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- Author or Editor: Franklin R. Hall x
Abstract
The physiological basis for plum (Prunus domestica L. cv. Fellenberg) fruit abscission induced by larvae of the plum curculio, Conotrachelus nenuphar (Herbst), appear to be pectinases and cellulase released into fruits by feeding larvae. About 45% more plums receiving active commercial pectinase and cellulase abscised than fruits receiving inactivated enzymes.
Abstract
Spring overtree misting using greenhouse mist nozzles was tested for effects on bloom delay, incidence of disease, European red mite populations, fruit size, maturity, fruit russeting and tree survival of ‘Golden Delicious’ apple (Malus domestica Borkh.) on Mailing 9 rootstock. Bloom delay of 9 and 8 days was observed in misted trees in 1975 and 1976, respectively, Apple scab was controlled with standard fungicide spray programs, but fireblight was severe in 1975 on misted trees. European red mite (Panonychus ulmi Koch.) egg hatch was delayed on misted trees but post treatment populations were not affected. Phytotoxicity occurred on calyx and foliar tissue in misted trees in 1975. Fruit set and yield were reduced in misted trees in both years. Fruit size in misted treatments in 1975 was reduced through late July, but was comparable at harvest. In 1976, misted fruit size was reduced. Fruit color, soluble solids and firmness tests indicated maturity was delayed by mist. Fruit russeting in spring misted treatments was reduced. Substantial tree losses occurred in misted treatments in 1975.
Apple (Malus domestica Borkh.) leaves were sprayed to runoff using a selection of pesticides, and subsequent spray retention was evaluated by weight. Timing, cultivar, leaf surface, and leaf type significantly influenced spray retention. Spray retention correlated significantly and positively with leaf hair density. The importance of these differences is considered in relation to the possible efficiency of the pesticide application process in apple orchards.