318 MASH. EXi'ERlMKNT HTATKjN BUJ.LETIN 247 



Bourne). Wealthy, Mcintosh and Baldwin apjtle trees have been used to 

 determine the latest date on which lead arsenate could be applied without 

 danger of too great residue. Both 1927 and 1928 had large amounts of 

 rainfall during the summer, and it was found that the Wealthy could be 

 sprayed as late as July 15: the Mcintosh during all July; and the Bald- 

 wins were under tolerance limits even when sprayed in mid-August. 



It is apparent that in dry seasons or with moderate rainfall, present 

 spray practices for later spraying will need modifications. Dust applica- 

 tions show less residue on fruit at harvest than sprays. 



Adaptation of the Recommended Spray Schedule for the Control of 

 Orchard Insects to Eastern Massachusetts Conditions. (W. 1). ^^'h■.tcomh) . 

 Studies at Waltham show tliat sjiraNing recommendations based on insect 

 studies of Amherst are generally applicable in eastern Massachusetts. With 

 the apple maggot, however, it was found that during a period of three 

 years the flies did not emerge in sufficient numbers to warrant spraying 

 before July 15, whereas the Amherst recommendations advise spraying by 

 July 1. It has also been found that a spray three weeks after the calyx 

 si)ray is more effective in combating the plum curculio and codling moth 

 in apples than has been realized hitherto, and that the pink spray has no 

 value against the plum curculio. 



Control of the Plum Curculio in Apples. (W. D. Whitcomb, Waltham). 

 Repeated studies now show that the plum curculio is most abundant from 

 June 15 to 22, and that the greatest amount of injury from feeding and 

 egg punctures takes place immediately thereafter; that oviposition ends 

 about July 31 but the feeding punctures continue until cold M'eather al- 

 though rather unimportant after August 10. Lead arsenate, 2 lbs. or 

 more in 50 gals, of water, applied seven to ten days, and again three weeks 

 after the calyx spray, seems to be the most effective for material and time. 

 Calcium arsenate and sodium fluosilicate are effective but liable to injure 

 fruit and foliage. Fish oil and molasses each tend to increase the effect- 

 iveness of the lead arsenate. Following this treatment, orchard tests 

 have given 91 per cent control as compared with 91 per cent injury on 

 adjacent untreated areas. 



Control of Red Spiders on Greenhouse Cucumbers. (W. D. Whitcomb, 

 Waltham). Studies during 1926 and 1927 show that the greenhouse red 

 spider may be effectively controlled in all stages by spraying with highly 

 refined white mineral oil emulsion if no carbolic or cresylic compounds 

 are used in its preparation. It can be applied to greenhouse cucumbers at 

 the rate of 1 part in 99 of water, except when sulfur fungicides are also 

 used. 



Red spider is also effectively controlled by three or more fumigations 

 with naphthalene^ iVs to 3 ounces per 1,000 cubic feet, with enough heat 

 to vaporize the material in not less than six hours. During this time the 

 house temperature must be 75° F. or above, and humidity 75 per cent or 

 higher. The cucumbers taste and smell of the naphthalene but, neverthe- 

 less, this treatment is being used by market gardeners. 



Biology and Control of Garden Cutworms. (W. D. Whitcomb, Wal- 

 tham). Seventy-three different kinds have been collected or reared. 

 Screen traps have been used very successfully for collecting these insects 

 to provide material for the experiments, and control tests show that a 

 mixture of 25 pounds of bran, 1 pound of Paris green, 1 quart of cheap 

 molasses and 2 gallons of water gives effective control. Sodium fluosili- 

 cate and white arsenic prove less effective than Paris green. Applications 



