What is X Disease?
Despite the name, peach tree X disease, also known as X disease of stone fruits, isn’t limited to peaches, as it can also affect nectarines and wild chokecherries, and has done extensive damage to California’s cherry crops. Although X disease of stone fruits was initially believed to be the result of a virus, experts have now determined peach tree X disease is caused by a tiny parasitic organism (X disease phytoplasma).
Symptoms of Peach Tree X Disease
Initially, X disease in peaches is indicated by discoloration of infected leaves on a few branches. In time, however, the disease spreads and the leaves gradually turn brick red, eventually falling from the tree but leaving a few leaves at branch tips. Peaches on infected branches, which ripen early and contain no seeds, fall from the tree prematurely.
Treating X Disease of Peach Trees
Leafhoppers should be controlled because they carry the parasite that causes X disease of peach trees. Encourage beneficial insects in your orchard to reduce the need for toxic chemicals. Keep the area clean, especially after harvest, as debris provides overwintering sites for the pests. Apply dormant oil during the peach tree’s dormant period to kill leafhoppers that have overwintered. Treat peach trees with appropriate chemical insecticides if more benign treatments aren’t effective. Additionally, treat other plants growing nearby. Remove chokecherry bushes and other host plants. Learn to identify wild chokecherries growing near your peach trees, as chokecherries frequently carry the parasite. Small clumps aren’t difficult to pull, but you may need to use an herbicide brushkiller, or even a bulldozer, to kill plants in large areas. Monitor their return closely, and kill seedlings or sprouts. Other host plants that may carry X disease phytoplasma and should be removed include dandelions and all types of clovers. Similarly, curly dock should be eliminated, as it a common host plant for leafhoppers. Additionally, infected trees should be removed, but only after spraying the trees for leafhoppers. Treat stumps to prevent them from sprouting.
