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BAKER, Dean Some Insect Enemies of Shade Trees and Ornamental Shrubs BY: M. W. BLACKMAN, Ph.D. Professor of Forest Entomology AND W. O. ELLIS, M.S. Instructor in Forest Entomology Published Quarterlyjby the University. Entered at the Postoffice at Syracuse as second-class mail mattel TRUSTEES OF THE NEW YORK STATE COLLEGE OF FORESTRY Ex OFFICIO. Dr, JAMES RK. Day, Chancellor... 0... tig ss oe seen Syracuse University. Dr. JoHN HusTOoN FINLEY, Commissioner of Edu- COLON hs Liln « Sek RO Reema ss See oe Stee Albany, N. Y. Hon. GEorGE D. PRATT, Conservation Commissioner. New York City. Hon. EpwarpD SCHOENECK, Lieutenant-Governor... Syracuse, N. Y. APPOINTED BY THE GOVERNOR. Hon. CHARLES ANDREWS Wo. 055.2506 4- sea eee = Syracuse, N. Y. Hon. ATEXANDER T! BROWS. => >-eul> ee 6 ~~ =n Syracuse, N. Y. Fon. JOHN KR; GUANCY ii wis Gee ang eee. wep Syracuse, N. Y. Hon. LARoLp -D, “CORBNWAEL 2+... 5°20 16 eee Lowville, N. Y. Hon: “Groner W. DRISCOLL 2)... 4.5 ct seo eee ee Styracuse, N. Y. Hon, FRANCIS: HENDRICKS \. ....N eho. oS 2s eee Syracuse, N. Y. Hon. HEenpRick §.. HOLDEN.» - 295% sce «loys sine Syracuse, N. Y. Eon. T00is MABSEAT Io). oom yea tne ee ee New York City. My. WoWARD GOV EABAS oi Gis swine mts is Soa e Bsa ee Syracuse, N. Y. OFFICERS OF THE BOARD President. 205646084 os eee ee eee Hon. Louis Marshall. Vice-President o. ois << se Seema in bes 8s Hon. John R. Clancy. TPTCASUTET Nha i > «dees Ue ee oe Hon. Hendrick S. Holden. ey { ease | oe) LO. a FACULTY OF THE NEW YORK STATE COLLEGE OF FORESTRY AT SYRACUSE UNIVERSITY JAMES ROSCOE DAY, S. T. D., D. C. L., LL.D., Chancellor of the University. HUGH POTTER BAKER, M. F. (Yale 1904); D. Oec. (Munich, 1910), Dean of the College and Prof. of Silviculture. FRANK F. MOON, B. A. (Amherst College 1901); M. F. (Yale 1909), Professor of Forest Engineering. MAULSBY WILLETT BLACKMAN, A. B. (Univ. of Kansas 1901) ; Ph. D. (Harvard Univ. 1905), Professor of Forest Entomology. EDWARD F. McCARTHY, B.S. (Univ. of Michigan 1911), Professor of Forestry at the State Ranger School. NELSON COURTLANDT BROWN, B. A. (Yale College 1906); M. F. (Yale University 1908), Professor of Forest Utilization. J. FRED BAKER, B. S. (Michigan Agricultural College 1902); M. F. (Yale University 1905), Director of Forest Investigations. LEIGH H. PENNINGTON, A. B., 1907, Ph. D. (Univ. of Michigan 1909), Professor of Forest Pathology. GEORGE A. GUTCHES, M. F. (University of Michigan 1910), Director of State Ranger School. JOHN WALLACE STEPHEN, B. A., M. S. F. (Univ. of Mich. 1907; M. P. D. (Mich. Normal College 1915), Assistant Professor of Silviculture. REUBEN PARKER PRICHARD, B. 8S. (Dartmouth College 1907) ; M. F. (Yale University 1909), Assistant Professor of Forest Products. (3) 4 College of Forestry CHARLES CHRISTOPHER ADAMS, B. 8. (Illinois Wesleyan 1896) ; M. 8. (Harvard Univ. 1899); Ph. D. (Chicago Univ. 1908), Assistant Professor of Forest Zoology. HENRY. R. FRANCIS, B.S. (Massachusetts Agricultural College 1910), Assistant Professor of Landscape Extension. HARRY P. BROWN, B. A. 1909, A. M. 1910, Ph. D. (Cornell Univ. 1914), Assistant Professor of Forest Botany. SHIRLEY W. ALLEN, B. S. A. (Iowa State College 1909), Assistant Professor of Forest Extension. LAURIE D. COX, A. B. (Acadia College 1903); B.S. L. A. (Harvard University 1908), Assistant Professor of Landscape Engineering. WILLIAM A. McDONALD, B. S. F.. (Michigan Agricultural College 1913) Assistant Professor of Forest Extension. RUSSELL TAYLOR GHEEN, B. S. F. (Pennsylvania State College 1912); M. F. (The New York State College of Forestry 1914), Assistant Professor of Forest Hatension. HOWARD BLAINE WAHA, B.S. (Pennsylvania State College 1909), Assistant Professor of Forest Engineering. HENRY HARRINGTON TRYON, A. B., M. F. (Harvard University 1913), Instructor in Forest Utilization. ~WILLIAM O. ELLIS, A. B. (Lebanon Valley College 1911) ; M. 8S. (Iowa State College 1913), Instructor in Forest Entamology ALVIN G. SMITH, B. S. (The New York State College of Forestry ©. 1915), Field Assistant in Forest Investigations. MILDRED FE, WOOD, B. L. E. (Syracuse University 1914), Librarian. “4 LILLIAN M. LANG, Secretary to the Dean. WALTER W. CHIPMAN, B. S. (Wabash College 1893), Cashier. MARTHA JEANETTE HARRINGTON, B. L. E. .(Syracuse University 1914). Assistant Librarian. Faculty 5 Members of University Faculty, Outside of College of Forestry, Giving Instruction to Students in Forestry. FRANKLIN JAMES HOLZWARTH, Ph. D. (Syracuse), Professor of German. ERNEST NOBLE PATTEE, M. 8. (University of Rochester) , Professor of Chemistry. THOMAS CRAMER HOPKINS, Ph. D. (University of Chicago), Professor of Geology. WILLIAM L. BRAY, Ph. D. (University of Chicago), Professor of Botany. WARREN GARDNER BULLARD, Ph. D. (Clark University), Professor of Mathematics. CHARLES HENRY RICHARDSON, Ph. D. (Dartmouth College), Professor of Mineralogy. FREDERICK WILLIAM REVELS, B. Ar. (Syracuse University), Professor of Architecture. LEON BRUCE HOWE, B. Ar. (Syracuse), Professor of Drawing. CHARLES JULIUS KULLMER, Ph. D. (University of Tubingen), Professor of German, DAVID L. DUNLAP, D. Sc., M. D. Professor Physical Education and Hygiene. HERBERT A. CLARK, Ph. D. (Columbia University), Professor of Physics. — MORGAN G. SANFORD, M. S. (Syracuse), Lecturer on Meteorology. WILLIAM CHARLES LOWE, Ph. M. (Syracuse), Professor of German. ADOLPH CHARLES BAEBENROTH, A. M. (Harvard University), Professor of English. JULIAN CHASE SMALLWOOD, M. E. (Columbia University), Associate Professor of Experimental Engineering. FLOYD FISKE DECKER, Ph. D. (Syracuse), Associate Professor of Mathematics. WILLIAM JOHN GORSE, A. M. (Syracuse), Assistant Professor of German. 6 College of Forestry J. HERMAN WHARTON, A. M. (Syracuse), Assistant Professor of English. ARTHUR E. BRAINERD, M. S. (St. Lawrence University, Syracuse University), Instructor im Geology. RAYMOND T. BIRGE, Ph. D. (University of Wisconsin), Instructor in Physics. HARRY E. BARNES, A. M. (Syracuse University), Instructor in Historical Sociology. HARRY J. CARMAN, A. M. (Syracuse University ), Instructor in History. HAROLD DOUGLAS BUELL, B. 8. (Colgate), Instructor in Chemistry. SCIENTIFIC STUDIES PUBLISHED BY DOCTOR M. W. BLACKMAN, PROFESSOR OF FOREST ENTOMOLOGY IN THE NEW YORK STATE COLLEGE OF FORESTRY. The Spermatogenesis of the Myriapods. I. Notes on the Spermatocytes and Spermatids of Scolopendra. Kans. Univ. Quart., Vol. 10, pp. 61-76, pl. 5-7. The Spermatogensis of the Myriapods. II. On the Chromatin in the Spermatocytes of Scolo- pendra heros. Biol. Bull., Vol. 5, pp. 187-217, 22 fig. The Spermatogensis of the Myriapods. III. The Spermatogenesis of Scolpendra heros. Bull. Mus. Comp. Zool. Harvard Col., Vol. 48, pp. 1-138, pl. 1-9, 9 text fig. The Spermatogensis of the Myriapods. IV. On the Karyosphere and Nucleolus in the Sperma- tocytes of Scolopendra subspinipes. Proc. Amer. Acad. Arts & Sci., Vol. 41, pp. 331- 344, 1 pl. The Spermatogensis of the Myriapods. V. On the Spermatogenesis of Lithobius. Proc. Amer. Acad. Arts & Sci., Vol. 42, pp. 489- 520, 2 pl. Theories of Sex Determination Resting on a Cytological Basis. | The Cleveland Med. Journ., Vol. 7, pp. 197-209, 1 text fig. The Spermatogenesis of the Myriapods. VI. An Analysis of the Chromosome Group of Scolo- pendra heros. Biol. Bull., Vol. 19, pp. 138-156, 2 pl. 4 fig. (7) 8 College of Forestry The Anal Glands of Mephitus mephitica. Anat. Rec., Vol. 5, pp. 491-515, 5 pl. On a Supernumerary Median Ocellus in Melanoplus femur- rubrum. Psyche, Vol. 19, pp. 92-96, 3 fig. Observations on the Life History and Habits of Pityogenes hopkinsi Swaine. Tech. Pub. N.Y. 8.) Coll) Koti NG. 3a. 11-79, 6 pl. CONTENTS PAGE SS MRPOMUCTION «ois, cc ctntaliin ak ni oa OMT i ce occ wee as 11 ck. How Insects are injurious Ge trees... Faelit WYSE EP)... eee 18 A. Leal-eating Inaeote.. 5... os. RRS, a) ne oa 18 1. The Apple-tree Tent-caterpillar..................0006. 20 2. Ths Norah Lent-Cn GGr ial ss s.e nen cnsnras CERES hiss 25 cee, URGE ROOM ATOR: «Bai ccth Camis asiviee a) bebe atm dein idig o) acm 29 a The Mourning Cloak Buthertly ioc lca eee wdc n ees 34 tee gt de 2S) | ore enn Seer Ae eee 37 hs Prt cue: REE INES re oe ans? hc x eR ae sues Se wake a ye 42 Cay ee a eee eee een tee tre eae 45 uw 8 4 = Ten) bp — py Fig. 51. Hibernating larvae of the elm bark louse. 1 and 2. Larvae in winter condition around and under dead females (x16). (S. B. Doten, Nevada Agri. Exper. Sta.) Insect Enemies of Shade Trees and Shrubs 107 The scale can also be controlled by thorough application of a contact insecticide such as 10 per cent kerosene emulsion. This can be applied as a spray but on small trees it is recom- mended that it be applied by scrubbing the tree with a stiff brush frequently dipped in oil emulsion. Oil emulsion is most effective when applied in the early spring just after the scales have resumed activity or later, just after the young have hatched. 24. THE COTTONY MAPLE SCALE (Pulvinaria nnumerabilis Rothu. ) This conspicuous native scale insect is distributed through- out the State from Long Island to Buffalo. At times it oceurs in such great numbers as to do noticeable injury to some of the maples. The favorite host is the soft or silver maple, but, it also occurs upon the Norway maple and box- elder. It has been taken on 47 trees and plants including the oak, linden, willow, elm, honey-locust, black locust, black walnut, poplar, beech, virginia creeper, spirea, dogwood, ete. The egg-sacks, formed by the deposition of eggs in a mass of white, waxy, cottony secretions, are found on the limbs and branches during late May and June. The eggs are a reddish- yellow in color. A single female rarely deposits less than 500 eggs and most frequently 2,000 or more, Forbes having found in Illinois the average number to be 3,410 eggs. In the latitude of Albany and Syracuse, the young appear the latter part of July. They may remain in the ovisacks for a few days but sooner or later migrate to the tender shoots and twigs. Many settle along the mid-ribs on the under surface of the leaves. Growth proceeds slowly, the females becoming only half-grown by fall. The larvae migrate back to the branches before the leaves fall and here they hibernate, com- pleting their growth in the spring. There is but one generation. Interesting among the predacious enemies of this scale is that of a moth whose caterpillars feed on the scales, eggs 108 College of Forestry and larvae. Lady-bird beetles and hymenopterous parasites do effective work in keeping this insect down. Controt Mrasurrs.— Spray 10 per cent kerosene emul- sion in the summer just when the young are emerging; on hibernating scales use 25 per cent emulsion. Both sprayings should be effective if properly applied. 25. THE BLACK BANDED SCALE (Lecanium nigrofasciatum Perg.) This scale insect is apparently a native and is rather sa over the eastern half of the country. Writers regard it as the most in- jurious of the Lecaniums found on soft and sugar maples. Other trees, how- ever, are attacked — namely sycamores, pop- lars, hawthorns and _ sev- eral ornamentals of in- frequent occurrence. The female scales are hemispherical, — reddish- brown, marked with black lines and normally are coy- ered with a delicate waxy bloom, which when rubbed causes the scale to appear Fig. 52. The black banded scale or ter- highly polished. The fe- rapin scale. (Original) male, slightly smaller than the so-called tulip scale, is 14 of an inch long and is one of our largest species. Eggs occur in May. The young appear in June and many establish themselves on the tender branches and on the petioles and midribs of the leaves. Those on the leaves migrate back to the branches in the late autum where they hibernate, completing their growth in early spring. Insect Enemies of Shade Trees and Shrubs 109 Controt Mxrasures.— This species is ordinarily held in check by hymenopterous parasites. When the infestation and injury are marked, apply 10 per cent kerosene emulsion at the time the young are migrating either to or from the leaves. | 26. THE TULIP TREE SCALE (Toumeyella liriodendri Gmel. ) The tulip tree scale is distributed over the northeastern United States, west to Michigan and southward. When numerous, the seales seriously injure the tulip tree, especially in nurseries. Besides the injury incident to its feeding, the scale secretes a great quantity of vile smelling honey-dew. This furnishes a medium for the growth of a black fungus which often does considerable damage to the leaves by clogging up the stomata, thus interfering with the transpiration of the tree. , The females are the largest of our scale insects, measuring about 14 inch in diameter. They are light brown, knotty and very convex. Apparently in the latitude of central and southern New York the insect hibernates in the larval stage, the larvae appearing late in August and during September. There is but one generation a year. Controt Mrasvures.— A thorough spraying with 10 per cent kerosene emulsion late in September just after the young have appeared, has been found to be quite effective. Or in late autumn after the leaves have fallen scrape off as many scales as possible and apply 20 per cent kerosene emulsion. 27. PLANT LICE (Aphididae. ) Much has been written regarding these delicate, incon- spicuous and soft-bodied insects. They are of interest on the one hand because of their habits and enormous reproductive powers and again because of the toll they collect from vegeta- tion of all kinds. The millions of tiny beaks continually 110 College of Forestry drawing off the sap obviously weaken the plant. The steady withdrawal of the vitality causes many succulent plants and hardier shrubs to succumb to their attack. Fortunately, however, the mortality among aphids is high. A sudden change in temperature, or wind, or rain, kills millions of them. Yet withal, on account of their enormous powers of reproduction and their adaptability, aphids are able to stand the stress of the struggle and perpetuate their kind. There are many and various kinds of plant-lice which differ widely from each other, either in bodily structure, or in feeding habits, or in their unique methods of procuring protection from their enemies. Thus some aphids are wholly leaf-feeders; others are subterranean and live throughout their lives on the roots of plants, frequently causing serious nodular swellings and malformations; while still others pro- duce galls on the twigs or branches or leaves of hardy trees. Many of the plant-lice are covered with a waxen “wool” which protects them to some extent from external agencies. These are known as the woolly aphids and they include some of our most destructive forms. Many aphids excrete a sweet. watery substance popularly known as honey-dew. This is really undigested portions of the plant juices which are passed through the aphid’s body. This sweet substance is often produced in such quantities as to cover the leaves of the tree and quite frequently the walks under badly infested trees are kept moist by its constant dropping. The withdrawal of so much sap must produce a very serious injury to the tree but in addition there is another injury which is often quite striking. The “honey-dew ” covering the leaves offers an excellent culture medium for the development of certain fungi. So that quite frequently leaves are covered by a black fungus and killed by it. The sweet ‘“ honey-dew ” often also serves to attract ants which have a decided liking for sweets of all kinds. In return for this sweet substance, ants often care for and give protection to the feeble-bodied and defenseless aphids. In many cases a very interesting relation certainly exists between ants and aphids. Insect Enemies of Shade Trees and Shrubs 111 While each species of aphid is likely to present differences of its own, a fair example of the life-history of a plant-louse through a season may be given in the following generalized way: Aphids pass the winter in the form of eggs, de- posited in the fall by the true, wingless females. In the early warm days of spring these hatch into the so-called wingless stem mothers which without fertilization lay eggs or give birth to living young. This new brood matures into a generation of wingless females, which reproduce without. fertilization and which bear their young alive. As many as 8 to 11 successive generations may occur in a season. In the course of the season, one or more genera- tions may arise of which either all or part of the indi- viduals may be winged. The winged forms fly away to other trees or plants and there found new colonies. In the fall a brood of true winged males and wingless females appear and after mating each female ordinarily deposits a single large egg and in this condition the winter is passed. Fig. 53. The woolly aphids of pine bark (Chermes pinicorticus). Nat- ural size. (Original) Some of the forms most injurious to shade trees are: The elm-rosette aphis which migrates from the apple and which is often called the woolly apple aphis, causes some injury to elms as there are two forms, one living on the branches and 112 College of Forestry another on the roots. A closely allied species produces the elm-leaf curl which so commonly occurs on many of our elms, and still another species occurs upon the bark of elms. The Pine Bark aphid lives on white pine and probably on Scotch and Austrian pines (Fig. 53). The box-elder plant louse does considerable injury to this tree, especially by secreting a large amount of honey-dew in which grows an injurious black fungus. Controt Mxrasures.— Since these insects feed by sucking the juices from plants, a stomach poison sprayed onto the surfaces of leaves will not control them. Rather an insecti- cide must be used which will kill on contact, either by closing up the breathing organs or by corroding the body-covering. This holds good for all sucking insects; one must hit them with a spray which kills on contact. To control plant-lice use a 10 per cent kerosene emulsion. ‘ Black Leaf 40” at the rate of one part to 800 or 1,000 parts of water has proven of equal value. Whale oil soap mixed as recommended on page 116 of this bulletin ig very effective. A strong stream of water from the ordinary pander hose has been used with a measure of success against plant-lice. The aphids washed from the tree or plant are unable to get back to the host. It is well worthy of trial in cases where the infestation is localized to several branches of the tree. It should be emphasized, however, that the full strength of a solid stream of water should strike the infested part in order to knock off a high per cent of the aphids. III. SPRAYS AND SPRAYING APPARATUS After learning the manner in which insects feed either by denuding branches of their foliage or by withdrawing the sap from the host or again by boring into the tree, the next important step is to adopt proper measures for their artificial control. ‘This in most instances means the selection of in- secticidal remedies. ‘Therefore it will at once be seen that it is of much importance to know of what spraying materials are composed, how they are mixed for use and finally how and under what conditions they may be applied without injury to the tree. Any one insecticide obviously cannot be employed for all purposes. Thus an inert arsenical poison is perfectly harm- less to a sap-eating insect which always evades a surface film of poison by drawing out the juices from within the plant. Consequently sprays are divided into several groups. Each group of materials is only effective when used against a particular set of insects. They are: (1) stomach poisons, (2) contact. sprays, (3) repellants, (4) fumigants. 1. STOMACH POISONS Poison-sprays are effective only against insects which defoliate or which chew their food. To be efficient as a poison it should be insoluble, suspensible and adhesive. One which is partially soluble and which settles rapidly is in large measure valueless. The poison which goes into solution burns the foliage the resultant injury frequently exceeding that of the insects. In all cases the water serves merely as a carrier of the insecticide and serves likewise to spread the material over a greater area. When the water evaporates, a thin film of poison remains on the leaves. This is a pro- tection to the tree for a longer or shorter time depending on the poison used and how applied. On a rough leaf the particles will lodge in the numerous depressions and may (113) 114 College of Forestry remain for months whereas on a smooth leaf, a heavy rain or a strong wind may remove the greater part. ‘The finer the material the better it settles into the crevices of the leaves and because of this Paris green is the poorest and arsenate of lead the best of poisons on the market. The addition of soap to an arsenical increases both suspensibility and adhesiveness. Arsenate of lead.— This is sold in two forms, as a paste and as a powder, the exact chemical composition varying according to process of manufacture and purity of the ma- terials used. It is made from arsenate of soda and lead acetate or lead nitrate. Owing to the small percentage of soluble arsenic, the paste is used at from 2 to 6 pounds to a 50 gallon barrel of water, the ordinary usuage in shade tree work being 8 pounds to the barrel. It is the best poison in general use today. Owing to competition among producers the price has varied considerably. Usually, it can be pur- chased in 100 pound lots at 12—14 cents or at 20 cents a single pound package. If properly applied, it should give good results. The powdered form of lead arsenate does not mix as readily with water as does the paste. Consequently it has not had the extensive use by the public. Apparently also it does not stay in suspension as well as the latter and very little is known regarding its adhesiveness. The powder is twice as strong as the paste, being used 1144 pounds to 50 gallon barrel of water, but 214 pounds’may be used without injury to the tree. Paris green.— Paris green was first used to combat insects in 1868. _It thus is an old remedy and previous to the introduction of lead arsenate, was the mainstay for the control of all leaf-feeders. It is a coarse, green, crystalline powder manufactured by the union of copper oxide, arsenic and acetic acid. It settles rapidly in water, contains soluble arsenic and is easily washed off by rains. Paris green 1s soluble in ammonia, hence it should never be used in am- monical combinations. The usage is 3-8 ounces to a 50 Insect Enemies of Shade Trees and Shrubs 115 gallon barrel of water. When mixing stir up the poison to form a thick, even paste and add an equal amount of quick lime to absorb soluble arsenic. London Purple.— This is a by-product from the manu- facture of aniline dyes. The percentage of soluble arsenic is high and therefore when used as a spray, a hberal quantity of lime should be added. The poison costs 10 cents a pound but is not nearly as effective as Paris green. It is used frequently in mixing poisoned bait for cutworms which occur in gardens, greenhouses and nurseries. + 2. CONTACT INSECTICIDES Contact insecticides are used exclusively against insects which suck the sap from plants by inserting fine needle-like mouth parts into the tissues and which cannot be injured by the inert arsenicals on the foliage. Sucking insects must be reached by a contact insecticide in order to kill them. Therefore it can readily be seen that to practice economy and yet effectively to control, one must use care in the selec- tron of sprays and also must have them properly applied. Kerosene emulsion — Kerosene emulsion should be pre- pared as follows: Hard soap % lb. (or for limited use) Soap 2 oz. Water 1 gal. . Water 1 qt. Kerosene 2 gals. Kerosene 2 qts. Dissolve the soap in soft water, using heat. Remove from the fire and add the oil while the soap solution is warm. Agitate the mixture vigorously until a creamy white emulsion appears. This can be done very well by churning with a bicycle or a bucket pump. This is the stock solution and it should be diluted before being applied. For scale insects in the winter time, spray a 25-20% emulsion, i. e., 1 part in 4 or 5 parts of water; in the summer time to control plant lice and for use against scale insects apply a 10% emulsion, 1 part to 10 parts of water. In damp, rainy weather the emulsion should never be applied at the strength used on a bright, sunshiny day. The kerosene, owing to its slower 116 College of Forestry evaporation, has an injurious effect on the foliage in muggy and wet weather. Miscible oils.— These are composed largely of mineral oils. However, they generally contain a small quantity of vegetable oil and a small amount of alkah. Frequently they are referred to as “ soluble oils ” and appear on the market under various trade names. They have a wide use and are easily diluted, readily apphed and will kill many injurious insects; but they are primarily designed for use against scales. One should be very cautious in applying them. Lime-sulphur.— There are a number of good commercial lime-sulphur -washes on the market. They are valuable in combating scales and in addition have excellent fungicidal properties. A commercial lme-sulphur wash, as a rule, tests 33° Beaume, which refers to its specific gravity. The value of this insecticide as a spray is proportional to its specific gravity or density. The dilution for 33° Beaume lime- sulphur when used'as a dormant spray is 1 gallon of the wash to 814 gallons of water; for summer work 1 gallon to 42 gallons of water. Further information regarding lime- sulphur sprays may be had from Bulletins 329-330, New York Agricultural Experiment Station (Geneva). Always apply the lime-sulphur at dormant strength late in winter before the tree resumes its activity. To much stress cannot be placed on the cautious use of hme-sulphur solution. It is very seldom advisable, if at all, to spray lime-sulphur on shade trees after the foliage has appeared as it stains and discolors the leaves. This ruins their appearance as ornamentals for the season, not to men- tion the offensiveness of the spray to the passing public. Apolication of insecticides is a difficult task under most city conditions especially so if various householders operate individually. Operations should always be carried out with the utmost regard for the rights of others. Whale-oil soap.— For scale insects this may be applied in the winter at the rate of 114 to 2 pounds to 1 gallon of water. In the summer the maximum strength should be 1 pound to 4 gallons of water and an even greater dilution is effective Insect Enemies of Shade Trees and Shrubs 117 against plant lice. It is similar to kerosene emulsion in its insecticidal qualities. Tobacco extracts.— Two liquid tobacco extracts are manu- factured and sold under the trade names of “ Black Leaf 40 ” and “‘ Nico-fume.” The former contains 40% active nicotine and 60% inert ingredients, the cost being $10.75 per 10 pound gallon, 2 pounds for $2, 1/5 lb. at 75 cents and 1 oz. at 25 cents. It is ordinarily diluted for plant-lice 1 part to 800 to 1000 parts of water (or °4 of a pint to 100 gallons of water) plus 3 to 5 pounds of soap. If wanted in smaller quantities mix 1 oz. to 7 or 8 gallons of water plus 5 oz. soap. When used with lime-sulphur a precipitate appears and the insecticidal value of the tobacco extract may be modified by such a combination although this has not been accurately determined. * Nico-fume ” lkewise contains 40% nicotine but it is much more volatile. It is used in greenhouses by vaporiz- ing one ounce of the extract to 2,000 cubic feet. It can also be used as a spray. The cost is $10.50 per 8 pound gallon. Carbolic wash for borers.— This is valuable as a preventive against borers laying their eggs on vaiuable trees but should properly be called a repellant rather than a contact insecti- _ eide. Use 1 pint of crude carbolic acid (or 14 pint chemically pure carbolic) to which add 1 gallon of soft soap thinned by the addition of 1 gallon of hot water. Ailow the mixture to stand over night then dilute with 8 gallons of soft water. The usual method of application to the trunk is by brush. However, it may be sprayed but this is not usually economical. Carbon disulphide.— This is a clear, highly volatile liquid giving off fumes heavier than the air. It is sold in 25 to 100 pound lots at 10 to 12 cents, single pounds selling from 15 to 20 cents depending on the purity of the sulphide. This chemical is highly inflammable and its vapor uniting with air is explosive so that when being appled fire should never be near. The operator must not smoke. The gas is deadly to all insect life. It has come into somewhat general use against borers in valuable shade trees and has been success- 118 College of Forestry fully used in New York city against the leopard moth and also in Washington, D. C., against the carpenter worm. It is injected into the openings of larval burrows and these are immediately closed with various substances such as putty or grafting wax. For introducing the poison a machinist’s long-nozzled oil-can may be employed on large trees, although glass syringes have been found very serviceable, since it requires only a very small amount of the disulphide, a tea- spoonful of the hquid being sufficient for each burrow, and by using glass syringes the quantity can be gauged. After application, plug the openings with grafting wax as this has been found by workers to give best results. Difficulties naturally arise in the use of this material. It is often im- possible to plug all the holes in infested trees, since there may be several ventilation openings to the same gallery and unless they are all plugged, the operation is unsuccessful. Then too, many of the burrows are wholly or partially filled and blocked with sawdust so that distribution of the vapor is not uniform. In the case of valuable shade-trees, the writer believes, nevertheless, that by careful application some measure of success may be attained. B. SPRAYING APPARATUS Hand atomizers.— Hand atomizers can be bought in most any hardware store at small cost. They are not adapted to extensive use, but may be employed to advantage in spraying house plants or a few valuable low-growing garden plants. Bucket pumps.— Of bucket pumps there is a big variety on the markets. The pump should have an air-chamber so that a steady pressure may be maintained. Many con- cerns are selling such outfits at from five to ten dollars. These are mounted in large galvanized iron buckets with a foot-rest on the pump and a clamp which fastens the pump to the bucket. This type is useful for spraying shrubs and small ornamental trees in private yards. It also gives satis- faction when used in a limited way in nurseries. Berti gtiiet —— Insect Enemies of Shade Trees and Shrubs 119 Knapsack pumps.— The best type of ean pump (Tig. 54) has a portable copper tank, a lever handle for pumping, an agi- tator and brass valves and seats. They are heavy to carry when filled with spray and consequently this limits their use. The cost is from eight to fifteen dollars. They are far superior to the bucket type for some sorts of work. Barrel pumps.— A good barrel pump (Fig. 55) should have the following points in its favor. It should maintain a pressure of 85 : . to 100 pounds to the inch; the air Fig. 54. Knapsack sprayer. mye . Note the agitator, pump, chamber should be within the bar- (+ gigiaber, Tigustiel ead rel; the cylinder, plunger and the _ straps for carrying. (The working parts should be of brass; it Deming Co.) should have a good mechanical agitator; and should possess valves with durable seats and cages. This pump may be used to good advantage in spraying small shade trees and transplants but may also be employed to spray any other low-growing vegetation. The cost is from fifteen to twenty- five dollars. Power outfits.— For the spray- ing of shade trees on an extensive scale, for city work and for wood- lands a power outfit means not only economy and efficiency but is a necessity. Apparatus more or less suitable are of many makes and Fig.55. Barrel pump. Desirable degrees of efficiency, but these type for trees and shrubs of naturally fall into two types. the yard. (The Deming Co.) (1) Orchard types.— The very best sprayer of this class consists of tank, gasoline engine, and 120 College of Forestry tower mounted upon a strong and durable truck. Naturally the gas-engines vary according to the purchase price of the outfit. The best gas-engines, 2 or 3 cylinders, meet the demands for spray work and are able to maintain a uniform potential pressure of 100 to 175 pounds. Most of the pump manufacturers and many gas-engine companies are selling these engines with truck, tank and tower complete for from $250 to $400. Such outfits (Fig. 56) will be found service- able for use in towns and small cities. With towers and ladders, the very highest trees can successfully be sprayed, Fig. 56. Power outfit. A modern three-cylinder power pump designed for orchards, shade-trees and wood-lots. (The Deming Co.) although the cost per tree may be greater than with the high power outfit. ; (2) High-powered type.— This sprayer is unexcelled for the spraying of trees in municipalities, in large parks or in woodlands. Work can be done with expedition and economy. The machines are large, being mounted on heavy wagons or motor trucks. The engine is a 2 or 4 cylinder and develops a pressure of 200 to 250 pounds. They are extensively used in New England in the fight against the gypsy and brown tail moths. ‘The cost is moderate for value received, $900 Insect Enemies of Shade Trees and Shrubs 121 to $2,500, or even more, depending on the quality of the motor truck. For extensive spraying there is no machine to equal this type for cheapness, durability, effectiveness and reliability. However, when purchasing a power outfit of any design, the mechanical construction of the machine should be carefully studied, and if possible tested, as all machines on the market are not equally efficient. Nozzles and Accessory Apparatus.— A good nozzle is just as essential as a good pump for successful spraying. The best nozzles now in common use are of four types. (1) Vermorel Nozzle. This nozzle consists of a small chamber into which the liquid spray is forced in at a tangent and leaves through a small hole in a removable cap, thus producing a fine cone-shaped spray. This makes a finer spray than any of the types which follow and is used therefore only in the application of oils and fungicides, since these are free from insoluble products. The nozzle clogs very readily which prevents it being used with arsenicals and lime-sulphur. As a rule, in shade tree work two or three are attached to a Tor Y. (2) Disk Nozzle-— Here the chamber is flatter and broader, thus as the spray enters, it is given a strong rotary motion and it is broken up, emerging as a fine spray through a large aperture. The nozzle is light, does not catch on twigs and rarely clogs. It allows the passage of a large amount of unstrained liquid, one of these spraying three or four times as much as a Vermorel. (3) Bordeaux Nozzle.— In this type the spray is formed by a strong stream, hitting a metal lip and breaking it up, so that it comes out of the nozzle fan-like. The fineness of the spray varies with the width of the aperture. It is usually preferred for spraying shrubs and low plants, but it is sometimes used for trees. (4) Worthley Nozzle-— This is a special nozzle designed for the gypsy and brown-tail moth work in New England, and it is used wholly for the spraying of shade trees where a large stream backed with high pressure is employed. The 122 College of Forestry spray material comes out in a straight solid stream as from a garden hose at full pressure. This stream at a certain distance from the nozzle breaks into fine particles forming a spray. The distance from the nozzle at which this occurs can be regulated by the operator and it is this quality which makes this type of nozzle so very valuable for trees of various sizes. The Gypsy Moth Commission in New England makes use of it in connection with their high-power outfits. Extension rods.— In the spraying of shade trees an exten- sion rod is often a necessity. The ordinary type of rod is a straight piece of 3% to 1% inch galvanized-iron pipe, threaded for the nozzle and stop-cock. This may be wrapped with burlap to make the grip of the operator secure. Many rods are of bamboo, enclosing a light brass tube, its tip having threads for the attachment of elbows and nozzles, and pro- vided with a stop-cock at its lower end, so that the stream may be turned on or off when moving from tree to tree. Towers.— A tower on a power outfit gives the operator the advantage of spraying more rapidly and more thoroughly. Most of the power outfits are built with a tower. In every case the tower should be as high as the weight of the truck and outfit will allow and should be surmounted by a railing which should come to the operator’s waist. C. SPRAYING The application of insecticides to city trees is difficult under most conditions; especially is this true if various house- holders operate individually. As a rule there are but few trees on any one lot and usually these are tall, thus requiring an expensive spraying outfit. Therefore, only in large estates is it practicable and economical for individuals to own and operate sprayers adequate for use on large trees. In the city the only sensible solution of this problem is the institution of a City Forestry Department, and the employ- ment of a Municipal Forester. This is desirable and prac- ticable for all cities, for then the sprayer will be operated by competent, experienced men, whose business it is to look after Insect Enemies of Shade T'rees and Shrubs 123 publie trees and who should be peaipore to do private work for a reasonable charge. Time and w eather are important factors which must be carefully considered if the spraying of trees is to be successful. | Insecticides should always be applied before the injury becomes acute, for after the damage is apparent it is usually too late for effective spraying. Therefore, to know just when to spray involves an understanding of the life history of the insect, revealing the point at which it is most vulnerable to the method adopted for control. Then, too, all sprays cannot be apphed to foliage at the same strength in all kinds of weather. Thus, as was pointed out elsewhere, kerosene emulsion must be more dilute when applied on a damp, rainy, muggy day than on a bright warm one. The kerosene in the absence of sunlight injures the leaves. The weather, time, the development of buds and blossoms should always be carefully noted preliminary to spraying. Having decided on the time to spray, apply the material with thoroughness yet with economy, and there will be a large measure of success as a reward for the effort. vg State University College of Forestry 393 _at Syracuse. 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