The mites are too small to see with your naked eye, only .02 mm long. A lens with at least 14X magnification is needed to see them. So identification is generally done based on symptoms rather than sighting. The first sign of an infestation is rather subtle, the stems of the plants will turn from bright green to a russet color as you can see in the photo above. Trouble starts at the base of the plant and works its way up. The leaves at the bottom of the plant will start to die and eventually turn a russet color as well. In hot weather the entire plant can become defoliated fairly quickly as the infestation works its way up the plant. If the plant is not treated it will die.
Only one of my plants, a Blue Beech paste tomato is showing serious signs of infestation right now. The stems on that plant are russeted up to about 2 feet and the bottom leaves are just starting to die as you can see below. You can also see the traces of the treatment I applied in both of the photos.
The treatment I used is wettable sulfur, which happens to be an organic treatment. The recommended rate is 1 to 2 tablespoons of wettable sulfur powder per gallon of water. I used 1 tablespoon of sulfur in a gallon of water and thoroughly sprayed the affected plant, making sure to get the stems and both sides of the leaves. I also sprayed the bases of the neighboring plants. If the infestation continues to spread up the plant then I'll try a 2 tablespoon concentration next week. Never spray with sulfur when the temperature is 90F or above, you will damage the plants. Spray only when there is no wind and be sure to keep the spray off your skin.
I've never heard of those before. Most mites like dry weather and that is something we don't get much of, especially this year. I hope your tomatoes survive.
ReplyDeleteDaphne, you are quite correct, these mites love dry and especially dusty conditions. They tend to be a common problem here because of our lack of summer rain. Fortunately, sulfur is a very effective control.
ReplyDeleteGood luck, Michelle. I lost my little tomato crop to some kind of mystery disease last summer, and after raising them from seed and getting so close to seeing a crop ripen, it was really disappointing. Here's hoping the wettable sulfur treatment works!
ReplyDeleteJamie, Thanks so much. I remember reading your posts about your tomato tribulations. I know it must have been a huge disappointment.
ReplyDeleteGood luck battling the mites. I've got something going on with my tomatoes, too. I'm thinking it's early blight on the lower leaves. Black spots that eventually coalesce and kill the leaves. The problem isn't too bad, yet. I treated them with diluted milk yesterday. On some plants there is a yellowing of a few lower leaves, instead of the black spots. How can I tell the difference between mites and fungus (e.g. early blight)? Thanks! -Jackie
ReplyDeleteHi Jackie, Growing healthy tomatoes sure is a challenge. I'm not really an expert, but from what I can tell early blight starts with brown or black spots that expand, often showing concentric rings. Russet mite damage on leaves is all over with an eventual yellowing and then browning of the leaves. Another problem that can cause leaf yellowing is powdery mildew. A website that might help you to diagnose some tomato problems is UC IMP Online - here's a link to their tomato page http://www.ipm.ucdavis.edu/PMG/GARDEN/VEGES/tomato.html
ReplyDeleteIt seems as though there are as many tomato problems as there are folks trying to get some homegrown tomatoes! I fall into the lasseiz-faire camp, watching my early (or is it late?) blight move up the tomatoes. . . hoping I'm going to get a lot before they die.
ReplyDeleteIt's overwhelming. Good to see you have a better handle on managing their troubles.
Stefaneener, there are probably more tomato problems than there are tomato growers! I remember leafing through an entire book (a big book) about nothing but tomato pests and diseases that almost made me wonder why we bother.... almost. This is the first time in 3 years that I've got tomato plants that might give me a decent crop so I just can't bear to watch them succumb to something before they really even get started.
ReplyDeleteOk, thanks, will have a look tomorrow morning, although they looked healthy tonight. Good luck with yours.
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