Nectarine Pox

Nectarine pox is a disorder that reduces packout of commercially grown nectarines. It was first identified and studied in West Virginia and has since been found in nearly all areas of the Cumberland-Shenandoah fruit-growing regions.

The disorder is characterized by superficial warty or raised outgrowths that in some years may occur on 20 to 80 percent of the fruit in an orchard block. Symptoms are usually observed within 40 days after full bloom as pale white or light-colored circular spots or raised areas. In some instances spots may cluster together, forming a large irregular rough raised area. As fruit develops and enlarges, the spots expand and raise higher than surrounding tissue. Raised areas are usually redder than the surrounding tissue. Slicing through the raised areas shows normal fruit tissue below.

Research results suggest that the disorder is accentuated in overly vigorous trees and in trees with high levels of fruit nitrogen and potassium and low levels of fruit calcium. Suggested control measures include the use of cultural practices that reduce excessive shoot growth. Such practices are proper fertilization, good pruning, and regular leaf analysis to monitor nutrient levels. Root pruning has also been shown to help reduce the incidence of nectarine pox, probably owing to the effects of reducing shoot growth. Avoid excessive nitrogen applications and excessive dormant pruning. Since this disorder appears to have the same causes, growers may want to try, on an experimental basis, the control strategies used for corking in apples.