2023 Fusarium Wilt on Seedless Watermelon Experiment – Week 3 Observations

From Clemson Plant Pathologist Tony Keinath

This year’s Fusarium wilt experiment includes three seedless cultivars, three fungicide treatments applied via drip irrigation, and grafting. This experiment is supported in part by a USDA SCRI grant. There also is a side experiment with SP-7 pollenizers grafted onto ‘Carolina Strongback’ rootstock and non-grafted SP-7 supported in part by Tri-Hishtil. Transplants were set on April 5 in a field infested with Fusarium races 1 and 2.

At the first rating, three weeks after transplanting, transplants looked vigorous. Plants in a few plots were starting to run, which is a bit early. Normally I see plants starting to run four weeks after transplanting. Only 1 of 480 plants showed symptoms of Fusarium wilt.

Symptoms of Fusarium wilt on this plant include stunting, yellowing, leaf curling, and death of lower leaves.

Pythium stem and root rot also was low this year. Only three watermelon plants showed symptoms so far. No Pythium symptoms were seen on SP-7 pollenizers yet

The greasy brown lesion on the stem at the soil line is a typical symptom of Pythium stem and root rot on cucurbits.

Watermelon plants also showed symptoms of ozone injury on the oldest leaves as seen throughout the lower half of South Carolina in mid-April. As with other affected crops, these watermelons are growing fine with no aftereffects.

Symptoms of suspected ozone damage on the three oldest leaves on a young watermelon plant transplanted on April 5, 2023.

More updates to come as the experiment progresses.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: