Fumigation investigations in California . INJURY RESULTING TO SCALE [NFESTED TREES. 15 to the fruit, as docs also the red scale, resulting in expense for thecleaning of fruit in- rendering it of a lower grade and, in extremecases, entirely valueless. The black scale, although a much larger insect than either the redscale or purple scale, appears to have, generally, little effect on thevitality of the tree. Trees severely infested with the black scale mayappear as healthy as neighboring trees which are clean. Branchesare seldom if ever destroyed by its attacks alone. The commercial importance o
Fumigation investigations in California . INJURY RESULTING TO SCALE [NFESTED TREES. 15 to the fruit, as docs also the red scale, resulting in expense for thecleaning of fruit in- rendering it of a lower grade and, in extremecases, entirely valueless. The black scale, although a much larger insect than either the redscale or purple scale, appears to have, generally, little effect on thevitality of the tree. Trees severely infested with the black scale mayappear as healthy as neighboring trees which are clean. Branchesare seldom if ever destroyed by its attacks alone. The commercial importance of the Mack scale arises largely fromits habit of secreting honeydew, which spreads over the leaves, fruit,. Fig. 7.—Orange tree show; branches at center partly destroyed and stripped of leaves by purplescale (Lepidosaphes beckii). (Original.) and branches, furnishing a growing medium for a black or sooty-moldfungus, resulting in a black coating throughout the tree. Thiscoating is removed from the fruit by washing, or in light attacks bybrushing. In the investigation by Mr. (1. Harold Powell0 of thecauses of decay of oranges while in transit from California, it wasshown that the decay was greater in washed than in unwashed avoid the washing of fruit ii is necessary to destroy the scale inthe orchard-. a Bui. Ii1:;. Bur. Planl Industry, U. S. Dept. of Agriculture, L0O8. 16 FUMIGATION INVESTIGATIONS IN CALIFORNIA. The black scale confines its attack mainly to the branches, vet it iscommonly found on the leaves during its earlier stages of develop-ment and sometimes matures in this situation. Seldom does itmature on the fruit. The red and purple scales infest the branches,leaves, and
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