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Pear Leaf Blister Mites

Posted by Russ Martin 
Pear Leaf Blister Mites
June 07, 2017 02:28PM
I have two pear trees that appear to have Pear Leaf Blister Mites (PLBM). These trees are not bearing yet, but I am sure they affect the tree's growth. These trees get sprayed along with my bearing apple trees. I follow the holistic schedule with Neem Oil, dish soap, Effective microbes, BT, molasses, Fish during cover sprays, Spinosad, Seaweed, along with four teas- horsetail, stinging nettle, comfrey and chives. I have not controlled them very well and I would appreciate any experience with this pest. Seems like the control time is early spring/ late winter with an oil spray to suffocate over wintering mites. Does anybody have other strategies that take advantage of other weaknesses of PLBM?

Russ Martin
Zone 4b Extreme west Central Wisconsin Hager City, WI
Re: Pear Leaf Blister Mites
July 10, 2017 09:49PM
Hi Russ,

I had Pear Blister mite surface a few years ago on two 3 year old young Magness Pears (OHxF87 Rootstock). I took the route of hand picking off the leaves at the end of the growing season (1st week of October here at my location in the Siera Foothills of California) and before the first frost. Id say just time it for about 3 weeks before your 1st estimated frost in the fall and you will catch large numbers still living large on those leaves.

I had 90-95% success in this method. Sure it took a little while, but it was no more time consuming than thinning fruit and I didnt need to get the sprayer queued up to do it. Consider it quality time with your good friends (your trees) and your smile will follow.

The following year, I had Pear Blister Mite show up on only a handful of leaves and I picked those off, as I saw the evidence surface. Been blister free on those two trees for two seasons now.

Not full proof, but for young trees, and when there is only a few to deal with . . . This is the method I would recommend.

Then consider dropping the hammer on those microscopic dudes in the dormant season with oil and/or lime sulfer soak.

Good luck!

Gopher Hill Apples
Zone 8 in California
Re: Pear Leaf Blister Mites
July 18, 2017 03:01AM
Thank you Paul,

I like your picking leaves idea. These are young trees and I can reach most leaves without ladders. I was also planning several dormant sprays. Any thoughts on using 2% Neem oil and soap on leafless trees, one late fall application (warm day) and one or two warm spring day applications?
Re: Pear Leaf Blister Mites
July 07, 2018 06:18AM
Hi Paul,

A follow up to this post. I picked off and burned every leaf off my pear trees last fall 2-3 weeks before first frost. I sprayed once last fall and once in early spring with 2% Neem oil prior to leafing out. I am very pleased with results. 95-98% effective. Pear leaves look great this year.


Russ Martin
Zone 4b Extreme west Central Wisconsin Hager City, WI
Re: Pear Leaf Blister Mites
July 07, 2018 03:26PM
Pear blister mites went from burgeoning problem in my eight or so pear varieties to not a single trace this season. The warm fall last season followed by quick cold in November and then even deeper cold in early /December literally froze leaves on numerous trees. I expect some PBM were already in buds by that point but apparently the cold penetrated bud scales equally effectively. I was plain lucky to have a test winter come along and do some good. These mites got here in a tree from a commercial nursery, then spread to my more mature trees over the course of several years. Meanwhile, it's also brilliant that removing leaves early enough in fall -- prior to PBM migrating inward -- is a solution that works. Credit to Paul for this insight. And to Russ for confirmation in another ecosystem entirely.

Lost Nation Orchard
Zone 4b in New Hampshire
Re: Pear Leaf Blister Mites
July 07, 2018 05:12PM
I have also had PBM for a number of years here in Quebec.
For my part I have controlled this by heavy winter pruning of new growth and burning the cut wood, plus application of dormant oil just before budding.
This strategy has been efficient to keep the infestation under control, but never completely eradicated the mites. Sometime during the season I would always see a few shoots affected. Probably because my pear trees are getting quite big (these are standards that were planted between 1988 to 1992) and it is a bit difficult to perfectly spray them everywhere with the dormant oil.
However this year, I yet haven't seen a single shoot affected. Here also, as Michael mentioned, we had a quite hard and cold winter, and this may very well be the reason for their dissapearance.

Jolicoeur Orchard
Zone 4 in Quebec
Author, The New Cider Maker's Handbook
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