ANNUAL REPORT, 1938 53 



The seed which is to be cleaned is fed from a funnel into a rectangular chamber 

 about 2 inches wide, 24 inches high, and 48 inches long. A blast of air obtained 

 from a 12-inch fan is directed through this chamber. A removable trough at the 

 bottom of the chamber serves to collect the seed. The seed in the trough will 

 be graded from heavy to light, the best seed being found near the front end and 

 the very light seed at the far end of the trough. The chaff is blown to the far 

 end and caught in a container below the device. The operator arbitrarily decides 

 the division point between seed which is to be used and that which is to be dis- 

 carded. 



DEPARTMENT OF ENTOMOLOGY 

 Charles P. Alexander in Charge 



Investigation of Materials which Promise Value in Insect Control. (A. I. 



Bourne and W. D. Whitcomb, Waltham.) 



Oil Sprays for Dormant Applications. The winter and early spring of 1938 

 reflected in considerable measure the abnormal weather conditions which cul- 

 minated in the September hurricane. Heavy rains in January removed most 

 of the snow, which was not replaced to any extent during the remainder of the 

 winter. Very few periods of subzero temperatures were experienced so that, 

 while the winter was somewhat more severe than the previous one, little or no 

 damage was caused to fruit buds except in the most exposed locations. Unusually- 

 warm weather in late March and throughout most of April caused a rapid advance 

 in seasonal development, so that orchards were ready for the dormant and de- 

 layed dormant applications of oil sprays fully 10 days earlier than normal. The 

 lack of snow and early thawing of the ground combined to give excellent condi- 

 tions for spraying and allowed accurate timing of the oil sprays, while the con- 

 sistently warm weather following their application prevented injury from these 

 sprays so that orchards throughout the State were remarkably free from thi^ 

 type of damage. 



The European red mite infestation in the college orchards was slightK' heavier 

 than in 1937 but was very light in comparison to other years. All of the oils gave 

 96 percent control or higher and no serious increase in mite population was noted 

 throughout the season, a fact which would have been more significant if the 

 original infestation had been heavier. 



The new type of oil containing 96 percent mineral oil and 4 percent dinitro- 

 ortho-cyclo-hexy-phenol, which was first applied in 1937, was again tested. A 

 special goulac-bentonite mixture is furnished by the manufacturer to emulsify 

 this oil. Considerable difficulty was experienced in this process due to the faulty 

 condition of the emulsifying agent. It was necessary to secure a special shipment 

 of newly prepared emulsifier before the spray could be applied. A more stable 

 emulsifying agent would be desirable. Once thoroughly prepared, however, this 

 oil spray proved very effective against eggs of the red mite and caused no injury 

 to fruit buds. 



Substitutes for Lime-sulfur in Summer Sprays for Orchards. Tests with these 

 materials were conducted in the college orchards, in cooperation with the Depart- 

 ments of Pomology and Botany. Commercial liquid lime-sulfur with spray 

 catalizer was applied in pre-blossom and cah'x sprays, followed by micronized 

 sulfur in the 4 cover sprays. Liquid lime-sulfur was also used at diminishing 

 strengths through the calyx spray: i. e., 1-50 in the pre-pink, 1-60 in the pink, 

 and 1-70 in the calyx, followed by micronized sulfur in the cover sprays. A mix- 

 ture of dry lime-sulfur and finelj' divided sulfur was employed throughout the 



