0 ts fh ¥ a ‘ fe Ay paar iN a pee: CUE ab) ae x Fe non 4 a . PANU enc akigaey| LIBRARY OF THE UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN no.66G - 299 yea lict a ‘Rew i 8-atnum ; . 19 LT LICe 00 tiie ; @,* avearves ism = at 1% ¢ 7 ow aSiti) aM. ore” a Arts panies: «' | grat! “4 : o~ Pyles on." Ger 24" * bee" TREE AND SHRUB HOSTS OF Venticillinm olbo-otnum E.B. HIMELICK BIOLOGICAL NOTES NO. 66 ILLINOIS NATURAL HISTORY SURVEY URBANA, ILLINOIS JULY, 1969 STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION NATURAL HISTORY SURVEY DIVISION TREE AND SHRUB HOSTS OF VERTICILLIUM ALBO-ATRUM VERTICILLIUM WILT, caused by Verticilliwm albo- atrum Reinke and Berth., has become increasingly prevalent among plantings of ornamental trees and shrubs in Illinois. Persons not familiar with Verti- cillium wilt symptoms frequently attribute plant deaths resulting from this disease to other causes, such as transplanting shock and winter injury. Because this fungus affects a wide range of woody ornamental plants, it is difficult to estimate the economic loss it causes to nurserymen and homeowners. Rankin (1914) first reported the disease on maple in the United States and identified the fungus as a species of Acrostalagmus. Zimm (1918) later proved pathogenicity and identi- fied the fungus as a species of Verticillium. A mono- graph on the disease by Rudolph (1931) lists the known host range up to 1931. Engelhard (1957) pub- lished a host index for V. albo-atrum that included both herbaceous and woody plants. NEWLY IDENTIFIED HOSTS Routine isolations have been made at the Illinois Natural History Survey from branch samples of dis- eased trees and shrubs since 1926. During the last 42 years V. albo-atrum (including V. dahliae Kleb.) has been obtained from several hosts growing in widely scattered areas of the state. Table 1 shows the woody hosts reported for [linois by 1956, including 30 tree and shrub species and varieties (Carter 1938, 1940, 1945; Engelhard & Carter 1956). Since the last of these reports was published, 26 additional species and varieties of woody ornamentals, also listed in Table 1, have been identified as hosts in Illinois. Twenty-two of the plant species or varieties, identified at the IIli- nois Natural History Survey and listed in Table 1, are believed to be previously unrecorded hosts in the United States, as no records of these hosts were found. However, at least 3 of these 22 hosts have been re- ported in other countries. A few of the new Verticil- lium hosts reported here have been mentioned in re- ports which were primarily field survey reports. Where there is no indication that the fungus was isolated from infected wood and positively identified, the field report usually is not cited. PATHOGENICITY TESTS Since 1957 Verticillium isolates from various hosts have been tested at the Illinois Natural History Survey for pathogenicity to the respective host plant. Most of E. B. Himelick the trees and shrubs were available in our research arboretum. Occasionally certain species were not available and had to be purchased as seedlings. These seedlings were established in pots in our greenhouse. Pathogenicity was tested by inoculating 5-20 plants of each species or variety, and an equal number of uninoculated plants was used as a control for each species. Each plant was inoculated by placing a drop of spore suspension in a ehisel wound made in the base of the trunk. An attempt was made to reisolate the fungus within 7 days following the initial appear- ance of foliage symptoms. External symptoms were produced 2 weeks to 3 months after inoculation on all species except silver maple. Silver maple did not produce typical foliage symptoms, but did have scattered faint green streaks in the twigs 4-5 feet from the point of inoculation. The fungus was re- covered from the discolored area 2 months after inoc- ulation. Pathogenicity was established for 18 of the 22 plant species listed in Table 1 as new hosts in the United States. Pathogenicity was established for an addition- al four plant species that were newly discovered hosts in Illinois and for an additional eight species from which V. albo-atrum had been isolated but for which proof of pathogenicity had not been established. HOSTS OUTSIDE OF ILLINOIS Table 2 lists the Verticillium tree and shrub hosts identified in addition to the 1957 list of Engelhard and those listed for Illinois in Table 1. Most of these hosts have been reported since 1957. Engelhard’s list and Tables 1 and 2 include most of the world’s known Verticillium wilt hosts among trees and shrubs. VERTICILLIUM WILT SYMPTOMS Some tree and shrub species tend first to show foliage symptoms during a limited period of the grow- ing season; other species have symptoms appearing at any time throughout the growing season. The times when plant growth begins and ceases are variable in Illinois, since the state has three climatic zones (Rehder 1940:ii,xii). In Illinois, Verticillium wilt ap- pears to be most prevalent in trees and shrubs in the area that demarks the line between climatic zones IV and V and appears progressively less prevalent on both sides of this imaginary line. Both temperature and moisture may be factors that contribute to the Tasie 1.—Tree and shrub hosts of Verticillium albo-atrum in Illinois. Verticillium Isolations for Illinois, 1926-1968 Pathogenicity Tests Reported as a Host Number Host Plant First Year Number of Number Number Isolated of Years Naturally of Plants of Plants United States Other Countries in Illinois Isolated Infected Inoculated Infected Plants Almond (Prunus amygdalus Batsch. ) 1932 1 1 Ill. (Carter 1938) Ash spp. ( Fraxinus spp.) 1957 8 10 Black (F. nigra Marsh.) 1962 1 1 This report Blue (F. quadrangulata Michx. ) 1957 3 3 20a 14 This report European (F. excelsior L.) 1964 10» 6 This report Green (F. pennsylvanica Marshall var. subintegerrima (Vahl) Fernald) 1957 3 4 20a 7 Colo. (Thomas 1950) White ( F. americana L.) 1959 3 o 20a 15 This report Azalea (Rhododendron molle G. Don) 1964 1 1 10 3. This report Barberry spp. ( Berberis spp.) 1957 2 vA Japanese (B. thunbergii DC.) 1933 3) 6 10a 3. Mass. ( Boyd 1930) Ill. (Carter 1945) N.J. (White 1936) Boxwood, Korean ( Buxus microphylla koreana Nakai) 1960 if 1 5a 1 This report Catalpa spp. (Catalpa spp.) 1942 6 8 Western (C. speciosa Warder) 1936 3 4 Ill. (Carter 1938) Kans. (Rogerson 1957) Coffee tree, Kentucky (Gymnocladus dioica (L.) K. Koch.) 1966 20b 6 This report Cork tree ( Phellodendron amurense Rupr. ) 1964 5b 2. This report Elm, American ( Ulmus americana L.) 1931 28 406 10a 4 Ill. (Carter 1938), Canada (Quebec widespread (Kel- 1961) sheimer & May 1940) var. Augustine Ascending 1955 1 1 Ill. (Engelhard & Carter 1956) Henry Field 1960 1 1 This report Littleford 1939 1 4 Ill. (Carter 1940) Moline 1939 3 5 Ill. (Carter 1940), Kans. ( Rogerson 1957) Chinese ( U. parvifolia Jacq.) 1951 1 1 Ill. (Engelhard & Carter 1956) English (U. procera Salisb. ) 1955 1 1 Ill. (Engelhard & Carter 1956), wide- spread ( Kelsheimer & May 1940) Slippery (U. rubra Muhl.) 1951 2 7 Ill. (Engelhard & Carter 1956), wide- spread ( Kelsheimer & May 1940) Goldenrain tree ( Koelreuteria paniculata Laxm. ) 1948 2 3 5a 3 Ill. (Engelhard & Carter 1956) Linden, American ( Tilia americana L.) 1939 4 4 20a 12 sill. (Carter 1940) Little leaf (T. cordata Mill.) 1964 20b 11 ‘This report Locust, Black ( Robinia pseudoacacia L.) 1932 2 2 Ill. (Carter 1938 ) Italy (Goidanich 1935) Magnolia spp. (Magnolia spp.) 1951 3 3 Ill. (Engelhard & Carter 1956) Saucer (M. soulangeana Soul.) 1959 3 3 5a 5 Ind. (Schreiber ct al. 1961) Star (M. stellata (Sieb. & Zucc.) Maxim. ) 1963 1 1 5a 2 = This report Maple spp. ( Acer spp.) 1947 9 24 Calif. ( Baker et al. 1940) Amur (A. ginnala Maxim.) 1958 1 1 10a 5 This report Black (A. nigrum Michx. f.) 1936 1 1 Ill. (Carter 1938) TaBLeE 1.—Continued Verticillium Isolations for Illinois, 1926-1968 Pathogenicity Tests Number Host Plant First Year Number of Number Number Isolated of Years Naturally of Plants of Plants in Illinois Isolated Infected Inoculated Infected Reported as a Host United States Other Countries Plants Norway (A. platanoides L.) 1935 17 26 10 3 N.C.&Va.(Hept- Italy (Goidanich ing & Toole 1950), 1934) lll. (Carter 1938), NW states (Bedwell & Childs 1938), Ore. (Martin 1929) var. Crimson King 1960 1 1 This report var. schwedleri Nichols. 1937 5 6 Ill. (Carter 1938) Holland (van der Meer 1926) Red (A. rubrum L.) 1933 4 4 Ill. (Carter 1938) Canada ( Quebec 1961) Sugar (A. saccharum Marsh. ) 1926 22 50 20b 11 NC. (Hepting & Canada (Quebec Toole 1950), Mass. 1961) ( Martin 1926), Ill. (Carter 1938), N.Y. (Rankin 1914) Hedge (A. campestre L.) 1964 5b 4 This report Silver (A. saccharinum L.) 1964 5e 2 This report Oak, Pin (Quercus palustris Muenchh.) — 1960 1 1 15a 7 This report Red (Q. rubra L.) 1960 15b 4 This report Pagoda tree (Sophora japonica L.) 1964 5b 3. This report Italy (Goidanich 1935) Privet, Amur (Ligustrum amurense Carr.) 1943 3 3 Il. (Carter 1945) Persimmon ( Diospyros virginiana L.) 19404 1 1 Ill. (Carter 1945) Redbud (Cercis canadensis L. ) 1941 9 18 102 6 Kans. ( Rogerson 1957 ), Ill. (Carter 1945) Rose, Multiflora (Rosa multiflora Thunb. ) 1947 1 1 Ill. (Engelhard & Carter 1956) Rose daphne (Daphne cneorum L.) 1966 1 1 5b 2 This report Russian olive (Elaeagnus angustifolia L.) 1956 4 9 25a 16 Kans. ( Rogerson 1957), N. Mex. (Smith 1960) Sassafras (Sassafras albidum ( Nutt.) Nees. ) 1940d 1 1 Ill. (Carter 1945) Smoke tree (Cotinus coggyzria Scop.) 1936 11 12 Ohio (Ellett 1957), Europe (Rudolph Ill. (Carter 1938), 1931) R.I. (Caroselli 1961 ) Sour gum (Nyssa sylvatica Marsh.) 1955 2) 2 Ill. (Engelhard & Carter 1956) Sumac, Fragrant (Rhus aromatica Ait.) 1943 2 2 5b 5 This report Smooth (R. glabra L.) 1936 6 9 Ill. (Carter 1938) Europe ( Rudolph 1931), England (Rudolph 1931) Staghorn (R. typhina L.) 1960 2 2 This report Tulip tree (Liriodendron tulipifera L.) 1949 8 18 20b 8 Conn. (Waterman 1956), Ill. (Engel- hard & Carter 1956), W. Va. (Kessler & True 1960) Viburnum spp. (Viburnum spp.) 194] 4 5 Wayfaring tree (V. lantana L.) 1937 3 3 Ill. ( Carter 1938), Ind. (Baines 1945) Doublefile (V. tomentosum Thunb. ) 1964 1 1 5a 1 Ind. (Baines 1945) (V. burkwoodii Burkwood ) 1964 1 1 5b 5 This report Yellowwood (Cladrastis lutea ( Michx.) K. Koch.) 1938 3 3) Ill. (Carter 1940) “Pathogenicity was proved by inoculation of the isolated strain into the respective plant species, development of typical wilt symptoms, and reiso- lation of the fungus. Susceptibility was proved by inoculation with inoculum containing at least four different host isolates of V. albo-atrum, production of typical wilt symptoms, and reisolation of the fungus. ©Inoculated with a strain of V. albo-atrum from the sugar maple. The fungus was reisolated 2 months later from twigs having faint green streaks. No leaf symptoms were observed. Verticillium spp. isolated. The fungus was not characteristic of V. albo-atrum. 6 variability in the prevalence of the disease, along with the presence of a large number of tree species growing in this area. Because of the loss of elms, a greater variety of tree species is being planted than previously. Our plant disease clinic records indicate that 34 percent of the confirmed V. albo-atrum isolations oc- curred in the month of July, 20 percent in June, 20 percent in August, 10 percent in September, 8 percent in May, 6 percent in October, and only 2 percent in March, April, and November. For the past several years observations have been made of Verticillium wilt symptoms on various tree species (Table 3). Variation in symptom expression and in extent and speed of decline often occurs among the different species. For simplification, the table in- cludes the more commonly observed symptoms for each of the host species listed. SUSCEPTIBILITY OF HOSTS A summary of our laboratory records for the past 42 years indicates that nine tree and three shrub genera are most commonly affected by Verticillium wilt. V. albo-atrum was recovered most frequently from branch specimens of ash, barberry, catalpa, elm, magnolia, maple, redbud, Russian olive, smoke tree, sumac, tulip tree, and viburnum. In recent years strains of V. albo-atrum have been isolated that are quite virulent to numerous tree and shrub species. One strain isolated from a naturally infected pin oak tree (Quercus palustris Muenchh. ) and inoculated into both pin oak and red oak (Q. rubra L.) produced wilt symptoms and internal dis- coloration similar to those of the oak wilt disease. The pin oak strain appears to be more virulent than maple strains in maple, ash, magnolia, and Russian olive. However, inoculation tests indicated that the pin oak strain was not pathogenic on white oak (Q. alba L.) or bur oak (Q. macrocarpa Michx.). In addition, a strain isolated from ash and inoculated into vigorous, grow- ing trees, such as maple, redbud, and tulip tree, did not produce wilt symptoms. However, when this strain was placed in Russian olive, typical wilt symp- toms were produced in 2-3 weeks. Trees susceptible to Verticillium wilt occasionally show symptoms of this disease while they are still in a weakened condition following transplanting. Since there is evidence that V. albo-atrum isolates differ in Tasie 2.—Tree and shrub hosts of Verticillium albo-atrum outside of Illinois. Host Plant Reported as a Host Apricot (Prunus armeniaca L.) Azalea (Rhododendron spp.) Boxwood ( Buxus spp.) (B. sempervirens L.) Cherry (Prunus avium L.) (P. cerasus L.) Chestnut, Spanish (Castanea sativa Mill.) Dogwood (Cornus florida L.) Elm, Scotch (Ulmus campestris L.) Holly olive (Osmanthus ilicifolius (Hassk.) Mouillef.) Horse chestnut ( Aesculus hippocastanum L.) Judas-tree (Cercis siliquastrum L.) Magnolia (Magnolia grandiflora L.) Maple, Japanese (Acer palmatum Thunb. ) Oregon (A. macrophyllum Pursh. ) Painted (A. mono Maxim.) Striped (A. pennsylvanicum L.) Sycamore (A. pseudoplatanus L.) Oak spp. (Quercus spp.) Turkey (Q. cerris L.) Osage orange (Maclura pomifera ( Raf.) Schneid.) Peach (Prunus persica (L.) Batsch.) Peony (Paeonia spp.) Plum (Prunus domestica L.) Canada (P. nigra Ait.) Rose (Rosa spp.) Tree of heaven (Ailanthus altissima ( Mill.) Swingle) * Verticillium sp. isolated. Other Countries Canada (Quebec 1961) United States Widespread ( Parker 1959) Mass. (Edson & Wood 1936) Eastern U.S. (Hutchinson 1931 )a Va. (Harrar 1937) Widespread (Parker 1959) Widespread (Parker 1959) Calif. (McCain 1963) Mass. (Holmes 1957) Canada (Quebec 1961) Canada (Quebec 1961) Italy (Goidanich 1935), Hol- land (van der Meer 1926) Va. (Gruenhagen & Fordyce 1963 ) Pa. (Armstrong 1941) Italy (Goidanich 1935 ) Calif. (McCain 1963) N.Y. (Martin 1926) NW states (Bedwell & Childs 1938), Calif. (Mielke 1935) Tenn. (Felix 1955) N.Y. (Hibben 1959) Canada (Quebec 1961), Italy (Goidanich 1934) Russia (Krangauz 1958 ) Hungary (Georgescu et al. 1959) Italy (Goidanich 1934) Canada (Quebec 1961) Conn. (Waterman 1941) Widespread (Parker 1959) Kans. (Martin 1926; Rogerson 1957 ) Widespread (Parker 1959) Canada (Quebec 1961) Canada (Quebec 1961) Canada (Quebec 1961) ) Italy (Goidanich 1935 virulence to various hosts, the transporting of infected ornamental plants from one area to another may account for the appearance of the disease in tree and shrub species not previously attacked by it. It seems u likely that the continued indiscriminate movement of nursery stock from one region to another will eventual- ly bring about a complete distribution of all virulent strains to areas where they did not exist before. TaB_e 3.—Symptoms of Verticillium wilt observed on trees and shrubs. Vascular Symptoms Host Plant Type of Decline Leaf Symptoms ant Xylem Ash Twig or branch dieback. Abscission when still green; Faint tan streaks (when they Young trees usually appear to yellowing and scorching of occur); seldom found in recover. other leaves twigs. Azalea Usually rapid decline, 2-4 weeks. Yellowing and browning Yellowish-brown to brownish- Shrubs usually die. black streaks Boxwood Twig dieback. Some plants may Browning and defoliation Brown discoloration recover. Catalpa Twig or branch dieback; occa- Yellowing and scorching Purplish-pink to bluish-brown Coffee tree Cork tree Elm Goldenrain tree Linden Locust, black Magnolia Maple Oak Pagoda tree Redbud Rose daphne Russian olive Smoke tree Sour gum Sumac Tulip tree Viburnum Yellowwood sionally branches or whole tree wilts. Trees appear to re- cover. Twig dieback. Young seedlings recover. Branch wilt. Young trees appear to recover. Twig dieback. Sometimes whole tree dies. Usually rapid decline, 2-4 weeks. Young trees may recover. Usually branch dieback. Some trees may recover. Twig dieback. Usually rapid decline; sometimes only branches are affected. Varies with species from rapid to no decline. Symptoms may disappear and reappear years later. Twig dieback, slow decline Slow decline, 1-2 years. Usually rapid decline, 2-4 weeks. Trees usually die. Slow decline over 2-3 years. Twig dieback; may occur each year or skip a year or two and reappear. Some trees may die. Rapid decline. Trees usually die. Usually rapid decline, 2-4 weeks. Trees usually die. Rapid decline, 2-4 weeks. Shrubs usually die. Rapid decline, 2-4 weeks. Trees usually die. Rapid decline, 2-4 weeks. Shrubs usually die. Rapid decline, 2-4 weeks. Trees usually live. Yellowing, scorching, and de- foliation Yellowing and defoliation Flaccidity, yellowing, and de- foliation Scorching and browning Yellowing and browning Yellowing, browning, and de- foliation Yellowing, browning, and de- foliation Scorching, browning, and de- foliation Flaccidity, discoloring, brown- ing, and some defoliation; similar to oak wilt. Yellowing and browning Flaccidity, yellowing, brown- ing, and some defoliation Yellowing and defoliation Yellowing and browning Margins reddish-purple; later yellowing, browning, and defoliation. Scorching and browning Yellowing and browning Yellowing and defoliation Browning and defoliation Browning and defoliation upon drying Light brown streaks Faint brown streaks Brown streaks Brown streaks Brown streaks Light to dark reddish-brown streaks ‘Greenish-brown streaks Light to dark green streaks; often difficult to find. Brown streaks and sometimes bands; similar to condition caused by oak wilt. No discoloration observed. Brown streaks Brown streaks Brown streaks Yellowish-brown to brownish- black streaks Chocolate brown streaks Light green streaks Greenish-brown streaks. Bark may be killed in strips on trunk. Light to dark reddish-brown streaks Brown streaks eee Baker, K. F., W. C. Snyper, and H. N. HANsen. 1940. Some hosts of Verticillium in California. Plant Disease Reporter LITERATURE CITED ARMSTRONG, NEWTON G. Verticillium wilt of horse- chestnut. Arborist’s News 6:82-83. Baines, R. C. 1945. Verticillium wilt and die-back of Vi- bumum. Phytopathology 35:145-147. 24:494-495, BEDWELL, J. L., and T. W. Cuuixps. 1938. Verticillium wilt of maple and elm in the Pacific Northwest. Plant Disease Reporter 22:22-23. 8 Boyp, O. C. 1930. Some diseases of shrubs and ornamentals in Massachusetts. Plant Disease Reporter 14:20]. Caroseut, Nestor E. 1961. Verticillium wilt of smoke bush. Plant Disease Reporter 45:24—25. Carter, J. C. 1938. Verticilltum wilt of woody plants in Illinois. Plant Disease Reporter 22:253-254. . 1940. Some isolations of Verticillium in Illinois during 1938 and 1939. Plant Disease Reporter 24: 133-134. 1945. Isolations of Verticillium from trees and shrubs in Illinois, 1940-1944. Plant Disease Reporter 29:95-96. Epson, H. A., and Jessie I. Woop. 1936. Diseases of plants in the United States in 1935. Plant Disease Reporter Supplement 96:115—289. Exrterr, C. W. 1957. Diseases not previously reported in Ohio. Plant Disease Reporter 41:369-371. ENGELHARD, ARTHUR W. 1957. Host index of Verticillium albo-atrum Reinke & Berth. (including Verticillium dahliae Kleb.). Plant Disease Reporter Supplement 244:21-50. , and J. C. Carrer. 1956. Isolations of Verticillium albo-atrum from woody hosts in Illinois, 1945-1955. Plant Disease Reporter 40:459-462. Fevix, E. L. 1955. Some tree diseases in Tennessee. Plant Disease Reporter 39:882. Georcescu, C. C., S. OreNscut, and M. Petrescu. 1959. In- vestigations of a verticilliosis of Q. cerris [in Romanian with Russian and French summaries]. Omagiu lui T. Savulescu 39:247-257. (English abstract in Review of Applied My- cology 39:743-744. ) Gomanicu, G. 1934. Verticilliosis of Acer platanoides L., Acer pseudoplatanus L., and Maclura aurantiaca L. [in Italian, English summary]. Bollettino della Roma Stazione di Patologia Vegetale, new series, 14(2):268-272. (En- glish abstract in Review of Applied Mycology 13:811.) 1935. New cases of tracheomycosis caused by Verti- cillium in Italy. Observations on a new species of tracheid- inhabiting Verticillium [in Italian]. Bollettino della Roma Stazione di Patologia Vegetale, new series, 15(4):548-554. (English abstract in Review of Applied Mycology 15:474.) GrRUENHAGEN, R. H., and C. Forpyce. 1963. Osmanthus ilicifolius, a new host of Verticillium albo-atrum. Plant Disease Reporter 47:688. Harrar, J.G. 1937. Some unusual diseases of ornamentals in Virginia. Plant Disease Reporter 21;217. Heptinc, Georce H., and E. Ricnarp Too ce. southeastern tree diseases—1948 and 1949. Reporter 34: 135-137. Hipsen, Craic R. 1959. A new host for Verticillium albo- atrum Reinke & Berth. Plant Disease Reporter 43:1137. Hoimes, F. W. 1957. Verticillium wilt of dogwood. Phyto- pathology 47:17. (Abstract) Hutcuinson, W.G. 1931. Study of a disease of boxwood in the eastem United States. Proceedings of the Pennsylvania Academy of Science 5:13-14. 1950. Some Plant Disease KetsHermer, E. G., and C. May. 1940. Verticillium wilt of elm. 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Plant Disease Reporter Supplement 255:37-61. QveBEC, MINISTERE DE L’AGRICULTURE DE LA PROVINCE DE. 1961. Noms Francais des maladies des plantes au Canada. Publication 263. 169 p. Rankin, W. H. 1914. Thrombotic disease of maple. Phyto- pathology 4:395-396. Renper, Atrrep. 1940. Manual of cultivated trees hardy in North America exclusive of the subtropical and warmer tem- perate regions. 2nd ed. The Macmillan Company, New York. 966 p. Rocerson, Crark T. 1957. Verticillium wilt in Kansas. Plant Disease Reporter 41:1053-1054. Rupotrn, B. A. 1931. Verticillium hadromycosis. Hilgardia 5:197-361. Scuremer, LAwkeNce R., Craupe Forpyce, Jr. and R. J. Green, Jr. 1961. Verticillium wilt of saucer magnolia, magnolia soulangeana. Plant Disease Reporter 45:108. Smiru, T. E. 1960. Occurrence of Verticillium wilt on Rus- sian olive. Plant Disease Reporter 44:72. Txomas, W. D., Jr. 1950. New shade tree diseases in Colo- rado, Plant Disease Reporter 34:83. VAN DER MEER, Jikke H. H. 1926. Verticillium-wilt of maple and elm-seedlings in Holland. Phytopathology 16:611-614. WaterRMAN, ALMA M. 1941. Diseases of shade and oma- mental trees: annotated list of specimens received in 1940 at the New Haven office, Division of Forest Pathology. Plant Disease Reporter 25: 181-186. 1956. Verticillium wilt of yellow-poplar. Plant Dis- ease Reporter 40:349-350. Wuirte, R. P. 1936. Notes on new or unusual outbreaks of diseases of ornamentals in New Jersey in 1935. Plant Disease Reporter 20:79-81. Zim, L. A. 1918. A wilt disease of maples. Phytopathology 8:80-81. (Abstract) ee eee This paper is published by authority of the State of Illinois, IRS Ch. 127, Par. 58.12, and is a contribution from the Section of Botany and Plant Pathology of the Illinois Natural History Survey. Dr. E. B. Himelick is a Plant Pathologist at the Survey. 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