350 



STATE BOARD OF AaRICUiLTURE. 



The importance of this trouble in the Upper Peninsula was revealed during 

 a survey which was made during the latter part of July 1919. Potato fields 

 in six different counties were visited and in five of these Hopperburn had 

 caused serious loss. Many fields were visited which were a total loss, the 

 tops being killed before the tubers had reached marketable size. The loss 

 from this cause in 1919 was estimated by J. W. Weston, Assistant County 

 Agent Leader, as $1,000,000. Hopperburn was found to be more serious 

 on light than on the heavier soils, early varieties were more susceptible than 

 later maturing varieties. [ Observations made on the variety plots at the 

 Station confirmed the findings of the survey. Of the early varieties 

 Bliss Triumph was found to be the most susceptible and was followed 

 in order by Early Ohio and Irish Cobbler. Of the late varieties the Idaho 

 Rurals were most susceptible and were followed in order by Green Moun- 

 tain, Russet Burbank, and Rurals. The last two varieties remained green 

 throughout the entire season although the foliage was curled upward. 



Fig. No. 21. Potato leaf hopper adults (top row), leaf hopper nymphs (middle row), plant lice, aphids 

 (bottoni row). The leaf hoppers, especially the nymphs, cause the burning of the leaves. No 

 burning results from the attack of plant lice. 



The importance of the leaf hopper (Empoasca mali LeB) as a potato pest 

 having been determined, the 1920 investigations comprised life history studies 

 and control measures. The former revealed that the Potato Leaf Hopper 

 passes the winter in the adult stage, and in the spring after hibernation feeds 

 on various field crops and weeds until the early potatoes break through the 



