Both types for decades and spider mites almost every year. I always heard that they didn't like wet conditions but I have even seen them start up when we are getting a shower most afternoons and we rarely have humidity less than 75% except during droughts; but they don't usually get really bad unless they are allowed to go unchecked for a long time, attacking a sick plant or during very dry conditions. Last year there were times when it felt like the west instead of the southeast around here and it went on for months and I had the most devastating and almost overwhelming mite infestation I have ever had in over 40 years of growing tomatoes. The main reason most people don't think about mites too much down here is because most of them stop growing tomatoes by this time of the year and only a few try to grow in the fall. I have been growing in staggered plantings for so long that I get to see them at their worst in the months of July and August when it usually gets really dry and plants are suffering from age and disease so they are welcome hosts to the little buggers. Since I also try to grow fall tomatoes they can pounce on the young seedlings in late summer and destroy any hope of a fall crop if they aren't treated quickly and stopped.
Years ago before I became more interested in keeping my garden more organically balanced I would treat them with some pretty intense poisons which usually did the trick but with some really long wait times. The strongest poison I have used in the last ten years was quite a few years back during a really intense infestation when in total frustration at the lack of effectiveness of Neem, pyrethrin, soaps and essential oils I pulled out the Malathion and used it at the strength labeled on the bottle for mites along with a big dose of soap and it finally stopped them but not before damaging my leaves pretty badly. Malathion at strong concentrations will damage tomato leaves but I only applied it at the recommended amount but that was stronger than I had ever used it on any thing I was eating. I didn't like using that potent a poison in my vegetable garden so when I read about combining DE into the spray a few years ago I started trying it out at various combinations to find what would work best with Permethin which is a far less potent poison to mammals and with a short wait time to harvest.
If I see spider mites early in the season I will treat them with a milder version of my mix and then check every day several times a day on the plant that looked most affected by them and see if there is any further spread or indication of them spreading. If I don't see anything and the new growth remains uninfected by them then I just keep a watch out for the rest of the season and if I see a return of the little monsters I hit them with the full strength version immediately and two days later I will sometimes hit them again. Then I just wait and see if there will be any new occurrences of them. I try to remove and bag all the affected leaves the next day after the spraying to remove as many eggs as possible as a further precaution. Doing this in the summer can result in some sun scald to the fruit exposed to the full sun but the DE coating on them does seem to help with that. Unless they are constantly coming in on the wind this usually takes care of the problem for quite a long while but sometimes a third spraying is called for.
I only use this spray in the very late afternoon because I still want to harm as few bees and helpful insects like wasps as possible. I have been using this method for a few years now and have yet to let them ruin more than a few plants and I hope it keeps working because if it doesn't I don't have a clue what will.
Bill
|