From the University of Florida News
by Brad Buck
UF/IFAS scientists find potential biological control for avocado-ravaging disease
GAINESVILLE, Fla. --- University of Florida scientists believe
they’ve found what could be the first biological control strategy
against laurel wilt, a disease that threatens the state’s $54
million-a-year avocado industry.
Red ambrosia beetles bore holes
into healthy avocado trees, bringing with them the pathogen that causes
laurel wilt. Growers control the beetles that carry and spread laurel
wilt by spraying insecticides on the trees, said Daniel Carrillo, an
entomology research assistant professor at the Tropical Research and
Education Center in Homestead.
But a team of researchers from
the Tropical REC and the Indian River Research and Education Center in
Fort Pierce have identified a potential biological control to use
against redbay ambrosia beetles that could help growers use less
insecticide.
First, they exposed beetles to three commercially
available fungi, and all of the beetles died. Then they sprayed the
fungi on avocado tree trunks, and beetles got infected while boring
into the trunk. About 75 percent of those beetles died, said Carrillo,
an Institute of Food and Agricultural Sciences faculty member.
Ideally,
the fungal treatments could prevent beetles from boring into the trees,
eliminating the risk that the pathogen would enter the trees, the study
said. But tests showed female beetles bored into the trees and built
tunnels regardless of the treatment. Still, researchers say their
treatment can prevent the female beetles from laying eggs.
UF/IFAS
scientists don’t know yet how much less chemical spray will be needed
to control the redbay ambrosia beetle. But Carrillo sees this study as
the first step toward controlling the beetle in a sustainable way.
“When
you want to manage a pest, you want an integrated pest management
approach,” Carrillo said. “This provides an alternative that we would
use in combination with chemical control.”
The redbay ambrosia
beetle -- native to India, Japan, Myanmar and Taiwan -- was first
detected in 2002 in southeast Georgia. It was presumably introduced in
wood crates and pallets, and its rapid spread has killed 6,000 avocado
trees in Florida, or about 1 percent of the 655,000 commercial trees in
Florida. The beetle was first discovered in South Florida in 2010.
Most
American-grown avocados come from California, with the rest coming from
Florida and Hawaii. The domestic avocado market is worth $429 million,
according to Edward Evans, a UF associate professor of food and
resource economics, also at the Tropical REC, Florida’s avocados are
valued at about $23 million, or about 5 percent of the national market.
The
redbay ambrosia beetle is not an issue with California avocados, so the
new tactic found by Florida scientists wouldn’t apply to this pest in
the Golden State, said Mark Hoddle, a biological control Extension
specialist with the University of California-Riverside. Hoddle studies
biological pest control for California avocados. Scientists there are
exploring ways to control a different ambrosia beetle, he said, and
bug-killing fungi may be useful for the new California pest.
More
than 95 percent of Florida’s commercial avocados grow in Miami-Dade
County, although many Floridians have avocado trees in their yard.
The
redbay ambrosia beetle feeds and reproduces on a very wide variety of
host plants, native oaks, sycamores, and of course it is very
detrimental to avocados.
The study, which also involved
scientists from the U.S. Department of Agriculture Crop Bioprotection
Research Unit in Peoria, Ill., was published online Nov. 30 in the
journal Biological Control.
By Brad Buck, 352-294-3303, bradbuck@ufl.edu
Source: Daniel Carrillo, 305-246-7001, ext. 231, dancar@ufl.edu
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Bibliography
Buck, Brad. "UF/IFAS scientists find potential biological control for avocado-ravaging disease." University of Florida News, University of Florida, Gainesville, FL 32611, 2 Dec, 2014, news.ufl.edu/archive/2014/12/ufifas-scientists-find-potential-biological-control-for-avocado-ravaging-disease.html. Accessed 21 May 2020.
Published 21 May 2020 LR
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