Tomato Plants in the City
I live in a rowhouse in the Riverside neighborhood. I am growing tomatoes in containers. I have four plants of four different varieties. I have successfully grown tomatoes for ten years, but the last two year they have been decimated by some kind of disease. The leaves get spotty, then turn yellow, then dry up and fall off. The plant puts on new growth, but the disease catches up. I have more photos if you need them. The four varieties are Husky Cherry Red. This plant is the most resistant/ least affected. I also have a Sweet 100 and a Sweet Million and a Patio tomato. The Sweet Million is almost completely stripped. It is the most affected. The Sweet 100 and the Patio tomato are badly affected, but have put on some fruit. I treated with Sevin spray because I saw aphids, but this is something else. I have not used any other treatment. They are planted in Miracle Gro Moisture Control potting soil. Any suggestions? Many thanks.
It looks like your tomatoes have spider mites. We do not recommend using Sevin for treatment; it will also kill the beneficial insects (natural predators) that help keep pest insects in check naturally. In other words, Sevin could make matters worse.
You can use a product that contains spinosad, labeled for use on tomatoes. You can also hose off the plants to dislodge the mites. Cooling the plants down with water also helps to control them. Increasingly hot temperatures favor spider mites (they emerge earlier in the season and have more generations per year). They are becoming more of a problem in a warmer climate.
Here is some additional information about spider mites and how to control them: