C6i 



STATE BOARD OF AGRICULTURE. 



with the result that hopperburn was not severe at any time during the 

 season. 



Only partial control was obtained in the 1919 experiments. This 

 was due to the inefficiency of the sprayer which was used. The pressure 

 of approximately 50 pounds which the outfit was capable of maintain- 

 ing was not sufficient to cover the vines adequately with the spray. That 

 a poor outfit is better than none at all was shown by the fact that the 

 spraj^ed vines remained alive about two Aveeks longer than the unsprayed 

 plots. The experiments conducted during the 1920 season showed a 

 difference of 2G per cent of hills afifected with hopperburn in favor of 

 spraying with bordeaux mixture. The first nymphs to hatch under the 

 1920 Upper Peninsula conditions were observed July 22, and counts 

 made on the sprayed and unsprayed plots on July 30, revealed com- 

 paratively few leafhopper nymphs. Only an occasional hill in the 

 sprayed plots revealed nymphs, and these averaged about three nymphs 

 to a hill. The insects were more numerous on the unsprayed plots and 

 more hills afi'ected. The average for the unsprayed plots was nine 

 nymphs to a hill. No burning was evident at the time the observations 

 were made. 



The 1921 season was ideal for spraying experiments for hopperburn 

 control. The season opened early and the potato leafhopper got an 

 early start. Hot dry Aveather prevailed during the growing season 

 which permitted rapid multiplication of the insect. By means of the 

 power sprayer Avhich was used during this season the vines in the sprayed 

 plots were kept well covered with bordeaux mixture. Observations made 

 on September 9, showed the unsprayed vines rapidly dying as a result 

 of hopperburn, while the sprayed plots Avere still green. (Fig. 12). 







.k ■ 



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Fig. 12. 1921 spray plot. 



The sprayed vines remained green while those which were unsprayed had a decided brownish cast 

 due to hopperburn. Photo taken Sept. 9, 1921. 



