Page 28 



BETTER FRUIT 



Ma)'ch. igso 



Green Tip Treatment for the Control of Apple Aphids 



IN carrying on fickl experiments for 

 the control of potato plant lice, com- 

 mercial lime-sulphur solution, among 

 other materials, was tested as to its ef- 

 fectiveness. Although this was used at 

 the rate of one gallon to 22 gallons of 

 water, about twice the ordinary sum- 

 mer strength, and in spite of the fact 

 that every precaution was taken to 

 drench thoroughly all parts of the 

 plants, the percentage of plant lice kill- 

 ed was so small, under ten per cent that 

 it could in no way be considered of 

 value as an aphidicide at a strength safe 

 to use upon potato foliage. 



Object of Comparative Tests 



The results of these tests led the 

 writer to question just how effective 

 the usual dormant strength, one to 

 eight, of lime-sulphur would prove 

 against apple aphids when applied at 

 the delayed dormant period, just after 

 the eggs have hatched. With a view to 

 determining this point, a number of 

 tests were carried out. In these experi- 

 ments commercial lime-sulphur solu- 

 tion was used alone and in combina- 

 tion with nicotine sulphate, and several 

 brands of proprietary miscible oils 

 were also tried out in comparison. 

 Tests were also made to determine the 

 effect of lime-sulphur and miscible oils 

 upon the unhatched eggs. 



By W. S. Regan, Agricultural Experiment Station, Amherst, Massachusetts 



Remarks might be prefaced here by to expand and show the least bit of 

 the statement that the term dormant is green available for feeding purposes. 



taken to mean the condition of the buds 

 in the winter or early spring before 

 they begin to swell. By late dormant 

 is meant the swollen condition of the 

 buds at the time just before they split 

 open, or in other words just before the 

 buds show the least bit of green. This 

 condition would normally be reached 

 during the early part of April in Massa- 

 chusetts. The term delayed dormant 

 is applied to that period in the develop- 

 ment of the cluster buds and foliage 

 when they have expanded from a quar- 

 ter to a half inch. 



It is more or less axiomatic that the 

 hatching of the aphid eggs is about co- 

 incident with the first splitting of the 

 apple buds, and that by the time the 

 buds have expanded from a quarter to 

 a half inch, the delayed dormant period, 

 practically all of the eggs have hatched 

 and the young plant lice have migrated 

 to the new growth for food. Observa- 

 tions have confirmed this. Twigs 

 brought in from the field and examined 

 on April 17 had numerous plant lice eggs 

 upon them, but none of these had 

 hatched. The buds were in the late dor- 

 iriant condition. Twigs brought in on 

 April 19 were found to have a few 

 newly hatched individuals, which had 

 migrated to those buds just beginning 



I 



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tax for each 25 cents of purchase. 



WOODARD-CLARKE & CO. 



Wood-Lark Building. Portland. Oregon 



WHEN WRITING ADVERTISERS MENTION BETTER FRUIT 



From the 19th to the 24th of April, 

 newly hatched aphids appeared in in- 

 creasing numbers. After the latter date 

 only a few new individuals appeared, 

 which could be readily determined by 

 their size. It is evident from this that 

 under favorable weather conditions 

 such as existed during the period men- 

 tioned the time of maximum emergence 

 is rather brief. The presence of a few 

 newly hatched individuals on some of 

 the twigs on May 1 indicated that a 

 small number of belated aphids were 

 still hatching from the eggs, but in no 

 case observed had the foliage expanded 

 beyond about half an inch before 

 hatching was completed. No vivipar- 

 ously produced aphids were in evidence 

 at this time. 



Object of Delayed Dormant Spraying 

 In the past the practice of spraying 

 with lime-sulphur for the control of 

 San Jose scale has been confined for 

 the most part to the dormant or late 

 dormant season. Comparatively re- 

 cently, however, the practice of delayed 

 dormant spraying with lime-sulphur 

 has been quite generally advocated, 

 based on the assumption that such 

 treatment is fully as effective as dor- 

 mant or late dormant season applica- 

 tions against the San Jose scale, and 

 that apple plant lice in their active 

 stages would offer less resistance to 

 this insecticide than the unhatched 

 eggs. In other words, it is believed by 

 some that a delayed application of lime- 

 sulphur at full dormant season strength, 

 just after the buds have split open and 

 have expanded perhaps not over half 

 an inch, will control the San Jose scale, 

 and to quite an extent the apple plant 

 lice as well. Applications at this time, 

 practice has shown, can be made with 

 little or no eventual injury to the foli- 

 age. Our tests, so far as the efficiency 

 of the delayed applications of lime-sul- 

 phur in controlling plant lice is con- 

 cerned, have by no means borne out 

 this conclusion. From the standpoint 

 of the fungicidal value of lime-sulphur, 

 delayed dormant applications appear to 

 have some advantage over those of the 

 dormant season. 



On the other hand it has been recog- 

 nized by some that only by the addition 

 of nicotine sulphate to the lime-sulphur 

 solution, when this is applied as a de- 

 layed dormant spray, can the aphids be 

 satisfactorily controlled. This would 

 indicate that the nicotine sulphate is 

 mainly responsible for the control of 

 the plant lice, and that the only reason 

 for delaying the lime-sulphur treat- 

 ment and combining it with nicotine 

 sulphate is to make necessary only one 

 application instead of two. Then, too, 

 some advocate the addition of an arsen- 

 ical to the above combination, at the 

 delayed dormant period, for the control 



