42 MASS. EXPERIMENT STATION BULLETIN 327 



drated copper sulfate-lime dust. All of these dusts gave satisfactory protection 

 to the plants without causing any apparent injury from their application. It 

 was necessary to apply the dusts five times beginning when the beetles first 

 appeared in moderate numbers. 



As a result of two seasons' experiments, it is apparent that during the first 

 month of the growing season dust applications are necessary (1) whenever the 

 beetles become abundant, (2) when two inches or more of unprotected new 

 growth have been made, and (3 ) after each heavy rain especially when followed 

 by warm clear weather. Such conditions are so dependent on the weather 

 that it is practically impossible to determine in advance the number and time 

 of the applications necessary for satisfactory control, but it seems probable 

 that at least five applications will be required. 



Control of the Squash Vine Borer. In 1935, at the Waltham Field Station, 

 the average infestation of untreated Hubbard squash vines was found to be 6.5 

 borers per plant. 



Four sprays of 1 percent summer oil emulsion and 40 percent nicotine sulfate 

 1-500 applied at weekly intervals beginning July 1 reduced this infestation to 

 0.84 borers per plant as compared to an average of 1.44 borers in vines sprayed 

 with the standard treatment of 40 percent nicotine sulfate 1-250. A commercial 

 spray of thiocyanate diluted 1-400 was comparatively ineffective. 



The outstanding result of this experiment, however, is the good control 

 obtained from four applications of derris-clay dust containing .6 percent 

 rotenone. Due to the difficulty in operating a spray machine in squash fields, 

 dust applications are more practical in many plantings. Furthermore, derris- 

 clay dust is an effective treatment for the contol of the striped cucumber beetle 

 earlier in the season and the continued use of the same material for borer control 

 has many practical advantages. 



Control of Cabbage Maggot with Mercury Compounds. In the experimental 

 planting, 100 percent of the untreated cabbage plants were infested by cabbage 

 maggots and 81.33 percent were either killed or so badly injured that they were 

 worthless. In adjacent rows corrosive sublimate solution (1 ounce in 10 gallons 

 of water ) applied when the maggot eggs were first found and repeated one week 

 later gave 100 percent protection from moderate or severe injury and produced 

 86 percent large or medium-sized heads. One treatment with this material 

 applied one week after eggs were found gave 94 percent protection and was 

 slightly more effective than a single treatment made as soon as the eggs were 

 found. 



Two applications of a 4 percent calomel-gypsum dust made early in the 

 period of maggot activity gave about 75 percent protection, but one treatment 

 or two late treatments were ineffective. 



A new method of treating cabbage seedlings gave promising results when 

 tried for the first time. This consists of shaking or rolling the plants as they 

 are taken from the seedbed in a calomel-gypsum dust until the roots and stems 

 are thoroughly coated. Dusts containing 50 percent and 20 percent calomel 

 applied in this way gave 79 percent and 73 percent protection respectively, and 

 the plants made good growth; but dusts containing 4 percent and 8 percent 

 calomel were much less effective. Since no dust is wasted and later treatments 

 are not necessary, this method seems to have several practical advantages. 



Control of Codling Moth with Nicotine Sprays. Two blocks of Mcintosh 

 apples at Littleton, Massachusetts, which were heavily infested by the codling 

 moth in 1934 were sprayed: one with a commercial preparation of soluble and 

 insoluble nicotine, and the other with 40 percent nicotine sulfate plus a sulfur 



