ANNUAL REPORT, 1941 57 



Summer Sprays for Apples. (A. I. Bourne in cooperation with Departments of 

 Pomology and Botany.) Studies of the value of modifications of the standard 

 spray program were continued. The yield was light, and the prolonged drought 

 in the early season greatly influenced the prevalence of disease, particularly apple 

 scab. The standard spray program, involving lime-sulfur in all spra\s through the 

 caK X with wettable sulfur thereafter, was contrasted with a similar program with 

 the addition of a midbloom application of wettable sulfur, and an optional stand- 

 ard in which no lime was used in the cover sprays. The standard schedule was 

 also contrasted with a program of wettable sulfur throughout the season. Lead 

 arsenate was used in all applications except the pre-pink and midbloom sprays. 

 The dosage was 4 pounds to 100 gallons in the calyx, and 1st and 2d cover sprays; 

 3 pounds in the pink and .3d cover sprays, and 2 pounds in the 4th cover spray. 

 Liquid lime-sulfur was used at the rate of Ij^ gallons per 100 and wettable sulfur 

 at 8 pounds per 100 gallons. 



The pathologist reported that scab infection was appearing on the foliage 

 of Mcintosh check trees in the period of May 23 to 26, and a few infected fruits 

 were observed May 31. On the sprayed trees the spur leaves and fruits were 

 evidently protected b>' the pre-blossom sprays and the infection was confined 

 to the shoot leaves. The record of Mcintosh fruit at harvest supported these 

 observations. The fruit from unsprayed trees showed 44 to 45 percent scab, while 

 on sprayed trees it varied from to 1.8 percent. 



The season also was not conducive to spray injury on cither leaves or fruit. 

 Distinct injury, however, occurred in all plots where liquid lime-sulfur was applied 

 although this was not of so serious a nature or extent as in years of more normal 

 rainfall. Russeting of fruit was noted in all plots where lime-sulfur was applied. 



The control of insect pests was consistent throughout the entire orchard and 

 there was no significant difference between the standard program and the mod- 

 ified schedules. The record of unsprayed Mcintosh fruit was illuminating. Three 

 anplcs, or 0.6 percent were clean; 80 to 81 percent of the fruit was scarred by 

 curculio, and nearly 50- percent damaged by codling moth. Scab occurred on 44 

 to 45 percent of the apples (in a season very unfavorable for its development). 

 Detailed counts showed that on nearly 50 percent of the fruit there were injuries 

 by three or more insects or diseases on the same apple. 



Control of Cabbage Maggot. (W. D. Whitcomb, W'altham.) Definite infor- 

 mation showing that one of the largest sources of cabbage maggot flies in the 

 spring is late-planted cruciferous crops was obtained by sifting the soil in a six- 

 inch square and six inches deep around roots of cabbage, broccoli, and turnip 

 which had remained in the ground over winter. These plants were apparenth- 

 infested by a third generation of the maggot in September. Soil examination on 

 April 18, 1941, showed a maximum of 51 pupae per plant, with an average of 

 19.9, on a small planting of yellow turnip; a maximum of 14 per plant with an av- 

 erage of 4.9, on a small planting of broccoli; and a maximum of 11 per plant, with 

 an average of 1.9, on a large planting of cabbage. 



The first eggs of the cabbage maggot in the spring of 1941 were found on May 1, 

 which is five days earlier than the average date for the past ten years. The 

 normal field infestation was 85.72 percent commercial injury on the Golden Acre 

 variety. One application of corrosive sublimate solution on May 3 gave 92.04 

 percent commercial protection and yielded 78 percent large and medium heads. 

 Two applications of corrosive sublimate solution gave 96.67 percent commercial 

 protection and yielded 83 percent large and medium heads. Calomel-talc powder 

 containing 4 percent calomel applied at the rate of a teaspoonful around the stem 

 of each plant on May 3 was also satisfactory, giving 100 percent commercial 

 protection and yielding 75 percent large and medium heads. 



