Not exactly an upbeat topic, but something that should be addressed. And who knows, perhaps my knowledge can help you. Fusarium wilt is a soil born fungus that attacks the young roots of plants and travels up into the xylem tubes, blocking the flow of water. Solanaceous crop plants like tomatoes and potatoes are especially prone.
Some tomatoes varieties are “resistant” to Fusarium and you’ll find, when you buy your seeds, the disease resistance listed as “F2” (resistant to strains 1 and 2). Tomatoes that are resistant, will display signs of stress (the yellowing of the lower leaves), but not the wilting on the new growth. Varieties that have no immunity will show both wilting and lower leaf yellowing. Non resistant plants will die in a manner of a couple to a few weeks. Resistant varieties will continue to grow and usually grow through it and give you a harvest, even with many of the lower leaves dead. The good news is that the fruit is not affected, unlike late blight, which renders everything a bust.
It should probably go without mentioning that you shouldn’t compost these affected plants. Discard them in such a way so as they can’t further infect your soils. But now that your soil is infected, what to do? Well, there are a few things that you can do. After extensive research on my part, there are some organic solutions at your disposal. There are a few things that are mentioned in the literature here and there that are, for the most part, ineffectual. For example, crop rotation most like will prove a waste of time as a solution to fix the problem. It’s a good suggestion in general, but once it’s in your soil. it’s pretty much there. So, here are some tips:
1. Plant resistant varieties. My Big Beefs are resistant, and are showing the yellowing and eventual dropping of the lower leaves, but are healthy otherwise and producing quite well. Having said that, growing heirlooms is not out of the question (see below). All is not lost here. You could ignore this tip and rely on the ones below to help.
2. Plant a brassica in the beds you want to plant your tomatoes/potatoes in. A brassica that is especially good is mustard (Pacific Gold). These plants have high levels of glucosinolates and act as a fungicide. There’s quite a bit of research on this topic and it’s a partial solution. And an organic one at that. Typically, you might grow the mustard at the beginning of August, get it to about 3-4 feet, chop it up and till it in green. You could also grow it in the same year and start it in the spring to transplant your tomatoes into in June. Usually it’s best to wait a couple of weeks after you till in order to give it time to break down.
3. Rye, also, has been shown to help. You could get the rye started around the end of September, let it overwinter, and then it will come back to full height in the spring. You’d cut it down at ground level before you’d transplant your tomatoes. You can till it in or leave it as a mulch.
4. Corn meal is a well known fungicide. One way to use this could be to add some when you till in the mustard. About a pound of it on a 20 foot row should be enough. It was interesting to read the history of corn meal. People have been using it for athlete’s foot for a long time. Evidently it’s quite effective.
5. There is a product called Root Shield. I haven’t tried it, but Johnny’s sells it. It’s essentially a beneficial fungus that “protects” the roots of your plants by increasing the numbers of the good guys to help fend off the bad guys. It has spent almost 20 years in testing and supposedly works quite well.
6. Lastly, and this is something that is based my own observation, a hoop house or green house. All but one of my tomato plants inside the hoop house are unaffected by the disease and they’re all heirlooms. I know the disease is there because soil is shared and compost is shared throughout. My guess as to why only the outdoor plants are affected is that the indoor plants aren’t prone to over-watering by torrential rains in the summer. One of the main benefits of a hoop house is that you’re in control of irrigation. A huge rain storm will dump a couple of inches of water in a short time. If you get a few of these the ground becomes saturated. This largely wet ground encourages fungus to grow. By keeping the ground much drier inside the hoop house the tomatoes aren’t fighting the disease as much. As of this writing only my Paul Robeson plant inside the hoop house is succumbing to it, and I’ve already got a good harvest from it already.
I hope this was helpful.
As a final note I thought I’d share this other experience on pest management. If you find one of these guys in your garden, don’t put off taking care of it.
Remove him/her immediately. These things will defoliate your plant within 24 hours. They’re eating machines. Two of them showed up inside my hoop house plants chewing on the newer growth (which is where they prefer to chow). They’re big and they’re ugly, in an interesting sort of way. They’ll turn into the Luna moth if they’re let to mature. A beautiful moth. But hey, not at the expense of your tomatoes. Right?