It’s fall and we are enjoying the last flush of tomatoes from our early summer plantings here at Sunshine Care, A Community of Assisted Living Homes in Poway CA. The quantity and quality never quite match those from our late winter and spring plantings, but it’s great to have tomatoes from May through November (sometimes even later if the frosts don’t nip them).

Rows of tomatoes, squash, peppers and cucumbers are being pulled and prepared for our fall/winter veggies such as broccoli, cauliflower, lettuce and cabbage. In fact, we will harvest our first broccoli of the season today in mid October.

Regarding tomatoes, here’s a common scenario people tell me every year.

“I love my heirloom tomatoes and a few years ago we had lots of big, beautiful and delicious goodies from our vines. Last year, they were still delicious but didn’t seem to harvest as many and the size was down. This year, our plants struggled and were extremely less prolific and hardly had any tomatoes. WHAT’S UP?”

The problem could very likely be due to root-knot nematodes. These plant-parasitic nematodes are from the genus Meloidogyne and exist in soils with hot climates or short winters. Over 2000 plants are susceptible to infection by root-knot nematodes. Their larvae infect plant roots and cause nasty looking galls that suck the plant of nutrients and photosynthetic ability. Young infected plants die quickly. Infected mature plants will show a reduction of yield and quality. They are a microscopic wormlike animal, too small to be seen with the unaided eye.

Root-knot nematodes are one of the most economically damaging pests of horticultural and field crops throughout the world.

Here are few things to keep in mind to try to curb the damage of root-knot nematodes on your tomatoes.

  1. Inspect the roots of all tomato plants pulled from the garden– Root-knot nematodes cause swellings and visible galls on the root system. Galls can get to be up to 1” in diameter where they merge, but usually are not much larger than ¼” in diameter. If you aren’t sure what you are seeing, Google it.
  2. Sanitation- Nematode infected plants should be removed right after the last harvest. Flip the soil to bring up plant roots to the surface. Do this a few times in the winter to let the wind and sun desiccate the nematodes and eggs. Roots left in the soil over the winter, will maintain or kick up the populations.
  3. Disinfect your tools- Every time you finish or start work in the garden, sterilize your tools. You can be the nematodes best friend by spreading it around your garden on shovels, rakes, tillers, hands, stakes etc. Prior to prepping any bed where we have worked the soil, we douse our tools with a rinse of Clorox bleach. Mix 1 part bleach with 9 parts water, soak and wait 10 minutes at least then rinse. We do this with our tomato stakes as well. If growing in containers, plastic is easier to disinfect than wooden containers, but both should be rinsed as well. 70% alcohol, either grain, rubbing or wood will work well also. Dip, let dry and that’s it.
  4. Use Nematode Resistant Varieties. Unfortunately, I know of no true heirloom variety that has resistance to nematodes. Don’t let this stop you from growing that unique, weird -looking delicious tomato that you must have and cherish- but also include some standard varieties that do have “N”, nematode resistance. We grow Celebrity, BHN 1021 and Skyway varieties to give us tons of delicious red tomatoes from determinant plants. Big Beef, Better Boy and Lemon Boy are indeterminant plants that also have “N”, nematode resistance. There are even cherry varieties such as Nova and Granadero that have resistance. All these varieties can be obtained from Johnny’s Selected Seeds. It has been my experience that even though a variety may have nematode resistance, you will still see the problem at the end of the summertime, in areas of your garden that you know have the problem, but you will at least get a crop of tomatoes.
  5. Reduce Plant Stress- Deep watering on a less frequent interval will help develop a larger stronger root system to help fend off nematode damage. The use of organic soil amendments prior to planting, can improve plant vigor to produce healthier plants. Nematodes multiply faster in sandy soils than in clay soils. Organic material will help fortify your soils to make the roots happier.
  6. Organic Control- There are no proven products that I can recommend at this point for controlling or suppressing damage due to nematodes. We are working with beneficial nematodes and other organic products such as Monterrey Nematode Control, that contains saponin, to hopefully control nematode damage to some degree. I’ll keep you posted!
  7. Let Gardens Go Fallow and/or Rotate Crops-Rotate related vegetables in one family group with vegetables from another unrelated group. The practice of letting the garden go fallow prevents any vegetation from growing in the garden area, therefore starving the nematode population. Till the soil every two weeks to reduce weeds and expose nematodes to the sun.
  8. Soil Solarization- This is a simple effective means of control. Radiant heat from the sun acts as a biocide to everything in the soil such as nematodes, weeds, fungi and bacteria. First work your soil well, water and then cover with a clear polyethylene mulch or tarp. Do this in the heat of summer to obtain temperatures hot enough to kill off the parasites. Leave the tarp on 4-6 weeks in areas such as Southern California. There are many publications to give detailed procedures on how to be successful with the practice of solarization.

Hope I didn’t scare you and impede your desire to grow those fabulous garden tomatoes for your dining pleasure. Just be wary and check out the root system as your prepare for the next planting and keep these tips in mind. It hasn’t stopped me!

For more information on Horticulture at Sunshine Care, please check out our website and feel free to contact me Roy Wilburn, Horticulture Manager (858) 472-6059 or I welcome everyone to come tour our organic gardens, greenhouse and free monthly garden lectures.

Happy Gardening!

Categories: Horticulture

Tags: , , , , , , , ,

Leave a Reply

%d bloggers like this: