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shifting pest preferences and timing

Posted by Michael Phillips 
shifting pest preferences and timing
September 12, 2016 01:23PM
I'm rather certain that Apple Maggot Flies have umasked my American-Asian hybrid plums. The last two wine-making session revealed plums with dark spots had a white critter inside. I've been observing adult AMF on plum surfaces but just hoped it was in flitting about from one apple tree to the next. An "apple pest" wouldn't possibly go after the wrong fruit, would it?

This year, here anyway, the answer is probably yes. We have excessive AMF pressure following last season's heavy crop. That typically means fewer apples as well. Voila! the plum. The timing here is so wrong for plum curculio which makes its move in May/June, with fruitlets dropping to the ground prematurely around the time of "june drop". This allows PC larvae to burrow into the ground to pupate throughout the month of July and then be off as young adults to overwintering grounds in the woods by now. Has anyone else witnessed this evolutionary move by AMF?

This insect take on dealing with erratic climate curveballs has me wondering what other shifts will become apparent. Look for an extra generation of Codling Moth (CM) in most locations. I'm definitely observing more Lesser Appleworm (LAW) damage in the calyx end of apples, which tells me "control timing" for internal Lepidoptera has shifted forward in the summer months. That warning about ambrosia beetles in New York orchards is like a grenade launched into our unsuspecting midst. Just as others are probably seeing European Apple Sawfly (EAS) for the first time as it moves westward and southward at a greater pace than anticipated.

What's changing in your corner of the world?

Lost Nation Orchard
Zone 4b in New Hampshire
Re: shifting pest preferences and timing
September 12, 2016 11:23PM
Michael Phillips Wrote:
>Just as others are probably
> seeing European Apple Sawfly (EAS) for the first
> time as it moves westward and southward at a
> greater pace than anticipated.
> What's changing in your corner of the world?

Well, today I harvested the tree that historically always had a lot of sawfly which reduced drastically its production.
Guess what: this year this tree had its biggest crop ever, with absolutely no traces of sawfly...
They are just gone, or some natural predator found them.
And this has nothing to do with any intervention from my part, as I didn't spray anything.
So sometimes things move in the right direction just by themself!

By the way, David, do you still have your study going on EAS control? How is it going?

And I should add about Apple maggot that yet I haven't noticed any increase of pressure here. There is some, but not very much and there aren't too many fruits affected - those go to the cider press anyway, so there isn't any losses.


Jolicoeur Orchard
Zone 4 in Quebec

Edited 1 time(s). Last edit at 09/12/2016 11:29PM by Claude Jolicoeur.
Re: shifting pest preferences and timing
September 13, 2016 08:40AM
My study of the use of Quassia amara for control: yes, this is still - sort of - ongoing. It suffered a major setback when my fellow researcher, who is a very good scientist, cut me loose. (I have never been able to elicit a clear answer why). I struggled on on my own, but ultimately lack the skills in statistical analysis needed to be able to extract valid information from my results. In addition, I have failed to dedicate the time and stick-to-it-iveness needed to the project. But, in crude terms, it appears that Quassia amara is effective in markedly reducing the damage caused by EAS, (generally to < 5%). The appropriate timing of the spray is a little uncertain, and obtaining the material is even more problematic. (I got my original supply on a research exemption, requiring massive amount of paperwork with government, and, I think probably dependent on my association with the researcher from Agriculture Canada, which is now defunct.) (I did note that she obtained approval from the Minor Use Pesticide Program, I think 2 years ago, to pursue official funded research on the use of Quassia, (what we were doing together was both unfunded - she pinched funds from another project - and unapproved by her bosses, at a time when science was under major attack by our (previous) government.) But where this went I have no idea, and, as I said, she isn't even talking to me, so I don't know what, if anything she has done.)

But, the EAS did not leave me here in Nova Scotia.

Broomholm Orchard
Zone 5b in Nova Scotia
Re: shifting pest preferences and timing
September 14, 2016 05:36PM
If I wind up with maggot in my plums I am going to have a nervous breakdown. After years of squat on the plum front, we are finally seeing some nice cropping. As for apple maggot, I was coincidentally chatting today with another area grower, commiserating on the EXTREME intensity of apple maggot this year. As a kick in the rear, our apples were hauntingly devoid of both sawfly and codling moth. Perhaps I was awesome in management, but there were trees without a single codling moth. Really. Scab clean fruit almost exclusively. The punchline...nearly our entire crop has been reduced to cidergrade due to apple maggot. Beautiful fruit, as a tease, only to be opened up to reveal the critter, one apple after the next. Due to a lot of berry understory, I usually avoid any heavy summer insecticidal sprays, but even with a lot of sticky traps out there, that may have to change.

Walden Heights Nursery & Orchard
Zone 3 in Vermont
Re: shifting pest preferences and timing
September 14, 2016 06:19PM
This reminds me of an article I read many years ago, about the evolution of the Apple Maggot Fly. This insect is indigenous of North America, but the apple tree is not... Originally, the AMF used the hawthorn fruit and it took quite some time before it started to attack the apples after the Europeans introduced the apple in America. Eventually, if I remember correctly, the species evolved in 2 different species, one stayed on the hawthorn, while the new species "worked" on the apple.
Would we be seeing the same phenomenom with plums?

Jolicoeur Orchard
Zone 4 in Quebec
Re: shifting pest preferences and timing
November 28, 2016 11:37PM
Todd , I've done extremely well since swinging over to holistic practices . If we hit 1% our local authorities get crabby ( for codling moth ) For the last three years I can count all the worms we've found on one hand . I wonder if you might have noticed something I have . I have an absolutely huge population of very aggressive Lady bugs . These guys have as many as 10 spots on them as compared to our regular 4-5 and they are quite willing to chew on me . Not something I remember as a kid . There are signs of CM being here , stings within unthinned clumps , but no takers . Theres is also sheddings of lady bug larva in the clumps as well . I also have a great population of praying mantis . As this is the third year in a row I'm wondering about a possible correlation .
Re: shifting pest preferences and timing
November 29, 2016 11:55AM
David, I am going to guess you are seeing the asian ladybug (asian ladybird beetle). These tend to have more spots, and the ones I have seen are a bit on the orange side. They were introduced at least by the 70s, to you guessed it, control insects. Even though they are criticized as an invasive, they do predate. This is the one that is likely coming out of the house walls if you are unlucky. There are quite a few species of these beetles (do note bugs have piercing mouthparts, which lady"bugs" do not. You might reference some online images and compare. It is all academic I think, but nice to know who your neighbors are.

Have you witnessed the beetles or larvae attacking codling moth larvae, or them being harassed?

Walden Heights Nursery & Orchard
Zone 3 in Vermont
Re: shifting pest preferences and timing
December 09, 2016 07:27AM
No , haven't seen any harassement Todd , ( would have to be here in the day light to see . smiling smiley ) just remnants of lady bugs in where there are stings and the lack of codling moth .

Hillview Heritage Farm
Zone 5*in British Columbia
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