Spider Mites On Tomatoes - Bonide 8

gilmoregalAugust 6, 2014

Hello - We live in the OKC area and my six tomato plants (various varieties) looked beautiful until last week when the leaves on some started to curl and turn yellow. I thought it might be a watering issue so adjusted my watering, but it got much worse over the weekend. After some internet research and checking the plants, I realized that it is spider mites. I am not an experienced vegetable gardener, and I have never dealt with mites before, so I went to one of the large garden centers for advice. I had read that Neem oil was a good product to use, but the clerk steered me toward Bonide 8 instead. I treated the plants last night, but now I wonder if I should have used something different. It may be too late at this point, since I didn't recognize the problem when it first started....The clerk advised not treating again for 14 days, but is there anything else I can do besides wait and watch? Should I fertilize to encourage new growth? I appreciate any advice.

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I bought some Bonide 8 several years ago and sprayed my lawn and part of the pasture to try to get rid of an army worms. We did save most of the lawn and pasture, but my first choice is to not spray anything. I don't have good luck fighting spider mites, mainly because I don't like killing other insects. I think one of the best things you can do is to keep your plants watered and healthy. Some people use neem oil but I don't even use that because I think you can burn your plants in hot weather.


    Bookmark   August 6, 2014 at 6:09PM
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rhizo_1 (North AL) zone 7

Permethrin is well known to cause an INCREASE in spider mite population by killing off the predatory mites and insects that help control them. Keep a close watch. It's not something I would use.

    Bookmark   August 6, 2014 at 6:30PM
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AmyinOwasso/zone 6b(6b)

I have not tried it, but I read that cilantro, made into tea and sprayed on would repel them. It is probably a preventative measure, rather than a cure. Odly, the spider mites like my herbs...oregano, thyme and peppermint. They have left my tomatoes alone.

    Bookmark   August 6, 2014 at 7:54PM
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Okiedawn OK Zone 7


Tomato plants can tolerate a fairly significant amount of spider mite damage and survive it and produce just fine if they are otherwise healthy.

Rhizo took the words right out of my mouth. The same thing is known to occur when you use Sevin as well, so one of the worst things you can do with spider mites is to spray the plants with a broad-spectrum insecticide that kills off all the beneficial insects that actually help keep the spider mites under control.

Usually, particularly when you're only dealing with a small number of plants, you can blast the majority of the mites off the undersides of the leaves by spraying them with a sharp stream of water. Sometimes you have to do it every day for 3 to 5 days in a row because they keep coming back for a while. I will do this occasionally if I think there are too many of them on a specific plant and it seems to be struggling more than the other plants, but we have mites on literally every plant on our 14+ acres, so I am not so foolish as to think I can somehow eliminate them from a veggie garden that is a few thousand square feet when they occupy all our acreage and all the acreage that surrounds our acreage. We all live and garden in the real world, and the real world is an ecosystem full of living creatures of all kinds---including spider mites.

I started out this spring with a little over 100 tomato plants and saw spider mites out as early as April, so my plants have had them for months....and they haven't killed a single tomato plant, and we have had bumper crops of tomatoes. I've canned until I simply cannot bear the thought of canning any more. If the spider mites were a real threat to my tomato crop, based on how many we have, there wouldn't be a tomato crop at all. Spider mites are a constant issue in our hot climate, but the predatory mites and the lady bugs usually keep them somewhat under control and I just tolerate them otherwise. I could spend all day every day in the warm weather season fighting them (and then I'd have to fight them in the greenhouse in winter too), and we'd have them anyway. If you even could get rid of them all, more would just blow in on the wind......

Regarding your question about fertilizing the plants, the quick answer is that you probably shouldn't do it. Want to know why? If the plants are not showing signs of nitrogen deficiency, for example, then they don't need nitrogen. By feeding nitrogen to plants that don't need it, you've overfed them, and plants that are overfed with nitrogen will attract more spider mites. So, feeding the plants could give you exactly what you're hoping to avoid. Research has shown that plants which are fed excessive nitrogen above and beyond what they need become more attractive to spider mites. I believe it is because the excess nitro leads to extra carbohydrates in the foliage and the spider mites are attracted to the extra carbs.

Often, as gardeners, we over-react and try this, that and the other thing when we really just need to chill, watch the plants and take simple steps like spraying the undersides of the leaves to knock the mites off. You also have to be very cautious about spraying the plants in very hot weather because some substances that do not harm foliage in cooler weather can burn foliage when used when the temperatures are in the 90s and 100s.

Amy, I see them first on tomato plants every year, but then they usually do move on to herbs, and sometimes flowers and sometimes melons, but don't do enough damage to them either to really alarm me. They also heavily infest my cilantro and culantro (and borage but usually not basil) plants every spring so I am not convinced spraying the plants with cilantro tea would be any more effective than spraying with plain water.

I learned the spider mite lesson as a child in the 1960s and 1970s when my dad, who was a lifelong farmer/gardener, fought them fiercely in our backyard garden. His best friend who lived and gardened a couple of blocks away fought them in the same manner. They sprayed with Kelthane, which certainly didn't seem to help. They sprayed with Sevin, which seemed to increase the population of the spider mites. The more they sprayed, the more mites they had. So, even as a child, I knew that spraying wouldn't eliminate the spider mites and would, in fact, increase their population. It was an important lesson to learn young. You don't forget those kinds of lessons that you learn from seeing a specific activity occur every garden season year after year and decade after decade. By the 1980s, my dad wasn't spraying his plants for spider mites any more, and they were much healthier than his plants had been back when he sprayed.

Usually, after mid-August and after the temperatures begin to fall a bit, the spider mite population begins to decline as well.


    Bookmark   August 6, 2014 at 9:20PM
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Well - darn. I had a gut feeling that I shouldn't take the advice of the guy at the garden center - but it is one of the larger ones in OKC, and he seemed adamant that 8 was preferable to Neem. I definitely didn't want to kill the 'good' bugs and should have thought/asked about that....
I don't know that some of my plants will survive until the temps drop. I think they may be too far gone. The ones that continue to look good have blossoms but no new tomatoes. So I'm afraid our harvest may be over. But at least I'll know more next year.
Thanks so much for your input.

    Bookmark   August 6, 2014 at 10:40PM
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Okiedawn OK Zone 7

Gilmoregal, You're welcome. Next time, trust your gut feeling because it usually is right.

This year, for the first time ever, I sprayed much of my front garden (not the butterfly plants and not the ornamental flowers that butterflies and bees visit) one time with a broad-spectrum pesticide to kill grasshoppers that have been eating my plants down to bare stems. I have stedfastly resisting using a broad-spectrum pesticide (even the organic ones) forever because I didn't want to harm the beneficial insects, and it just about killed me to do it. The pesticide did kill the grasshoppers---and many of the beneficials. Then, in the absence of the beneficials, aphids magically appeared all over the watermelon and muskmelon vines. Billions of aphids. The plants then developed black mold because of the honeydew from the aphids. I can't really say I was surprised----I knew there would be serious consequences from using a broad-spectrum pesticide but I didn't know specifically what pest populations would rebound most quickly in the absence of a large population of beneficial insects. Apparently it was the aphids.

Luckily, the bees and other pollinators generally diverted to the back garden where squash, cucumbers, Armenian cucumbers and purplehull pinkeye peas were in full bloom, along with many flowers, so I didn't find too many dead bees in the front garden over the next few days---maybe a couple of dozen. Still, seeing the disappearance from the garden of so many of the good guys kinda made me regret spraying. (I knew I'd regret it, but I just couldn't tolerate the grasshopper damage any more---they had moved from herbs and tomato plants to pepper plants, and I grow tons of peppers to make pepper jelly and other things so I was determined that the hoppers weren't going to be allowed to eat the pepper plants down to naked stems as they had done with the beans.)

Last week I noticed wheel bugs and assassin bugs in the garden so I could see the beneficials beginning to make a comeback in the garden. This week, an army of lady bugs descended upon the aphids on the melon plants, and I am seeing tons of ladybug larvae. Unfortunately, the grasshopper population is soaring as well as new ones migrate in, but I will not spray again. Usually at this time of the year the grasshopper and spider mite populations already have peaked and will begin falling, so I'll try to tolerate the hopper damage that occurs from this point forward.

About the garden center guy----his job is to sell you stuff. Sometimes the employees at those places are gardeners themselves and sometimes they aren't, so the advice they give might be great advice....or it might not be.

Your good bug population will rebound.

One way to help your tomato plants next year is to grow plants with small flowers that will attract lady bugs and other beneficial insects. I grow lots of yarrow, catnip, catmint, chamomile, verbena bonariensis, sweet alyssum, and other plants for them and I let herbs like lemon balm, catnip, catmint, cilantro, and basil flower all summer long (selectively cutting them back to keep them reblooming). Beneficial insects flock to gardens that have plants they like and need. In late winter and early spring I even let henbit bloom in my garden because the beneficial insects love it so much. If you can keep beneficial insects in and around your garden, they normally keep the spider mites at a lower level and that allows the plants to survive and to produce. The mites generally peak in my garden in July and then their population begins to drop. The garden won't be spider mite-free in the fall, but they'll be at a progressively lower level each week and you'll see less and less damage.

Don't give up on your tomato plants. They could rebound. I have seen plants that seemed dead make almost miraculous recoveries in the fall, and then they bloomed and set fruit and we had tomatoes until Thanksgiving or even until Christmas if I covered up the plants on the freezing cold nights.

Chalk up this spider mite experience as a 'lesson learned' and file it away for future reference. I have gardened my entire life and still learn something new constantly. You never stop learning and the more you learn, the better of a gardener you will become.


    Bookmark   August 7, 2014 at 9:16AM
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AmyinOwasso/zone 6b(6b)

Dawn, I found one reference to cilantro in a book recently. I have read everything I could find on companion planting and had never seen this before. So I should have known that one was too good to be true.

    Bookmark   August 7, 2014 at 10:56AM
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