POTATO SPRAYING AND DUSTING. 



15 



Cost of Spraying and Dusting. 



The expense of applying insecticides varies with the material and the type of 

 machine employed in spraying or dusting, as the case might be. Even if we consider 

 Bordeaux mixture alone, it would not be possible to state a cost which would hold 

 good for all localities and for the various stages in the growth of the same crop within 

 the same locality, because the degree of luxuriance of the fohage influences the 

 amount of material necessary to cover the plants satisfactorily. Jones* states the 

 average cost of spraying one acre of potatoes three times, using 200-500 gallons 

 at one cent per gallon, as £1 9s. id. ($7). 



Control of the Potato Flea-Beetie. 



In New Jersey, as well as in most of the other potato-growing States, this diminutive 

 insect has long been recognised as a serious pest, detrimental not only because of 

 the damage committed directly by its fenestrating the leaves, but also indirectly, 

 in that the injuries serve as a means of incursion for early blight. When one considers 

 that in cases of severe attack, anything from 10 per cent, to 20 per cent, of the leaf 

 surface on a single hill might be destroyed, one can form a somewhat rough idea of 

 the adverse effect on the yield which this reduction in the assimilating power of the 

 leaves causes. 



Fig. 2. Potato Flea-Beetle (Epitrix ciiciimeris). 

 (After Chittenden.) 



Probably on account of its insignificant size, very little attention has been paid 

 to the life-history or means of control of the flea-beetle, and one author seems to 

 accept without test what another may have previously experienced. Indeed, it is 

 only quite recently that the true facts of its larval behaviour have been ascertained, 

 and whereas it was generally accepted by Harrisf , KileyJ, and Packard§ that the 

 larva was a leaf-miner like others of its congeners, such as Haltica nemorum, the 

 flea-beetle of turnips and other Cruciferae in England, it is only within recent 

 years that it has been found to feed on the tubers and roots of the potato, as well as 



* Jones, L. R. — Sixth Ann. Kept. Vermont Agr. Exper. Sta., 1892. 

 t Harris, T. W. — Insects Injurious to Vegetation, 1862, p. 127. 

 t Riley, E. V.— Missouri Rept. State Ent. I, 1869, p. 101. 

 § Packard, A. S. — N. S. Geol. and Geog. Survey of Colorado and Adjacent 

 Territory, 1875, p. 732. 



