Hydrilla's Resistance to Herbicide Gives Scientists a New Challenge
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Category: AgricultureType: News
Source: USDA Agriculture Research Service
Date: Tuesday, November 1st, 2005
Scientists with the Agricultural Research Service (ARS) and a private firm have encountered a troubling turn of events in the fight against an invasive weed that's choking many waterways in the southeastern United States.
The researchers--at ARS' Natural Products Utilization Research Unit in Oxford, Miss., and with SePRO Corporation, a Carmel, Ind.-based plant-protection management firm--found that a form of hydrilla (Hydrilla verticillata) has developed resistance to fluridone, the most effective herbicide against it.
They've pegged the resistance to a gene mutation in the dioecious, female form of hydrilla. So far, this mutation has been found only in hydrilla inhabiting several Florida lakes. A monoecious hydrilla--a form that has both male and female flowers on the same plant--that 1st appeared in the middle Atlantic states has, to date, not shown resistance to the herbicide.
The ARS studies in Oxford were conducted by plant physiologist Franck Dayan and molecular biologists Brian Scheffler and Albrecht Michel. Scheffler now leads ARS' Mid-South Area Genomics Lab in Stoneville, Miss., while Michel is no longer with ARS.
Hydrilla's ability to thrive even in adverse conditions has led researchers to dub it "the perfect aquatic weed." Rooted in bottom sediments, it grows long, thin stems that rapidly reach the water's surface and form a thick mat. It was introduced to the U.S. from Southeast Asia in the 1950s near Tampa, Fla.
According to Dayan, the resistant hydrilla has increased treatment costs for affected lakes.
The new discoveries have spurred government and SePRO scientists and aquatic systems managers to seek additional environmentally friendly ways to combat the weed. Biological agents being studied for controlling hydrilla include some insects and the fungal pathogen Mycoleptodiscus terrestris, which when used with fluridone seems to increase hydrilla's susceptibility to the herbicide.
Read more about this research in the November 2005 issue of Agricultural Research magazine.
ARS is the U.S.D.A.'s chief in-house scientific research agency.
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