Subject: Re: Phermones

From: [email-masked] (Joel Clark)
Date: 20 Jul 1995 00:04:36 GMT

In article <[email-masked]> [email-masked] (Mike Nelson) writes:
>Joel Clark ([email-masked]) wrote:
>
>: Then we visited a 200 acre Filbert Orchard where an Extension agent
>: spoke on the use of phermones in controlling orchard pests.
>: We went on to a 2000 tree apple orchard. 
>: Another speaker from private industry spoke on some trials 
>: of a phermone/pesticide mix.  This is applied as a couple of drops of
>: tar like substance per tree.
>
>My neighbor tried pheremone traps on his nectarine trees to stop "borers". 
>He doesn't use them anymore, because he thinks that the traps attracted
>too many insects that did not end up in the traps and resulted in more
>damage to the tree. 
>--
>Michael T. Nelson == Real-Time Controls == The Embedded Systems Specialists 

Notice I did not say anything about phermone traps.  In fact neither of
these two speaker would recommend phermones traps alone as a method of
"stopping" insect damage. The Extension agent did recommend phermone 
traps for monitoring when certain insects are present in the orchard.
This is usually used to tell when pesticides will be most effective.
Most of these listeners are trying to raise commercial crops of fruit and
deal with a constant annual presence of particular insects. Insects 
coming from other orchards represents a significant factor in an orchard
with annual control measures, but in an orchard with no control measures
migrating insects would be insignificant.  For example an orchard
with annual pesticide spray program might be experiencing a 5% damage 
rate of which a big portion is probably due to migrating insects, but
an orchard with no control measures would probably experience a 50%-75%
damage rate of which the majority is from overwintering insects.

He also discussed the pros and cons of trying to use phermones for
confusing male insects. This is usually tried by putting so many 
phermone sources in an orchard (many per tree) as to prevent the male
>from  ever finding a female.  There are several problems with this 
technique too.
The other speaker's subject was using a phermone/insecticide mix at
a rate of 2 or 3 spots per tree to kill any males attracted to the
phermones.  Both speakers explained that no phermone method did anything
for fertilized females that wander into the orchard and lay their eggs. 

My own experience with 4 apple trees would lead me to believe phermone
traps can provide some control of insect problems in this small sample.  
By putting two traps per tree and changing them every 4-6 weeks it appears 
we have reduced the damage rate from 80%-90% to 15%-20%.  This kind of
program would be very labor intensive in a large orchard, and the 15%-20%
damage rate might well eliminate any potential profit. Its pretty hard
to generalize as to the success or failure without understanding the
goals of the grower and the history of the orchard.

My filbert orchard had been controlled with annual pesticide spraying
when I first bought it.  The first year we owned it we did not spray
and only suffered 0.48% damage. Great Success!! Eh?  The next year
of no spray we suffered 5.1% damage.  The next year 19% damage. 
This year we are spraying.  This orchard is surrounded by controlled 
orchards on three sides and an abandonded orchard on the fourth side.
It clear reducing pest control will lead to greater damage.  
It would also seem overwintering insects eventually present a greater 
problem than insects that migrate in. And while phermone traps may be
a usefull tool, they have not been proven to be a satisfactory sole
remedy for a commercial grower. 

joel clark