ANNUAL REPORT, 1Q4U 61 



Mcintosh crop showed very little scab either in the lime-sulfur plots or 

 where wettable sulfur was used in a complete season's program, although 

 it was much more prevalent where sulfur was omitted and only lime was 

 used in the cover sprays. Scab was found on 61 percent of the fruit from 

 unsprayed trees. The record showed little or no significant difference 

 between any of the programs followed, in the matter of relative control 

 of insect pests. 



Control of Striped Cucumber Beetle. (W. I). Whitcumb, VValtham.) 

 Unfavorable weather conditions resulted in very poor growth of 

 melons and cucumbers in the experimental planting al Waltliam in 1940. 

 Beetles did not appear in appreciable numbers until after July 1 and were 

 less abundant than normally at all times. Of the 3029 beetles recorded 

 on 70 hills each of cucumbers and melons, 82.8 percent were on the 

 cucumbers. 



In these experiments, eight applications were made between June 14 

 and July 18, the treatments being applied wiien considered necessary 

 rather than at regular intervals. 



Under these conditions, nine of tlie eleven niateiial.s used reduced the 

 number of beetles on the plants 90 percent or more and three of them 

 gave 100 percent protection on the melons. 



Both rotenone dusts and calcium arsenate dusts were effective in re- 

 ducing the beetle population, the most effective materials being a com- 

 mercial copper-rotenone dust and a homemade calcium arsenate- 

 fibrous talc dust. Other satisfactory dusts were a commercial stabi- 

 lized rotenone dust; a commercial calcium arsenate-red copper oxide 

 dust; copper oxychloride-pyrophillite talc 1-14; rotenone-talc (.75 

 percent rotenone), home jnix; and calcium arsenate-pyrophillite talc 

 1-14. Calcium arsenate-rnonohydrated copper sulfate-lime 10-20-70 

 gave good protection against the beetles but caused slight to moderate 

 foliage injury. A tobacco-pyrethrum dust was relatively ineffective and 

 had very little repellent action. An experimental derris spray burned 

 the vines so badly it was discontinued after three applications. 



A direct comparison between fibrous talc and pyrophillite talc as a 

 carrier for calcium arsenate resulted in a 5 percent advantage for the 

 fibrous talc, but this slight advantage is not highly significant. 



Control of Cabbage Maggot. (W. D. Whitcomb, Waltham.) Because 

 of the cold, wet weather early in the season, the first eggs of the cabbage 

 maggot were not found until May 10, the same date as in 1939, and the 

 latest date in the ten years that records have been made. 



The field infestation at Waltham was moderately heavy, averaging 68 

 percent; but the growing conditions for cruciferous crops were extremely 

 favorable, and in spite of this injury about 53 percent of the untreated 

 plants produced large or medium heads. Only 22 percent of the heads 

 were worthless where no treatment was applied, compared to 49 percent 

 in 1939. 



Under these conditions, liquid treatments consisting of corrosive sub- 

 limate solution (1 ounce in 10 gallons of water) and calomel-gum arable 

 suspension (4 ounces calomel and 3^ ounces gum arable in 10 gallons 

 of water) gave perfect commercial control of the maggot, and produced 

 70 to 80 percent large or medium-sized heads. 



Because of the cold weather, an application made May 18 (8 days 



