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Oni anti A ~ ’ rah CE vibe whe “ ’ + ef j : ‘ * g + t - ¢ * d 4 4 ie a a , a | ~ ‘ c 4 YiAL Sere a ’ vA je * . é) ry + ¢ ae try Ait an 4 . : ‘ ’ ; * ~) f u! 6 “ eee ee meastory of _infestation_—_=-—-—~-~—~~ 2 | Weak dosages of lubricating-oil emul- Factors influencing increase of the Signe =e ae ie RS abel Piet sn tes 9 Bette OSG: Seale 28) se 2 Use of oil emulsion for dormant Distribution of injurious infesta- spray in commercial orchards_-__—~— 9 “SORTS ee oo wee es pe noes 3 | Summer treatments with oil emul- Seriousness of injury in Arkansas SiOMpe 2 ee same mae Sere Anes Leon ee ee 10 PPEGRCLRGG 48 ee Ses SS See ea et 4 Advantages and disadvantages of oil Comparative susceptibility of apple EM STON Ss Ee: Ee Ee 12 BEMINC GON =e os Se Se 5 SDPLAy Ain yO ry ae Se eee eee 12 Control methods prior to 1922_____ 5 Method of preparation_——_—-__-___ 13 praying experiments in the fall of Soapseand o1ls See a ee eee 17 peers eee Poe ee eT a G liRecommendations—= 22 ss 5s == eG RECENT INCREASE OF THE SAN JOSE SCALE IN NORTHWESTERN ARKANSAS. _ The San Jose scale has increased in such alarming numbers during the last two years in several localities of the Ozark region of Arkan- sas as to threaten the destruction of the apple industry. During 1920 this pest was present in a large number of orchards and in the fall of that year much fruit was spotted with the scale, though only a few trees had been killed. Following the complete crop failure of 1921 the San Jose scale developed into the most serious problem fruit growers of this section had ever faced. Many acres of trees were dead by late summer and many orchards were so thoroughly infested with the scale that it became necessary to check the pest before the next growing season in order to save the orchards. Growers were extremely discouraged in view of many failures to control the scale with dormant sprays during the preceding two seasons. 1The writer wishes to acknowledge his indebtedness to Leslie Pierce, of the Bureau of Plant Industry, for his cooperation and assistance during the entire progress of this investigation, and to W. W. Yothers, of the Bureau of Entomology, for his many helpful Suggestions on oil-emulsion sprays based on several years’ experience in Florida. 30836°—23——_1 > | Bhan’ y) Department Circular 263, U. S. Dept. of Agriculture. ~ Such being the critical situation, the laboratory of the Bureau of | Entomology at Bentonville, Ark., began, as soon as practicable in © the fall of 1921.2 a series of experiments. for the control of the San — F Jose scale. Of all the insecticides used in the experiments best re- _ sults were obtained with the so-called paraffin-oil or lubricating-oil emulsion. The selection of oils of this type for experimental work against the San Jose scale was in consequence of the excellent results obtained with lubricating-oil sprays by W. W. Yothers, of the Bureau of Entomology, in the control of various citrus insects in Florida. A pr eliminary announcement * of results in the use of lubricating oils for the San Jose scale was made as soon as sufficient evidence had been obtained to indicate strongly its suitability for this insect. This circular gives results obtained to date in the experiments with lubricating oils for the control of the San Jose scale, together with methods for the preparation of the emulsion and recommendations for the use of the insecticide. Investigation of this subject is being continued to obtain further information on the use of the emulsion in various parts of the country, and on various host plants, and to ascertain what injury, if any, will result to the various classes of deciduous fruits treated. HISTORY OF INFESTATION. During the season of 1918 the San Jose scale caused little or no damage to fruit or trees in northwestern Arkansas. At that time orchardists, as a rule, applied one dormant spray of liquid lime- sulphur solution in the spring just as late as possible before the fruit buds began to swell. At harvest time in 1919 several orchards showed fruit badly spotted with the scale, though practically no dead limbs or trees were evident. The beginning of the serious scale in- festation in this region dates from the fall of 1919. In 1920 a large number of orchards were badly infested with the scale, much fruit was damaged, and limbs and trees were being killed. Even at that time, with the exception of an occasional orchardist, little anxiety was shown by the growers, as they were confident ‘that the scale could be controlled with the dormant applications. : Orchards received little attention during the growing season of 1921, following the complete killing of the fruit crop by freezes in the spring of that year. By the fall of 1921 the San Jose scale had spread so rapidly that it could be found in practically every orchard of the region, and it had either killed entire orchards or portions of them in many instances. It was fully realized by this date that the scale must be controlled immediately or many of the growers would be driven out of the orchard business. FACTORS INFLUENCING INCREASE OF THE SAN JOSE SCALE. Several reasons can be assigned for the serious damage caused by the San Jose scale in this region. Foremost, without doubé, is un- 2 The writer returned to the Bentonville laboratory of the Bureau of Entomology on November 1, 1921, after an absence of nine months, and Leslie Pierce, of the Bureau of Plant Industry, returned to this station about the middle of November, 3 Department of Agriculture Clip pier 193, March 6, 1922. “A Promising New Treatment for the San Jose Scale,’ by A. L. Quaintance. Control of San Jose Scale With Lubricating Oil. 3 intentional carelessness in spray methods on the part of many growers. In the past one thorough dormant spray with liquid lime- sulphur solution has always controlled the scale satisfactorily, and practically all growers made the dormant application. When the scale first began to increase, some growers failed to apply the dor- mant spray and others were careless in their work. The tips of branches, especially in the tops of trees, were often missed, and scale infestations began at those points. There was carelessness, also, as to the amount of spray material used in the tank. Often mistakes ' were made in the size of measuring buckets or even in the size of spray tanks, so that the dilute spray solution was not strong enough. Many growers hurried their spraying operations to such an extent _that the covering of spray material was insufficient to insure a thorough coating of all parts of the tree, which is very essential. The first marked increase of the San Jose scale followed soon after the advent of the spray-gun. Many orchards in which spray-guns were used did not receive a thorough application. The coarse adjust- ment of the gun was used in trying to reach the tops of trees, with - the result that the tips were not thoroughly coated with spray mate- rial. Several gun-sprayed orchards showed scale infestations which began in the tops of the trees. . Perhaps one of the most important factors in the scale increase has been unfavorable weather. At the time of the spring dormant spray, rainy weather and high winds often interfere with an appli- cation. This was especially true in the spring of 1920, when unfa- vorable weather delayed the spring application and warm weather opened the fruit buds before opportunity was afforded to apply the spray. With the buds opening as quickly as they did in 1920, some growers caused burning by spraying late and others were not able to go over their entire orchards. Thus, m trying to take advantage of the warm spring days when lime-sulphur solution is most effective against the scale, growers often did not find time enough to complete the spray application. The prevailing winds at this time of year -blow strongly from the south, which makes it difficult to cover the north side of a tree thoroughly. It has often been noted that the young scale “crawlers ” of the first generation are first observed in the spring on the north side of trees. The lack of a sufficient number of parasites and the scarcity of predacious enemies of the San Jose scale has been another important reason for the rapid increase of the insect.: This, together with a long, favorable breeding season, has tended to cause an unusually _ rapid increase in the scale infestation. Where a few scales escaped the dormant treatment, they increased to such numbers by late fall as to be scattered all over an orchard. ‘The scale spread so quickly in 1921 that some orchards, which growers considered free from the scale in the spring, were either partially or almost entirely killed by late fall. DISTRIBUTION OF INJURIOUS INFESTATIONS. Speaking generally, the San Jose scale has become destructive during the past year throughout the southern limits of the apple belt in the Central Western States. Besides northwestern Arkansas, 4 Departinent Circular 265, U. S. Dept. of Agriculture. severe infestations occur at several points in the Ozark region of Missouri, and in southern Illinois and Indiana. The Missouri River ~ region in Nebraska, Kansas, and Missouri, centering about St. Joseph, Mo., at present is almost entirely free from the scale. Interior Kansas is also comparatively free from this insect. In the Ozarks of Arkansas the most serious damage by the scale has been caused in the northwestern corner of the State. Orchards in the vicinity of Pea Ridge, Bentonville, and Centerton have been unusually hard hit. Orchards south of Bentonville and Rogers have not been so seriously damaged. SERIOUSNESS OF INJURY IN ARKANSAS ORCHARDS. The orchards which have been most seriously injured by the San Jose scale have been those which were the most productive and well cared for. Orchards in which the trees have made a vig- Il'ig. 1.—Trees attacked by the San Jose scale, dehorned, and ultimately killed. orous growth are the ones where the scale has thrived. Figure 1 shows a block of trees in an orchard formerly one of the most pro- ductive in the Bentonville vicinity. These trees were cut back in the fall of 1921, and the following summer, when the photograph was taken, they failed to show any new growth. If the scale had been controlled by the spray application that was made during the dormant season of 1920-21, most of the trees in this orchard could have been saved. This orchard was so hard hit by the scale that 30 acres out of a total of 35 acres of trees were killed in two seasons. Five hundred acres of bearing apple trees killed by the San Jose scale would be a conservative estimate of the damage caused in northwestern Arkansas. Control of San Jose Scale With Lubricating Oil. 5 COMPARATIVE SUSCEPTIBILITY OF Bas Sie VARIETIES. The varieties of apples that have been most severely injured by the San Jose scale in Arkansas are Grimes, Ben Davis, Gano, Western Beauty, and Oliver. Some of the moderately susceptible varieties are Early Harvest, Mammoth Black Twig, Ingram, Jona- than, and Maiden Blush. Winesap, Arkansas Black, and Givens are rather resistant to scale attack. Ben. Davis is the leading commercial variety of the region. When large limbs of this variety are killed by the scale it is almost cer- ‘tain that blister canker ‘will enter where the lar ge pruning cuts '-have been made. For this reason Ben Davis trees, even when only partly killed by the scale, have small chance of surviving. Figure 2 shows a block of Ben Davis trees in which most of: “the scale- Fic. 2.—Ben Davis trees severely injured by the San Jose scale. killed limbs have been pruned out. It is questionable whether many trees in this block can be saved, even after the scale has been controlled. Vigorous-growing varieties like Mammoth Black Twig or. Jona- than can be brought back after a severe pruning of limbs killed by the scale. Jonathan, which is probably the second variety in commercial importance in this region, is far more resistant to scale injury than Ben Davis or Gano. Ne vertheless, it 1s not rare to find Jonathan trees incrusted with the scale. CONTROL METHODS PRIOR TO 1922. Before the San Jose scale became destructively abundant in north- western Arkansas, the usual control procedure consisted of,a single spring dormant spray appled as late as possible before the buds 6 Department Circular 263, U. S. Dept. of Agriculture. opened, so as to take advantage of warm weather. Commercial liquid lime-sulphur solution was very generally used, although a few © growers preferred miscible oil occasionally. When the scale began to increase, two dormant sprays were more frequently applied, one — in the fall after the foliage was off and a second in the spring. At the same time many growers increased the strength of their spray — mixture from the recommended 25 gallons of “33° Baumé lime- — sulphur solution to as much as 35 or 40 gallons in a 200-gallon spray — tank. In spite of this the majority of crowers failed to obtain a satisfactory control of the scale. On incrusted trees enough scales _ escaped to provide breeding stock for the following season. A few growers, however, were able to control bad infestations of the scale | with two thorough applications of lime-sulphur. In such instances all parts of the trees were thickly coated with spray, which required an unusually large amount of spray material on each tree. _ The expense involved in making two dormant sprays with lime sulphur solution, together with the unsatisfactory contro] obtained, d led the orchardists to welcome any new methods to fight the scale, ; When it was found that lubricating-oil emulsion gave a splendid killing of the scale, the growers were “enthusiastic about using it. SPRAYING EXPERIMENTS IN THE FALL OF 1921. A block of young Early Harvest trees, so badly incrusted with the — scale that many limbs had already been killed, was obtained for the spraying experiments in the English & Boles orchard at Benton-— | ville, Ark. The experiment consisted of 26 plats, and included tests of several different strengths of lubricating-oil emulsion, kerosene emulsion, a proprietary miscible oil, several brands of dry lime-— sulphur, three brands of commercial liquidlime- sulphur, and home- made lime-sulphur solution. The spraying was done with a barrel — spray rig which maintained a pressure of about 125 pounds for a single rod with one nozzle. The trees were small enough to avoid — any ; difficulty j in covering their entire surfaces by means of this outfit. — The tests were made during the middle of December, 1921, after the - trees were completely defoliated and before cold weather had beoun, Each plat consisted of at least 4 trees, and examinations to deter- ‘mine the mortality of hibernating scales were made under a binocular microscope from twigs of 4 record trees. | All oil emulsions were made by the boiled process, and potash fish- oil soap was used as the emulsifying agent. No examination of twigs at the time of first-generation hatching or of the fruit at harvest time — -was made. Observations of the fruit on the oil-emulsion sprayed plats, however, showed scarcely any scale spotting at picking time. Table 1 gives a summary of the experiment, showing the various” insecticides and dosages used, with the percentage of dead scales in each plat at the time of examination. It requires about 30 days after spraying with oil emulsions before absolute determination of dead scales can be made. The killing power of lime-sulphur extended over a considerably longer period than that of oil sprays. 4 The results from the dry lime-sulphur plats are not included 7 this circular. Control of San Jose Scale With Lubricating Oil. ( TABLE 1.—WMortality of hibernating San Jose scales from spraying with oil emul- sions, lime-sulphur, and a miscible oil, English & Boles orchard, Bentonville, - Ark., 1921-22. Date of | Date of cee sale Percent Plat. Insecticide. Dosage. applica- |examina-| of dead tion. | tion. | Scales | scales | ates dead. | alive. | : 1921 1922 | | Pact. 1 | No. 1 oil emulsion....... | 3gallonsin 100;2percent} Dec. 14 | Jan. 11] 3,400 3 99. 91 “Lip [ane ee OES ie tee Gt 6 gallons in 100; 4 per cent 14 11 1,100 2 99, 82 245 aes LOE EBA SS et eee. 9 gallons in 100; 6 per cent 14 11} 1,000 0} 100 ACES Eh Ei So 5 See eG ieee | 12 gallons in 100; 8 per 14 11 | 1,000 0} 100 cent. 5 | No. 2 oil emulsion..-..-. 6 gallonsin 100; 4per cent 14 11 | 1,000 0} 100 Byres ote oo | 9 gallonsin 100; Ener cent 14 11} 1,000 0} 100 74 Bae (te ee eee | 12 gallons in 100; 8 per 14 11} 1,000 0} 100 cent. 8 | Kerosene emulsion.......| 20 per cent............-. 14 19 | 1,040 35 96. 74 Dy aes Clppten see ier ee 25 per cut Se ee ee 14 19} 1,012 17 98. 35 20 | N ae cunuerzat lime- | 32° B., 63 gallons in 50.. 16 18 830 207 80. 04 sulphur. 21 ES eeinnion commercial lime- |..... GO nes eae oe 16 21 803 224 78. 19 S 22 No. 3c Scnnemtectad lime- | 29° B., 10 gallons in 50.-- 27 | Feb. 5] 1,015 125 89. 03 sulphur. 23 | Homemade lime-sulphur-. oe B., 9 gallons in 50.- 27 5} 1,012 225 81. 81 25 1 Miscible oil. 35. 2 2222122 33 gallons i THO ees 27 5] 1,200 29 97. 64 Par me hecks@inSprayed ) = 522 |S. ae ses oo 5 eal esan aces Jan. 11 221 802 21. 60 It will be Rated that Plats 1 to 7, inclusive, comprising tests with various strengths of two different ‘brands of lubricating oil, gave very encouraging results. When it was found that Plat 1, a 9 per cent lubricating-oil emulsion, was showing good killing, a large number of scales were examined to get an approximate estimate of the efficiency of this low-strength oil emulsion. Examination of a large number of scales in the higher- strength oil-emulsion tests was deemed unnecessary. Plats 8 and 9, sprayed with a 20 per cent and 25 per cent kerosene _ emulsion, respectively, gave a fair kill of scales. Trees in these two _ plats looked oily for a period of perhaps 10 days or 2 weeks after _ the spray application, whereas trees in Plats 1 to 7, inclusive, had a very oily appearance for more than a month following the spray. Likewise the scale insects of the kerosene-emulsion plats, either dead or alive,showed no trace of oiliness on the date of examination, while the scales of the lubricating-oil emulsion plats still retained a thin oil film 30 days after they were sprayed. Apparently high dosages of kerosene emulsion with their corresponding high volatility were less effective at this time of year against the San Jose scale than the low-strength lubricating-oil ‘emulsions with their low percentage of volatility. Plats 20 and 21, sprayed with two different brands of commercial lime-sulphur, gave about equal kill. The concentrated lime-sulphurs used in Plats 22 and 23 tested so low that they were applied extra strong. All lme-sulphur plats, at the time of examination, showed poorer results than the oil-emulsion plats. Plat 25, sprayed with a proprietary miscible oil, gave about the same kill of scales as the kerosene emulsions. This oil, like the kerosene emulsions, was far more volatile on the trees than the heavier grade lubricating-oil emulsions. Under Plat 26 the percentage of dead scales on twigs of unsprayed trees is given. 8 Department Circular 263, U. S. Dept. of Agriculture. — TESTS WITH SEVERAL BRANDS OF LUBRICATING OIL. Following the success with a 2 per cent lubricating-oi] emulsion in the experiments of December, 1921, it was decided to test several different brands of oil sold in this district. For this experiment a _ block of large Ben Davis trees, entirely incrusted with scales, in the R. O. Pickens orchard at Bentonville, Ark., was available. AG 200-gallon power sprayer with a pressure ‘of 295 pounds, two rods, | % and double angle nozzles was employed for this work. One man _~ sprayed from the ground and the other in the tower, spraying one i side of a tree row at a time. One 200- gallon tank of spray material — was used for each plat. The results ‘of the experiment are given — in Table 2. ; Plats 1 and 2 were treated, respectively, with a 1 per cent and a © 13 per cent emulsion of the No. 1 lubricating oil used in Plats 1 : to 4 of Table 1. Plat 3 received a 2 per cent ‘emulsion of the same _ oil as that used in Plats 5 to 7 of Table 1. Plats 4 and 5 received 2 per cent emulsions of two other brands of 011 which may be termed — No. 3 and No. 4 lubricating oils. Thus, this experiment embodied a test of four different brands of heavy commercial lubricating oils — the analyses of which differed only shghtly one from another. The — essential object of this experiment was to determine the comparative effectiveness of several different brands of lubricating oil. For this reason there was no need of an unsprayed plat for a check. Ex- — amination of the trees before spraying showed an abundance of — live scales. . A very severe spell of cold weather occurred during the middle of — January, just before Plats 1 and 2 were sprayed. Again, during the last of January and prior to the dates of spraying Plats 3, 4, and 5, — very cold weather prevailed. On the dates of the applications rather : mild winter weather was encountered. Table 2 shows the mortality of the scales resulting from the various oil emulsions. TABLE 2.—Mortality of hibernating San Jose scales from spraying with several brands of lubricating-oil emulsion, R. O. Pickens orchard, Bentonville, Ark.., 1922. Date of | Date of a es of |rercent — Plat. Insecticide. . Dosage. applica- |examina-| ¢ ealasnb aii dead : tion. tion. dead. | alive, | Scales. . | 1922 1922 P.d. 1 14 gallons in 100; 1 per) Jan: 21) Mar. of {2.33265 35 98.94 7% (No. 1 SEDER T en 9 emulsion. a4 gallons in 100; 14 per 21 7 | 3,000 6 99. 80 = | ~“cent. 3 | No. 2 _ lubricating-oil | 3 gallonsin 100;2percent} Feb. 3 28 | 1,500 12 99.21 @ emulsion. 4| No. 3 _ lubricating-oil | 3 gallonsin 100; 2 per cent 3 27 | 2,100 t 99.8h emulsion. | * 5| No. 4 _ lubricating-oil | 3 gallonsin 100; 2 per cent 4 28 | 1,675 i 99.76 emulsion. The weakened dosage of the No. 1 lubricating-oil emulsions in Plats 1 and 2, respectively, gave a very good kill of scales. A 2 per cent emulsion of this same oil under similar orchard conditions, as shown in Plat 1, Table 1, was very effective. Plats 3, 4, and 5 in Table 2 show a rather uniform killing of scales for 2 per cent emulsions of three different brands of oil. ths? ee ee ee . : 4 Control of San Jose Scale With Lubricating Oil. 9 WEAK DOSAGES OF LUBRICATING-OIL EMULSION. The success attained with a 1 per cent and a 14 per cent emulsion, Plats 1 and 2 of Table 2, suggested the possibility that weaker dosages than the 2 per cent emulsion might be effective against the scale in the dormant season. Tests with three brands of oil, each with dilutions of } per cent, 1 per cent, and 13 per cent, were "made in the Pickens orchard at Bentonville on F ebruary 11. Conditions pertaining to degree of scale infestation and spraying equipment were similar to those outlined in the preceding experiment. Table 3 gives the results from the use of weakened oil-emulsion sprays. TaBLeE 3.—WVortality of hibernating San Jose scales from spraying with weak dosages of lubricating-oil emulsions, R. O. Pickens orchard, Bentonville, Ark., 1922. | | re | Date of | Date of ae eu of Per cent Plat Insecticide. | Dosage. applica- | examina- eealccalseaied of scales Ons sel t1On- Pe ead. | ; | dead. | alive. | —| | : 1922 1922 Pre l)w PhS Ue | {14 gallons in 100; 2 per cent.-| Feb. 11 | Mar. 22 1,000 20 98. 04 2 No. 4 nga 13 gallons in 100; i per cent. - 11 22 L 000 18 98. 23 el) SOR: 24 gallons in 100; 13 per cent. 11 23 |. 1,675 2| 99.88 4 spits 1% gallons in 100; 2 per cent.. 11 23 | 1,046 20 98. 12 5 zee Seeceine oll J iL gallons in 100; i per cent... 11 Zon e075 24 97. 82 6 |j- emulsion. |2t gallons in 100: 14 per cent. ul 25| 1,625 4| 99.75 7 Reet -, |({14 gallons in 100; 2 per cent... 11 25 | 1,000 35 96. 62 g |}No. 2 lubricating-oil |); ¥ gallons in 100; 1 per cent... i 25 | 1° 000 19| 98.14 9 Spates 22 gallons in 100; 13 per cent. 11 25 | 1,550 6} 99.61 | The three-fourths per cent emulsion of the three different oils apparently gave a fair kill of scales. The 1 per cent emulsions were practically no better than the slightly weaker three-fourths per cent emulsions. The 14 per cent emulsions in all cases killed over 99 per cent of scales. It was evident from this experiment that a 2 per cent emulsion was not the minimum dosage at which a good kill of scales might be effected. For practical purposes, however, it 1s likely that the 2 per cent emulsion is the lowest dosage that could be used by growers to insure a successful control of the scale. USE OF OIL EMULSION FOR DORMANT SPRAY IN COMMERCIAL ORCHARDS. é Soon after it became evident that lubricating-oil emulsion was - giving good control of the San Jose scale in an experimental way during the dormant season, it was decided that the growers should be informed of the data already at hand. Accordingly, all the details of the experimental work that had been carried on were given to growers in the vicinity of Bentonville. Although the investiga- tion was far from complete, many growers were interested to get any new suggestions on scale control. Nothing was known about the possibility of injury to trees following an application of this emul- sion. With the knowledge that much information covering this subject was still lacking, a large number of growers voluntarily decided to use the emulsion for the spring dormant treatment. A plant for the manufacture of oil emulsion was set up at Benton- ville, and growers were first supplhed with the product early in 30836°—23 2 e 10 Department Circular 263, U. S. Dept. of Agriculture. February, 1922. Following this initial venture, plants at two other a points in northwestern Arkansas began the manufacture of this insecticide. About 1,000 barrels of oil emulsion were used commer- cially, taking the place of approximately 4,000 barrels of concen-- trated lime-sulphur solution. A 2 per cent emulsion, or 6 gallons of stock in a 200-gallon spray tank, was the strength used by practically all growers. The period during which oil emulsion was applied for the dormant spray in various orchards extended from the middle of, February until after — the buds had opened, some growers even using it as late as the pink spray. Growers who made the application late secured unusually good control of the green apple aphis in addition to killing the scale. In fact, many growers later used the oil spray against the green aphis when they found that this insect, usually of little eco- nomic importance in this section, was causing considerable damage. A very satisfactory control of the scale in commercial orchards was obtained with the 2 per cent emulsion in practically all instances. The scale was brought under control in orchards in which it had been increasing gradually in previous years in spite of dormant spraying. While the scale was by no means eradicated, growers felt more optimistic of their ability to hold it in check than heretofore. Ex- aminations of twigs from a large number of oil-sprayed orchards showed just as good kill of scales as was effected in the experimental spraying. Occasionally a few live scales were found in protected places, such as crevices on the fruit spurs or in deep depressions or cracks of old hail bruises. Of course, some trees were not covered completely with the spray, and missed spots showed live scales. SUMMER TREATMENTS WITH OIL EMULSION. Tests with lubricating-oil emulsion were made during the summer, from the time the young scale crawlers of the first generation ap- peared until the fruit was harvested. Only a partial control of the scale was accomplished at this season in any of the tests, although oil emulsion of the same strength was used as for the dormant spray. The high summer temperatures caused the spray solution to evaporate so quickly that only the most tender stages of the insect were killed. All the crawling scales that were hit by the spray were killed, as well as the newly settled young. Many of the young which had not emerged from under the scale covering of the adult female were also reached by the oil spray, and in such cases the young near the exit hole were killed, which prevented those that were not touched from escaping. Some half-grown scales and a few full-grown females were killed by the summer sprays. In the course of a week or 10 days following the spray, however, young crawlers would be found emerg- ing and settling down. Many growers used oil emulsion in the standard summer Bordeaux sprays, and there is no doubt that the scale was held in check to such an extent that much spotting of fruit and damage to limbs was pre- vented. Much of the scale was cleaned off the fruit by the summer sprays. Most of the live scales left on such fruit were found deep in the calyx or stem cavities, where the spray solution failed to reach them. | - % —s Secioened y walters, fn dod om , . — vee ta eine Ree eres Control of San Jose Scale With Lubricating Oil. ‘el Complete eradication of the scale can not be expected with sum- ' mer treatments with any insecticide. With trees in full foliage it _ is impossible to cover entirely all parts of the trees with a spray solution. The best results that can be hoped for with a summer ap- plication are to hold the scale in check until the dormant sprays can be applied. The only time when bad infestations of the scale can be completely cleaned off is during the dormant season. As soon as continued cool weather occurred some tests with late summer sprays were conducted. These were applied on September 91 and 22 on trees thoroughly infested with the scale. The appli- cation was made on the Ben Davis variety about a month before the fruit was harvested. The weather remained generally cool after the tests were made. In Table 4 are given the data covering this experiment. png ‘TABLE 4—Mortality of all stages of the San Jose scale from the use of late summer sprays, English & Boles orchard, Bentonville, Ark., 1922. Date of | Date of Ne abe Per cent Plat. Insecticide. Dosage. applica- | examina- SST S)| SERS of scales es tion. tion. esate | aincek dead. | 1922 1922 | Pa Ch. se ro ee 1 | Lubricating-oil emulsion | 3 gallonsin100;2percent.| Sept. 21 ee a a ie a Fe Lubricating-oil emulsion-} 3 gallons in 100; 2percent. \ 92 { 1 | 1,700 53 96. 98 ‘Rordesax Se rae rer. A= HOE TEE tees. 222 741 20 | 1,550 51 96. 81 oo ee ee = as 1 1, 000 7 92. 00 3 | Liquid lime-sulphur..... 14 gallons in 50.........- | 22 { 90 | 17556 939 64.97 Liquid lime-sulphur..... 134 gallons in 50.......... \ 99 | 1{ 1,000 31 96. 99 4 |<40 per cent nicotine sul- |\1 to 800.................. ea 20 | 1,698 816 67. 54 ‘pie: | 1,288:|° Gas! 66.8 = 1 8 - 87 5 | Check (unsprayed).....-|-------+--+-+-++2+202222t ee )eeee eee e ee i 001 17566| $39] 65.11 Two examinations of scale-infested twigs from the various plats were made, the first 10 days after the spray application and the other about 20 days later. The reason for the first examination was to get an idea of the mortality of the scales, particularly the young -erawlers, before the dead bodies were blown away. Plats 1 and 2, 2 per cent lubricating-oil emulsion plats (a weak Bordeaux being used with the lubricating-o1]l emulsion on Plat 2) showed a fair kill of the scales on the dates of both examinations. At the time of the last examination all the young stages of the scale were dead, only a few of the full grown females in protected crevices escaping.