Cankers oozing amber-colored gum and swelling are some indications of diseased limbs on peach trees. Other symptoms include scale infestations and gumming on the limbs.
Cankers can form on the buds, limbs and trunks of peach trees. The growth of bacteria on these parts form cankers that spread in an upward direction and discharge amber-colored gum. Bacterial cankers are common in young peach trees and trees planted in sandy soil with poor drainage. Cankers most often appear in spring, when the temperature is low and moisture content is high. Spraying the trees with copper before the flowering season can prevent cankers from forming.
Galls or swelling on the limbs, roots and crowns of peach trees are also the result of bacteria growth. The swelling is fleshy and white in color in its initial stages and turns brown over time. The primary causes of galls are alkaline soil and poor drainage. An effective solution is to plant the peach tree in well-drained soil.
Scale insects can attack peach trees and cause white peach scale or San Jose scale. Scale insects produce a white coating on the tree that later turns black. These insects also transmit toxins when they feed on the limbs, trunks or fruit. Heavy scaling can lead to gumming, and the infected branches tend to die. Spraying trees with horticultural oils can kill the scales.