Sterilizing Soil for Tomato Bed

My Mom and Dad have had quite a bit of wilt the last 2-years plus. Tomato plants that die or look wilted something terrible. I did an internet search months ago and read about mustard as a cover crop or mustard meal. That’s about all I recall from it all.

Any general advice you may have to help resolve this issue whether organic or not is appreciated. The problem with non-organics that I came up with while searching was the difficulty to get the product is what I’m remembering and/or pricing.

Thanks a lot,


Do they rotate their tomato crop? Ideally you should leave 2 years in between plantings in the same spot. Planting in the same area builds the fusarium/verticillium wilt in the soil. Rotate with crops not in the same family as tomatoes.

Other option I know of is to solarize your soil. This takes an entire summer, but is pretty hands off after initially getting the area prepared. Then the next year, all the bad stuff should be gone from the soil.

I’m doing the mustard thing now but results aren’t in yet

Dax, did they wilt without a leaf color change? Or did the leaves change color around the edges? Turn yellow? Have black spots on them?
When the plants were pulled up, were there knots on the roots? Or what was the general condition of the roots?
May be advisable to get a soil test too, so whatever the problem, the plants don’t totally succumb to it.

My Mom is standing right next to me. They wilted she says. All the leaves started to droop. She thought oh no. Last year one plant wilted and this years plant in that spot was fine. Two plants this year in different locations she said. No black spots but yes to chlorotic looking leaves. She pulled her plants and didn’t look at the roots, unfortunately.

@ltilton did you use mustard meal? Where did you purchase it if I may ask, please?

@VSOP My parents are not going to rotate. We know about that though. They have a city lot and a raised bed just for tomatoes and that’s how it’s always been and I mean 30-years… but your advice is certainly sound. Thank you.


Those of us with limited growing areas need other stategies besides crop rotation although that is sound advice.
A sudden major plant wilt down w/o leaf color change usually means something big has disturbed the roots like moles or voles (with the former just disturbing them and the latter actually eating them). This happened to a healthy thriving pepper this past season. I pressed down around the root area and found tunnels, so I stomped the area well, covered the traumatized plant with several layers of row cover (this was end of June) and watered it well. It completely recovered and bore fruit.
If the wilt down is more gradual and occurs to a few branches with no color change, then likely there is nematode damage which will look like nodules on the otherwise fibrous roots. Often people recommend solarization but this just sends the nematodes into survival mode and they go deeper and dormant. I had a celtuce do this in the hoop house one winter, and then another next to it before I figured it out. I made a nasty soil drench balanced with some nutes and both plants fully recovered. It is best to treat when you plant otherwise it is a waste of time and materials, then note on the calendar to repeat in another 6 weeks or so.
If leaf color change to yellow occurs with the wilt down then likely a fungus is growing in the xylem/phloem of the plant (blight). Often the leaf edges will turn brown showing dehydration from the infection. This is best treated prophylactically with anti-fungals from the very beginning of the season because it is hard to remedy the blocked tubes. That is a big problem in moist warm areas and my tomatoes are a constant battle (the good news is that I hardly have to water)
If we garden in the same spot year after year we have a tendency to add too much good stuff to the soil and create an imbalance which produces weakened plants. That’s why it is good this time of year to submit a soil sample for testing if it hasn’t been done for a while.

About mustard meal - I am not sure if it possible to buy it in enough quantity in regular stores, but it is traditionally sold in Russian stores in US (Not sure though if you have one near by). This is how 400g pack looks like (you can show the picture in the store, they will help you to find it):

To sterilize the soil, you need to keep it vacant in the hottest months of the year(at least two). Vacant means no weeds as well. Water it well, then cover with clear greenhouse(UV resistant) plastic and keep like that for two weeks. In two weeks, remove plastic, turn soil , water and cover with plastic again. Repeat this procedure every two weeks. You can combine it with mustard meal application. Rotation of you night shade family plants(tomatoes, peppers, eggplants) with any other greens/vegetables even every year helps.(Two is better, three and four is a luxury!) Also pay attention to where you get your seeds and what they are resistant for. Now there are a lot of great tasting hybrids that are much less troubles to grow. There is nothing bad about hybrids - they are not GMO (people often mix them together). Good luck!

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I sowed mustard seed in the early fall, as a cover crop

My Mom has gardened all her life. She has weed free beds year-round and she’s the type to pull weeds at McDonalds on her way in or her way out. And, she taught me that watering is what makes a good gardener.

Her thought is that pelleted organic fertilizer that she used the previous two years burned her plants. I can’t tell you if it is chicken or turkey or something else, but it seems to me it was turkey…

What we don’t understand is it’s only affecting one in six or two in six plants. She went so far in a positive manner as to replace the soil for an unhealthy plant I’m going to say mid growing season with a couple bags of topsoil - digging out a wide and fairly deep hole. It did remedy itself.

I’ve too thought about the seeds we have been using, but this all may be as simple as fertilizer. I save the seeds and have been growing my folks plants year after year. I wondered if I was transferring the problem yearly thru those seeds.

I need to read to her what you all have written and get back later this afternoon or this evening.

I’ll say this too, this change in fertilizer was when the trouble began. Previously we’ve always gone and gathered buckets of horse manure. On average that would be about every other year but sometimes it’s been annual.

We grow: Beefsteak mainly and couple plants each year of Hillbilly which is a big beefsteak type.

Thanks so much for your time. It’s appreciated.


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I want to thank you all again.

My Mother truly believes my Father put too much fertilizer in that bed. She said after asking him that he put a lot in there. She blames it on him as how the old story goes.

Appreciate your knowledge. It is very enlightening.


It’s always the husband’s fault! :yum:

But if you do still suspect it could be fusarium/verticillium wilt, and since you have told me your parents are not going to rotate or skip a year to solarize, here is what I would do:

  1. replace the soil in the raised bed with new soil (not a bad idea for the in-ground garden either, but perhaps less practical)

  2. Buy disease resistant varieties (VF on the tag)

  3. Make sure the tomatoes are planted and staked far enough apart so they get as much airflow as possible to all parts of the plant. (Most people over-crowd their tomatoes to get as many in as possible.)

  4. Spray with a fungicide every two weeks or after a rain

  5. (optional) Use good quality yard-waste compost to mulch. Some things I read say that the organisms in the compost can outcompete the “bad stuff” in the soil and help keep them in check. I’ve never read any definitive scientific studies saying this, but it falls into the “won’t hurt, might help” category, so no reason not to do it.

Good luck to your parents and I hope they grow great tomatoes for another twenty years.

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Super VSOP.