474 



STATE BOARD OP AGRICULTURE. 



Lead arsenate was used on both dusted and sprayed plots in the two appli- 

 cations after blossoms had fallen. 



The pre-blossom application was not made on the Montmorencies but was 

 made on the English Morellos as they bloom later and are much more sus- 

 ceptible to leaf-spot. In 1920 dust only was used at the July application on 

 the Montmorencies as the fruit was so nearly ripe that the spraying materials 

 would have stained it. In 1921 the same conditions prevailed and as no 

 leaf-spot had developed even on the checks, neither the dust nor spray was 

 applied. The "after-harvest" application of both materials was omitted on 

 this variety for the same reason. 



Weather conditions. During the season of 1920 there was so much rainfall 

 that conditions were quite favorable for leaf -spot development. There was 

 a bad infection period in June and another later in the summer. In 1921 the 

 early part of the season was very dry and unfavorable for leaf-spot but was 

 more favorable from the middle of July until September. 



Fig. 22. — An English Morello tree from check plot showing the degree of defoliation which occurred 

 by early August in 1920. In 1921 defoliation to a similar extent developed by September. 



RESULTS. 



Leaf-Spot Control. In the season of 1920, leaf-spot never became serious 

 on the Montmorency trees, even the untreated ones showing no serious 

 infection. These trees lost some foliage but not a noticeable amount. At 

 the end of the season, the dusted plots showed some leaf-spot in the early 

 stages but it did not cause any leaves to drop. The lime-sulphur plot showed 

 some leaf-spot a little earlier in the season. In 1921 results with Montmorency 

 were even less conclusive than in 1920 as no appreciable amount of leaf-spot 

 developed even on the check trees. 



