I deal with a fair share of pests in the garden, a valiant battle against rodents, worms and the like. I’d come to a place where I felt that my understanding of these foes and subsequent method of dealing with them was becoming like second nature. Now all of that is ABOVE ground. This week I have been humbled, to put it mildly, by the forces of mother nature that I essentially can never fully control. I’ll just get to the point. Root Knot Nematodes.
Brandywine tomato beginning the process of dying back in early August, just after it started ripening it’s first tomatoes.
I know that every season differs and crops can alter from year to year depending on the conditions and weather. But this year things have been WAAAAY different than last. My indeterminate (produces long season yields) tomatoes produced one crop and then died. ALL of my pumpkins grew with vigor and then all baby pumpkins yellowed and fell off (and the leaves). My green bean plants yellowed already and stopped producing. The cantaloupe vines suddenly stopped growing. We’re not even at the end of August! It’s been a sad, sad state. 99% of all vegetables are susceptible to root knot nematodes. Total bummer.
Just a partial sample from one of the tomatoes. Imagine this times 100 and that’s what I saw when I began pulling up my dying veggies.
When I pulled up some of my plants, I noticed round, nodule-like growths all over the root systems of these poor veggies. Not good, I thought. Not at all. The internet ushered in the bad news. Root knot nematodes are microscopic, eel-like roundworms that live and feed around plant roots. The knots that they form on the roots effects the water and nutrient conducting abilities of the roots, causing plants to grow more slowly and weaker, dying off quickly with smaller crops of edibles. Management is difficult. Of course.
The best site I’ve found in my research on identification and management is through UC Davis. Go if you have these pests in your garden!
Today I covered the effected area with thin, clear plastic sheeting that will remain there for 6 weeks, aka solarization. Yup. There goes my fall plantings for half of my plots. The idea is that you heat the upper two feet of soil in the hottest months of the year under this sheeting, which in turn kills the nematodes and also weed seeds (an added bonus). It’s not a guarantee, but it’s the best organic alternative according to multiple reliable sources.
My newly solarized bed. It was relatively easy to install. I have found evidence of nematodes in my other main bed as well, but nothing near the concentration of this bed.
** Make sure you bury the perimeter of the plastic in a trench under the dirt. Deeply water the level area before covering, as this will help heat the soil. The key is to pull the sheeting taught so that it’s as close to the dirt as possible to maximize heating. I purchased my plastic at a home improvement store in the paint section. 1 mil thickness is best, as it allows maximum heat without tearing or blowing away.
I will also plant French marigolds among the future veggies, which emits a deadly oil for the little buggers. I could go on and on about this topic, but instead head on over to the above link and do a little reading if you’ve got root knot nematodes like I do. Wish me luck!
Bountiful Backyard 
Thank you for the helpful information! I enjoy your posts and pictures a lot.
You’re quite welcome! Thanks for the positive feedback. 🙂
I have read that mustard planted as a cover crop works for nematodes and fungal diseases also. I am going to try it.
Last year, when I lost all of my Brandywines, I blamed it on blight. I never even thought about nematodes. Now, with nematodes ruining most of my carrot crop, you have me wondering if that was what happened with the tomatoes.
Those darned nematodes have effected quite a variety of things in my garden. I read that they don’t like most herbs, corn and garlic. There are some nematode resistant tomatoes out there that I may try next year if I still have a problem. I had to pull my largest Cherokee Purple tomato the other day because it wasn’t ripening it’s fruit properly and it was practically dead. That had the most root knots on it out of anything else I pulled.
Today I saw this, “Most nematode species are active during warm summer months and can’t penetrate roots at soil temperatures below 64°F. Therefore, you can reduce nematode injury to fall-planted crops such as carrots, lettuce, spinach, and peas by waiting until soil temperatures have dropped below 64°F.” So, it seems that you CAN grow carrots in the cooler months!
I have been getting my garden ready for fall and have been pulling out all of the tomato plants. I found one plant that had really bad nematode damage. One of the roots was bigger than my thumb and all knotted up. Ugh!!!!! Now I really do have to plant mustard!
Interestingly, the other tomato plants in the same bed didn’t have any damage.
Peggi-Wow! Bigger than your thumb!?? The other day I read that it can take 3-4 months for nematodes to move even a foot in the garden. So, it stands to reason that one tomato could be infested and the others are ok at this point.
Oh no! I have never heard of those before. What horrible luck. I feel your pain tho – I’ve had entire crops go to blight in the past. There’s nothing more heartbreaking than pitching out an entire summer’s worth of hard work. So sorry, but thanks for the info!
Supposedly these nematodes are most prevalent in sandy soils of the south east and south west. No matter the cause, it is tough throwing away our edibles. I agree!
I have sandy soil, and it was my early carrots that were infected. Now, in these hot (90-100+) days I’m getting beautiful carrots with smooth roots! Go figure!
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I would love to use your image of Brandywine tomato showing early dying from root knot for a project that I’m doing for the plant pathologists’ professional society…which will benefit home gardeners. Would you please contact me by email so that we could discuss this possibility? Many thanks! mld9@cornell.edu