Return to the Garden Clinic Forum | Post a Follow-Up

Spider mites on difficult foliage

Posted by mharris1x 8 (My Page) on
Sun, Jul 25, 10 at 23:55

I have a spider mite problem on:
- Iceplant ground cover
- Rosemary bush
- 30' Walnut tree

I have tried 25% alcohol/75% water solution on the iceplant and rosemary yesterday with a general "soak the plant" sprayer approach that seems to have done very little- today I see more webs (although many are gone- but still- something tells me in a week the entire area will be infested again). I suspect the mites are underneath the leaves and for these plants, I can't really spray there.

The tree is another matter. The tree also has powdery mildew along with the mites. For this I sprayed with bleach and water, and I tried to get the back of as many leaves as I could, it definitely made a difference for the leaves I could get to but what about the tops of high trees? I am planning to do a massive prune of the tree and apply Bayer tree and shrub because something else is wrong with the tree I fear.

But as for the mites- help! Thanks for any advice. This is Northern CA, a moderate climate.

Follow-Up Postings:

RE: Spider mites on difficult foliage

Using bleach to control Powdery Mildew is non productive and much more hazardous to the environment then some of the other harsher, commercial, controls. Baking Soda can be a good control.
Spider Mites become problems in plants when the weather gets hot and dry because they feed on the plants more and that is an aphrodesiac to them sothey mate more and produce more Spider Mites. Increasing the humidity of the affected plant, on a regular basis not just once or even once a week, is needed to help control them. Spraying a 25 percent soluton of rubbing alcohol (already diluted) does littel more than waste your money, time, and energy. Spraying most all pesticides or miticides in an attempt to control these wee buggers actually only kills off any predators and so allows the population of Spider Mites to grow unchecked.

Here is a link that might be useful: About Powdery Mildew

RE: Spider mites on difficult foliage

I'm worried about your plans for the tree. In particular, the 'massive pruning' you mentioned. Are you aware that heavy pruning of mature trees can cause permanent damage? If the tree is valuable to you, I strongly suggest that you bring in a couple of ISA certified arborists to take a look at it. Anyone who suggests 'topping' as a remedy is a quack, by the way. What else do you think might be wrong with the tree? Is there any way that you could take pictures of the problems?

Bleach, unless diluted quite a bit, can do damage to the foliage and very little to control powdery mildew. It's considered a strong phytotoxic material.

Alcohol is a well known home remedy for spider mites, and I've used it on outdoor plants myself. But you are talking about a couple of plants that can do a pretty darned good job at hiding mites. I've never had this pest on my ice plant, which I have a lot of, and I hope I never do. I DO deal with the pests on Rosemary, however.

I use a sharp spray of water from the hose, making sure I get the underside and interior of the plants when I spray. My goal is to dislodge. I never get rid of all of them, but between that and their predators, we manage to keep them in control. This happens to be a very hot and dry summer for us, and I may end up bringing out the rubbing alcohol before too long, however.

RE: Spider mites on difficult foliage

It's difficult to get rid of spidermites but with repeated applications in rotation it is possible. Never use the same product twice in a row. Alternate between 2 products. Always rotate or they will become immune. Below is a link with directions on how I got rid of two spotted spidermites with pictures of all stages of the mites and damage.

Here is a link that might be useful: does this sound like spider mites?

RE: Spider mites on difficult foliage

thanks for your help, I posted a new post under "sick walnut tree" with a picasa album for help with the tree, since it could be more than just mites. Any advice appreciated!!!

RE: Spider mites on difficult foliage

  • Posted by jean001 z8aPortland, OR (My Page) on
    Mon, Jul 26, 10 at 19:11

Your new post is at

I added a suggestion there also.

Here is a link that might be useful: your new post & images

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Garden Clinic Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here