Environ. Horticulture, Pears, Cherries, and Viticulture
University of California
Environ. Horticulture, Pears, Cherries, and Viticulture

I'm Stuck

Here's one for all of you that I just can't figure out.  Symptoms (see Photo 1 below) are on fruiting primocane blackberry, under tunnels.  Maybe 5% of leaves affected, mostly limited to the bottom third of the hedgerow but issue does occur in bunches.  Temperature-wise, as you all know, we've had warm weather the week prior to this one.

I fully expected this to be eriophyid mites, who tend to gather around leaf veins and leave this distinctive stippling, but surveying these leaves under the dissecting scope, even all the waaaaay up to the highest power, revealed nothing, no disease signs either by the way.

Interesting too that the obverse side of the leaf shows no signs of anything (Photo 2).

We've got a pretty elite group for readership here, so please send me your thoughts if you have any ideas.  Because yes I am stuck.

 

 

Odd stippling on tops of leaves of primocane blackberry.
Odd stippling on tops of leaves of primocane blackberry.

Obverse of same leaf is not at all affected.
Obverse of same leaf is not at all affected.

Posted on Wednesday, September 2, 2020 at 10:49 AM

Comments:

1.
I'm not sure which eryophyid mite you are looking for, but if its broad mite I have some experience. If broad mite was able to reach high enough populations they will cause scaring on the petiole leading to the leaf veins. Judging from the leaf stage its not a recent population. They tend to focus on the new growth. Not to mention they hate hot and dry weather.

Posted by Dominic carmassi on September 3, 2020 at 6:45 AM

2.
Dominic- interesting. It is indeed the time of year for broad mites on primocane blacks. So what you are saying they may have been on the leaf and bailed in the meantime because of hot / dry weather?

Posted by Mark Bolda on September 3, 2020 at 9:03 AM

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