During the first season of testing, the Surround WP product has been extremely effective at
suppressing plum curculio, one of the most devastating and difficult-to-control apple pests for
orchardists in the Midwest. The codling moth, another very serious pest of apples was trapped in the
orchard only in very small numbers. While we did find some codling moth damage, we believe there
simply were not enough insects to make a fair conclusion of the product's effectiveness against that pest.
Leaf rollers, on the other hand, were commonly trapped throughout the season, and were not significantly
affected by Surround WP treatments. Much of the leafroller damage was caused early in the season when
coverage of the small fruit with the material was perhaps less effective. Surround WP also significantly
suppressed both fungal diseases flyspeck and sooty blotch. These are superficial fungal diseases that ruin
the appearance of the apple, reducing their market value. The foliar disease cedar apple rust was
significantly reduced on one cultivar only suggesting an interesting relationship between cultivar and
treatment.
Perhaps most intriguing are the conclusions that frequency of application is more important than
rate in suppressing fungal diseases whereas rate of application is most important for suppressing the
insect plum curculio. There could be many speculative reasons for this phenomena, but it seems logical
that a constant but not necessarily strong coating of film on the fruit may somehow interfere with fungus
development, while a good strong dose of film is required to repel insects such as plum curculio. This
hypothesis tends to agree with the data in that a high dose sprayed frequently tends to repel the curculio
better.
An interesting question raised by this study that cannot be presently answered is the following: If
an entire orchard were treated, thereby leaving no unsprayed "control" trees for insects to find and easily
attack, would the insects be forced to "break through" the particle film barrier to feed and lay eggs or
would they be completely repelled from the entire orchard?
This study has been very exciting and challenging. We are anxious to complete the second
season of the study in 2001 which will make our results scientifically valid. From there we look forward
to providing specific guidance to organic orchardists wishing to try this new and extraordinary
technology.
Related Grant:
Outcome PDF:
