36 MASS. EXPERIMENT STATION BULLETIN 436 



Rose Chafer. In two series of laboratory tests against the rose chafer, DDT 

 spray at dosage of 0.4 and 0.8 pound DDT (Gesarol AK-40) and a 5 percent 

 DDT dust proved very effective. Within one-half hour beetles began to show 

 poor coordination, and became more and more inactive and helpless. After 5 

 to 6 hours practically all beetles were quite inactive and in about two days all 

 died. There was practically no evidence of feeding or other normal activity 

 after treatment. 



Gypsy Moth. In three series of tests, one-half to three-fourths grown larvae 

 soon began to show ill effects, poor coordination of muscles gradually increasing 

 to inactivity. Within two to three days practically all had died. Full-grown 

 larvae succumbed somewhat more slowly and in few cases attempted to form 

 pupae. There was very little or no evidence of feeding after treatment. 



A young planting of one-year-old apples, which showed an average infestation 

 of about three half-grown larvae per tree and considerable foliage injury before 

 treatment, was cleared of the infestation with one application. Half the block 

 was sprayed with 0.8 pound DDT (2 pounds Gesarol AK-40) per 100 gallons, 

 combined with a wettable sulfur fungicide. The rest of the block was sprayed 

 with lead arsenate, 5 pounds to 100 gallons, plus wettable sulfur and excess lime. 

 Examination five days after treatment showed no larvae on DDT rows, but one 

 larva following arsenical spray. 



Tarnished Plant Bug on Potatoes. A commercial planting of potatoes was 

 attacked by tarnished plant bugs migrating from a recently cut field of clover 

 and swarming o\'er the plants of several rows of potatoes. Almost every growing 

 tip was attacked and many were killed. One spray application of DDT, 0.5 

 pound per 100 gallons, cleared the field of bugs in about three days, and subse- 

 quent application to potatoes and an adjoining strip of clover stubble prevented 

 further migration. The plants recovered and yielded an excellent harvest. 



European Corn Borer. The infestation throughout the State was very light 

 in 1945, particularly in the Connecticut Valley region. This was due in large 

 part to adverse weather conditions during the period when moths were present. 

 Emergence was prolonged, moth activity was seriouslj' reduced by cold, wet 

 weather, and egg laying was very slight and irregular. 



A spray containing 2 pounds Gesarol A-20 (0.4 pound DDT) per 100 gallons, 

 plus Ultrawet spreader, was used in four applications on sweet corn. Gesarol 

 A-5 dust was also used in a similar schedule. Counts of tassel breakage as an 

 index of stalk infestation, made just before harvest, showed no breakage at all 

 in DDT plots (either sprayed or dusted) and only 9.5 percent breakage in un- 

 treated checks. 



Yield records showed 2 infested ears out of a total of 265 (0.75 percent) in the 

 plots sprayed with DDT. No infested ears were found in the dusted plots. Un- 

 sprayed checks yielded 239 ears, of which 4 (1.7 percent) were damaged by corn 

 borer. 



The Value of Control Measures to Supplement the Standard Spray Program 

 for Apple Pests in Massachusetts. (A. I. Bourne, in cooperation with the De- 

 partments of Pomology and Plant Pathology.) The set of fruit was so light and 

 uneven that the schedule of tests originally planned for this block had to be re- 

 arranged and all of the DDT series had to be relocated. Such records as were 

 possible were taken from Mcintosh plots at harvest. The crop of Baldwins, 

 which was due to be light, was practically wiped out by the freeze and subsequent 

 hailstorm. 



