As you can see on the picture, the roots have bumps on them and are swollen. You can click on the picture to enlarge and see the details. These roots are tomato roots damaged by nematodes. Nematodes are a problem in Florida and they usually attack nightshade family of plants, such as tomatoes, peppers and eggplant.
One school of thought to remedy nematode problem is to "solarize" your soil, which involves covering the soil with plastic and let it sit in the heat of the summer, thus raising soil temperature to some 130 degrees and killing nematodes. I do not like this method because in addition to killing nematodes it will also kill beneficial insects and organisms that are much welcome in the garden, especially earth worms. If I were a fisherman, or fisherwoman, I could dig at least a shovel full of worms from my garden every day. And I like that! Earth worms make best manure because they eat and excrete plant matter, as well as dig furrows in the garden and aerate the soil.
So my answer to nematodes or other damaging pests is crop rotation. In a small garden crop rotation might be a challenging task. I have devised an "easy" plan to accomplish this.
First, divide vegetables that you plan to grow in three groups: Nightshade (tomatoes, peppers, eggplant and regular potatoes), Cover Crop (cowpeas, snap peas, beans) and Other (carrots, lettuce, broccoli, cabbage, okra, amaranth, radish, etc).
Second, draw your garden on a piece of paper and divide it in three parts, that's your master plan. I actually divide each bed into three parts, which takes care of dividing the whole garden. Then rotate your crop:
| Fall | Nightshade | Cover Crop | Other |
| Winter | Other | Other | Cover Crop |
| Spring | Cover Crop | Nightshade | Other |
| Summer | Other | Cover Crop | Cover Crop |
| Fall | Cover Crop | Other | Nightshade |
| Winter | Other | Cover Crop | Other |
| Spring | Nightshade | Other | Cover Crop |
| Summer | Cover Crop | Cover Crop | Other |
Pictured above is a 2 year rotation plan. As you can see, Nightshade family is not planted in the same space for a year and a half, which I think is a pretty reasonable time.
Since Nightshade family is most successible to pest damage, it is important to move it around; the rest of the vegetables, Other and Cover Crop are interchangeable: you can create your own rotation schedule with them freely depending on your vegetable needs.
In addition to crop rotation I always tuck flowers, especially Marigolds, and herbs in "Nightshade" and "Other" parts of the garden to provide bio-diversity and beauty to the garden, as well as attract beneficial insects.
Wow. I just started a home garden in central florida and this was EXACTLY what I was looking for - one question: when you're first starting - can you start with nightshades, or do you have to grow two seasons of cover crops before planting there?
ReplyDeleteAlso - is there a way to know if you have nematodes in your soil?
You can start with nightshades, just fertilize the soil. In a brand new garden just add cow manure from the store, and if the soil is dense, dig in some leaves from under the trees.
ReplyDeleteYou will know that you have nematodes after the fact. When you pull the plant you would see roots severely damaged. No way to know in advance, well possibly if you have soil analyzed, but I would not go that far. Just rotate the crops and you will be OK.
Thank you for publishing your recommendations for crop rotation in our gardens. Can you be more specific and list plants specifically in each of the categories? For example, we recently pulled up our summer squash to find the roots were clearly infested with sting or root-knot nematodes. So, assuming squash falls under the "other" category, what would be good choices to plant now for the next crop? I imagine cover crops, but which ones are suitable for planting in June/July. Snap peas, peanuts, and beans seem like the obvious choice.
ReplyDeleteAlso, looking at UF research on nematodes, Telone (1, 3-dichloropropene) seems to be the best product for control of sting/root-knot nematodes, but where can this be purchased?
Also, I wanted to mention that my previous crop before the squash was sweet potatoes, which actually did not do very well, but we did not notice any issues with nematodes at that time (but we were not looking for them either). After pulling the sweet potatoes and aerating the soil, I put a lot of very well cured horse manure compost. I thought the compost would help, but apparently it made things worse.
ReplyDeleteJim, right now is a perfect time either to solarize the soil (cover with clear plastic and keep on for three to four weeks), or plant cowpeas and Marigolds. Also, I noticed, the less you disturb the soil, such as digging, the better. I now don't even pull the plants. I simply cut the plant as close to the base as possible and just let the root rot.
ReplyDeleteAs for sweet potatoes, they like very light soil. They grow perfectly in compost piles or even in wood chips.
ReplyDeleteThanks for your advice. I didn't rotate my tomatoes one year because I changed my crop rotationcrop rotation plans and ended up with a bad case of blight. Won't do that again. (Plus I read not to compost store-bought tomatoes because they can spread blight. So I stopped doing that, just in case.) Generally, I rotate my raised beds like this (but I still tweak things now and then, and add other minor crops to these main ones): Year 1 is cukes and cabbage family. Year 2 is tomatoes/peppers. Year 3 is legumes. Year 4 is zucchini. Year 5 is tomatoes/peppers. Year 6 is garlic/onions. Year 7 is compost and letting the bed rest (a biblical concept). I try to keep two years between planting plants in same spot. It's still a work in progress. But it's fun work.