ERIOPHYID MITES found in grape buds were first associated with certain abnormal symptoms of grapevines in 1938 by H. A. Weinland, then Farm Advisor for Sonoma County. They were later identified (Keifer, 1944) as a physiologically distinct strain of the common erineum mite, Eriophyes vitis (Pgst.).Anatomically identical, the two strains can be distinguished by their habitat on the vine and by the damage they cause. The bud-mite strain lives only in the buds, causes no erinea on the leaves, and produces deformities on grapevines not attributed to the leaf-inhabiting erineum mite. Damage to California vineyards by the erineum strain has been negligible, but the injury caused by the bud-mite strain can result in loss of crop and, possibly, the eventual death of the vines.A similar case is reported by Lamiman (1939) in the biology of the pear leaf blister mite. The pear bud mite is also identified as being the same mor phologically as the leaf-inhabiting pear leaf blister mite, but the bud mite does not form leaf blisters and confines itself entirely to the buds.Distribution. In California the grape bud mite has been found in Sonoma,
Problems of evaluating chemical control of San Jose scale are discussed on the basis of experiments in deciduous fruit orchards. Methods are described for sampling and counting scales for mor tality determinations and for measuring the resurgence of a popu lation after it has been reduced. The methods used did not show conclusively any differences in performance among a number of the more effective insecticides used with oil in dormant or spring sprays. The methods were ade quate to show that scale populations on peach trees do not increase as much in the growing season when trees are sprayed in May as when they are sprayed during fall or winter. On lightly infested peach trees sprayed in the dormant season or in May, the survivor progenies increased faster during the growing season than they did on trees that were more heavily infested when sprayed. The effects of variation in initial pest density on control were mini mized by using pretreatment counts with the annual twig-count method. This method measured degree of population resurgence after treatment but did not show how numbers of survivors, effects of natural enemies, and other environmental factors acted together to produce the results observed. Sequences of samples for mortality determinations indicated trends in population change after treat ment.
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