How to Diagnose Verticillium Wilt in an Apple Tree in Rhode Island
- 1). Search for curling, wilting leaves that become yellow or red between the veins. Look at the ground beneath the tree for dead leaves that have fallen from the tree as a further sign of a verticillium wilt fungal problem. Look for branches that suddenly die and display only few leaves as well as striping and peeling bark on branches.
- 2). Look for similar symptoms of other common problems to narrow down your diagnosis. Search for wilting and drying of branches that occur with bacterial fire blight, typically during wet weather. Search for cankers, or areas of dying plant tissue, on branches, buds and leaves. Examine your leaves, fruit and blossoms closely for a powderlike growth. Powdery mildew, a fungal disease of apple trees, results in dying plant parts and fruits that display brown lines.
- 3). Inquire with your local county extension agent about a lab test of a sample of your apple tree to diagnose what is wrong with your tree. Follow through with the test before treating your tree for verticillium wilt.
- 4). Treat your tree according to the diagnosis while maintaining appropriate growing conditions. Maintain trees in full sun exposure and well-drained soil. Irrigate your apple tree if verticillium wilt is the problem. Apply a fertilizer high in potassium but low in nitrogen to help weaken the disease.
- 5). Remove a tree killed by verticillium wilt, pulling as much of the roots and entire plant as possible to reduce future problems as verticillium fungi are soil-borne. Avoid planting plants susceptible to verticillium wilt there for several years.
- 6). Apply an appropriate fungicide or bactericide for other problems, but do not apply a chemical fungicide for verticillium wilt as there are no curative fixes, according to the University of Illinois Extension.
