POTATO DISUASUS-JN KJO"/. T> 2 9 



As a general precautionary measure against all potato diseases 

 the collection and burning of all weeds, litter and tops as soon 

 as the crop is harvested cannot be too strongly recommended. 



Red Lead as an Insecticide. 



Last spring a correspondent at Gray wrote the Station that 

 Mr. J. E. Leighton of that place was successfully using red 

 lead as a substitute for Paris green to destroy the larvse of 

 Colorado beetles on potatoes. Investigation showed that Mr. 

 Leighton had been using this material for 3 years, applying dry 

 about 10 pounds per acre, diluted with wood ashes. He stated 

 that the red lead was very adhesive and remained on during 

 the entire season. That, whereas he was obliged to go over 

 his field repeatedly with Paris green, it was unnecessary where 

 red lead was used, except to protect new growth. Mr. Leigh- 

 ton stated that in his experience, not only did the red lead keep 

 the foliage clean from the Colorado beetles but the leaves on 

 the plants where it was used remained green for 2 or 3 weeks 

 longer than was the case where Paris green alone was used. 



To test the matter one-half of a small field of potatoes was 

 sprayed on July 9 and again on July 20 with bordeaux mixture 

 containing 10 pounds of red lead to 50 gallons of mixture. 

 The other half was sprayed with bordeaux mixture containing 

 1 pound of Paris green to 50 gallons. The spraying was quite 

 thoroughly done so about 75 or 80 gallons of mixture per acre 

 was applied, thus using about 15 pounds of red lead and 1^2 

 pounds of Paris green per acre. The red lead proved to be 

 very hard to use with bordeaux mixture. On account of its 

 relatively high specific gravity it all settled to the bottom of 

 the spray tank, forming a thick, pasty mass by the time the 

 field was reached. In order to spray it on at all it was neces- 

 sary to remove the hose from the nozzles and pump the mixture 

 back through the hose into the tank for several minutes, till 

 it became thoroughly mixed. Then the mixture had to be kept 

 constantly agitated and applied at once. 



Both the Paris green and the red lead cleared the foliage of 

 insects, but while the former killed them, as was evidenced by 

 the dead on the ground, the latter simply acted as a repellent. 

 No dead insects could be found under the plants sprayed with 



