44 EXPERIMENT STATION BULLETIN 354 



ranging from one to four pounds, when the plots were ungrazed. The but- 

 tercup at maturity is somewhat less tolerant of heavy concentrations of 

 borax than most grasses. Clovers were destroyed as well as the buttercup. 

 Ammonium sulphamate seemed to hold the best promise for eventually 

 destroying buttercups without permanent injury to grasses and clover. At 

 North Haverhill, in early and mid-June, applications of %6> K) and ^ 

 pounds, each dissolved in one gallon of water and sprayed to cover the fo- 

 liage within 100 square feet of area, made effective kill of the buttercup 

 and at the concentration of %6 pound per gallon had no harmful effect on 

 grasses. The Ladino clover was injured somewhat. The area at North 

 Haverhill was ungrazed throughout the summer and fall of 1943 and dur- 

 ing the spring of 1944. At Durham, in June and early July, plots were 

 treated with varying concentrations of ammonium sulfamate both under 

 grazed and ungrazed conditions. The most effective treatment was ob- 

 tained with a concentration of %6 pound of the sulfamate per gallon of 

 water, applied to a grazed portion of the pasture. The results were very 

 evident in the spring of 1944 on one particular plot. A decline was noted 

 in number of medium and large-sized buttercups from 30 before treatment 

 in 1943 to 4 or 5 in 1944. Other weeds were destroyed, the grasses were 

 apparently stimulated and the area had been extensively grazed. Adjacent 

 areas left as check plots were ungrazed ; grasses were scarce and weeds 

 and buttercups, in particular, were dominant. In the treated plot, clovers 

 apparently had been partly destroyed but were reproducijig actively in 

 June, 1944 by seedlings. 



A. R. HODGDON 



PLANT PATHOLOGY 



Developing Disease Resistance in Early Tomatoes 



I. Early Blight Control by Spraying 



Tomato plants of the New Hampshire Victor variety were set in the 

 field on June 5, 1943, and were sprayed eight times during the period, Ju- 

 ly 16 to September 9, with the following fungicides: 



Bordeaux mixture 8-4-100 



Copper oxychloride-sulphate 6-100 



Neutral copper fungicides 5-100 



Fermate (ferric-dimethyl-dithiocarbamate) 



2-100 plus DuPont sticker spreader (8 drops per gallon) 

 Five plants were used in each of the treatments and the check. The 

 plants were arranged in a Latin square and the fungicides applied with a 

 knapsack sprayer. The ripe fruits were picked, weighed, and counted at 

 weekly intervals and the incidence of defoliation recorded. Early blight 

 was first found on July 13. At the end of the season, almost complete de- 

 foliation of the treated plants as well as the check plants had occurred. 



A decrease in the numbers of fruits set on the plants in the Bordeaux 

 treatment was obtained but this injury was partly compensated for in that 

 the fruits produced on these plants were larger. With the exception of the 

 Fermate-treated plants, there were no significant dift'erences found when 



