42 Station Bulletin 372 



On Green Mountain potatoes Zerlate, Parzate, and Manganese ethylene 

 bisdithiocarbamate gave the best control of early blight as well as the best 

 yields. With the Irish Cobbler variety Parzate and Bordeaux mixture gave 

 the best control of early blight, but Tribasic copper sulfate and manganese 

 ethylene bisdithiocarbamate gave the best yields. Phygon used at two pounds 

 per hundred gallons of water gave good control of early blight but cut yields 

 below that of the check. 



On New Hampshire Victor tomatoes Bordeaux mixture, 6-6-100; Par- 

 zate (2-100) gave the best control of early blight, but highest yields were op- 

 tained from the plant sprayed with Fermate, (2-100) ; Manganese ethylene 

 bisdithiocarbamate, 2-100; and Phygon, 2-100. 



Puratized Agricultural Spray gave better control of apple scab on Mc- 

 intosh trees and pear scab on Flemish Beauty than wettable sulfur. Where 

 scab was prevalent on Mcintosh leaves Puratized applied in combination 

 with Arsenate of lead, 2-100, caused yellowing and abscission of the infected 

 leaves. Under similar conditions greater injury to the foliage occurred when 

 liquid lime sulfur 1^-100 was applied. 



During the summer of 1946, DDT in the form of a 3 per cent dust was 

 tested for European corn borer control in the field plots of sweet corn. The 

 number of applications varied from one to four. 



Corn harvested from plots which received four applications, a week 

 apart, was entirely free of borer infestation. Where the fourth application 

 was omitted 4 per cent of the ears were infested at harvest time. Satisfactory 

 control was obtained in plots receiving only two applications, the first two 

 in the series. 



In seeking to obtain better control of potato aphids through the use of 

 im.proved spray equipment, DDT in the form of a 50 per cent wettable pow- 

 der was applied throughout the season to potato plots. An improved sprayer 

 was designed to give better coverage to the underside of the foliage. 



Better coverage of the potato foliage was attained than had been pos- 

 sible with the older conventional type of potato spray apparatus. Excellent 

 control of potato insects was obtained. However, because of adverse weath- 

 er conditions in August, which prevented normal build-up of this species, it 

 was impossible to secure accurate information on control of the green peach 

 aphid. 



For a second season DDT in the form of a 3 per cent dust was applied 

 to field-grown tomatoes in order to determine whether or not injury to the 

 plants would result. In all cases excellent control of flea beetles was secured 

 without any apparent injury to the plants, and with no apparent reduction 

 in yield of tomatoes. 



M. C. Richards, J. G. Conklin 



POULTRY HUSBANDRY 



Protein Requirements of Chickens at Various 

 Stages of Growth and Development 



The last phase of this study has been concerned with the pH of the gas- 

 tro-intestinal tract. Data on 247 chickens from 16 days to 101 days of age 

 have been taken with nearly 5,900 pH readings recorded. Compilation and 



