Open this morning for Easter was my Lobivia famatimensis. Not, perhaps, a spectacular flower but very pretty nonetheless. Unfortunately, the cactus epidermis browned all over in the GH this winter--an effect, I imagine, of no water and sun on it during the cold of winter. There appears to be a very slight greening around some of the areoles.
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The P. buiningii flower opens daily and by now seems to be at its biggest. The M. elongata has some more open flowers on its longest segment with discernible buds on another small branch.
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Catch a falling star--but don't try it with a cactus!
iann wrote:The Lobivia has, or had, mites. With a bit of luck they all froze
That's damage from mites? I never knew. Will a systemic kill them off if they're still there? Why is it otherwise so healthy? Don't mites kill cacti, or do they just make cacti look unsightly?
Catch a falling star--but don't try it with a cactus!
Mites can kill, but it takes a while. First they brown over, but they can grow out of that. If the mites keep at it for long enough the plant may give up.
Don't rely on mites being killed by insecticides They're not insects! Check the label. I doubt you have a systemic miticide. They exist but you have to search hard to find them. Often they aren't true systemics, only translaminar, but that still produces a persistent toxicity over at least several weeks.
iann wrote:Mites can kill, but it takes a while. First they brown over, but they can grow out of that. If the mites keep at it for long enough the plant may give up.
Don't rely on mites being killed by insecticides They're not insects! Check the label. I doubt you have a systemic miticide. They exist but you have to search hard to find them. Often they aren't true systemics, only translaminar, but that still produces a persistent toxicity over at least several weeks.
What's the best way to get rid of them?
Catch a falling star--but don't try it with a cactus!
iann wrote:Mites can kill, but it takes a while. First they brown over, but they can grow out of that. If the mites keep at it for long enough the plant may give up.
Don't rely on mites being killed by insecticides They're not insects! Check the label. I doubt you have a systemic miticide. They exist but you have to search hard to find them. Often they aren't true systemics, only translaminar, but that still produces a persistent toxicity over at least several weeks.
What's the best way to get rid of them?
Ian is correct. The Tau Fluvalinate in Bayer 3-in-1 does well against mites, although as he says, the effect is translaminar, not systemic. I also highly recommend TetraSan, which you can find here:
Not cheap, but at a dilution of 1/4 tsp. per gallon for spraying, a little bit goes a long way. Use 3-in-1 spray to kill the mites, then TetraSan to kill the eggs, and this is what'll end their lifecycle. I believe you'll need to follow the treatment only once per year in the spring, although if the mites come back, you may have to do it again. I'm not sure about the Bayer product, but TetraSan is a great preventative because mites don't develop resistance to it over time.
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Steve Johnson wrote:
Ian is correct. The Tau Fluvalinate in Bayer 3-in-1 does well against mites, although as he says, the effect is translaminar, not systemic. I also highly recommend TetraSan, which you can find here:
Not cheap, but at a dilution of 1/4 tsp. per gallon for spraying, a little bit goes a long way. Use 3-in-1 spray to kill the mites, then TetraSan to kill the eggs, and this is what'll end their lifecycle. I believe you'll need to follow the treatment only once per year in the spring, although if the mites come back, you may have to do it again. I'm not sure about the Bayer product, but TetraSan is a great preventative because mites don't develop resistance to it over time.
Are these environmentally safe? I am so concerned nowadays about using anything harmful to bees (bumble- and honey-) and to monarch butterflies. The small amount I would use would not have any impact on soil or water, as all the cacti I would treat are in pots and not attractive to either of the above-mentioned.
Catch a falling star--but don't try it with a cactus!
Tetrasan is essentially non-toxic to bees, or any other insect. It is fairly specific to mites. In the US it is not labelled for use against flat mites, which I suspect is the pest that caused your damage, but anecdotally it is effective. Very few products are specifically labelled for flat mites, and those that are tend to be aimed at different species of commercial importance such as citrus mites. A product labelled for spider mites may or may not be effective against flat mites, but often they affect both.
Tau-fluvalinate is a pyrethroid, a wide spectrum insecticide and miticide. Yet it is much less toxic to bees than most pyrethroids for reasons that aren't entirely understood, and is used to control Varroa mite in honeybees. Unfortunately Bayer 3-in-1 has been produced under the philosophy of "kill everything and ask questions later", so it also includes Imidacloprid which is certainly toxic to bees. Avoid spraying when bees are likely to be present, certainly don't spray on flowering plants.
I would take issue with the idea that Tetrasan is anything special as a preventative though. It has a persistent effect, but we're talking a few weeks., so not really great for prevention. Strangely it does not kill adult mites, although it does make them sterile. Eggs are only killed by contact, since they don't feed on the treated plant. Mites can certainly develop resistance to Tetrasan but this is not widespread. Consider rotating different products to avoid resistance. Pesticides in a greenhouse environment are particularly prone to developing resistance because you can get very high, but not 100%, kill rates. Hence the next infestation develops from a tiny population that survived the last treatment. Or from newly introduced pests with no resistance at all, depending on your luck.
