18 N. H. AGR, EXPERIMENT STATION. [Bulletin 192 



The research work carried on was as follows : 



A— ADAMS PROJECTS. 



1. Studies on the Effects of Fungicides and Insecticides on Plants. 



(a) Cwprammonium Washes. — During the year work on the methods of 

 preparation, biological properties, and application of the cuprammonium 

 washes was completed, the conclusions derived from the completed study being 

 briefly as follows: 



The cuprammoniums met with in practice belong, chemically, in one or the 

 other of the following groups: (1) cuprammonium sulphate; (2) cuprammonium 

 hydrate; and (3) cuprammonium carbonate. 



When decomposed by drying cuprammonium sulphate deposits the copper 

 as a basic sulphate, cuprammonium hydrate yields a copper hydrate, and 

 cuprammonium carbonate, a copper carbonate. 



Cuprammonium sulphate is very unstable; cuprammonium hydrate and 

 carbonate, very stable. 



The cuprammoniums are more toxic when slowlj^ than when quickly dried. 



The toxicity of the cuprammoniums during drying and on weathering is due 

 to soluble copper. 



The copper sulphate and ammonia wash and Johnson's mixture are less inju- 

 rious than the malchite washes. 



The cuprammonium washes are more effective and efRcient than Bordeaux 

 mix-ture when large amounts of soluble copper are required to give protection. 



The cuprammonium washes are less effective than Bordeaux mixture when 

 small amounts of soluble copper suflfice to give protection but with the excep- 

 tion of the malchite-ammonium carbonate wash are shghtly more efficient. 



The relative efficiency of the unit copper in the cuprammoniums is in de- 

 creasing order as follows: copper sulphate-ammonia, malchite-ammonia, cop- 

 per sulphate-ammonium carbonate, malchite-ammonium carbonate. 



The cuprammoniums may be used at 11.7 times their lethal concentration 

 for Plasmopra vilicola on plants not affected by 0.0075 per cent soluble copper. 



The cuprammoniums are of hmited practical applicability and should not be 

 used in lieu of Bordeaux mixture whenever the latter yields suflBcient soluble 

 copper to give protection. 



(b) Bordeaux Mixture. — During the past year studies on the stimulating 

 action of Bordeaux mixture have been continued and the results obtained 

 indicate that: 



Transpiration is increased by spraying with 1 per cent Bordeaux mixture in 

 which the ratio copper sulphate to hme is unity. 



The increased transpiration is not due to the copper salt, but to the excess of 

 lime. 



One per cent Bordeaux mixture 1: 1 does not stimulate plant growth but 

 rather has a depressing effect which, however, is more marked in weak than 

 strong light. 



Soil fertility is without effect on the stimulatory action of Bordeaux mixture. 



(c) Relative Adhesiveness of the Copper Fungicides (in collaboration with Mr. 

 T. O. Smith, Department of Chemistry). — Work on this subject has been con- 



