In this case it is usually better to harvest the crop and monitor leafhopper populations for possible insecticide treatment of the regrowth. Potato leafhopper damage in mid-summer is sometimes mistaken for drought damage since the stunting and yellowing of the plant can resemble drought damage. In fact because of the plugging of the vascular system, damage by leafhoppers is more severe in dry years when the plant is under moisture stress. Loss in quality . As mentioned earlier the leafhopper injects a toxin as it feeds, which causes a chemical change within the plant.
Plants produce less protein and more sugars, resulting in a major reduction in feed value.
Protein is the most serious loss in alfalfa due to potato leafhopper feeding. Five percent loss in protein occurred when the leafhopper population increased from 5 to 50 leafhoppers per sweep, the latter being a common population level attained in Indiana when controls have not been applied. Loss in yield. Loss in dry matter yield occurs, but is usually less significant than quality loss, according to Wilson. Loss in plant vigor .