Behavior and Control of the Grape Mealybug on Pear

Abstract

The grape mealybug, Pseudococcus maritimus (Ehrhorn), is a chronic pest of pears which became a serious problem in several pear-growing areas in 1960 and 1961. Biology studies showed that the over wintering crawlers invaded and fed upon tissue in the fruit buds from the period of bud crack until petal fall. After this time, the mealy bugs migrated to the base of sucker shoots where rough bark provided protection. Because the insects are exposed within the open fruit buds, a spray timed at the cluster bud stage of tree development is preferred. Spray trials were conducted at the dormant, cluster bud, and petal fall periods on Bartlett pears. The results indicated that parathion or Diazinon® ( O,O -diethyl O -(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate) at a dosage of 2 pounds 25% per 100 gallons or a 1 pound dosage combined with either oil or a welting agent provided the best control. Dormant oil combined with lime sulfur, polysulfide, dinitrophenol, and dimethoate did not provide acceptable control. Zectran® (4-dimethylamino- 3,5 -xylyl methylcarbamate) and Dilan (a mixture of I part of 1,1-bis( p -chlorophenyl)-2-nitropropane (Prolan) and 2 parts of 1,1-bis( p -chlorophenyl)-2-nitrobutane (Bulan)) reduced meal. bugs. but were less effective than either parathion or Diazinon.