September 2020 - 16

Apple scab curbed with seafood industy byproduct
By Lori Tyler Gula
New Hampshire Agricultural
Experiment Station
University of New Hampshire
(UNH) researchers have teamed up
with colleagues from Pennsylvania
State University to investigate
whether a byproduct of the seafood
industry could help manage one of
the most devastating fruit diseases
facing the U.S. apple industry.
UNH graduate student Liza
DeGenring is investigating the
development of new tools to manage
apple scab for Northeast farmers.
Specifically, she is investigating the
combination of beneficial microbes with
a natural compound called chitosan - a
byproduct of mostly shrimp shells from
the seafood industry.
Many beneficial microorganisms
associated with plants have been
commercialized and sold as
biopesticides for use in agriculture to
reduce plant diseases. The tree fruit
industry has begun adopting these
alternative tools with some success.
These products include Serenade
ASO and Double Nickel 55, both of
which rely on beneficial bacteria.
Widespread adoption of biopesticides,
however, has been limited due to
inconsistencies in their effectiveness.
" Because biopesticides are living
products, their activity is affected by
environment. Biopesticides often fail
to grow and maintain high enough
population levels in the orchard or do
not produce antifungal compounds
at levels necessary to suppress the
disease. It is increasingly recognized
that solving these issues is key to
increasing adoption of biopesticides.
I am investigating a way to enhance
biopesticide effectiveness using
chitosan. There is evidence that
chitosan may act as a food source
for the biopesticides and stimulate
MacIntosh and Golden Delicious seedlings in the growth room at the University of New Hampshire Macfarlane Research Greenhouse.
Photos: University of New Hampshire
production of antifungal enzymes,
thereby enhancing their usefulness, "
she said.
Much of the research around
chitosan has focused on the reduction
of postharvest disease once the fruit
or vegetable has been harvested.
Chitosan has shown to be effective in
reducing plant disease and preserving
fruits and vegetables during storage
and transport. Researchers at UNH
would like to extend this research to
investigate the effect of a chitosan
application during crop production
and in combination with an
application of biopesticides.
DeGenring is working with NH
Agricultural Experiment Station
researcher Anissa Poleatewich,
assistant professor of plant pathology
and her faculty advisor. Collaborators
include George Hamilton and Jeremy
DeLise, both with UNH Cooperative
Extension, and Kari Peter at the
Pennsylvania State University Fruit
Research and Extension Center.
" Reduced fruit quality is a major
concern for the New Hampshire
tree fruit industry since NH growers
primarily market retail sales of fresh
apples through pick-your-own, farm
stands, and direct sales to grocery
stores. Apple scab lesions on the fruit
can result in decreased revenue to
the grower due to consumers' low
threshold for imperfections on their
apples, " DeGenring said.
Apple scab, caused by the fungus
Venturia inaequalis, is one of the
most destructive diseases of apple
worldwide. This disease is a significant
threat to growers in the Northeastern
United States because of the warm,
moist conditions during the growing
season that favor disease development.
Apple scab can cause up to 100% crop
loss and significant reduction in fruit
marketability. According to the USDA
National Agricultural Statistics Service,
the market value of apples nationwide
was $2.4 billion. The New Hampshire
tree fruit industry includes 228 farms
growing 1,701 acres of tree fruit, valued
at $9.3 million.
According to Poleatewich, apple
growers in New England and the
Potomac states have been battling apple
scab and fireblight for decades. These
diseases are more problematic in the
Northeast than the Pacific Northwest
due to the Northeast's warm, wet
climate that favors disease outbreaks.
" UNH has a historical reputation
of conducting apple scab research.
Much of what we know today about
the disease is based on work done
by William MacHardy, professor
emeritus of plant biology. New
Hampshire tree fruit growers have a
strong history of collaboration with
UNH to develop and adopt more
environmentally and economically
sustainable practices. In the 1980s,
MacHardy and colleagues developed
disease-forecasting models that
growers still use today to predict
outbreaks and apply fungicides
only when disease risk is high. New
Hampshire growers also have adopted
integrated pest management, which
incorporates cultural, biological, and
16 | FruitGrowersNews.com

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September 2020

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