214 MASS. EXPERIMENT STATION BULLETIN 280 



Weather conditions during early spring were very favorable. Most of the 

 delayed dormant applications were made at temperatures of 55° to 65° F. No 

 injury was noted following any of the oils tested. Tests of comparative coverage 

 of two standard brands of miscible oil, an oil emulsion, and commercial lime- 

 sulfur applied under similar weather conditions and to trees of uniform size and 

 spread, again showed a marked advantage of the oils over lime-sulfur both in 

 time necessary for application and in amount of material used, the oils requiring 

 noticeably less material and approximately two-thirds of the time necessary for 

 equivalent coverage by lime-sulfur. The tests failed to show any significant ad- 

 vantage of one type of oil over another, in these respects. 



Further studies of various spray materials and combinations were made, in 

 cooperation with the Department of Pomology. Especial attention was directed 

 upon their compatibilit}-, effectiveness as insecticides and fungicides, and rela- 

 tive toxicity to fruit and foliage as compared with the standard combination of 

 lead arsenate and lime-sulfur. All the materials were applied in combination 

 with lead arsenate, since up to the present this has proved superior to any other 

 arsenical for general orchard use. 



Combinations of lead arsenate with Sulfocide, with dry lime-sulfur, and with 

 dry mix sulfur lime were compared with the usual combined spray of lead ar- 

 senate and liquid lime-sulfur with and without the addition of hydrated lime. 

 These tests were made in a block containing five standard varieties of apples, 

 namely, Baldwin, Northern Spy, R. I. Greening, Mcintosh and King. The spray 

 schedule consisted of a pre-pink, a pink and a calyx spray and two cover and two 

 July sprays for apple maggot. 



The addition of hydrated lime to the lead arsenate-lime-sulfur combination 

 checked somewhat but did not entirely prevent spray injury to foliage. Con- 

 siderable burn was noted on all varieties sprayed with the Sulfocide combination. 

 Burn was particularly noticeable on Baldwin and King, and was accompanied 

 by considerable yellowing of foliage and some premature drop of leaves. Dry 

 lime-sulfur caused very little burn even on susceptible varieties. No burn was 

 noted following the application of dry mix sulfur lime. Both Kolofog and flota- 

 tion sulfur combined with lead arsenate and applied in a similar schedule to a 

 block of Mcintosh and Baldwin showed excellent persistence and gave very 

 uniform coverage. No foliage injury was noted following the use of flotation 

 sulfur, and but a very slight amount of burn on trees sprayed with Kolofog. 

 The lead arsenate-lime-sulfur spray in this orchard caused extensive burn on 

 Baldwin and considerable foliage injury on Mcintosh. 



The relative effectiveness of these materials is shown in the following record 

 of Mcintosh at harvest. 



The addition of hydrated lime to the lead arsenate-lime-sulfur combination 

 apparently did not impair the insecticidal value of the spray but did not give as 

 successful control of scab as did the standard combination without lime. The 

 Sulfocide combination failed to control scab satisfactorDy and was not conspic- 

 uously successful as an insecticide. Dry lime-sulfur and lead arsenate gave good 

 control against insects and held scab as successfully as did liquid lime-sulfur. 

 The dry mix combination gave practically the same results as did dry lime- 

 sulfur. Flotation sulfur and lead arsenate held scab very successfully and showed 

 good control of insects. Kolofog did not control scab quite as well but did not 

 impair the insecticidal action of lead arsenate. 



