TUBER CROP PROJECTS 217 



2. When should potatoes be sprayed? 



3. What kind of sprayer would you select ? 



4. How should the spray material be applied ? 



6. What do you recommend for combating diseases of potatoes ? 

 Insect enemies ? 



6. How should the spray material be prepared ? 



The potato flea beetle, which is also common on tomato plants, 

 retards the growth of potato plants because it feeds on the 

 first unfolding leaves, and especially on earlier varieties where 

 it causes extensive reductions in the number of tubers. 



The Colorado potato beetle, originally feeding on the Buffalo 

 Bur, Solarium rostratum, west of the Missouri River, has spread 

 across the country more rapidly than any other pest of late years. 

 The beetle passes the winter as an adult under rubbish or in the 

 soil. Just about the time early planted potatoes appear, the beetles 

 emerge, feed on the tender foliage, and then lay their orange yellow 

 eggs on the under side of the leaves. The dark red black-headed 

 grubs hatch in four to nine days, and when mature enter the soil 

 to pupate. The adults emerge about five or ten days later. After 

 feeding for a short time they may go into the ground for a resting 

 period, or lay eggs for a second generation. Normally all stages 

 may be found throughout the summer. Arsenical poisons are 

 effective control measures, especially if applied as soon as the 

 grubs hatch. Although a slower poison than other compounds, 

 arsenate of lead is being more generally used, because it seldom 

 injures the foliage. Four or five pounds of lead arsenate "are 

 used to each acre to be sprayed. One hundred gallons of spray 

 will be sufficient to cover an acre of potatoes. 



