilt disease, the most serious disease of pines in the Midwest, is caused by the pine- wood nematode. In Illinois the nematode is transmitted from pine to pine principally by the Carolina pine sawyer and southern pine engrav- er beetles after the beetles emerge from hiberna- tion in dead or dying pines from NOW to early autumn. Nematode transmission occurs when No. 6 • May 6, 1991 the long-horned beetles feed on first- and second-year twigs of pines. Although virtually all species of pines growing in the Midwest are known hosts of the nematode, Scotch pine is by far the most commonly infected species. The disease is much less common in Austrian and jack pines; infrequent in red, mugo, and loblolly pines; and extremely rare in white pines. The disease usually hits older pines growing under stress conditions. The needles on entire pines turn light gray- ish to yellowish green, then a yellowish brown, and finally reddish brown or brown. Most trees decline and die within a few weeks or months. Pines infected late last year are now showing symptoms, usually with one or more dead branches (flags). Large, old Scotch pines die from the upper crown downward. Total death of such trees may take up to a year. Control: Remove dead and dying trees to the ground line or deeper as soon as possible. Do NOT store the wood for firewood. Burn or bury the trees to prevent beetle emergence. There are no practical chemical controls. Suitable replace- ments of dead pines (with conifers where de- sired) include Norway or blue spruce, Douglas fir (southwest seed source), cedar, or hemlock. There are no known resistant cultivars within very susceptible species of pines. For more in- formation obtain a copy of Report on Plant Dis- eases No. 1104, Pine Wilt Disease. Cyclaneusma (Naemacyclus) needle cast is a disease of Scotch pine causing early dropping of needles. Light green spots appear on 2- and 3- year-old needles in September. The spotb later enlarge, and the needles, which turn yellow, develop dark brown horizontal bands. From October to May the yellow needles drop off and cream-colored, waxy fruiting bodies form on the fallen needles. The fruiting bodies swell and split open in wet weather. Scotch pines of ail ages are susceptible to infection. Most trees be- come infected between mid-April and late June. Control: Apply a registered, preventive fun- gicide (such as a fixed copper, mancozeb, maneb, or Daconil) every 2 to 3 weeks between mid-April and late June. Start before Scotch pine buds open. This program gives only about 50 percent control. For complete control, con- tinue the spray schedule into late fall (not prac- tical even for Christmas tree growers). Northern European seed sources are more resistant than the Mediterranean sources. Avoid planting next to old Scotch pines. Tulips: Fire or Botrytis Blight This very common and serious disease attacks all parts of the tulip plant. Emerging plants are stunted and have twisted and blighted leaves. Tulip fire Minute yellowish brown spots with a dark, water- soaked border form on the later emerging leaves and stems. These lesions enlarge rapidly in wet weather, turn whitish gray, and may involve part or all of a leaf. Flow- er buds are spotted and may fail to open. Whitish or tan spots form on flower petals, which may enlarge rapidly in damp weather to completely blight flowers. All infected parts are covered with a dense, fuzzy gray mold in damp weather. Control: Purchase only the largest, blemish- and disease-free bulbs available. Plant tulips in the same location only once in 3 years or more. The site should be sunny with good air and soil drainage. Avoid a wet mulch and overwatering. Fertilize based on a soil test. Dig bulbs carefully in dry weather no later than 3 weeks after the petals have fallen. Discard all spotted, damaged, or moldy bulbs. Dry and clean the bulbs promptly and store in thin layers in a dry, well- ventilated location. Collect and destroy all leaves, stems, and blossoms as soon as bloom- ing is over. Carefully remove and destroy all infected plants and plant parts when first noticed. Fungicide sprays are effective starting when the leaves emerge from the soil. Several sprays are needed at 5- to 10-day intervals and should continue to early bloom. Suggested fun- gicides include Botran, Daconil, Benlate, man- cozeb, Omalin, and Chipco 26019. Botran and Benlate help control when applied as a soil drench at planting time and again just before emergence. For much more information, read Report on Plant Diseases No. 609, Tulip Fire or Botrytis Blight Greenhouse Plants: Rhizoctonia Stem and Crown (Foot) Rot Specimens of various greenhouse plants have been received at the Plant Clinic with sunken, well-defined, reddish brown to dark brown le- sions at or close to the soil line. Under moist conditions, the weblike brown hyphae of the fungus can be seen coming from the lesions. Rhizoctonia is also a common cause of damping- off of seedlings and, under favorable conditions, may produce a root rot of mature plants. Infec- tion is favored by an intermediate moisture range and warm to hot temperatures. The fun- gus is found in all natural soils, where it can No. 6 • May 6, 1991 survive indefinitely as small, round to egg-shap- ed, brown to black sclerotia. Control: Purchase ONLY top-quality seed and treat the seed with Captan plus Apron. Buy disease-free, vigorous plants from a reputable nursery. The plants should be grown in a light, well-drained, pasteurized soil mix. Fungicides applied as a soil drench are effective in control- ling damping- off and crown and root rot. Rhizoc- tonia- effective fungicides include PCNB, 75% WP (Terraclor, Fungi-clor, PCNB), Chipco 26019, Benlate 50% WP, Topsin-M, Banrot, and SA- Terraclor Super-X. Treatment is only effective as a preventive measure or at an early stage of infection. For additional information on control of Rhizoctonia and other soilborne diseases, read Report on Plant Diseases No. 615, Damp- ing-off and Root Rots of House Plants and Gar- den Flowers. Many Trees, Shrubs, Flowers, Vegetables: Verticillium Wilt This serious disease affects more than 300 host plants, including many weeds. The two soil- borne fungi are active NOW, invading plants through wounds above or below ground. Once introduced into soil, the fungi can survive for 5 years or more. Symptoms include the wilting, yellowing, and death of leaves and the death of branches or entire plants. Chronic symptoms may follow, including stunted, chlorotic, and deformed foliage; leaf scorch; slow growth; ab- normally heavy seed crops; and the dieback of shoots and branches. The vascular tissue is dis- colored, usually light-to-dark green, a shade of brown, or black. Resistant varieties are available for a few plants, such as strawberry (see Report on Plant Diseases No. 707, Verticillium Wilt of Strawberry) and tomato. Fertilizing to promote vigorous growth and watering thoroughly will often aid affected trees and shrubs. Soil treat- ment with steam or a preplant soil fumigant (containing chloropicrin) is necessary for bench crops in the greenhouse and nursery. Do NOT grow susceptible crops on land where crops susceptible to Verticillium wilt have been grown previously. A rotation of 5 years or more for vegetables and flowers may help to reduce the amount of inoculum. For more information, in- cluding lists of susceptible and nonhost crops, plus additional control measures, read Report on Plant Diseases No. 1010, Verticillium Wilt Disease. Tomato: Leaf Blights Early blight appears as light to dark brown, round to angular spots with concentric rings. Similar spots may form on the shoot and flower stems. Septoria leaf spot or blight is common following cool, moist weather. Look for numer- ous small, round spots with dark margins and tan to white centers. These spots will later be sprinkled with black dots (pycnidia of the Sep- toria fungus). Spots also form on the petioles, blossoms, shoots, and flower stems. Both of these common leaf blights cause the leaves to yellow, wither, and drop early in large numbers, usually starting at the base of the plant. Fruit size and quality may be greatly re- duced. These diseases usually become evident about the time the first blossoms form. Control: Spray weekly with chlorothalonil (Bravo), Dyrene, or mancozeb, starting a week or two after transplanting. Staking or caging plants and providing good air circulation and all- day sun will help reduce these and other foliar diseases as well as a variety of fruit rots. Varieties with some resistance to early blight include Floramerica, Jetstar, Manalucie, Roma VF, and Supersonic. For more information, read the newly revised Report on Plant Diseases No. 900, Controlling Diseases in the Home Vegetable Garden. Plant Clinic: Collecting and Submitting Samples for Diagnosis Accurate diagnosis depends on two factors: (1) the rapid receipt of a fresh, representative plant sample with the observed symptoms, and (2) the completion of a specimen data form for each sample. Dead plant material or decomposed plant tissue is of little or no value in diagnosis; these samples will not be diagnosed. Samples that arrive without a completed specimen data form will be handled as time is available; sam- ples without accompanying identification will be discarded. Collecting Samples 1. Disease types: Leaf: Collect early and late stages of infec- tion. Fleshy plant parts: Samples with a rot dis- ease should not be sent in an advanced stage of decay. Collect fresh specimens with early symptom development. Cankers: Select cankers that were produced recently. Submit the entire cankered portion if possible, preferably with healthy wood above and below the canker. Wilt or general decline: If feasible, send the entire plant, with roots intact; submit several plants, ranging from healthy to severely in- fected. So that diseased roots will remain in- tact, dig— do not pull— plants from the soil. If 6 No. 6 • May 6, 1991 you cannot send the entire plant, select sam- ples from areas of active symptom develop- ment. Include the intact root system if root rot is suspected. Turf: Submit several 4-inch plugs of grass that are cut as deeply as the roots will hold soil. Plugs should show a gradation from healthy to severely diseased grass. 2. If air pollution injury is suspected, the pol- lutant or possible local sources of pollutant should be noted on the specimen data form. 3. Diseases caused by nematodes require spe- cial attention. See Report on Plant Diseases No. 1 100 for detailed instructions on hand- ling and shipping nematode-infested material. 4. For fertility- induced problems, send soil sam- ples taken according to prescribed proce- dures to a private laboratory for analysis to determine possible nutrient deficiencies or excesses. Except in nematode-caused dis- eases, soil samples are of little value in diag- nosing parasitic diseases. Submitting Samples 1. Disease types: Leaf: Press the dry leaves between heavy paper or cardboard. Fleshy plant parts: Wrap individually in newspaper or paper toweling; pack in a crush-proof box. Do NOT add moisture to the samples. Cankers: Wrap loosely in paper and ship in a crush-proof mailing tube or box. Wilt or general decline: If the whole plant is submitted, wrap the root ball tightly in plas- tic; send the entire plant in a crush-proof container. To send excised diseased areas, follow the instructions for mailing cankers. Turf: Plugs should be collected and sent quickly. If mailing the samples, pack plugs tightly with newspaper in a crush-proof box or plastic bag. Do NOT add moisture to the sample. 2. Nematode-infested samples should be ship- ped as directed in Report on Plant Diseases No. 1100. 3. If different plant species or samples are sent in the same mailing container, label each sample separately and keep the labels away from moisture. Include a specimen data form for each sample. 4. Enclose the completed specimen data form with the sample. Keep one copy for your files. 5. Mark the container: ' Plant Sample— Perishable 6. If samples are mailed, mail them early in the week whenever possible. Early mailing will help reduce the likelihood of samples decom- posing in the post office over the weekend. Keep the samples cold until they are mailed. NOTE: Diagnosis and recommended controls by the University of Illinois Plant Clinic are based solely on the material and information sub- mitted. The less representative the sample and the less complete the information provided, the greater the chance for misdiagnosis. Reports on Plant Diseases Copies of any Report on Plant Diseases men- tioned in this or other letters are 50 cents each; five copies or more are 25 cents each. Checks should be made payable to the University of Illinois and mailed to Extension Plant Pathology, N-533 Turner Hall, 1102 South Goodwin Ave., Urbana, IL 61801. If you would like to have a copy of the complete listing of all 230 Report on Plant Diseases, send a postcard or note to the same address. There is no charge for the list. Home, Yard & Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Wiiliams. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Agricultural Engineer- ing, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Ani- mal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology U25 Helping You Put Knowledge to Work Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD ^ GARDEN PEST Newsletter No. 7 • May 15, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Bronze Birch Borer Bronze Birch Borer Bronze birch borer feeds underneath the bark of most kinds of white-barked birches, eventually killing the tree. Because this insect tends to \ attack the top of the tree first, the early sign of dam- age is small dead branches in the top of the tree. Control in a normal year involves the use of insecticides at the end of May in cen- tral Illinois. Accord- ing to Don Orton's book, Coincide, ap- plications should start when Spirea x vanhouttei finishes bloom or when Viburnum opulus is blooming. This cor- responds to our estimates that this year spring appears to be about a week earlier than normal. Thus application of insecticides should begin immediately in southern and central Illinois, and probably about 2 weeks from now in northern Illinois. Control of this insect with insecticide invol- ves a variety of options. Dimethoate (sold as Cygon 2E) can be applied once as a concentrate in a 4 to 6 inch band on the white bark of the trunk of the tree. An alternative is two sprays of diluted dimethoate spaced 3 weeks apart on the trunk and branches. A third option is three sprays of diluted chlorpyrifos (sold as Dursban) at 2 week intervals on the trunk and branches. If you use chlorpyrifos in northern Illinois, begin your sprays immediately. Use of Cygon 2E as a concentrate for bronze birch borer control confuses many people. This insecticide works in this way because it is sys- temic; that is, it penetrates the bark and is car- ried upward throughout the tree in the vascular tissue. White-barked birches have very thin bark that is easily penetrated by the Cygon. It is effective against bronze birch borer because the borer feeds in the cambium, the tissue just under the bark where most of the Cygon is transported up the tree. This insecticide does not work systemically for most other trees be- cause their bark is too thick for Cygon to pene- trate it. Nor does it work against most other borers because they feed deeper in the wood where the transport of fluids, including systemic insecticides, is much less; thus a killing dose is not encountered by the borer. Cultural control of this borer includes giving the tree better growing conditions. Birches are shallow-rooted trees and do not cope well with very warm soil temperatures. Since birches do not have wide spreading branches and heavy foliage, the soil around the tree is not shaded very much. In mid-summer, soil temperatures can get very high. Watering the tree frequently during the summer reduces this stress. For the same reason, birches planted in low-lying, poor- ly drained areas usually do better than those grown in well- drained areas. Because birches have a shallow root system, plants such as grass growing over the roots compete with them for nutrients and water. Shredded bark in a several-foot radius around the tree eliminates this competition and helps reduce dryness and heat. Birches are also susceptible to salt injury, so site trees away from paved areas where salt is applied during winter. Resistant birches are available that bronze birch borers do not normally attack. Heritage is a variety of river birch that has light-colored bark and is not attacked by these borers. Whitespire is a Japanese species of white- barked birch that is only attacked under very severe stress and does not become infested in normal growing conditions. Lilac Borer Lilac borer tunnels into the larger trunks of lilac; as a common borer of ash, it is frequently called ash borer. The adult of this borer is a clear- winged moth. With its dark-colored body and transparent wings, this moth looks like a wasp. The moths lay their eggs into wounds, including pruning wounds, storm dama^a branches, and old borer holes. ^t>* Control of this insect on lilac i«^corj&\ plished by pruning out the large^Tunk£vieav ing relatively young, small, fa £2 State • County • Local Groups • U.S. Department of Agriculture Cooperating The Illinois Cooperative Service provides equal opportunities in programs and employment. rowing stern^* >' No. 7 • May 15, 1991 that are not susceptible to borer attack. On ash, insecticide sprays are usually needed, es- pecially to protect young, newly transplanted trees that are particularly susceptible to trunk damage. On older trees, attack by this insect is limited to injured branches in the canopy, which is normally not controlled. Timing of insecticide applications for lilac borer is critical on ash, since once the hatching larvae enter the tree, control is not practical. An important tool in timing these sprays is the use of pheromone traps. These traps attract and catch male borer moths, indicating when female moths are laying their eggs. Insecticide sprays of chlorpyrifos (sold as Dursban) should start when males are caught in the traps. Another application of Dursban is needed 4 weeks after the first application. According to Don Orton in his book Coin- cide, larvae are hatching as Spirea x vanhouttei and Lonicera korolkowi 'Zabelii' are in full to late bloom, and the first spray would be applied at that time. Flea Beetles In early spring, many species of flea beetles damage various vegetable crops. These small, shiny jumping beetles feed on the foliage of many plants and leave small holes between the leaf veins. The best description of the results is that the leaf ends up looking like a piece of Swiss cheese. Below are some species of flea beetles and the crops they attack. Potato flea beetle: Potato, tomato, green pepper, eggplant Spinach flea beetle: Spinach, beet Striped flea beetle: Cabbage, broccoli, turnip, radish, mustard Palestriped flea beetle: Cabbage, bean, tomato, corn, pea Sweetpotato flea beetle: Sweet potato Red-headed flea beetle: Cabbage, bean, beet, potato Other Beetles on Vegetables Another flea beetle, cornjlea beetle, attacks corn plants including sweet corn. These black, small jumping beetles scratch the surface of com leaves. Severe feeding can cause wilting plants. These beetles may also transmit a wilt disease to the plants, stunting or killing suscep- tible varieties. Bean leaf beetles have emerged from hibernation and now are seeking out new stands of garden beans or soybean fields. These beetles have overwintered as adults and soon will chew large holes in new bean foliage. Sevin or rotenone sprays or dusts will control both corn flea beetles and bean leaf beetles. Striped cucumber beetle Red and black asparagus beetles have been observed laying eggs on new spears in aspara- gus beds in many gardens. The conspicuous dark eggs can easily be seen on the spears, but control at this time is difficult. It is much more effective if asparagus beds are scouted for beet- les on fern growth during July and August. Again, a Sevin or rotenone spray applied to the fern growth will control beetle populations for the next several years. Striped cucumber beetles feed on vine crops, including melons, cucumbers, pumpkins, and squash, both summer and winter varieties. These yellow and black strip- ed beetles could be found on these crops last summer and fall. Now they are waiting for new plants to emerge from seed or for transplants to be set out. Cucumber beetles are strongly attracted to new melon, cucumber, pumpkin, or squash plants and will feed on the new foliage of these plants. Pumpkins and squash can be severely dam- aged by this feeding, and an application of Sevin or rotenone when damage is first ob- served will control them. Bacterial wilt, a disease of young melons and cucumbers, is often transmitted to these sus- ceptible plants as the cucumber beetles feed on the leaves, since they often have the disease within their mouth. Successful beetle control with repeated dusting or spraying of Sevin or rotenone is necessary to prevent loss of plants after emergence or transplanting. New foliage should be covered by the product every 5 to 7 days during the first 2 to 3 weeks of the sea- son to control overwintering cucumber beetles. Cutworms Transplants in the vegetable garden, especially tomatoes, need to be protected from cutworms. For the home gardener, large tomato patches can be protected by spraying the base of the plants with diazinon or rotenone. Smaller num- bers of plants can be protected with collars of metal, cardboard, plastic, or any other solid ma- terial that is sunk at least an inch into the soil and sticks up at least an inch above the soil. Tin cans or milk cartons with both ends cut off work well for this purpose. These collars should be put into place when the transplant is plant- ed to make it less likely that a cutworm is al- ready in the soil next to the plant. These collars work because the cutworm is unwilling to crawl over or burrow under the barrier and thus never reaches the plant. No. 7 • May 15, 1991 Another method is sticking a large nail into the ground next to the transplant's stem. Be- cause cutworms normally curl the end of their abdomen around the base of the plant to feed, the additional diameter to the stem created by the nail makes it difficult for the cutworm to attack the plant. Collars and nails can be re- moved several weeks after transplanting, when the stem has increased in diameter and become woody. PLANT DISEASES Apple, Crabapple, Pear, Mountain-ash, Hawthorn, Fire thorn (Pyracantha), Amelanchier, Cotoneaster, Japanese or Flowering Quince, Quince, and Spiraea: Fire Blight Blossoms and fruit spurs turn brown (black on pear). Later, new shoots suddenly look as if they had been scorched by fire. Brown or black- ened leaves cling to the blighted twigs. Fire blight is often followed by black rot and wood decay. Control: To control blossom blight, commer- cial tree specialists can apply streptomycin two to four times, at 4- to 7-day intervals, during the bloom period when the temperature is above 65°F. To control twig blight, several weekly sprays of streptomycin are needed starting at petal fall. Carefully follow the manufacturer's directions. The best control will occur when the spray is applied at night. (Homeowners cannot legally apply streptomycin unless they are cer- tified to handle restricted chemicals.) Other controls include avoiding overfertilization with high-nitrogen materials and pruning when the plant is dormant to eliminate infected twigs, branches, suckers, and water sprouts. Certain species and varieties of cotoneaster, hawthorn, pyracantha, and possibly other plants are sensi- tive to streptomycin. For more information on fire blight and its control, obtain a copy of Re- port on Plant Diseases No. 801, Fire Blight. Woody Plants: Iron-induced Chlorosis Chlorosis is or soon will be common on pin oak, sweet gum, and other susceptible plants. These include arborvitae, bald cypress, birch, boxelder, forsythia, silver and other varieties of maple, ginkgo, honeylocust, and varieties of oak, spruce, sycamore, tuliptree, walnut, and willow growing in neutral or alkaline soil (a pH of 6.5 or above). The symptoms include partial-to-com- plete yellowing (chlorosis) of the young, expand- ing leaves. The midrib and principal veins re- main green. If chlorosis is severe, growth slows, leaves are dwarfed and quickly turn brown, and twigs and branches may die back. Although a lack of available iron is usually the cause, chlo- rosis may also be induced by poorly drained or compacted soil, root injury or disease, or a defi- ciency of other nutrients. Control: Supply plants affected in the past with iron NOW. The iron may be sprayed onto the chlorotic foliage, introduced into the trunk, or added to the soil. Spraying the foliage with ferrous sulfate, iron chelate, or a soluble or- ganic iron complex (commonly sold as Iron-Gro, Nulron, or Uraples) usually corrects chlorosis in treated leaves within a few days. Spraying will NOT benefit leaves produced later in the season. It is necessary to spray the leaves several times at 2- to 4-week intervals to keep the developing foliage green. Introducing an iron salt (such as ferric or ferrous citrate, ferric ammonium citra- te, or chelated iron) into the trunk of an af- fected tree should control chlorosis for 2 to 4 years. Recovery may be seen within 30 days. Iron chelates are the best soil treatments. Trade names for iron chelates include Versenol Ag 4% Fe, ClawEl Iron Chelate, Hamp-01 and Hamp- ene Iron Chelates, Rayplex-Fe and Rayplex Che- lated iron, Iron Chelates, Chelated Iron Solu- tion, Iron Chelate Solution, THIS Liquid Iron Chelate, Sequestrene 138 Fe Iron Chelate, and Sequestrene 330 Fe Iron Chelate. Trees and shrubs that have been treated should become green within 30 days after application. When properly done, a single soil treatment should be effective for up to 4 years. Application of an iron salt to the foliage, trunk, or soil should be done by a licensed and experienced arborist with the proper tools and equipment. For more information, read Report on Plant Diseases No. 603, Iron Chlorosis of Woody Plants: Symptoms and Control Chlorosis caused by inadequate soil drainage or excessive soil moisture (poor root aeration) should be dealt with by avoiding overwatering and installing plastic drain tile or using another method to get rid of the excess water. Rose: Cane Cankers, Black Spot, Other Foliar Diseases, Powdery Mildew If you haven't already done so, now is the time to check over rose canes and carefully remove all dead and discolored parts, which can later cause girdling and dieback or poor stem growth. Minute, black fruiting bodies of a canker-pro- ducing fungus (or fungi) are usually visible in the cankered areas. Infections occur chiefly through wounds made by improper pruning No. 7 • May 15, 1991 cuts, thorn abrasions, frost cracks, insect punc- tures, and rodent injuries. Control: Maintain plants in high vigor, han- dle plants carefully to avoid injuring the canes, and thoroughly spray all aboveground parts with triforine (Funginex), chlorothalonil (Dacon- il), maneb, mancozeb, benomyl (plus one of the above fungicides), Zyban, Duosan, Topsin M, Ziram F-4, or Banner. These fungicides control not only canker diseases but also cane blight, black spot, spot anthracnose, anthracnose, and fungus leaf spots. Sprays should be applied at 7- to 10- day intervals starting when new growth appears. Shorten the spray interval to 5 or 7 days in rainy weather. Maneb, mancozeb, tri- forine, chlorothalonil, Duosan, and Zyban also control rust. A contact fungicide should be PLANT CLINIC HIGHLIGHTS May 1 to 5, 1990 Plant samples are beginning to arrive at the Clinic in ever increasing numbers. We are seeing a wide range of problems, many with overlapping symptoms. Please take time to provide as much information as possible with your samples and use our specimen data forms when possible (consult your local Cooper- ative Extension Adviser). With limited information we can be of limited help. CROP DIAGNOSIS COUNTY Exacum Sclerotinia & Botrytis canker Kane Geranium Botrytis Cook Bacterial blight Cook Holly Fusicoccum canker Champaign Kalanchoe Sclerotinia & Botrytis stem canker Kane Lilac Oystershell scale Champaign Maple Verticillium wilt Champaign Pine Sphaeropsis blight Winnebago Tulip Bulb rot Winnebago Botrytis Winnebago Weed ID Small flowered buttercup Vermilion Shepherd's purse Vermilion Field pennycrest Mercer Purslane speedwell McLean Marestail Coles Butterweed Coles, Vermilion Virginia pepperweed Coles Foxtail barley Coles Daisy fleabane Coles There has been some confusion concerning the cost of nematode samples sent to the Plant Clinic. The $10.00 charge for Soybean Cyst or Pinewood Nema- tode Analysis is for each sample submitted; $20.00 for each sample of any other Nematode. added with Banner to control black spot. Powdery mildew can be controlled by beno- myl plus one of the fungicides listed directly below, which includes Karathane, Bayleton, tri- forine, Zyban, Duosan, Rubigan, Banner, and Topsin M. Milban is an excellent mildewicide but is a restricted-use pesticide because of pos- sible injury to eyes. Pipron is another excellent product but for use only in commercial green- houses. Always follow the manufacturer's direc- tions when using any fungicide. Sprays are needed at 7- to 14-day intervals to control pow- dery mildew. Start when new growth appears. Thorough coverage is required for control of powdery mildew, black spot, cankers, and other rose diseases. The following Reports on Plant Diseases cover rose problems discussed above- No. 610, Black Spot; No. 611, Powdery Mildew; and No. 626, Cane Cankers. Hawthorn: Leaf Spot or Blight Small, dark, round to angular spots, commonly clustered along the veins, appear on English hawthorns, especially the cultivar Paul's scarlet. Cockspur and Washington hawthorns are resis- tant. Control: Apply three or four sprays at 7- to 10-day intervals starting as new growth ap- pears. Continue to spray during rainy seasons. Suggested fungicides include captan, maneb, mancozeb, dodine (Cyprex), chlorothanlonil, and benomyl. The last-named product should be combined with another fungicide to avoid resis- tance problems. Maneb, chlorothalonil, and mancozeb also control rust diseases that are active now. The fungicides listed for control of leaf spot or blight also control scab and other fungus leaf spots. For more information, read Report on Plant Diseases No. 637, Leaf Spot or Blight of hawthorn. Home, Yard 8l Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, Thomas Fermanian, Floyd Giles, Daniel Meador, James Schmidt, Tom Voigt, and David Williams. Plant Pathology, Nancy Pataky and Malcolm Shurtleff. Agricultural Engineering, Loren Bode and Bob Wolf. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. /P&c^zS <£&%i Roscoe Randell Extension specialist Entomology G35 Helping You Put Knowledge to ork Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME, YARD c GARDEN PEST Newsletter No. 8 • May 22, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Spruce Needleminer White, Norway, and other spruces in northern Illinois are commonly attacked by spruce needleminers. These caterpillars tunnel through several needles during their development, leav- ing holes in the ends of the needles and using silk to tie the mined, brown needles to the twig. These accumulations are easily seen at this time of year because one species of spruce needleminer in Illinois is now completing its larval development. Fully grown larvae pupate in the mass of needles, silk, and frass on the twig, emerging as moths in June. Chlorpyrifos sprays in late June in northern Illinois should be effective in controlling hatching larvae before they enter the needles. Another species of spruce needleminer occurs in Illinois and causes similar damage. If you have spruces with needleminer damage, check to determine which species is present. Control of this other species is most effective in early spring and an application in mid- to late June will not be very effective. Pupae of this species will be reddish brown, oval capsules about 1/4 inch long. Mature larvae will be greenish cater- pillars about 1/4 inch long. If pupae or mature larvae are not present, check other needles on the tree for the presence of mined needles con- taining much smaller larvae. Scale Crawlers Scale insects are resistant to chemical control throughout much of the year. Many species of scale can be controlled with dormant oil sprays as described in an earlier newsletter this spring; however, some species are not controlled by this method or are present on evergreens and other hosts that are more susceptible to damage from the dormant oil. Early spring weather conditions can also be unsuitable for application of dor- mant oils due to cold temperatures, wind, pr rain- ...MiiTiKlEUBWW AbtU cutfutt Another control method is appling a crawler spray right after the eggs hatch. The hatching nymph is called a crawler. This stage is not protected by a thick, hard or waxy covering as are later nymphal stages and adults. A variety of insecticides are usually effective against these crawlers, such as acephate (sold as Orthene), malathion, diazinon, and chlorpyrifos (sold as Dursban). Keep in mind several things concerning crawler sprays. Crawler sprays are only effective for the 10 to 14 days that the crawlers are un- protected. After this of time, they settle down onto the host and begin developing the hard or waxy coverings that protect later stages from most insecticides. The other complication is that different scale species produce crawlers at dif- ferent times of the year. Pine needle scale is a white, elongated scale that is common on Scots and mugo pine. The reddish crawlers are active in late May in cen- tral Illinois or when Zabeli honeysuckle is in bloom. Euonymous scale crawlers are yellow and are usually active in early June in central Illinois; but they commonly emerge earlier in warm, early springs. Since our spring still appears to be several days ahead of schedule, keep a watch for an early hatch. Euonymous scale males are white and elongated, whereas the fe- males are brown and roughly oval in shape. They are common on many varieties of euony- mous and will kill the plant when present in very large numbers. Leaf Galls Galls are masses of plant tissue that are pro- duced in response to injury or secretions pro- duced by insects, disease, or injury. Several kinds of insects have developed the ability to cause plants to produce galls, including sucking insects, flies, and wasps. As the insect feeds on the plant, undifferentiated plant cells grow and divide rapidly to produce a bizarre growth that encloses the insect. By producing the gall, it is believed the plant is trying to compartmentalize, or wall off, the attacking insect and thus protect the rest of the plant from attack. The gall pro- tects the insect inside from attack by predators and parasites, thus increasing its chances of survival. Gall insects are very specific about which plant they attack. A particular plant species will produce the same shape and color of gall when State • Coifaffi Qbd*1 (SWps • U.S. Department of Agriculture Cooperating The Illinois Cooperative Service prowides equal opportunities in programs and employment. No. 8 • May 22, 1991 attacked by a particular species of insect. If a plant is attacked by several species of gall in- sect, the plant will produce a different kind of gall for each species. Usually, several kinds of gall will be found on an individual plant, with each kind caused by a different species of in- sect. Because these galls are so different in appearance, the insect that caused a gall can usually be identified by the species of plant attacked and the shape and color of gall pro- duced. Succulent oak gall Galls normally do not seem to harm their host plants seriously. Attacked plants growing near unattacked plants of the same species, variety, and age and growing under similar growing conditions usually are as large and healthy as the unattacked plants. For this rea- son, as well as the difficultly of timing effective controls, control measures are not normally re- commended for most galls. An exception to this rule are galls that attack and girdle branches; in this case, the gall (such as gouty and horned oak galls) may kill the branch where it is at- tached. Leaf galls, particularly those caused by fly larvae, are common on trees in late spring. We have been seeing some of these galls in the last week. One of these is the box elder leaf gall, in which the leaflet midribs are swollen to about 3/8 inch in diameter. A similarly appearing gall on ash is the ash midrib gall, which will turn from green to red in early summer. On sugar maple, we have been seeing gouty vein gall, in which the veins on the underside of the leaves are swollen to about 1/8 inch in diameter. These galls also turn from green to red as they get older. If any of these galls are opened up, you can usually see the white, 1/16-inch long maggots inside. Carpenter Bees Carpenter bees resemble large bumble bees, but have shiny black abdomens. In contrast, bumble bees possess black and yellow, hairy abdomens. Carpenter bees are usually metallic blue-black, with relatively few yellow hairs. Nor- mally, they are found buzzing around natural wood siding or unfinished wood products. The adults of both sexes hibernate in tunnels of abandoned nests that are constructed by burrowing into wood and then forming a series of chambers. These chambers are especially designed for the rearing of young. The adult female bee provisions each chamber with a pollen mass, on which she lays a single egg; she then caps the chamber with disks of wood particles. These galleries usually run parallel to the wood grain. Females often enlarge existing galleries or use old ones. In some cases, very complex gal- lery systems are established, possibly reducing the structural strength of the wood. The galler- ies can be up to 12 inches long. Nests may be found in siding, eaves, wooden shingles, porch ceilings, windowsills, doors, telephone poles, fence railings, posts, and wooden lawn furni- ture. The carpenter bees prefer unpainted or well-weathered wood to hardwood or well- painted wood surfaces. In Illinois, carpenter bees complete one gen- eration per year. The tunnels are constructed in the spring, followed by egg laying; then the larvae and pupae develop during early summer within the tunnels. Adult bees emerge in late summer and return to the tunnels to over- winter. In the spring, the adults emerge, mate, and lay eggs, completing the life cycle. The males do not possess stingers, and the females only sting if they are handled or confronted by people. Occasionally, the bees will make rapid flights around the head of a person who in- trudes near the nest sites. Swatting bees is usually not effective. There are no permanent ways of eliminating carpenter bees from an area. Painted wood ap- pears to be less attractive, but stained or var- nished wood appears to be just as vulnerable to attack as unfinished wood. Control of carpenter bees can be accomplished by dusting or spray- ing the entrance hole with Sevin. Do not plug the hole. No. 8 • May 22. 1991 PLANT DISEASES Registrations Ridomil 2E is labeled for control of leather rot and red stele of strawberries. These two soil- borne fungi are effectively controlled by this product. Metalaxyl is the common name. The diseases occur most commonly in wet, poorly drained soils, and in sites with a thin or no mulch, which allows the berries to be in contact with damp soil. In wet years even this chemical may fail in a poorly drained soil, but it is the most effective treatment available. Caddy fungicide, used for many years on turf to control Sclerotinia dollar spot, can be sold through the end of 1991 and used until the supply is exhausted. W. A. Cleary, which manu- factures this product, which contains cadmium chloride, has voluntarily canceled its registra- tion. Broadway - Dow-Elanco has recently ob- tained a label for this turf product, a premix of Daconil 2787 and Rubigan. A fungicide that combines contact and systemic modes of action, it has label coverage for a large number of turf diseases. Lawns: Cultural Practices to Control Diseases Good cultural practices help maintain healthy turf despite the presence of disease-causing fungi and nematodes, both now or later in the season. Vigorous turf withstands wear better and recovers more quickly from injury caused by diseases and insects. The following cultural practices will greatly reduce turf disease prob- lems. For more information on cultural prac- tices and disease control, read Report on Plant Diseases No. 400, Recommendations for the Con- trol of Diseases of Turfgrasses. 1. Provide for good surface and subsurface drainage when establishing a new turf area. Fill in low spots. The seedbed should be well prepared, free of coarse debris, and fertile, with a pH between 6 and 7. 2. Grow locally adapted, disease-resistant grasses or grass combinations (blends and mixtures). See the table in Home, Yard, and Garden Pest Newsletter No. 5, May 1, 1991. 3. Buy only top-quality, disease-free seed, sod, plugs, or sprigs. When feasible, plant only when the weather is cool and dry. Avoid overwatering the soil, but keep the soil damp until the turf is well established. 4. Fertilize on the basis of a soil test. Avoid overstimulation with a quickly soluble nitro- gen fertilizer, especially in hot weather and late in the fall. 5. Mow frequently at the height recom- mended for your area and for the grasses being grown. Remove no more than one- third of the leaf height at one cutting. Mow until the grass stops growing in the fall. 6. Water an established turf thoroughly dur- ing extended droughts. Moisten the soil to a depth of at least 6 inches with each irriga- tion. Water as infrequently as possible. Avoid frequent light sprinklings, especially in late afternoon or evening. Such watering encour- ages infection by disease-causing fungi and shallow rooting. 7. Increase airflow and light over the turf by pruning or removing dense trees and shrubs that border turf areas. 8. Remove thatch that has accumulated to half an inch or more now (if not done earlier) and in late summer. 9. Cultivate compacted areas by core aerify- ing and reduce traffic by strategically placing walks, fences, shrubs, and other landscape elements. 10. Follow suggested insect- and weed-con- trol practices for your area and for the grass- es grown. Broadleaf Trees: Tubercularia (Nec- tria), Cytospora (Valsa), Fusicoccum, and Botryosphaeria Cankers and Dieback The fungi Tubercularia, Cytospora, Fusicoccum, and Botryosphaeria are "opportunistic" and of- ten found associated with dead or dying twigs and branches of several kinds of maples, elms, beeches, honeylocust, tall hedge, euonymus, apple, peach, plum, cherry, hawthorn, holly, mountain ash, and many other broadleaf trees and shrubs. The fungi are easily identified by the presence of many small, coral pink fruiting bodies {Nectria) or black, erupting fruiting bo- dies {Cytospora, Fusicoccum, and Botryo- sphaeria) in the dead bark of affected twigs and branches, even the trunk. These fungi are con- sidered as weak pathogens, incapable of doing significant damage on their own. It is believed that the fungi enter bark or wood that has al- ready been injured by factors such as drought, extreme cold, and improper pruning or following another disease such as fire blight, and that they then cause additional damage by girdling No. 8 • May 22, 1991 affected parts. These fungi can also grow on dead tissue. Control: Prune out and destroy all dead twigs and branches now if not already done ear- lier. Be careful to prune into healthy wood at a side branch or bud a full several inches below the dead cankered area, and not to get any fun- gus on the pruning tools. If the tools become contaminated, they will spread the fungus or fungi to other pruning wounds, resulting in more infection. To sterilize pruning shears, wash in soap and water to remove sawdust and dark chips, then dip in 70 percent rubbing al- cohol or liquid household bleach (1 part bleach to 4 parts of clean water). Bleach will eat away at metal, and tools should be washed with water as soon as pruning is complete. Junipers, Arborvitae: Phomopsis Twig Blight New shoots progressively die back, turning from a light yellow to reddish brown to ash gray. As dieback continues, the entire branch gradually dies and turns brown or ash gray. The central part of a plant is often more affected than its outer portion. Black specks (pycnidia) later ap- pear erupting through the surface of blighted parts. Control: Plant resistant species, varieties, and cultivars. Prune and destroy (burn) all PLANT CLINIC HIGHLIGHTS May 10 to 17, 1991 PLANT DIAGNOSIS COUNTY Blackberry Orange rust, Anthracnose Madison Bluegrass Buckeye Cork Tree Crabapple Geranium Helminthosporium Rust Verticillium wilt Apple scab Bacterial blight Cook Champaign Champaign Champaign Cook Iris Iris leaf spot, Soft rot of rhizomes Ford Juniper Phomopsis twig blight LaSalle White Quince rust Champaign Lake Maple Scale Pike Spring leaf tatter Verticillium wilt Carroll Cass Oak Anthracnose Herbicide drift Champaign St. Clair Peach Peach leaf curl Peoria Spruce Vinca Chemical injury Herbicide injury Sclerotium stem rot Winnebago McDonough Kane Yew Water stress Wabash blighted parts as they appear. Prune in dry weather. Benomyl (Benlate), Zyban, Duosan, Cleary 3336, mancozeb, and Topsin M are sug- gested fungicides. Spray several times at 2-week intervals. The key to control is to keep new flushes of growth protected during wet periods. Spray applications should start at budbreak. For more information on symptoms, disease cy- cle, and control (especially in nurseries where the disease is most serious), read Report on Plant Diseases No. 622, Phomopsis Twig Blight of Juniper. This report also lists the suscep- tibility of many juniper species, varieties, and cultivars to damage by Phomopsis twig blight. Geranium: Bacterial Blight Bacterial blight, also known as bacterial leaf spot, stem rot, or wilt, is a major disease in warm, humid weather. Small, angular, dark brown to black spots form in the leaves. The leaves quickly wilt, wither, and drop off. On some plants the leaf spots are large, angular, and brown. Affected stems are a dull gray to blackish brown and later shrivel from a dry black rot. Roots are blackened but not decayed. Plants become defoliated except for a few dwarf- ed leaves at the stem tips. Diseased cuttings fail to root, and the stems slowly rot and turn a dull blackish brown from the base upwards and later die. Control: Start with culture-indexed cuttings or cuttings taken from indexed, disease-free mother plants. Follow stringent sanitary precau- tions. Remove and destroy all infected plants as soon as you see them. Maintain good cultural conditions and ventilation. There are no protec- tive or eradicative chemical treatments. For more information, write for a copy of Report on Plant Diseases No. 607, Bacterial Blight of Ge- ranium. Home, Yard 8i Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, James Schmidt and Tom Voigt. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Information for this newsletter is gathered by these people with the help of staff members, county Exten- sion advisers, and others in cooperation with the USDA Animal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology ces Helping You Put Knowledge to Work n /> Illinois Cooperative Extension Service College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME, YARD r GARDEN PEST Newsletter No. 9 • May 29, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Cottony Maple Scale Every 5 to 10 years this scale species appears in some area of the northern or central Illinois. This week we have received reports of cottony maple scale containing egg sacs from Ford, Iroquois, Kankakee, and Will counties. The in- fested area is probably larger than these few counties. The cottony maple scale is a small, sedentary insect that is flat, oval, and legless. It has suck- ing mouth parts and is about 3/8 of an inch long. The scale is covered by a green-to-brown, waxy shield that darkens as the scale matures. The most prominent feature of the cottony maple scale is a white "cottony" egg sac that develops under and protrudes outward from the female scale by late spring. The sacs on the host tree's branches make it appear to be cover- ed by popcorn. The immature scales, or crawl- ers, that hatch from the egg sacs are tiny, light green insects that are oval, six-legged, and wingless. Each one is about the size of the period at the end of this sentence. The mature male scales resemble the crawler in size and color, but are winged. The cottony maple scale overwinters as a flat, inconspicuous, immature female on the twigs of the host plant. As growth resumes rapidly in the spring, the scale soon triples in size. By late spring, the mature female begins to produce a white egg sac, constructed out of waxy filaments excreted by its body. The sac grows larger as the female produces more eggs. The egg sac may contain up to 1,000 eggs. The eggs will start hatching in early June, and hatch is completed by the first week of July. The crawlers migrate to the underside of leaves where they settle down to feed for the remainder of the summer. The mature males emerge in the late summer and mate with the immature females. The females remain on the ,,, underside of the leaves until just before the '$$* leaves drop. Then, the females return to the twigs, shed their legs and antennae, and secrete the waxy shield. There is only one generation of cottony maple scale a year. Cottony maple scale (crawler stage) The favored hosts of this insect are soft maple trees, such as silver maples. The insect may also be found on a wide variety of other woody plants. The cottony maple scale feeds on the sap of the host plant. This competition for moisture by a heavy population will cause twigs and branches to die back and some leaves to drop prematurely. During feeding, the scale excrete large quantities of honeydew. This is soon colonized by black, sooty mold fungi. The mold does not damage the tree, but is unsight- ly. Cars, lawn furniture, or anything else under the infested tree will be covered by the sticky honeydew. Control: What are effective natural or biological control measures? Many natural enemies such as wasp and fly parasites, as well as lady beetle larvae and adults, will feed on the scale eggs and the crawlers on the foliage. What are effective chemical control measures? A dormant oil spray applied ahead of bud break next spring will greatly reduce the overwintering scale without affecting any predators or para- sites. Do not apply dormant oil to Japanese, Norway, sugar, or any other hard maple. If the honeydew excreted by the crawlers feeding during the summer months is a severe problem on cars, patios, etc., a spray of mala- thion on the infested foliage of the lower limbs will control the scale crawlers. Do not apply until after July 1, when hatch is complete. This crawler spray will also kill the scale's predators and parasites. When will the scale disappear? After 3 years, the scale is usually not observed because of the abundance of a predator called twicestabbed State • County • Local Grc+ipf*' U.S. Department of Agriculture Cooperating The Illinois Coooerative^rvtee provides equal opportunities in programs and employment. No. 9 • May 29, 1991 lady beetle. There is a red dot on each of the black wing covers on this lady beetle. Some areas of the state may be in their second of 3- year cycles of this scale insect. Whether insec- ticide sprays are applied or not, the infestation is gone after 3 years. Is cottony maple scale a serious pest? No. It is very visible in the spring because of bright popcorn-like egg sacs, the honeydew in July and August, and the black sooty mold on the foliage. Rarely is an applied control justified. Although some thinning of the foliage and die- back of small branches may occur due to this scale, attacked trees easily recover. Bronze Birch Borer The bronze birch borer beetles are flying in central Illinois. White-barked birches that are showing damage in the form of top-branch die- back should be treated, preferably with dimeth- oate (sold as Cygon). Chlorpyrifos (sold as Durs- ban) can also be used to protect the trees, as stated in Home, Yard & Garden Newsletter no. 7, May 15, 1991. Since Dursban will not kill young borer larvae that have already enter- ed the tree, this insecticide applied in central and southern Illinois will not control all of the borers unless a spray has already been applied in the past several weeks. Because Cygon is a systemic insecticide that will kill borers within the tree, beginning applications at this time should give better control in the southern two- thirds of the state. In northern Illinois, either Dursban or Cygon should be very effective, but applications should begin immediately. Dead Flies Every year at this time, we get reports of dead flies hanging on the ends of leaves and twigs. This year, most of the flies seem to be on the ends of maple leaves. The flies, which are usu- ally in the family Anthomyiidae, are not pests of these plants, but are killed by a fungus. While the fungus is killing the fly, the fly will tend to perch at the tip of an upright object and then die there. Thus, these dead flies will not only be on the tips of leaves and twigs, but also on the tops of fenceposts, roof ridges, and the top edges of cars. Perhaps the fungus causes these flies to do this so that spores will be spread farther on the wind. Woodroaches These insects continue to be active this spring, with increased reports over the last week or so. As a reminder, since woodroaches are strongly attracted to lights at night, keeping porch lights and other outdoor lighting at a minimum during the next several weeks will reduce the number of these flying roaches that enter the home. The mating season will soon end for these native outdoor roaches, and they will cease to be a problem. For additional information, consult Home, Yard & Garden Newsletter no. 4, April 24, 1991. Fleas Preventative measures started now will help prevent a major indoor flea problem later this summer. Dogs and cats, particularly those that spend time both indoors and outdoors, should be treated once a month with a flea and tick powder rubbed into the skin. Although these powders are only effective for about a week, this occasional use during the warm seasons of the year should eliminate any early indoor infesta- tions. Any time pets develop a flea problem, these flea and tick powders should be applied weekly to control the infestation; and associated treat- ments for fleas in carpets, upholstered furni- ture, and cracks and crevices indoors may also be needed. Monthly applications as described above will not eliminate a heavy infestation, but will help prevent one from starting. PLANT DISEASES Asparagus Rust Rust is the most common disease on asparagus in Illinois. There are actually several distinct stages to the disease cycle. The most conspic- uous and damaging stage will show up after the harvest season when the ferns emerge. At that time, brick red pustules, known as uredia, will form on the leaves and stems. These infections weaken and kill foliar tissue, which is needed to feed the crowns so that they can produce the following season. Heavy rust infections weaken crowns and reduce yields. Another stage of the disease, known as the aecial stage, forms on the edible spears. The aecia are light green, very difficult to detect, and do not directly reduce yield or quality. They do, however, provide the inoculum that infects the ferns and produces the more damaging uredial stage. One practice that helps to control the disease is to cut off the spears below the soil surface. If spears are cut off above the soil surface, aecia may develop on the exposed tissues. Below- ground cutting eliminates this source of inoc- ulum and delays development of the disease. Unused beds and any wild asparagus within 300 yards of the planting should be destroyed because they can also serve as sources of in- No. 9 • May 29, 1991 oculum. The fungicide mancozeb (sold as Di- thane M-45, Manzate 200, and Penncozeb) can also be applied to help control rust. This fun- gicide is a protectant, thus it will only stop the spread of the disease and protect healthy tis- sues. Mancozeb will not eradicate established infections. Applications should start after the end of harvest, and should continue on a 7- to 10-day schedule through August. Do not apply mancozeb to spears that will be harvested. Bacterial Wilt of Cucumber and Muskmelon The most devastating disease that occurs on cucumbers, muskmelons, and several other cucurbitaceous crops in the Midwest is bacterial wilt. This disease is similar to Stewart's wilt of sweet corn in that it is caused by a bacterium (but not the same bacterium), is transmitted by an insect (in this case the striped and spotted cucumber beetles), and spreads systemically throughout the plant by way of the plant's vas- cular system. When a cucumber beetle carrying the bacterium feeds on a susceptible plant, the bacterium is introduced into the plant's water- and food- conducting system, where it multiplies and spreads. The bacterial infection gradually cuts off the plant's ability to move water from the roots to the leaves, and so the most obvious symptom of the disease is that leaves begin to wilt. Initially only one or two leaves on a plant may show this wilt symptom; but as the disease spreads, entire vines will wilt and die, and eventually the whole plant will be killed. The disease can develop at any time during the season, but is most severe on young plants. Control: Cucumbers and muskmelons are the crop most susceptible to bacterial wilt. Pumpkins and squashes will occasionally get the disease, but they are not as susceptible as cucumbers and muskmelons. Although water- melons have been shown to get the disease after artificial inoculation with the pathogen, in the field watermelons appear to be almost im- mune from the disease. There is some variation in susceptibility among varieties, but resistance is not generally used as a method of controlling the disease. Control efforts are aimed at pre- venting infection by controlling the beetles that transmit the disease. Beetle control depends on early and continuous protection with a fast act- ing insecticide such as carbaryl (Sevin). Rogue- ing out infected plants will also help reduce the spread of the disease. Stewart's Wilt of Sweet Corn Because this past winter was a relatively mild one, a large number of flea beetles have proba- bly survived the winter and will be feeding on corn this spring. Flea beetles carry, or vector, the bacterium that causes Stewart's bacterial wilt of sweet corn. When the beetles feed on the corn, they deposit the bacterium in the result- ing wound. Once the bacterium has entered the leaf, it multiplies and spreads throughout the plant by way of the plant's vascular system. Symptoms of the disease start as light green to chlorotic stripes on the leaves, 1/4 to 1/2 inch wide, running the entire length of the leaf. These stripes characteristically have irregular or wavy margins. As the disease progresses, these stripes eventually turn yellow, then brown and necrotic, giving the plant a burned or blighted appearance. Late in the season, it can be dif- ficult to distinguish severe Stewart's wilt from severe northern corn leaf blight infections. Stewart's wilt is most damaging on young seed- lings, where total plant death may occur. Al- though older plants can get the disease, later infections have less of an impact on yield. Control: The best way to control this disease is to plant disease resistant hybrids. Standard (sugary) hybrids with good resistance include Comet, Honey 'N Frost, Sugar Loaf, Silver Queen, and Sweet Sue. Resistant sugar- enhanced (SE) hybrids include Calico Bell, Incredible, Miracle, and Classic. Resistant super sweet (shrunken or SH2) hybrids include Chal- lenger, Florida Staysweet, How Sweet It Is, and Sweetie 82. Hybrids susceptible to the disease include Jubilee, Sundance, Platinum Lady, Sugar Buns, Phenomenal, and Supersweet Jubi- lee. Early season control of the flea beetles with an approved insecticide can also aid in controll- ing the disease. Cytospora Canker of Spruce This disease is evident now, especially on Colo- rado blue and Norway spruces. Symptoms in- clude a browning of the tufts of needles at the branch tips. Death of the lower branches fol- lows. Occasionally, branches at the center or top of a tree are infected, even though the lower ones remain healthy. The needles may drop early from infected branches or persist for sev- eral months, leaving dry, brittle twigs. Con- spicuous patches of white resin commonly form on the bark in cankered areas. Underneath the thin layer of outer bark, the diseased tissue is brown. Black, pinhead-size, spore-producing bodies of the causal fungus form in the dead inner bark. Control: Plant healthy nursery stock on sites that are favorable for their growth. Avoid shal- low, light soils, crowding with other trees or buildings, and unnecessary bark wounds. Do not plant in exposed sites (such as a soulh or No. 9 • May 29, 1991 southwest slope). Apply a thick organic mulch to retain soil moisture and to prevent deep freezing and alternate freezing and thawing. Water trees thoroughly (moisten soil 12 to 14 inches deep) during extended dry periods, and fertilize at least every few years on the basis of a soil test. Cut down and burn severely canker- ed trees. All diseased and adjacent branches on less severely damaged trees should be pruned back to the nearest living lateral branch or to the trunk. Do not prune or work around trees when foliage, twigs, and branches are wet, or you will help spread the causal fungus and aid infections. No effective chemical treatment exists for this disease. For more details, see Report on Plant Diseases No. 604, Cytospora Canker of Spruce. Crazy Top of Sweet Corn Abundant rainfall has flooded fields in several areas of the state, and this will almost certainly result in an increased incidence of crazy top on sweet corn that has already emerged. Crazy top is caused by Sclerophthora macrospora, one of the downy mildew fungi. At least nine different downy mildews attack corn, but only a few oc- cur in Illinois, and of those, crazy top is the most prevalent. The fungus that causes crazy top survives in the soil as resting spores called oospores. When the soil becomes saturated, the oospores germinate and produce a swimming spore, or zoospore, which swims to and infects the corn plant. Crazy top is most severe when flood waters rise above the top of young seed- lings, allowing the zoospores to enter the whorl and infect the rapidly growing leaf tissue. Twen- ty-four to forty-eight hours of flooding are enough to start the infection process. Once the fungus has infected, it spreads systemically throughout the plant. Infected plants usually show excessive tiller- ing, and a rolling or twisting of the upper leaves. The most characteristic symptom, how- ever, is the proliferation of the tassel into a mass of leaf-like structures. Infected plants will also be stunted and develop chlorotic stripes on the leaves; if they produce an ear, it will often be malformed. Crazy top is most likely to occur in the low areas of the field that are most sus- ceptible to flooding, and can cause substantial yield losses in these areas. Control: Crazy top does not usually cause enough damage to warrant much effort to con- trol the disease. The primary means of control- ling the disease is to insure good soil drainage. Applying fungicides to infested soils may effec- tively control the disease, but such applications are probably not economically feasible. For more information, read Report on Plant Diseases No. 207, Crazy Top of Com. Septoria Blight of Tomato With all the wet weather we have experienced in the past weeks, we expect Septoria blight on tomatoes to be plentiful this year. Look for cir- cular spots on lower foliage. Spots begin as watersoaked areas and develop dark brown margins and sunken white or gray centers. Black specks (pycnidia) will later appear in the center of these 1/4 inch circles. Leaves will yellow and drop, beginning at the base of the plant and moving upward. Control: Apply mancozeb. Bravo, or Dyrene on a 7- to 10-day schedule after the first signs of disease. Staking or caging plants and provid- ing both good air circulation and all-day sun will help reduce this and other foliar diseases, as well as a variety of fruit rots. For additional information read, Report on Plant Diseases No. 908, Early Blight, Septoria Leaf Spot, and Anthracnose Ripe Rot of Tomato. Reports on Plant Diseases Copies of any Report on Plant Diseases men- tioned in this or other newsletters are 50 cents each; five copies or more are 25 cents each. Checks should be made payable to the Univer- sity of Illinois and mailed to Extension Plant Pathology, N-533 Turner Hall, 1102 South Goodwin Ave., Urbana, IL 61801. If you would like to have a copy of the complete listing of all 230 Reports on Plant Diseases, send a postcard or note to the same address. There is no charge for the list. Home, Yard &. Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, James Schmidt and Tom Voigt. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Ani- mal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology Illinois Cooperative Extension Service Helping You r- Put Knowledge to Wonv^-*— College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME, YARD r GARDEN PEST No. 10 • June 5, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, safe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Cottony Maple Scale Update The infested area of cottony maple scale that was discussed in last week's Home, Yard & Garden Newsletter (No. 9) now includes McLean and Champaign counties to the south and Will County to the north. White popcom-like scale egg sacs are easily observed on some soft maple trees, especially on the lower limbs. Eggs should soon be hatching; during July and Au- gust, the new crawlers will move on to suck plant sap from nearby leaves. This feeding can place stress on the tree, as did the drought in 1987 and 1988. Older trees that are low in vigor can be stressed by a scale infestation, causing loss of leaves and even some branches. We are concerned about efforts to organize communitywide spraying in some towns or cities. Not all urban trees are soft maples or trees low in vigor. Not all soft maples in a town are infested with scale, and some trees have only a very slight infestation. Whether infested trees are treated with an insecticide or not, the scale population will diminish after 3 years. This is the second year of this 3 -year period for many communities. Superior oil applied in the spring will greatly reduce scale numbers without affecting benefi- cial predators such as lady beetles. Sprays in July containing malathion or a similar insec- ticide will also reduce predator numbers. Other insecticides, such as insecticidal soap (sold as Safer's or M-pede), must thoroughly cover the scale crawlers to be effective and also can re- duce populations of immature ladybeetles. Scale control should be determined on a tree-to-tree basis, depending upon whether the tree is being damaged and how much of a nuisance is caus- ed by honeydew dripping on sidewalks, parked cars, etc. Generally, spraying the trees in all or part of a community to control an insect that does not threaten the life of the trees and that will be Newsletter controlled naturally within 2 to 3 years is prob- ably not justified from the standpoints of tree health, use of public funds, or impact on the environment. May Beetles May beetles, also called June beetles or June bugs, spend most of their lives in the soil feed- ing on the roots of grasses and other crops. After about 2 years as grubs, the adult beetles emerge from the soil in early summer to feed on oak foliage and several other tree leaves. They can defoliate young trees, leaving them stunted. Active at night, they feed on foliage and are attracted to outdoor lights. Potato Leafhopper on Trees Potato leafhopper numbers have greatly in- creased in the last few days. Samples of dam- age to redbud, red maple, and sugar maple have been submitted to the plant clinic. Potato leafhoppers have been very numerous during the last two summers, creating considerable damage on these two trees as well as black locust. Newly emerged leaves on red and sugar maple will be red and distorted; leaves on red- bud and black locust will also be distorted, with brown edges and V-marked brown areas near the edges. In the nursery, many types of woody plants will show distorted leaves from potato leafhopper injury. Control: Potato leafhoppers are about 1/8- inch long, green, slender insects that tend to walk sideways onto the other side of the leaf when disturbed. They can be controlled with pyrethroid insecticides such as bifenthrin (Talstar), cyfluthrin (Tempo), or permethrin (A- mbush, Pounce). Ambush and Pounce can only be used in the nursery. Maple Petiole Borer These sawflies tunnel into the petioles of maple leaves, causing the leaves to drop from the trees. Affected petioles will be partially hollow due to the boring of the insect. Control is not recommended because rarely is more than one- third of the leaves of a tree attacked. Red Plant Bugs We have been receiving reports from around the state of fast moving, reddish insects about 1/4 inch long feeding on a widej^^$ftMtylants U 7 1391 State • County • Local Groups • U.S. Department of Agriculture Cooperating ^ The Illinois Cooperative Service provides equal opportunities in programs and employment. _... Ac il I INOIS No. 10 • June 5, 1991 along house foundations. Although somewhat resembling box elder bug nymphs, these insects are much more active and are found feeding on many plants other than box elder or other maples. These insects are plant bugs, apparent- ly in the genus Lopidea, probably of several different species. Some of the common host plants of this genus are phlox, daisy, red clover, honey locust, black locust, elm, yarrow, willow, snowberry, poplars, goldenrod, hazelnut, ash, and river birch. Damage will appear as 1/16 to 1/8 inch diameter, dark, sunken leaf spots that are most visible on the upper leaf surface. The numbers of these insects and their associated damage are usually not great enough to warrant any control measures. If control is needed, carbaryl (sold as Sevin) and malathion will effectively control them. The insects will mature in the next month or so and disappear until next spring. Carpet Beetles Each spring, carpet beetles of various types enter homes because they are attracted to lights at night. This year, we are receiving more re- ports than usual of Anthrenus entering homes. This carpet beetle is about 1/10 inch long and rather spherical with very short legs. Various species are black, white, and yellow or black, yellow, and red in color. These insects over- winter as adults and are small enough to come through the mesh of window screening when attracted to lights at night. Remove these in- sects by vacuuming or by hand as they are seen. Reducing lighting near screened or open windows at night will also reduce their numbers indoors. Although primarily a nuisance by their pres- ence in the home, they may lay eggs on fabric made of animal hair and feathers; the resulting larvae may damage clothing and carpets made of wool or felt. These larvae will be about 1/8 to 1/4 inch long, tan, and hairy. Prevent damage to clothing by dry cleaning or laundering it and then storing it in airtight containers, such as sealed plastic bags. For added protection, place some moth crystals or cedar shavings in folds of the clothing. Carpets should be checked for strands of pile coming out of them, particularly under furniture or along the edges of the room. Control of infes- tations involves spraying cracks and crevices along baseboards and between floor boards with propoxur (sold as Baygon), chlorpyrifos (sold as Dursban), diazinon, or other acceptable crack and crevice insecticides. Very valuable carpets may be removed and fumigated. Bird Mites Bird mites feed on young birds in the nest and spend most of the day hiding in the nesting material. When the young birds become fled- glings and mature and leave the nest, the mites in the nest get hungry and come indoors. Al- though unable to survive for very long on people or other mammals, they will bite people and pets, being a nuisance for about 2 weeks if not controlled. Since house sparrows are starting to fledge in Illinois and are the most common bird nesting on buildings, bird mites are starting to become a problem. Interior surfaces infested with bird mites can be washed with soap and water or vacuumed to remove and kill the mites. Empty bird nests associated with window air conditioners, eaves, or other areas of the building should be re- moved; the area should be washed with soap and water or sprayed with a pyrethroid (sold as aerosol flying and crawling insect spray). The same spray can be used around windows to kill mites in cracks and crevices. PLANT DISEASES Oaks: Leaf Blister This worldwide disease, mainly of oaks in the red and white oak groups, occurs during wet springs. Fortunately, it seldom causes serious damage. Heavy infections may cause oaks to be unsightly but do NOT endanger the life of the trees. Young, partially grown leaves develop cir- cular, raised, wrinkled, yellowish white spots on their upper surfaces with yellowish brown to gray depressions of the same size on the cor- responding lower surfaces. The "blisters" later turn reddish brown and finally dull brown with age. Severe disease may cause some premature defoliation. Control: No controls are usually suggested. Collecting and composting or burning the leaves as they drop may be of some benefit in reduc- ing the inoculum for next spring. For more in- formation, send for a copy of Report on Plant Diseases No. 663, Oak Leaf Blister. Many Ornamentals: Tomato Spotted Wilt Virus (TSWV) This virus attacks hundreds of floral crops, bedding plants, vegetables, and weeds. It is found most commonly in garden and New Guinea impatiens, gloxinia, cyclamen, and ex- acum. It is a very serious problem in green- houses, where environmental conditions are favorable for the growth and maturation of No. 10 • June 5, 1991 thrips (at least 9 species of Thrips, Frankliniella, and Scirtothrips). The symptoms vary greatly from crop to crop and include various degrees of yellowing, browning, stunting, and enations. Many young plants decline and die. Terminal bud killing and white to yellow or dead ring- spots and line patterns on leaves are common in older plants. Infected leaves are often dis- torted with vein and petiole necrosis. Black or purple stem streaks, premature leaf or bud drop, stunting, distorted leaf shapes, whitish or black leaf spots (sometimes zoned), necrotic young leaves, and colored spots, line and ring patterns or stripes on flower petals are other symptoms. Flowers open late and are commonly distorted. Diagnosis based solely on symptoms is difficult. Symptoms vary greatly with the age of a plant, level of nutrition, and especially en- vironmental conditions. Some infected plants may even be symptomless. Control: Tomato spotted wilt virus (TSWV) is difficult to control where there is a source of the virus, many susceptible host plants, and an abundance of thrips vectors. Prevention, early detection, and quick action are required. This involves prompt destruction of infected plants, a routine thrips control program using insecti- cides suggested by University of Illinois Exten- sion entomologists and given in the Illinois Pest Control Handbook (available at all Cooperative Extension Service offices). For much more infor- mation including monitoring procedures for thrips in greenhouses, other controls, and a fairly complete listing of plants susceptible to TSWV, read Report on Plant Diseases No. 665, Tomato Spotted Wilt Virus. Many Trees, Especially Elms and Poplars: Bacterial Wetwood and Slime Flux Bacterial wetwood, a watersoaked condition of wood in the trunk branches and roots of many shade and ornamental trees, is cosmopolitan in all older elms and both young and older poplars and cottonwoods. In most trees, wetwood is nor- mally not serious. As a chronic disease, it may contribute to a general decline in tree vigor, especially of older trees growing under stressful conditions. Wetwood is most visible externally as a bubbling and seepage ("bleeding" or flux- ing) from wounded tissue in V-shaped branch crotches, pruning wounds, injection holes, and trunk cracks, ribs, or beaks. Internal gas pres- sure commonly reopens old wounds; the sour liquid is colorless to tan as it oozes out. Light or dark streaks occur where the gray to brown foamy liquid flows down the bark. As it dries, a light gray to white incrustation is left (slime flux). This liquid is toxic and commonly causes localized death of the cambium. Fluxing is most conspicuous during the summer, although it occurs from April to December. Control: There is no cure or preventive treatment. The following practices may be help- ful. Fertilize stressed trees in spring to stimu- late vigorous growth. The installation of per- forated plastic or iron drain tubes relieves the gas pressure and allows continual drainage away from the tree. (A disadvantage of drain tubes is that another deep wound is made that breaks the "compartment" the wetwood is in, thereby allowing the internal discoloration and any future decay to spread outside the wet- wood-affected area.) Removing dead and weak branches plus promptly pruning and shaping bark wounds is helpful. For much more infor- mation, read Report on Plant Diseases No. 656, Bacterial Wetwood and Slime Flux of Landscape Trees. Many Herbaceous Ornamentals and Vegetables: Fusarium Wilt Diseases With hot weather here and air and soil temper- atures in the 75° to 90° or 95°F range, we can expect Fusarium wilts of numerous vegetables, a few fruits and trees, and numerous other plants. Once a Fusarium wilt fungus is intro- duced into a garden, nursery, greenhouse, or field, it can live indefinitely in a wide variety of soil types independent of any host plants. This eliminates the rotation of crops as an effective control measure. Symptoms of Fusarium wilt are easily confused with crown or root rots, stem cankers, various insect injuries, drought, compacted or poor soil, and Verticillium wilt (which infects plants at lower soil temperatures -optimum about 70°F). Typical symptoms of Fusarium wilt include a drooping and yellowing of the leaves, often starting on one side, and stunting of the plant. Symptoms often start at the base of the stem and progress upward, causing the leaves and flowers to wilt, wither, and die. When infected stems are split, brown to black streaks are evi- dent in the vascular system. Control: The first step is proper diagnosis (via laboratory culturing). Disinfesting green- house seedbed and potting soil with steam prior to planting is essential. Also treat containers, benches, work surfaces, tools, etc. Do not grow susceptible plants in Fusarium-infested soil where the same or closely related plants have grown previously. Purchase only top-quality, disease-free seed, cuttings, transplants, bulbs, tubers, corms, or other plant material. Fusar- ium-resistant varieties and cultivars are avail- able for some plants for growing in wilt-infested No. 10 • June 5, 1991 soil. Check seed, nursery or other catalogs. Plant in fertile, well-drained, wilt-free soil. Con- trol soil insects following suggestions of Univer- sity of Illinois Extension entomologists. Many other controls, lists of plants susceptible to Fusarium wilt diseases, and typical symptoms on various selected flowering plants are given in Report on Plant Diseases No. 650, Fusarium Wilt Diseases of Herbaceous Ornamentals. Bacterial Diseases of Beans There are essentially three bacterial diseases of snap and dry beans that cause problems in the Midwest: Common or Fuscous Blight, Halo Blight, and Bacterial Brown Spot. All three of these diseases result in the formation of lesions on leaves and pods; thus differentiating the dis- eases can be difficult. The spread and develop- ment of these diseases is favored by wet weath- er and plant injury, including damage from wind-blown rain or sand, hail, or damage from people or equipment moving through the field. The symptoms of common blight show up as watersoaked spots on leaves which gradually expand into large irregular spots, and become dry and brown with distinct, narrow yellow margins. Spots may expand and coalesce and eventually affect most of the leaf surface. Simi- lar irregular blotches appear on the pods, and PLANT CLINIC HIGHLIGHTS May 27 to 31, 1991 PLANT DIAGNOSIS COUNTY Apple Fire blight Cumberland Powdery mildew Champaign Ash Anthracnose, Aphids LaSalle Oystershell scale. Champaign Wind injury Boxwood Winter injury McLean Cherry Cherry leaf spot St. Clair Crabapple Apple scab Champaign Lisianthus Rhizoctonia root rot Kane Maple Spring leaf tatter Bureau, Ogle Oak Leaf blister Jersey Sphaeropsis canker Champaign Peach Plum cucurlio Mason Pear Fire blight Cumberland Nectria canker Champaign Pine Pine needle scale Champaign Lawrence Pine wilt disease Mercer Sphaeropsis tip blight Lawrence Serviceberry Wooly hawthorn aphid Champaign Turf Powdery mildew Tazewell Red thread Champaign Vine a Rhizoctonia root rot Cook when severe the entire pod may shrivel. Symp- toms of halo blight also start as small water- soaked spots on leaves which gradually turn dark brown, but the spots remain small and become surrounded by a wide yellow-green halo. Dark sunken spots can also develop on the pods. With bacterial brown spot, the disease first shows up as chlorotic (yellow) flecks on the leaves, which later turn dark brown. Individual spots are usually irregular in shape and remain fairly small, surrounded by a narrow yellow margin, but lacking a wide yellow halo. The development of common blight and bacterial blight is favored by warm temperatures, in the range of 80° to 90°F, while halo blight develops best when temperatures are somewhat cooler, in the low to mid 70's. Control: All three of these diseases can be carried on and in infected seed; they can also survive in infested plant debris in and on the soil surface. Therefore, the best way to control these bacterial diseases is to plant only west- ern-grown, certified disease-free seed, and to follow good crop rotation and field sanitation practices, including the removal or burial of infected plant tissues and cleaning contam- inated equipment. Avoid working with plants when they are wet with rain or dew, as bacteria and other pathogens are easily transmitted in films of water. Application of copper-based materials, such as copper sulfate, copper hy- droxide, and Bordeaux mixture, at weekly inter- vals can help prevent or reduce the spread of the disease. Some resistant varieties are also available. For more information, read Report on Plant Diseases No. 92 1 , Bacterial Blights of Garden Beans. Home, Yard 8i Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, James Schmidt and Tom Voigt. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Ani- mal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology U35 Illinois Cooperative Extension Service Helping You C<^> Put Knowledge to Work College of Agriculture University of Illinois at Urbana-Champaign and Natural History Survey • Champaign, Illinois HOME. YARD ^GARDEN PEST Newsletter No. 11 •June 12, 1991 This newsletter is issued weekly to provide timely information on insect, weed, and plant disease pests of the home, yard, and garden. Current control pro- cedures, application equipment and methods, sqfe storage and disposal of pesticides, and other topics of interest are discussed. INSECTS Note on Cottony Maple Scale Tom Stoutenborough, Agriculture Extension Adviser for Coles County, reported observing immature lady beetles feeding on egg sacs on limbs of silver maple. This important predator is an effective control measure for this scale in- sect. Beetles on Linden Trees More than one report of beetles on linden trees has been received. At this time of the growing season, these are soldier beetles feeding on the flowers and pollen. No control is needed for soldier beetles. These beetles are also present on some flowering trees. They closely resemble lightning bugs, except there is no light produc- ing organ; the head of the soldier beetle is vis- ible when viewed from above, but the lightning bug's head is concealed by the pronotum, an area behind the head. Sometimes in areas where Japanese beetles are present, these copper and green beetles can defoliate linden trees. Japanese beetles usually emerge in July. Cabbageworms White butterflies flying back and forth over vegetable gardens signal the beginning of cab- bageworms feeding on cole crops. Cabbage- worms include the imported cabbageworm, a velvety green worm that hatches from eggs laid by these conspicuous white butterflies. Another cabbageworm is the cabbage looper, a green 1 and white striped worm that "loops" or mea- sures as it moves about on plants. The third j cabbageworm is the larva of the diamondback | moth, a small, green worm that moves rapidly when disturbed. All three species eat holes in the foliage of cabbage, broccoli, cauliflower, j brussel sprouts, and related crops. They also I attack the edible heads of these plants. Cab- ' bageworms increase in numbers throughout State • County • Local Groups • U The Illinois Cooperative Service provides the summer until parasites and diseases reduce them in early fall. Homeowners can obtain effective control of any of the three species with applications of the bacterial agent Bacillus thuringiensis. It is sold under the trade names of Dipel, Thuricide, Caterpillar Attack, and other similar names with B.t. as the active ingredient. These products are effective only on a few caterpillars including cabbageworms. They are nontoxic to warm- blooded animals, including man, and are de- stroyed on the plant by sunlight after a week to 10 days (making repeat applications necessary). Follow label directions for rates and methods of application. Annual White Grubs This is question-and-answer time for the annual white grub. Many persons have asked about grub biology, drought effect, control, etc. This section will answer these often-asked questions. Annual White Grub When will annual white grub adult beetles emerge and lay eggs? The tan beetles are emerging now in the southern two-thirds of Illinois. Egg-laying has begun in the southern part; it will peak in the central part during early July and 2 weeks later in the northern areas. Will there be grub damage on dormant un- watered lawns? Attractive egg-laying sites are moist soil areas because the eggs are buried and soil moisture is necessary to prevent des- sication of the eggs before hatch. Damage is possible, but not likely. Are irrigated turfgrass areas more likely to have grub damage? Yes. These areas attract more egg-laying and improve the survival ofjtfle eggs as well as of the newly hatching em^&T Will the annual white grub seasort$fc early, this year? Despite recent high^^peratur«gp\ S. Department of Agriculture Cooperating equal opportunities in programs and employment ..era s^ tf No. 11 • June 12, 1991 this year's heat unit accumulation is about normal. The first grub damage in central Illinois will be visible about mid-August, 2 weeks earlier in the southern area, and 2 weeks later in the northern area. When is the best treatment time for effective grub control? At the early stages of grub dam- age and when there are more than 10 grubs per square foot, drench an effective insecticide into the soil. In situations where there has been a history of grub infestations, the ideal treatment period is during the 3 to 4 weeks prior to the first damage period. Are there insecticides that can be applied 2 or 3 months earlier than the grub-damage period? No. At one time, Oftanol was effective when applied anytime during the 4 to 5 months ahead of the grub-damage season in August and September. Today, the labeled and effective grub control insecticides are effective for about 4 to 5 weeks. Which are better, granules or sprays? If the grass blades are already wet and the treatment is drenched into the top half-inch of soil, either method is effective. But granules can be effec- tively drenched in after a few hours or a day or two later; whereas, sprays should not be allow- ed to dry on the foliage. What are the suggested insecticides for an- nual white grub control? Diazinon is labeled as an emulsifiable concentrate and as a granular formulation for use on home lawns. Oftanol is labeled as a granular formulation on home lawns. Trichlorfon is formulated as Proxol, a soluble powder (SP), and Dylox as a soluble powder and granules. Turcam is labeled as a granular formulation and as a wettable powder. Triumph was first labeled in 1987 only as an emulsifiable concentrate for use on home lawns by commercial applicators. Which of these insecticides are available for homeowners to purchase and apply? Only diazi- non and Oftanol are available in garden centers and similar stores for purchase and use by homeowners. Bagworms Bagworms feed on a wide variety of evergreen and deciduous trees and shrubs, particularly eastern red cedar, other junipers, arborvitae, and spruce. Bagworm hatching is occurring or has finished in Illinois. Bagworms have indi- vidual silk tents to which they attach bits of the foliage from the host tree. They feed through most of the summer, starting at the top of the tree and working down. In late summer, they pupate, with the males emerging as clearwinged moths that fly around and mate with the fe- males that remain wingless in the bags. The female produces eggs in the bag in early fall and dies. The eggs overwinter in the bags and hatch in early June. Bagworm infestation Control: Bagworms are easily controlled during June before they get too large. Since the eggs hatch over several weeks or so, insecticide sprays applied before all the eggs have hatched may result in damage due to late-hatching eggs. Newly hatched bagworms will have bags that are about 1/8 inch long. To be sure that egg hatch has been completed, delay spraying until the smallest bags are 1/4 inch or longer, or spray a second time if additional eggs hatch. Small bagworms with bags less than 3/4 , inch long can be controlled with a variety of insecticides. Malathion, cyfluthrin (Tempo), chlorpyrifos (Dursban), trichlorfon (Dylox, Proxol), and Bacillus thuringiensis kurstaki (Di- pel, Thuricide, Caterpillar Attack) should all be effective. Once the larvae get larger, cyfluthrin, trichlorfon, and B.t. should still give adequate control. Homeowners can control bagworms without insecticides by hand-picking the egg- containing bags from their trees and shrubs anytime between October and May. Stable Flies Flies that look similar to house flies that bite, particularly around the ankles in sunny areas during the morning and late afternoon, are probably stable flies. These flies have been more common last summer and this summer, prob- ably due to the regulations prohibiting yard waste disposal in landfills. The resulting piles of grass clippings provide excellent conditions for the increase of these flies. Stable flies are grayish, about 1/4 inch long, with black stripes behind the head and black spots on the abdomen. They can be distin- guished from house flies by a needle-like beak that protrudes from the front of the head. The stable fly uses this beak to feed on the blood of I people and other animals. " No. 11 • June 12, 1991 Adult flies lay their eggs in wet straw, strawy manure, piles of grass clippings, and other de- caying organic materials. The eggs hatch into yellowish white maggots (larvae) that are taper- ed at the head end and squared-off at the pos- terior end. The maggots feed on the decaying organic matter for 11 to 30 days, becoming about 1/2 inch long. The maggots turn into pupae, emerging as flies 18 to 53 days after the eggs were laid. Control: Prevent stable flies by not collect- ing grass clippings while mowing or making compost piles of grass clippings. A properly made compost pile will not produce very many stable flies. Insect repellents containing DEET are effective in repelling biting flies. PLANT DISEASES Vascular Wilts of Tomato Several pathogens cause vascular wilts of to- mato, including several bacteria and two fungi, Fusarium oxysporum, and Verticillium dahliae. The symptoms of Fusarium wilt and Verticillium wilt are similar. Infected plants may be some- what stunted, and leaves turn yellow and die, often starting from the base of the plant and progressing upward. Leaves on one side of the plant may show symptoms, while leaves on the other side appear normal. Wilting may occur at or during the hottest part of the day or when the plants are stressed from dryness or a heavy fruit load. Infected leaves may dry up before wilting is detected. Both of these diseases cause a discoloration of the vascular (woody) tissue. With Fusarium wilt, the vascular tissue of stems and petioles becomes brown to reddish brown, while only the lower stem tissues take on a grayish color with Verticillium wilt. Labor- atory isolation is required to distinguish these two pathogens positively. Both fungi are soil- borne and infect the plants through the root system; both are able to survive in soils in the absence of a susceptible tomato plant for many years. Fusarium oxysporum can also be seed- borne. Control: Disease resistance is the most common way to control these diseases. Tomato varieties marked "VFN" have resistance to Ver- ticillium, one or more races of Fusarium, and nematodes. Short-term crop rotations do little to control these diseases, but long-term (5 to 7 years) crop rotation can help reduce the inci- dence of Verticillium wilt. Removing infected plant parts, including roots, may help reduce the buildup of inoculum. Using nitrate forms of nitrogen can help reduce the severity of Fusar- ium wilt, while ammonium forms promote dis- ease development. Low soil pH also favors Fu- sarium, so increasing soil pH to a range be- tween 6 and 7 can help control Fusarium wilt- but not above 7.5, as this will favor the devel- opment of Verticillium wilt. For more informa- tion, read Reports on Plant Diseases No. 929, Fusarium Wilt or 'Yellows' of Tomato, and No. 1010. Verticillium Wilt Disease. Botrytis Leaf Blight of Onions In the warm humid days of summer, it is not unusual for Botrytis leaf blight to develop on onions, leeks, and other members of the onion family. The disease shows up as small whitish spots with greenish halos. The centers of the spots often become sunken and straw colored. With numerous infections, leaf tips or entire leaves can die back, giving the plants a "blast- ed" appearance. At least 24 hours of relative humidity close to 100 percent is required for infection. Temperatures below 80°F are con- ducive for the leaf- spot phase, while higher temperatures are required for the leaf-blight phase. The pathogen, Botrytis squamosa, over- winters on onion leaf debris or as hard, black, resting structures, called sclerotia, in the soil. Windborne conidia serve as secondary inoculum to spread the disease. A related fungus, Botrytis cinerea, can cause similar symptoms when it invades leaf tissues that have been damaged by high levels of ozone air pollution. Control: Control of Botrytis leaf blight de- pends on sanitation (to remove the diseased tis- sue on which the pathogen will overwinter), crop rotation, and the application of a protec- tant fungicide such as Bravo (chlorothalonil) . For more information, read Report on Plant Diseases No. 931, Onion Leaf Blights. Lawn Diseases Dollar spot is now very common on numerous turfgrasses. The disease occurs during warm (60° to 85°F), humid, or wet weather— especially Dollar spot attacking Kentucky bluegrass . in turf deficient in nitrogen. In closely cut bentgrass and bermudagrass, the brown then straw-colored spots are 1 to 2 inches in di- No. 11 • June 12, 1991 ameter, while on taller, lawn-type grasses the spots may reach 4 to 8 inches in diameter. The key to diagnosis is the characteristic girdling lesions on the leaf blades of live plants at the margin of affected areas. The lesions are bleached white to light tan with a dark brown, reddish brown, or purplish border. The spots may merge and produce larger, irregular, sunk- en areas of straw-colored dead turf that has a drought-stricken appearance. Control: Follow the cultural practices out- lined in Home, Yard & Garden Newsletter No. 8 (p. 3). Fungicides effective against dollar spot include Banner L, Bayleton, Bromosan-F, Chip- co 26019, Daconil, Duosan, Dyrene or Dymec, Rubigan, and Vorlan. Several applications may be needed spaced 7 to 30 days apart. Check label directions. Lists of tolerant or moderately resistant Kentucky bluegrasses, fine-leaf fes- cues, and perennial ryegrasses, plus the disease cycle, and much more information is given in Report on Plant Diseases No. 407, Dollar Spot of Twfgrasses. Summer patch and necrotic ring spot are sepa- rate diseases that, formerly, were collectively known as Fusarium blight. These are probably the most serious diseases of established Ken- tucky bluegrass turfs that are managed inten- sively. The first symptom to appear is scattered light green patches 2 to 6 inches across. Necrotic ring spot In warm to hot weather, they soon enlarge and rapidly fade to a dull reddish brown, then a light tan, and finally to a straw color. The patches may become sunken elongated streaks, crescents, or rough circles 1 to 3 feet in diame- ter over a period of several years. The most characteristic symptom on Kentucky bluegrass is a roughly circular, doughnut-shaped area of dead or stunted grass up to 2 or 3 feet across, with tufts of apparently healthy grass in the center, giving a "frogeye" pattern. Serious turf damage occurs when the blighted areas are numerous and overlap. Control: Follow the cultural practices as for dollar spot. Avoid pure stands of very suscep- tible grass cultivars such as Delft, Fylking, Gal- axy, Kenblue, Merion, Newport, Nugget, Park, Pennstar, Plush, and Sydsport. The blending of 15 to 20 percent seed (by weight) of a turf- type perennial ryegrass mix (for example, All-star, Birdie II, Blazer, Cigil, Citation II, Delray, Man- hattan II, NK-200, Omega II, Palmer, Pennant, Pennfine, Premier, and Yorktown II) with seed of resistant Kentucky bluegrass cultivars will sharply reduce both diseases. Overseeding dis- eased turf in late August or early September with a blend of perennial ryegrasses or resis- tant cultivars of Kentucky bluegrass also pro- vides control. For much more additional infor- mation, including complete lists of resistant grasses, read Report on Plant Diseases No. 408, Summer Patch and Necrotic Ring Spot of Lawns and Fine Turfgrasses. Where cultural practices are not providing the expected control, systemic fungicides are available. The first spray should be applied before symptoms are evident or when night temperatures do not drop below 70°F for the first time (we're already past this!). Carefully follow the label directions. The two fungicides that control both diseases when properly ap- plied and watered in are Banner L and Rubigan AS. plus Chipco 26019 or FLO, Cleary 3336, Fungo 50, Tersan 199 1WP or Topsin M. Be- ware of "magic products" containing all kinds of weird chemicals that claim to control these diseases. Avoiding stress to turf through cul- tural practices, planting resistant grasses, and applying fungicides where needed are proven controls for summer patch and necrotic ring spot. Rhizoctonia brownpatch on higher-cut, lawn- type turf is common in dense, highly fertilized turfgrass during prolonged periods of hot, moist, overcast weather. Diseased patches are usually circular, light brown, matted down, and up to about 2 feet in diameter. The patches may de- velop green centers and resemble summer patch and necrotic ring spot. In light infections, the affected turf generally recovers in 2 or 3 weeks. When the attack is severe, however, the crown, rhizomes, stolons, and roots may turn brown and rot— causing such turf to be thinned or killed in large areas. Leaf lesions that are ash brown or straw colored and often surrounded by a dark border are often evident. Control: Follow the cultural practices given under dollar spot. Where cultural measures are not controlling brown patch, apply Banner L, Chipco 26019 or FLO, Daconil, Dyrene, Duo- san, Dyrene or Dymec, Fungo, Rubigan plus Daconil or Chipco 26019, Tersan 1991WP plus Daconil, or Vorlan plus Fungo 50. Follow label directions. Report on Plant Diseases No. 411, Rhizoctonia Diseases of Turfgrasses, gives more No. 11 • June 12, 1991 information on resistant grasses, disease cycle, and yellow patch or winter brown patch and its control— another type of disease caused by Rhi- zoctonia. Pythium blight (also known as grease spot, spot blight, and cottony blight) attacks all cultivated turf grasses especially during hot (80° to 95°F), wet, or very humid weather when the grass is dense and lush and there is little or no air movement. Look for small, distinct, round to irregular, sunken spots that are 4 to 6 inches in diameter. The grass leaves are first water- soaked, slimy, and dark. They quickly fade to a reddish brown to a light tan as the grass blades dry out and shrivel. Clusters of blighted plants may merge to form irregular areas 1 to 10 feet in diameter or long streaks up to a foot or so wide that follow water drainage or mowing pat- terns. When the air is moisture-saturated, the grass leaves collapse and appear matted togeth- er by a cottony, cobwebby mass of hyphae. Another symptom is distinct, straw-colored lesions on the leaf blades that lack the brown or reddish brown borders of dollar spot. Such grass blades commonly twist, collapse, and die. Pythium is also a major cause of wiltings, col- lapse, and dying of grass seedlings (damping- off) in irregular patches. Control: Follow the cultural practices men- tioned under dollar spot. Avoid mowing when the grass is wet and watering during periods of intense disease activity. There are no grass cultivars resistant to Pythium. A preventive fun- gicide program may be needed, especially on bentgrass greens, during extended periods of hot, wet weather. Suggested fungicides include Banol L, Koban, Subdue 2E, Terrazole WP, Ter- remec or Terraneb SP, Chipco Aliette, or Pace. Carefully follow label directions. The first fun- gicide application should be made as soon as night temperatures are expected to remain at 68°F or above, when daytime air temperatures are 80°F or higher, and the forecast is for con- tinued wet or very humid weather. For much more information, read Report on Plant Dis- eases No. 410, Pythium Blight of Turf grasses. Other turfgrass disease problems you may be experiencing include melting-out (the summer phase of "Helminthosporium" leafspot; see Home, Yard & Garden Pest Newsletter No. 4 and Report on Plant Diseases No. 405, Helmin- thosporium Leaf, Crown, and Root Diseases of Turfgrasses); fairy rings and mushrooms or toadstools popping up following wet periods (see Report on Plant Diseases No. 403, Fairy Rings, Mushrooms, and Puffballs); red thread (although the threat of this should be past; see Report on Plant Diseases No. 413, Red Thread and Pink Patch of Turfgrasses); and slime molds that suddenly appear after heavy rains or watering in warm weather. Slime molds will grow up and over any low-lying objects and vegetation (such as turfgrasses, strawberries, bedded flowers, ground covers, mulches, growing media, base of trees, etc. For more information, read Report on Plant Diseases No. 401, Slime Molds of Turf- grasses. Root Rots of Garden, Landscape, and House Plants The Plant Clinic continues to receive plants affected by root rots caused by such common soilborne fungi as Rhizoctonia and Pythium. Symptoms may include collapse and dying of seedlings (damping-off) or a stunting of older plants that lack vigor, grow slowly, or wilt on a warm day. The foliage of such plants may turn yellow to brown and drop prematurely, starting with the bottom or oldest leaves and moving up the plant until only the youngest tufts of leaves remain. If severely affected, plants eventually die when the roots can no longer supply suffi- cient water and nutrients to the aboveground parts. The severity of root rot depends upon the fungal pathogen, the susceptibility of the host plant, and the soil conditions. Control: Many cultural practices will pre- vent this disease complex. Start with only top- quality seed or transplants, etc. of well-adapted species and cultivars. Plant in fertile, light, well- drained soil (pasteurized with heat for house plants). Keep soil on the dry side— avoid over- watering. Rotate outdoor plantings with un- related plants for several years. Adding com- posted hardwood bark as a growing medium or mulch will help suppress root rotting fungi. Other control measures and discussions of the major root rotting fungi, disease cycles, etc. are contained in Report on Plant Diseases No. 615, Damping-off and Root Rots of House Plants and Garden Flowers." Chemical controls are also giv- en. What fungicides to use depends on what root rotting fungus or fungi are involved. Two fungicide mixtures that control most major fun- gi include Banrot and SA-Terraclor Super-X. If Pythium and Phytophthora only are involved, Aliette, Truban, Terrazole, or Subdue can be used. If Rhizoctonia is the major cause, PCNB (Terraclor, Fungi-clor or PCNB 75WP) is a good choice as is Benlate or Benomyl WP and Topsin M. Applications should start before symptoms are evident. Many Plants: Botrytis Blight Botrytis blight, or gray mold, attacks a wide range of tender tissues of ornamental plants, vegetables, and fruits in greenhouses or out- doors—especially during or following cool, damp, cloudy weather. It can also be a serious cold 6 No. 11 • June 12, 1991 storage and transit problem of many kinds of horticultural commodities. Flowers, stems, buds, leaves, fruits, bulbs, corms, tubers, seedlings and roots can all be attacked. Affected tissue is first water-soaked and brown. A conspicuous, tan to gray fuzzy mold forms on rotted tissues under humid conditions. (Putting suspected Botrytis-infected tissue in a sealed plastic bag with some moist paper toweling or tissue for 12 to 24 hours should result in a gray mold if Botrytis is the cause.) Control: Strict sanitation is of utmost im- portance. Avoid splashing water on foliage when watering. Provide for good air movement by proper spacing of plants. Avoid overfertilization and unnecessarily wounding plants. Other con- trols, disease cycle, and much more informa- tion is given in the following Reports on Plant Diseases: No. 623, Botrytis Blight or Gray Mold of Ornamental Plants; No. 704, Gray Mold of Strawberries; No. 931, Onion Leaf Diseases; and No. 942. Chemical controls for Botrytis will vary with the crop. Be sure to check labels to en- sure that the fungicide can be used on that particular plant. Good-to-excellent fungicides to control Botrytis include Ornalin, Daconil or Bravo, Topsin-M, Rovral, Benlate, Dyrene, Rona- lin, mancozeb, Duosan, Zyban, Chipco 26019, and Botran. Oaks: Oak Wilt This is the most serious disease of red and black oaks, although all oaks are susceptible to a greater or lesser degree. On trees in the red and black oak group, the leaves in the crown and tips of the lateral branches discolor, wilt, and drop in large numbers. The symptoms pro- gress downward and inward until the entire tree is affected. The leaves curl slightly and turn a dull pale green, bronze, or tan starting at the margins. A brown or black discoloration usual- ly develops in the current-season sapwood of wilting branches. Infected oaks in the red and black group do not recover. On other oaks the leaves on affected branches usually turn light brown or straw- colored from the leaf tip toward the base. The leaves curl but remain attached. Usually only scattered branches are affected. Infected trees may die in one year, but usually die back slow- ly over several years or more. Laboratory cul- turing is needed for positive identification. Sam- ples should be sent to the Plant Clinic before July 1. Control measures are complicated and in- volve not wounding or pruning oaks except during late fall or the dormant winter season; root graft control through cutting the roots mechanically or using a chemical treatment (Vapam Soil Fumigant); prompt removal of dead trees; creating barriers of poisoned oaks; and the use of growth regulators and systemic fun- gicides. For information on additional symp- toms, laboratory culturing, hosts, spread, and control, read Report on Plant Diseases No. 618, Oak Wilt and Its Control. Reports on Plant Diseases Copies of any Report on Plant Diseases men- tioned in this or other newsletters are 50 cents each; five copies or more are 25 cents each. Checks should be made payable to the Univer- sity of Illinois and mailed to Extension Plant Pathology, N-533 Turner Hall. 1102 South Goodwin Ave., Urbana, IL 61801. If you would like to have a copy of the complete listing of all 230 Reports on Plant Diseases, send a postcard or note to the same address. There is no charge for the list. PLANT CLINIC HIGHLIGHTS May 31 to June 6, 1991 PLANT DIAGNOSIS COUNTY Ash Geranium Hickory Impatiens PGR herbicide injury Botrytis Herbicide injury Midge gall Rhizoctonia, Pythium root rot Livingston Champaign Peoria Lake Lake Maple Oak Verticillium wilt Oak wilt Champaign DuPage Poinsettia Herbicide injury Pythium, Rhizoctonia root rot Peoria Putnam Pussy willow Willow blight McLean Turf Vinca Dollar spot Rhizoctonia root rot Champaign Lake Home, Yard &, Garden Pest Newsletter is prepared by the following Extension specialists from the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey: Entomology, Roscoe Randell and Philip Nixon. Horticulture, James Schmidt and Tom Voigt. Plant Pathology, Nancy Pataky, Malcolm Shurtleff, and Darin Eastburn. Information for this newsletter is gathered by these people with the help of staff members, county Extension advisers, and others in cooperation with the USDA Ani- mal and Plant Health Inspection service. Roscoe Randell Extension Specialist Entomology llinois Cooperative Extension Service Helping you c