North American Fruit Explorers mailing list at ibiblio

[Steve <sdw12986@aol.com>]

On 6/11/2012 12:39 PM, david.maxwell@dal.ca wrote:
> >  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.


David, thanks for that. I'm wondering about other ways to control these 
critters.
One thought would be treat the ground with some insecticide just before 
emergence time. That could eliminate the problem of killing the 
pollinators.
My other thought would be to cover the entire drop area of each tree 
with 2 big sheets of clear plastic (one for each side of the trunk, 
overlapped) or white plastic if clear would over heat the lawn grass. 
Put it on when the buds just barely show and remove it at petal fall. 
This could only work if your neighbor doesn't have a big neglected apple 
tree (I think I would be OK) AND if all your trees had clear open space 
all around them (2 or my trees do and 2 don't).

Steve in the Adirondacks