Winter Orchard Practices

November: Walk the orchard and look for infestations of white peach scale and San Jose scale. Since the trees are defoliating and the bark is more visible than during the spring and summer, white peach scale can be easily seen. Look carefully at the crotch angles and areas where buds have formed for females of white peach scale. In the wrinkles, both below the buds and where shoots or limbs emerge off larger scaffolds or branches, females will be most prevalent. In early November, female populations are starting to increase but large colonies of males have not formed yet in the Gainesville area. However, further south these colonies may already be present.

By late November, the presence of white peach scale can be easily detected by the fluff of the male colonies. These colonies are easily seen as snowy white elongated sections on one-inch or larger diameter limbs. Spot spraying with 1-3% Superior-2 dormant oil as recommended in UF/IFAS Fact Sheet, ENY-804, Insect Management in Peaches (http://edis.ifas.ufl.edu/BODY_IG075) oil will kill males, females, and crawlers of this scale. Avoid spraying the tender terminals or young leaves as the oil will burn this tissue. If the orchard has a history of scale and infestations are heavy now, then pruning the trees and applying the first of two oil sprays in December will be necessary.

Scouting for San Jose scale is harder because detection is not as easy as for white peach scale. San Jose scale is more prevalent on plums than peaches and is not as common as white peach scale. However, once it is established, damage can be severe. The scale appears as grayish waxy raised dots on the bark. Populations can be confirmed by slicing a small sliver of bark off at the cambial layer and observing purplish dots on the limb where the female has been feeding. Control measures are the same as for white peach scale.

December: Although pruning is usually thought of as a January activity, it is a good idea to start early and get some of the work done before the holidays. If there are scale problems in the orchard, then pruning must be completed before applying the December oil spray. Spray applications are best done when temperatures are from 60-70°F as the oil flows best at this temperature. Oil should not be applied when night temperatures will drop below 30°F for the subsequent 3 days. (J. Williamson/P. Miller)