North American Fruit Explorers mailing list at ibiblio

[david.maxwell@dal.ca]

> 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.