I think I've discovered why these two plants I've been asking about recently (viewtopic.php?f=1&t=165044 ) have a problem. Looking at both with a jeweller's eyeglass I've just discovered a dozen or so bugs on each plant which I think are red spider mites
Whether or not it's coincidence, but I bought both plants on the same day over a year ago - none of my other cacti seem to be affected but I've isolated these two.
I'm wondering if these are worth treating, and if so what with, and whether I should treat my other windowsill plants just as a precaution?
There are no chemicals available to the amateur that are particularly effective against spider mite. The best solution is to spray with SB Plant Invigorator which kills the beasties by physical means and is non-toxic to you - important when plants are in the house. It does not kill the eggs, so will have to be repeated a couple of times at about two week intervals.
Red Spider likes hot and dry locations, overhead watering seems to be the best way to keep it out of the greenhouse, I'm still using the old formula of Provado with imidacloprid which I thought also had a contact insecticide for red spider.
Stuart
Red spider mite always goes for soft tissue not the older harder tissue at the base of a plant, but the fresh growth at the tip of a plant. Was this where you saw the little pests?
As Terry says there is nothing available to the amateur which will get rid of these mites. They do thrive in hot dry conditions, but in my experience they also thrive in cool damp conditions!
Good luck and do try the SB Plant Invigorator, it works by suffocation.
Thanks Suzanne, the mites are not in any particular place, they're top bottom and middle! I did read in threads here on the forum that they prefer juicy new growth but searching on Google show lots of plants with damage at top and bottom attributed to them. As these are the only two plants I have that are displaying these symptoms I guess it must be the little critters that are causing it.
Even I if can eradicate them there's nothing much I can do about the damage so I suppose it's try propagation or bin them
picnic wrote:Even I if can eradicate them there's nothing much I can do about the damage so I suppose it's try propagation or bin them
Looking at the photos in the other thread, I can't see much wrong with your plants. Crawling things on your plant are not necessarily harmful - they could be lots of things. The marks you show on your plants are not what I would expect from red spider mite or (which I find more common on cacti) false spider mite. More likely, as others have suggested, they're just age in the way that green sappy twigs on trees become woody and brown. Keep an eye on them for sudden worsening but otherwise I'd leave them be until spring.
Phil Crewe, BCSS 38143. Mostly S. American cacti, esp. Lobivia, Sulcorebutia and little Opuntia
I agree that there are no obvious signs of mite damage in the photos. They could be there anyway, or you might have seen other things that happened to be passing through. Try to find a match online, or if you have a good camera snap the little things and post them on here.
Terry S. wrote:There are no chemicals available to the amateur that are particularly effective against spider mite. The best solution is to spray with SB Plant Invigorator which kills the beasties by physical means and is non-toxic to you - important when plants are in the house. It does not kill the eggs, so will have to be repeated a couple of times at about two week intervals.
Abamectin is a relatively safe and effective miticide, and while the concentrated product is off limits to the amateur, there is a ready-made spray available here in Portugal under the brand name "Fazilo" that may be worth looking into if you have a windowsill collection (other than that and the stuff becomes too expensive).
Abamectin is a good miticide. Westland Bug Attack used to have it (mixed with Thiomethoxam, stupid people) but is no longer available. If nothing else, it is different from other products you're likely to have tried so will help to reduce resistance and will be good if your mites are already resistant to what you've tried.
Fazilo isn't in B&Q but it is available in the UK, mixed with Pyrethrins which are also effective against mites: Fazilo
There are a number of other Compo products that can be used against mites: effectively Fazilo concentrate and Pyrhethrins in an aerosol. I'm pretty sure there is an aerosol with Abamectin but I can't find it for sale in the UK.
Perhaps want to try the simple stuff that is available in garden centres first, that's if you even have a mite problem.
