Insecticides Defend Florida Avocado Trees from Invasive Species

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The redbay ambrosia beetle is an invasive species that vectors a fungus, Raffaelea lauricola, that causes laurel wilt, a lethal disease of several plant species within the Lauraceae, including avocado… The spread of the fungus has affected large areas of native Lauraceae trees in the southeastern United States and is now threatening the avocado industry in south Florida.

“In February 2012, the first avocado tree in a commercial grove located in the northeastern quadrant of the avocado growing area was diagnosed with R. lauricola. As of July 2013, 90 trees have been diagnosed R. lauricola positive, and >1,900 symptomatic trees have been removed as part of a suppression and sanitation strategy. …Because of the lack of alternative pest management strategies (e.g. biological control, repellants, etc.), private landowners and avocado producers rely on applications of chemical insecticides to complement sanitation practices and protect trees in groves affected by this beetle-disease complex.

The current strategy is based in early detection and removal of diseased trees to eliminate beetle breeding sites and fungal inoculum sources. The diseased trees are uprooted, the stump and roots burned, the trunk and limbs are chipped, and the chips and adjacent trees are sprayed with insecticides.”

Authors: Carrillo, D., et al.
Affiliation: Tropical Research and Education Center, University of Florida.
Title: Potential of Contact Insecticides to Control Xyleborus glabratus (Coleoptera: Curculionidae), a Vector of Laurel Wilt Disease in Avocados
Source: Journal of Economic Entomology. 2013. December.

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Consumers Want Perfect Avocados: Growers Must Spray

Infected Avocados

Avocado Thrip Fruit Scarring

Historically, the production of avocados in California required little usage of insecticides. Avocado pests were kept under commercially acceptable control by a variety of beneficial organisms. This situation changed in 1996 with the appearance of avocado thrips which feed on the surface of the fruit. Feeding scars develop while the flesh of the fruit is a healthy green. Even partial fruit scarring results in downgrading of fruit in packinghouses because of cosmetic damage unacceptable to consumers .

“The California avocado industry is under increasing threat from the introduction of arthropod pests. The avocado thrips, was first detected in California avocado groves in June 1996, and it has since spread to most of the major production areas within the state where it has become the primary insect pest. The main source of economic loss arises from feeding damage that causes scarring of immature fruit, leading to a reduction in fruit quality at harvest.

In California avocado groves, the use of foliar insecticides is the predominant tactic adopted by growers for the management of arthropod pests, including the avocado thrips. Aerial applications by helicopter are needed for the majority of California avocado groves because most are grown on steep hillsides.”

Author: Byrne, F. J., et al.
Affiliation: University of California
Title: Field evaluation of systemic imidacloprid for the management of avocado thrips and avocado lace bug in California avocado groves.
Source: Pest Management Science. 2010. 66:1129-1136.

California Avocado Production Would be 82 million Pounds Lower with Conversion to Organic Practices

New Orchard Weeds

New Orchard Weeds

California farmers produce 550 million pounds of avocados annually. 8% of the avocado acres are managed with organic production practices. A recent economic analysis by the University of California shows why so few avocado acres are organic. Even though organic avocados receive a price premium, lower yields (15% lower) means lower profits than avocados grown with chemical inputs. The 15% lower yields would mean a loss of 82 million pounds of avocados if all the California avocado growers switched to organic practices. Weeds are the biggest problem for organic avocado growers.

“Profitability estimate of organic avocados in these counties is lower than avocados produced conventionally. Though organic avocados are considered to receive $0.20 more per pound than conventional avocados, organic avocado production shows lower yield than the conventional production.

Based on our discussions with growers and the UCCE farm advisor, organic yield is considered lower than the conventional production. In this study, organic avocado yield is estimated at 15% lower than the conventional yield.”

Author: Etaferahu Takele, et al.
Affiliation: Area Farm Advisor, Agricultural Economics/Farm Management, University of California Cooperative Extension (UCCE) Southern California
Title: Avocado sample establishment and production costs and profitability analysis san diego and riverside counties, 2011 organic production practices
Source: University of California Cooperative Extension. 2013.