Cause Verticillium sp., a fungus, was only found twice on begonia by the OSU Plant Clinic in the late 50s and early 60s. There are few other records of this disease and is considered rare since the use of soilless media. The fungus is soilborne and survives in soil indefinitely. The fungus enters plant roots, invades the xylem system of the stem, and cuts off the water supply. Toxins are also produced, which, along with xylem occlusion, result in wilt symptoms.
Symptoms Lower leaves lose color, gradually turn yellow, and wilt. Later these symptoms may appear on upper leaves. Occasionally, affected plants die.
Cultural control
- Avoid using soil used to grow solanaceous plants such as potato, tomato, peppers, or eggplants.
- Use soilless planting media. If field soil is a component of the growing medium, treat it with steam (122°F for 30 min.) or chemical fumigants.
- Avoid reusing pots or trays from a previous crop for propagation. If pots must be reused then wash off all debris and soak in a sanitizing solution or treat with aerated steam for 30 min.
Reference Chase, A.R., Daughtrey, M.L., and Cloyd, R.A. 2018. Compendium of Bedding Plant Diseases and Pests. St. Paul, MN: APS Press.