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saguaro

spider mites

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does anyone have advice for dealing with spider mites on cacti?

 

I've been trying to eliminate them for months and I've tried neem oil, 'bug boss king hit', wettable sulphur and spraying down the plants often.

 

despite all the effort, the infestation is at its worst, and even though I sprayed during the early evening when the sun was down, some of the plants have been burnt by the treatments. It seems like wettable sulphur gets recommend often, but this definitely burnt the cacti

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Spidermites are hard to treat and you need an Acaricide to kill them for good. Make a quick Google to find a few pesticides. Personally I spray my plants with 70% alcohol and it usually reduces problems to a minimum. It doesn't kill them entirely, but it reduces their populations dramatically. Can cause burns though, so never do it in full sun. 

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The residuals of what you’ve been trying might interfere with this getting started but we have had great success using predatory mites to control spider mites and russet mites on a range of plants.

Read about them first as how they get introduced is important for good results. Some are better suited for indoor use than others.

 

https://www.buglogical.com/spider-mite-predator/

 

https://www.arbico-organics.com/category/two-spotted-spider-mite-control-deciduous-fruit-trees

 

https://www.arbico-organics.com/product/mite-predator-phytoseiulus-persimilis-spidermite-killer-greenhouse/pest-solver-guide-mites

 

https://www.gardeninsects.com/spiderMiteControl.asp

 

https://greenmethods.com/persimilis/

 

There are lots of suppliers but check reviews as this is a live product and not all suppliers are equal. In some cases the mites can’t survive without food so need to be shipped with some green leaves infected white flies or another food source to ensure live arrival.

 

One other thing to keep in mind is that many approaches to pest control either cannot or should not be used on cacti. Anything that harms the waxy outer layer can result in scarring or burning. In some cases this is from losing their protection to the sun but sometimes it is due to the product causing actual damage. Oil sprays in particular should be avoided.

 

Predatory nematodes can be helpful additions to cactus gardens also depending on what pest is causing problems.

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I appreciate the suggestions 

 

I've looked into persimilis and californicus predatory mites, but I think using an acaricide is the best option for now considering how bad the infestation is. In the future I might use them as part of IPM when they are under control.

 

Now that there is a residue of sulphur on the plants, does anyone know how long should I wait before applying a pesticide? I will try the 70% iso in 2 weeks after spraying the plants down often to remove the sulphur.

 

I was thinking about using kill-a-mite (abamectin solution), although this is dissolved in a solvent that will probably damage the waxy layer. There is another product out there called broad blue protect which is apparently an 8-week systemic I've looked at, but there is no information on it.

 

In case anyone is thinking of trying bug boss king hit on cacti - don't! It dissolves the glaucus layer and causes scarring (I applied it at night, and this was before testing the sulphur).

 

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Posted (edited)

Best of success! I've been where you are with pests before and can totally empathize with your decision. If you have concern, wash off the sulfur and let the spider mites return to their full glory before the massacre.  It actually should not harm anything if you just went ahead

Milbemectin might be tried next if the mites turn out to be resistant to abemectin. Both can be had in concentrated forms that won't have that problem when diluted. I'm not suggesting powder as the risk to the operator and their surroundings is higher than many people are trained for but concentrates like Avid do exist. 

That solvent you refer to is for forming an emulsion with water. Shake the spraybottle frequently during application so it stays dispersed and use a white sheet to protect from sun afterwards. 

 

Edited by trucha
needed
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thanks, I'll give it a try 

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If you can dunk the plant in a bucket of water till they all drown

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There used to be a spray called "red dot" or something like that that you could get from hydro shops, worked wonders for spider mites but have not seen it around in a while so may have had some messed up stuff in it that got banned or something.

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diatomaceous earth is your friend......cover the entire plant & soil in DE for a few days or a week. 

 

yrs ago i had a serious bug infection in my arios....plants with many crevices for critters to hide in.....DE to the rescue

 

 

 

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