390 ANNUAL. REPORT OF THE Off. Doc. 



Terhaps the best kuowu insect which attacks the potatoes is the 

 Colorado beetle. They do not make their appearance every year, 

 but when they do corae in large numbers they must be kept under 

 subjection or serious loss will result. If hand picking is depended 

 upon it is very essential that all the old bugs be caught, as it has 

 been estimated that one female may lay as many as 1,000 eggs in 

 its lifetime, and 1,000 eggs, if not destroyed, usually means 1,000 

 young bugs. These bugs are most easily killed with poison while 

 young. 



There are a number of spraying devices for applying insecticides 

 in a liquid form. For small fields the knapsack sprayer is very con- 

 venient, but is not practicable for an extensive acreage. The 

 sprayer which covers four rows at a time, while speedy, does not do 

 as thorough work, on account of not having the spray as well di- 

 rected as the barrel pump, with two hose, under the direction of 

 two men. The grower of potatoes on a small scale can apply the 

 poison very effectively in a dry form which is preferred by many to 

 the liquid. 



Paris green is considered to be the best poison and should be 

 mixed with something that will form a paste when dampened with 

 the first deW' ; it will then adhere to the vines. If it does not adhere 

 to the vines until all are hatched a second application should be 

 made. Lime or gypsum is often used when applying arsenites in 

 a dry form, but wheat flour is more effective as it adheres to the 

 vines better. One pound of Paris green to fifteen or twenty pounds 

 of flour, is estimated by some to be sufficient for one acre, or more, 

 depending upon the size of the vines, while others advocate using 

 one pound of Paris green to 150 pounds of land plaster. It can be 

 applied by attaching a handle to a can, wdtli a perforated bottom, 

 and jarring the can with a stick, being careful to have the buds of 

 the plant covered, as the young bugs usually feed upon them after 

 h'aving the leaf upon which they w'ere hatched. 



One of the most serious fungus diseases of the potato is the blight. 

 It often makes its attack when the tubers are not more than half 

 grow^n, considerably reducing the yield. "When serioush' attacked 

 the tops die and the tubers stop growing. Some varieties are more 

 subject to blight than others, and for the practical grower the 

 safest plan is to select the varieties that are the most resistant of 

 disease. Strong, vigorous plants have more power to resist the dis- 

 ease than delicate plants have. 



A bulletin published by the Ohio Experiment Station says, that 

 growers often confuse the bacterial blight with the early bliglit, 

 and hence the difference of opinion as to the efficacy of spraying 

 with Bordeaux mixture. The bacterial blight causes the branches, 

 that are attacked to die, quickly turning black, and it is claimed that 



