Black root rot of Watermelon – Vegetable Crops Hotline

Black root rot of Watermelon

Wilt of watermelon due to black root rot

Figure 1. The symptoms of wilt in this watermelon could be from many causes. Black root rot can cause wilt such as seen here.

Black root rot of watermelon on hypocotyl

Figure 2. Dark areas on the hypocotyl of this watermelon seedling is caused by chlamydospores (resting spores) of the fungus that causes black root rot (Thielaviopsis basicola).

Black root rot symptoms on base of watermelon hypocotyl

Figure 3. Dark discoloration and poor root system are as a result of black root rot of watermelon.

Chlamydospores of Thielaviopsis basicola.

Figure 4. The structures seen here in root tissue are specialized spores known as chlamydospores. These spores are resilient resting spores that help the fungus survive for long periods in the soil. In addition, these spores impart a dark appearance to tissue.

Watermelon with black root rot in transplant trays.

Figure 5. The watermelon seedlings in this transplant tray are declining due to black root rot.

Black root rot on watermelon hypocotyl

Figure 6. The watermelon transplants in the tray above are declining due black root rot which can be seen causing dark symptoms here on the hypocotyl.

3 diseases on watermelon plant.

Figure 7. This watermelon is affected by gummy stem blight immediately below and above the cotyledon, black root rot at the lower hypocotyl and root knot nematodes on the roots.


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