DEAR GARDEN COACH: My tomatoes plants did well the first two months of their life and then went downhill fast. I fertilized, mulched and watered with care, all to no avail. I pulled them up and noticed they had the deadly nematodes. How do you possibly get rid of these nasty critters?
Roger Evans
Bay Area
Dear Roger: Tomato season is waning, so the bright side is there is always next year to plan for growing a good crop of tomatoes.
You say you had nematodes, but I am not sure how you diagnosed this, so I would like to give you some information that will hopefully confirm this is exactly what happened to your plants. I also recommend collecting a soil sample and having it tested to positively identify if this is the problem.
California is home to different species of nematodes, and they can attack a large number of garden plants including fruit trees and ornamentals; however, because nematodes are microscopic, you most likely did not see them but perhaps saw the damage caused to the roots of your tomatoes.
Like most pests in the garden, nematodes reproduce rapidly. There are six stages in the life cycle — egg stage, four different juvenile stages and then the adult stage. This entire process takes only 21 to 28 days, and as you might imagine, they are quick to reproduce.
The eggs are laid in the soil and can survive for many seasons. They become active once the soil temperature warms above 65 degrees. While in the juvenile stages, they begin to eat the roots.
Once the roots are damaged, the plants are unable to efficiently get water and fertilizer, which is why your plants began to decline. There is no way of knowing your soil has nematodes until the plants begin to decline.
You are probably wondering how you got nematodes in your soil. There are a variety of conditions, including purchasing plants that had them in their soil. You can also spread nematodes to other areas in your garden with shovels and even your shoes. Sanitizing your tools is very important, and be careful where you walk.
Water is another source of travel for them, so there is yet another reason to install a drip system in your garden.
Soil health is the basis for the health of a garden. According to UC Davis Integrated Pest Management publications, nematodes are more likely to damage plants that are water stressed. Experts recommend enriching your soil with compost, manure or other organic material to increase the water-nutrient holding capacity.
Lastly, you need to know how to get rid of them. Purchasing resistant varieties of tomatoes is essential. You can determine if they are resistant varieties by looking for an “N” on the plant label or seed package.
Crop rotation is always important for a number of reasons. You also can try solarizing your soil when the weather is warm. To do this, remove the plants, turn and moisten the soil, and then cover with clear plastic for 6 to 8 weeks.
UC Davis also recommends planting different types of marigolds in the garden to deter nematodes. As always, the IPM publications’ information is priceless. To find out more, go to the UC Davis site (www.ipm.ucdavis.edu) and search for nematodes.
Send your gardening questions to thegardencoachBANG@gmail.com.
