Persistent Spider Mites

sikadelic

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Hey folks. I am having a hard time getting rid of spider mites on my Korean Hornbeam. They have slowed it down quite a bit and it hasn't leafed out and I'm starting to get concerned about it.

I have used 2 applications of Bayer 3 in 1 and I have used 2 applications of Bonide Fruit and Vegetable Tree Spray...both indicated they would control mites but these bastards are hanging on. I've also put my hose sprayer on fan and blasted them off up close a couple of times. If anything, I think they're getting worse. I had also noticed them starting on my BC but it looks like what I used worked on that tree but not my KH.

Any recommendations for a stronger product? I have attached the only somewhat reasonable picture I could get. Thanks in advance!
 

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markyscott

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Hey folks. I am having a hard time getting rid of spider mites on my Korean Hornbeam. They have slowed it down quite a bit and it hasn't leafed out and I'm starting to get concerned about it.

I have used 2 applications of Bayer 3 in 1 and I have used 2 applications of Bonide Fruit and Vegetable Tree Spray...both indicated they would control mites but these bastards are hanging on. I've also put my hose sprayer on fan and blasted them off up close a couple of times. If anything, I think they're getting worse. I had also noticed them starting on my BC but it looks like what I used worked on that tree but not my KH.

Any recommendations for a stronger product? I have attached the only somewhat reasonable picture I could get. Thanks in advance!
I don’t think I’ve had spider mite problems on anything except for junipers.

Assuming those are spider mites, I don’t consider either of the products you mentioned to be miticides, really. They are insecticides with a low degree of effectiveness on mites and can often aggravate the problem by killing populations of beneficial insects. Imidacloprid is not very effective at all and malathion may be mildly effective, but can also make the problem worse. For mites, start with a good blast of water, then move up to pyrethrin and/or neem oil. If none of that works try an actual miticide like bifenfren and refrain from using insecticides.

And consider initiating a regimen of dormant season treatments that can prevent these issues from ever becoming a problem.

S
 

sikadelic

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Thanks for your comment. I will make sure and pick up something specifically for mites tomorrow. I did realize that I needed to use a miticide, I just assumed these products had the right additives since they were on the label. and I have not considered the possibility of killing off beneficial insects... That's a good point.

I'll update whenever I find something that works. Thanks.
 

markyscott

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Thanks for your comment. I will make sure and pick up something specifically for mites tomorrow. I did realize that I needed to use a miticide, I just assumed these products had the right additives since they were on the label. and I have not considered the possibility of killing off beneficial insects... That's a good point.

I'll update whenever I find something that works. Thanks.
Of the two you mentioned, I’d guess the one containing malathion is likely more effective. But as I mentioned, it can also, exacerbate the problem by killing the good guys too. Bifenthrin has good miticide activity - it’s sold under the brand name talstar among others.

https://extension.colostate.edu/topic-areas/insects/spider-mites-5-507/
https://www.canr.msu.edu/news/spider_mite_populations_thrive_in_hot_dry_summers
 

Bonsai Nut

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I buy concentrate by the gallon. Just be prepared... it has a definite odor :) I don't mind it, but my wife doesn't like it. Last time I sprayed my citrus trees my neighbors thought they had a natural gas leak :) It disappears in about 48 hours.
 

Billyjack

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I use azamax. Mixes with water a teaspoon to a quart. A bit pricy but it can be used in the soil and on the leaves. I recommend a 360 sprayer, sold at finer hydroponic shops. It sprays upwards, the spider mites live under their leaves. Quarantine and spray the underside of the foliage and soil. This stuff will kill off colonies and safely breaks down with UV exposure, so it will have to be reapplied.
 

sorce

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Have you seen mites?

Looks more like a spiderweb.

Sorce
 

Peterkorea

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I don’t think I’ve had spider mite problems on anything except for junipers.

Assuming those are spider mites, I don’t consider either of the products you mentioned to be miticides, really. They are insecticides with a low degree of effectiveness on mites and can often aggravate the problem by killing populations of beneficial insects. Imidacloprid is not very effective at all and malathion may be mildly effective, but can also make the problem worse. For mites, start with a good blast of water, then move up to pyrethrin and/or neem oil. If none of that works try an actual miticide like bifenfren and refrain from using insecticides.

And consider initiating a regimen of dormant season treatments that can prevent these issues from ever becoming a problem.

S
Hi, sorry to bother you. Could you elaborate on what you mean by "initiating a regimen of dormant season treatment". Are you talking about chemical measures or hygiene related actions? I'm completely new to bonsai and have constant mite issues. I'd love a new plan of action.
 

petegreg

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Hi, sorry to bother you. Could you elaborate on what you mean by "initiating a regimen of dormant season treatment". Are you talking about chemical measures or hygiene related actions? I'm completely new to bonsai and have constant mite issues. I'd love a new plan of action.
You can find it all in the resource section.
 

markyscott

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Hi, sorry to bother you. Could you elaborate on what you mean by "initiating a regimen of dormant season treatment". Are you talking about chemical measures or hygiene related actions? I'm completely new to bonsai and have constant mite issues. I'd love a new plan of action.
Hi - if you already have mites (and if you’re sure they’re mites) you’ll have to get rid of them with a spray. You have some choices. Pyrethrin is effective- especially when it’s combined with an insecticidal soap. A smothering oil like neem oil or horticultural oil is effective. There are a few miticides on the market like Bifenfren or Talstar. The resource (previously linked), along with good plant husbandry, is an effective preventative but not a cure.
 

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Neem oil for the win! Particularly on junipers! Should have no trouble nuking them on a hornbeam!
I have spider mites on my junipers (san jose and shimpaku). I was going to spray with neem oil but I keep reading that it can discolor them. Have you experienced that?
 

Bonsai Nut

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I have spider mites on my junipers (san jose and shimpaku). I was going to spray with neem oil but I keep reading that it can discolor them. Have you experienced that?
It does not discolor them. However you have to be careful because it makes them much more sensitive to the sun. Make sure you use the proper strength, and do not spray if there is going to be hot weather with intense sun in the forecast. I have the ability to move my junipers under shade cloth for a few days.
 

Japonicus

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I have spider mites on my junipers (san jose and shimpaku). I was going to spray with neem oil but I keep reading that it can discolor them. Have you experienced that?
I don't know about these 2 junipers, but procumbens, yes, it does indeed discolour them up to maybe more than a month
and the Sun can be an issue. Personally I would use neem oil for dormant treatment, or if no other miticide was pulling its weight.
The rotation with insecticidal soap is good husbandry regardless of your choice of action.

Oh, wait a minute...I got discoloration with Ortho's Volk Oil spray, still a horticultural oil spray, but discontinued.
Maybe Neem oil does not have this issue. I would be surprised if it did not, but my bad confusing the 2 oil sprays.
I would not let my junipers in the Sun directly for a month, which is not healthy of itself, when I used the Volk oil.
Carry on...
 

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I could move them to shade but I'd rather not. Should I just use something like Bonide Pyrethrin instead?

The bloody mites came on some plants I bought and I want to be sure the infestation doesn't spread so I'll probably spray everything. We're talking junipers (pro nana, blue chip, san jose, shimpaku, holger), azaleas, buckeye, mugo pine, jap maple, boxwoods, serissa, larch, beech, rain tree, white pine, trident maple, japanese holly, chinese elm, burning bush, dawn redwood, and hemlock.

In some of the reviews I read it said pyrethrin can damage foliage as well. I'm planning to sell most of the junipers in a few months so I can't do that!

@Japonicus, which insecticidal soap do you use?

Or maybe I should just leave well enough alone? I was reading that ladybugs eat them and I've been seeing more and more ladybugs on my plants.
 
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Bonsai Nut

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Pyrethrin isn't going to hurt anything. It is 100% organic and has been used for centuries. Just make sure the active ingredient is 100% pyrethrin. I have seen a number of pyrethrin products that use other chemicals as catalysts to improve the efficacy; but it not only makes the product non-organic, but it makes it difficult to know with confidence how the plant will respond to application.
 

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