Question of the Week: November 21, 2019

Tomato root system is impacted by root knot nematodes. Photo by M. and J. M.

“As we took out our gardens we noticed swellings on the roots of our tomatoes and cucumbers. The garden was not productive this year. What might the problem be?”

These photos were actually posted to my Facebook page a couple of weeks ago. I suggested to the Facebook friends that they send samples to the Texas Plant Clinic to have the roots and their soils tested for nematodes, which they did. Nematodes were detected, but the readers felt that subsequent plants had worse apparent symptoms when they pulled them out after the freeze.

Cucumber root system was similarly impacted.
Photo by M. and J. M.

Nematodes are microscopic, soil-borne worms that sting plants’ roots and withdraw nutrients and moisture from the roots. Most commonly galls are formed in the process, and that’s what you can see has happened here. Nematode-infested plants are stunted and usually struggle to produce new growth, flowers and fruit.

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Control of nematodes is difficult at best. There is considerable information about them online, but much of it is of questionable merit. I strongly suggest you stay with guidelines given by state university plant pathologists and horticulturists. To get these links I searched for the key word phrase “University plant pathology nematode control.” Here are three of the most useful links.

This write-up from North Carolina State University suggests crop rotation, staying with resistant varieties, planting in cooler weather and maybe even moving the planting sites to a new garden space. This is a 2018 (recent) publication and I found it to be very good.

• California and its huge plant industry has a very thorough publication:

• And finally, this is an extremely comprehensive explanation of nematodes from the University of Florida. Nematodes love sandy soil, so they love Florida. This gives tons of information if you really want to know just about everything.

TAMU Nematode Testing and Fees
Texas A&M has a great deal of good information regarding nematodes on various TAMU department websites. Specifically to submit samples for testing, however, here is a link to the page with instructions and fees.

Posted by Neil Sperry
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