Skip to Content.
Sympa Menu

nafex - Re: [nafex] Apple pest (part 2)

nafex@lists.ibiblio.org

Subject: North American Fruit Explorers mailing list at ibiblio

List archive

Chronological Thread  
  • From: david.maxwell@dal.ca
  • To: Steve <sdw12986@aol.com>, nafex mailing list at ibiblio <nafex@lists.ibiblio.org>
  • Subject: Re: [nafex] Apple pest (part 2)
  • Date: Mon, 11 Jun 2012 13:39:51 -0300

> OK, this was going to be my important question but I have it figured
> out. I had in the back of my mind that maybe the pest in question 1
> was the same as this question 2. I couldn't see how, since there were
> 2 distinct types of damage. My biggest apples are just bigger that the
> size of a nickle with some varieties still much smaller. I couldn't
> understand how I could have apparent coddling moth damage on so many
> tiny apples when I virtually never find them in mature apples. I also
> wondered why the entry hole wasn't at the calyx end. Well, I don't
> have coddling moths, I have European apple sawfly. The reason for two
> types of damage is that they start right at petal fall and make a path
> on the surface of very young apples:
> http://www.wvu.edu/~agexten/orchardmon/pest_descriptions/pest_images/p
> h1-35c.JPG

The beasts which you see just after petal fall are indeed EAS. But you may
still get coddlers
also; just later. The only two pests which attack the seeds are EAS and CM.
The EAS
emerge from the soil in spring over a very short time frame, (this year, in
my orchard, virtually
all emerged in a 5 day period). They mate almost immediately after
emergence, and then
the female seeks out a blossom to lay her eggs. She wants a blossom which is
just
beginning to open. My suspicion is that the variation in attack rate Claude
describes is due to
the EAS not getting its emergence quite timed with the bloom.

> Lastly, it's going to be hard to spray at the perfect time next year.
> I have multiple varieties grafted on 3 of the 4 trees. I can't spray
> the early bloomers right at petal fall when the later blooming
> branches still have bees working the flowers. I'll keep drowning the
> infested apples as long as I still find larva inside and next year
> I'll do what I can with spray. That should knock them back down to low
> numbers.

You are correct that it is difficult to time sprays so as not to interfere
with pollinators on later
blooming cultivars. But I think we have the solution. (We are still running
a trial). An extract
of a tropical tree, Quassia amara, seems to be remarkably effective, (reduced
damage in cv.
King last year from 60% to 2.8%), and, more to the point, is non-toxic to
bees, beneficials,
fish, mammals, humans... It needs to be sprayed on the developing fruit
prior to the hatch of
the eggs, (which takes place around 82 degree days,[base 9.8 degrees C] after
oviposition),
and seems to kill the first instar larvae particularly well. (Most of the
work on this was done
by a German researcher, Jutte Kienzle.)
The only problem with this whole thing is that Quassia extract is not
registered as a pesticide
anywhere in the world, and neither of the two (?) commercial producers in
Europe has any
interest in seeking registration, (which is enormously expensive and
arduous). It should be
quite easy to prepare one's own extract on farm, but you still have to have a
source of the
Quassia wood chips, (which come from the Carribean and South America). And
what that
would do to commercial growers' ability to market their fruit, (either
conventional or organic), I
don't know.








Archive powered by MHonArc 2.6.24.

Top of Page