. Biennial report of the Oregon State Board of Horticulture ... Horticulture -- Oregon; Fruit-culture -- Oregon; Gardening -- Oregon. Fig. 3—The Hop Plant-louse, third generation on plum-the generation which flies to the hop—enlarged ; head below at right—still more enlarged. By the time this generation has matured, which involves but a few days, varying according to the temperature, belated winged individuals, which are the true males (Fig. 5), fly in from the hop fields. These fertilize the wingless true females upon the plum leaves and these soon thereafter lay the winter-eggs. Thus there i
. Biennial report of the Oregon State Board of Horticulture ... Horticulture -- Oregon; Fruit-culture -- Oregon; Gardening -- Oregon. Fig. 3—The Hop Plant-louse, third generation on plum-the generation which flies to the hop—enlarged ; head below at right—still more enlarged. By the time this generation has matured, which involves but a few days, varying according to the temperature, belated winged individuals, which are the true males (Fig. 5), fly in from the hop fields. These fertilize the wingless true females upon the plum leaves and these soon thereafter lay the winter-eggs. Thus there is but one generation of sexed individuals produced and this at the close of the life-round—the females wingless on plum trees ; the males winged on hops. All intervening generations are composed of virgin females only (parthenogenetic). This is the invariable round of the insect's life. REMEDIES. From the life-history just given three important facts are obtained : (1) It will pay to make a pre- ventive application of some one of the mixtures mentioned further on, with apparatus there de- scribed, to all plum trees in the neighborhood of hop yards, either (a) in the spring before the appearance of the first winged generation and its consequent migration to hop, or (h) in the fall after hop- picking and after the lice have once more returned to the plum and are making their preparations for the laying of winter eggs. The latter time will, perhaps, be preferable, for the reason that in the fall the plum trees will be less susceptible to the action of the washes and a stronger solution. Fig. 4 —The Hop Plant- louse, true, sexual female — Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Oregon. Board of Horticulture; Oregon State Horticultural Society; Northwest Fruit Growers' Association. P
Size: 1266px × 1973px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcollectionbiodiversity, bookcollectionnybotanicalgarden
