24 N. H. AGRICULTURAL EXPERIMENT STATION [Bulletin 199 



BROWNTAILS AND GYPSIES STUDIED 



No sooner had the browntail and gypsy moths appeared in the 

 state than they were immediately made the objects of special 

 studies at the Station ; the information regarding them was spread 

 through the state; and there has been the closest possible touch 

 throughout between the agencies combating them and the en- 

 tomological laboratory at Durham. Because of the prevalence of 

 spraying for browntails in August, for example, the question was 

 raised as to the danger of poisoning persons eating the fruit, or of 

 poisoning the live stock eating the grass or hay from beneath 

 sprayed trees. This subject was given detailed study; and it was 

 demonstrated that the spraying could be conducted safely. 



INVESTIGATIONS IN BORDEAUX MIXTURE 



In similar fashion the Station has been the central source of in- 

 formation regarding the control of potato diseases in the state. 

 Many of the fungicides recommended in the literature on this sub- 

 ject have been found to possess no real merit at all. On the other 

 hand, a study of Bordeaux mixture has resulted in a number of 

 modifications in the practice of spraying for late blight which per- 

 mit a higher degree of protection from rot than has hitherto been 

 obtained. The importance of this work may be realized when it 

 is considered that the loss from late blight in the season of 1919 

 was estimated at $1,500,000. For every 100 potatoes lost where 

 sprajdng was not done, nearly 8 would still be lost by the ordinary 

 Bordeaux mixture, called "4-4-50." By using an 8-4-50 mixture, 

 however, the Station demonstrated that complete control could 

 be secured. The thoroughness with which the mixture is applied 

 was shown to be another important factor, a pressure of 180 

 pounds securing fifteen times as much protection as a pressure of 

 60 pounds. 



A disease almost as serious to the potato industry of the state 

 is mosaic, which it is estimated affects 20 per cent of the fields, 

 causing a decrease each year in vigor of the plants and cutting 

 the annual potato yield by over 200,000 bushels. Experiments 

 have shown that the yield of healthy plants is 25 per cent greater 

 than from plants affected with this disease. 



