662 



STATE BOARD OF AGRICULTURE. 



HOST PLANTS 



The potato leafliopper has been collected from a great number of 

 plants, but doubtless many of these are not true host plants for the 

 insect, that is, plants upon which the leafhopper lays eggs. Ackerman^- 

 reports that eggs of Empoasca iivali have been found in the leaves of 

 apple, pear, peach, plum, quince, cherry, alfalfa, beet and potato. In 

 addition to these the writer has found that the insect also lays eggs 

 on beans, sunflower, red clover and curled dock [Rwmex crispus). It 

 is common knowledge that weeds in a potato field, by virtue of their 

 stronger root systems, rob the potato vines of plant food and cause 

 material reducatiou in tlie yield of ])otat()es. This in itself is of sutticient 

 importance to warrant weed eradication, but when this knowledge is 

 further augmented by the fact that the destructive leafhopper breeds on 

 weeds the eradication of these plants becomes imperative. 



TRESEXT STATUS OF IXVESTIGATIONS 



While this work was in progress Ball continued his investigations 

 (this time working in Iowa) assisted by Fenton". Dudley and Wilson^"' 

 worked on the problem in Wisconsin. The results obtained in both 

 of these states agree with those obtained under Michigan conditions and 

 all together offer very tenable proof that the injury to potato foliage in 

 the middle western states is not ^^tipburn" due to excessive heat and 

 sunshine, but is "hopperburn" caused by the potato leafhopper, Em- 

 poasca mali. 



Fig. 11. A remodeled traction type sprayer. 



While better than no sprayer, this type does not maintain sufficient pressure for 

 best control of hopperburn. 



