142 MAINE AGRICULTURAL EXPERIMENT STATION. I902. 



of thorough spraying as a protection against blight and the 

 subsequent rot. The fact that pieces planted on land not well 

 drained and on farm manure suffered worse from rot than 

 where the conditions were different, points out the necessity for 

 careful selection of potato land. The ill effects of farm manure 

 seem to indicate that the fungus which produces the rot may 

 be distributed through the soil as well as through the tops. This 

 is in accord with observations made before Bordeaux mixture 

 was used and confirms the soundness of the usual practice of 

 planting on turf land with commercial fertilizers. 



Ready made Bordeaux mixtures were not used in experiments 

 in the Station this year. In former years they gave fairly satis- 

 factory results. Some users in 1902 are not as well satisfied as 

 though they had used the regular home made mixture. This can 

 probably be explained by the fact that if they had used the ready 

 made goods in accordance with directions which come with 

 them, they were only about one-half the strength of the home 

 made goods. 



EXPERIMENTS WITH PARIS GREEN, BUG DEATH AND ARSENATE 



OE LEAD. 



In the season of 1901 some users of Bug Death were satisfied 

 that they got a larger yield of potatoes where Bug Death was 

 used as an insecticide in conjunction with Bordeaux mixture 

 than where Paris green was used, also with Bordeaux mixture. 

 Many articles were written for the agricultural press condemn- 

 ing the use of Paris green on the ground that it injured the 

 foliage, thus stopping growth, and one writer made the claim 

 that the tubers themselves contained arsenic when Paris green 

 was used for killing bugs. Therefore, an experiment was under- 

 taken to compare arsenical poisons with Bug Death, with the 

 view of ascertaining whether arsenic in the fonm of Paris green 

 or arsenate of lead injures the growth of the potato vines so as 

 to affect the quantity or the quality of the tubers. 



Field experiments at best are apt to be unsatisfactory because 

 of lack of uniformity of soil and stand of the crop. In order 

 to avoid the former the experiment was arranged alternately in 

 ribbon strips, so the number of plots might reduce the inequalities 

 of soil as far as possible. The chief difficulty of the experi- 

 ments in 1902 was missing hills. The field which at planting 



