Fusarium wilt is a disease common to the southeastern United States. It is caused by the fungus Fusarium oxysporum and affects numerous garden plants, including vegetables, small fruits, and flowers. The most susceptible host species include:
- Sweet potatoes.
The disease is spread through infected soil. Once it is introduced, it is nearly impossible to get rid of, as it can survive for years without a host.
Fusarium wilt usually makes its appearance during a spell of hot, dry weather, meaning midsummer in most of Kansas. The fungi enter plants through roots, and then block up the vascular tissue of their hosts.
- Brown asparagus spears.
- Spotted runners and leaf stems.
- Yellow leaves with black spots.
- Crown rot.
- Discoloration of vascular tissue in root crops.
- Fruit drop and decay.
- Rapid death in hot weather.
Fusarium wilt in annual plants, such as vegetables, is not treatable. The affected plants should be removed and destroyed immediately. Next, solarize the soil by covering it with clear plastic.
You may want to make an attempt to save perennial plants such as asparagus. In this case, prune out all diseased plant tissue, sterilizing your pruning shears in bleach solution between each cut. If fusarium wilt appears again in following years, your best bet is probably to destroy the plants and start over.
A little caution about soil sanitation goes a long way:
- Introduce only healthy plants of fusarium-resistant varieties; better yet, raise your own plants from seed.
- Do not garden in soil with a past history of fusarium wilt.
- Use crop rotations in your garden.
- Regularly clean garden tools, plant stakes, and other materials that come into contact with soil.
Also, keeping your plants healthy will increase their resistance to diseases of all types. Pay attention to water and nutrition needs, and be sure to control weeds and insect pests.