ANNUAL REPORT, 1939 61 



greatly reduced their numbers and a similar spray on the 15th practically elimin- 

 ated them. 



The experimental plots received 12 applications from June 13 to September 6. 

 There was no evidence of blight, and except in the plots burned by commercial 

 sprays the plants remained green until the crop was dug on October 9 and 10. 

 The first frost occurred October 15, the latest date for this event in the college 

 records. Weekly counts of flea beetle injury showed that there was less damage 

 from flea beetles on plots which had received a 5-23^-50 bordeaux mixture than 

 on those given the standard 5-5-50 strength. The addition of calcium arsenate 

 somewhat reduced the injury in the low-calcium bordeaux plots but gave little 

 or no added benefit in the plots receiving standard-strength bordeaux. In a season 

 of very light and infrequent rains the extra deposit of lime on the foliage was 

 apparently not so essential as in a year of more normal precipitation with fre- 

 quent, heavy, driving rains. There was, however, greater tendency to burn 

 from the 5-23^-50 bordeaux and this was reflected in the yield records. 



Tests of commercial materials were confined to two new materials which were 

 being placed on the market for the first time in 1939: Arsco, a micronized copper- 

 arsenate mixture; and Cuprocide, a newly developed yellow copper oxide spray. 

 Talc and cherokee clay were used as adhesive agents with Cuprocide. Plants 

 sprayed with the yellow copper oxide began to show spray burn by the middle 

 of July, and the damage increased steadily until most of the plants were dead 

 by mid-August. 



None of the commercial materials furnished as persistent coverage as bordeaux 

 mixture, or as good protection against damage by flea beetle. Since most of the 

 plants in the yellow copper oxide plots were dead by the end of August, little or 

 no increase in growth of tubers could be expected beyond that point. 



The yield from these plots, in view of the abbreviated growing season, would 

 indicate that up to the time the plants died the tubers had made very satisfactory 

 growth, as compared to the rest of the plots, and that, with further improve- 

 ments by the manufacturers to render yellow copper oxide safer to foliage, the 

 material should prove a valuable spray for potatoes. 



Introduction of Parasites of Oriental Fruit Moth in Peach Orchards. (A. I, 



Bourne.) At the request of the peach growers, the work of rearing and distribut- 

 ing larvae of Macrocenirus ancylivorus, parasites of the oriental fruit moth, was 

 continued in 1939. As in the previous year, through the cooperation of the 

 Department of Entomology of the Connecticut Agricultural Experiment Station, 

 Mr. A. DeCaprio directed the collection of breeding material in New Jersey, 

 breeding of the parasites, and delivery to the growers. The breeding work was 

 conducted in the entomological laboratories at the college, and approximately 

 13,000 Macrocentrus ancylivorus were liberated in the orchards of more than 50 

 growers in 8 counties of the State. Macrocentrus parasites in New Jersey were 

 unusually scarce so that it was difficult to secure sufficient breeding material to 

 fill the quota for Massachusetts growers. Our supply, however, was supple- 

 mented by material secured through the kindness of Professor Philip Garman of 

 the Connecticut Agricultural Experiment Station, and was just sufficient to 

 fill the orders received. 



Weather conditions during the time the parasites were being liberated were 

 favorable for their establishment in the orchards. Because of the dry weather 

 which prevailed throughout late spring and early summer, growth of peach twigs 

 was so much slower than normal that larvae of the oriental fruit moth failed to 

 find the usual amount of succulent, tender twig growth and began in many 

 orchards to enter the young peaches soon after they were formed. When the 

 parasites were liberated, therefore, many of the oriental fruit moth larvae were 



