Hurricanes Increase the Need for Insecticides in Louisiana Sugarcane Fields

Fire Ant Killing Sugarcane Borer

Fire Ant Killing Sugarcane Borer

Louisiana is the top producing sugarcane state accounting for 40% of the nation’s sugarcane production. Approximately 3 billion pounds of raw sugar are produced annually by Louisiana sugar mills. The sugarcane borer is the most damaging insect pest of sugarcane in Louisiana. The larvae bore into the plant where they feed on the central tissue. Borers make tunnels up and down the stalk. The size and weight of the stalks are decreased. Sugarcane borers in Louisiana are controlled by an integrated system that consists of spraying insecticides, planting varieties with some resistance and by natural enemies of the borer. The most important natural enemy of the borer is the red imported fire ant. Typically, the predation of fire ants contributes an estimated savings of two insecticide sprays. However, when the sugarcane fields are flooded by hurricanes, the fire ants are negatively affected and insecticide use has to increase.

“On 24 September 2005, Hurricane Rita made landfall on the extreme southwestern coast of Louisiana near the border with Texas as a Category 3 hurricane.

Twelve thousand to 16,000 ha of sugarcane produced in south Louisiana were flooded by saltwater from Hurricane Rita storm surge.

During spring 2006, sugarcane growers and contracted agricultural consultants began observing that flooded areas seemingly had more [sugarcane borer] infestations, which might require earlier and more frequent insecticide applications for D. saccharalis control.

This study showed that growers had to treat more (2.4-fold increase) in zones impacted by the hurricane storm surge.

S. invicta [red imported fire ant] seemed to be negatively impacted 10-12 mo after the areawide habitat disruption caused by the storm surge flooding. When plunged into freshwater, S. invicta individuals gather and form floating clusters that can drift for more than a week without drowning. However… S. invicta is susceptible to saltwater, sinking within 30 min when in 3.5% saltwater (approximately equal to seawater), and within 48 h in 1% saltwater. …Susceptibility to saltwater flood and limited dispersal abilities may explain why S. invicta was negatively impacted by the storm surge and slow to recover back to prehurricane population levels.

This study suggests that Hurricane Rita disturbed the pest management stability between beneficial and pest anthropods for the subsequent production season, requiring additional insecticide applications…”

Authors: Beuzelin, J.M., et al.
Affiliations: Department of Entomology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center
Title: Impacts of Hurricane Rita storm surge on sugarcane borer (Lepidoptera: Crambidae) management in Louisiana.”
Source: Journal of Economic Entomology. 2009. 102[3]:1054-1061.

Rice Insect Pest Invades the World from the USA

Rice Water Weevil Larva

Rice Water Weevil Larva

The home of the rice water weevil is the southeastern US where the species feeds on
grasses in swampy areas. When rice plants were introduced into America, the
insect quickly found this new grass plant to its liking and has been feeding on
rice ever since. The weevils move into rice fields every year from nearby woods
and clumps of grass. Farmers have used insecticides since 1950 to control the
weevil populations in rice fields. The rice water weevil has spread from the
southeastern US to Louisiana, Texas, California, Japan, China and Italy where
it would decrease rice production without insecticide sprays.

“The rice water weevil, Lissorhoptrus oryzophilus, is the most destructive insect pest of rice in the United States. The insect is native to the southeastern United States but has, over the past 60 years, invaded important rice-growing areas in California, Asia and Europe and thus poses a global threat to rice production.

Small-plot research and sampling of commercial fields indicate yield losses from the rice water weevil would likely exceed 10% in many areas if no insecticides are used.”

Authors: Stout, M. J., et al.
Affiliations: Department of Entomology, Louisiana State University.
Title: The influence of rice plant age on susceptibility to the rice water weevil, Lissorhoptrus oryzophilus.
Source: Journal of Applied Entomology. 2013. 137:241-248.

Soybean Rust Stopped in its Tracks

soybean rust

Soybean Rust Pustules

Asian soybean rust (ASR) was first detected in the continental U.S. in 2004 in Louisiana. Before the discovery in the U.S., the yield losses caused by ASR in many parts of the world were devastating. In South America, especially in Brazil, yield losses ranged from 10 to 80%. Funding was made available for a network of ASR sentinel plots that would serve as an early-warning system for the presence of the disease. Sentinel plots are planted two to three weeks earlier than commercial fields. If ASR is found in a sentinel plot, this is a signal to scout surrounding fields. The growth difference in sentinel and commercial fields allows growers and farm advisors time to make decisions. If conditions are optimal for the rapid spread of ASR (warm and humid), the solution is treatment with fungicides.

“Soybeans and wheat made an awesome economic combination for growers in the Southeast this year, creating plenty of optimism for profits from this year’s beans and optimism for planting more of the crop in 2013.

Even the earliest appearance on record of Asian Soybean Rust did little to slow down what is shaping up to be one of the best soybean crops on record in some parts of the Upper Southeast.

Rust was detected along a southern tier of North Carolina counties on Sept. 12, but Mother Nature, a well-coordinated system of sentinel plots, and timely actions by growers stopped rust in its tracks.

Though the disease was documented on Sept. 12, in North Carolina, the earliest on record by three days, it appears there will be little damage to the state’s 1.65 million acre soybean crop.

Duplin County, N.C., Extension Agent Curtis Fountain says once the disease was detected in counties less than 100 miles from his county, growers quickly reacted and applied fungicides when needed.

North Carolina State University Plant Pathologist Steve Koenning and Soybean Specialist Jim Dunphy issued timely updates on movement of the disease and provided virtually day-to-day observations on when and what to spray to best manage ASR.”

Author: Roberson, R.
Affiliation: Farm Press, Editorial Staff
Title: Rapid Grower Response, Weather Stop Early Soybean Rust Outbreak
Publication: Southeast Farm Press, December 5, 2012.