Integrated Use of Endothall and a Fungal Pathogen for Management of the Submersed Aquatic Macrophyte Hydrilla verticillata¹

Abstract

Laboratory experiments were conducted in 55-L aquaria to evaluate the efficacy of the aquatic herbicide endothall and the fungal pathogen Mycoleptodiscus terrestris (Gerd.) Ostazeski, applied alone and in combination against hydrilla. Treatments included 0.25, 0.50, and 1.25 mg ae/L endothall, 100, 200, and 400 colony-forming units (CFU)/ml M. terrestris, simultaneous integrated treatments of 0.25, 0.50, and 1.25 endothall + 100 or 200 CFU/ml M. terrestris, sequential integrated treatments of 100 and 200 CFU/ml M. terrestris + 0.25 and 0.50 mg ae/L endothall, and untreated controls. By 42 d after treatment (DAT), all treatments had significantly reduced shoot biomass levels of hydrilla compared with the untreated controls. Combining the two lowest herbicide rates with M. terrestris provided better hydrilla control than either treatment alone. Based on these results, an outdoor mesocosm study was conducted to evaluate the efficacy and selectivity of endothall and the pathogen applied alone and in combination against hydrilla, Illinois pondweed, American pondweed, and vallisneria. Treatments included 0.25 and 0.50 mg ae/L endothall, 100 and 200 CFU/ml M. terrestris, integrated treatments of 0.25 and 0.50 mg ae/L endothall + 100 and 200 CFU/ml M. terrestris, and untreated controls. Unlike the laboratory results, none of the treatments controlled hydrilla 100%. The combined treatments worked better than either treatment applied alone. By 42 DAT, all the combined treatments except 0.25 mg ae/L endothall + 100 CFU/ml M. terrestris had reduced above-ground hydrilla biomass by ≥ 90% compared with the untreated controls. All nontarget species sustained varying amounts of injury from endothall and M. terrestris applied alone or in combination.

Influência do fotoperíodo e da temperatura na intensidade de doença causada por Fusarium graminearum em Egeria densa e E. najas

“…O hábito perene de crescimento, a profundidade de colonização, a facilidade de propagação por segmentos de plantas e o próprio ambiente aquático, levando à diluição de agentes de controle, são problemas a serem enfrentados. No entanto, o hábito perene e a formação de grandes colonizações as tornam alvos ideais para a adoção de medidas de controle biológico (Shearer, 1996). Este mesmo autor destaca o controle biológico como a medida mais viável para esse tipo de vegetação.…”

Bioherbicides for weed control.

“…Shearer and Nelson (2002) evaluated co-application of M. terrestris with the herbicide endothall to improve control of hydrilla (Hydrilla verticillata) and also to minimize injury to non-target vegetation. At high treatment levels, both the pathogen and the herbicide have been reported to cause disease or injury to other plants (Shearer and Nelson, 2002;Shearer and Jackson, 2006). When used together, however, greater than 90% control was achieved in mesocosm studies, even with reduced rates of endothall and M. terrestris.…”

“…When used together, however, greater than 90% control was achieved in mesocosm studies, even with reduced rates of endothall and M. terrestris. Non-target plant injury still occurred, but the researchers suggested that this integrated control offered a means of effective hydrilla control while altering the dosage of bioherbicide and chemical herbicide to protect desirable vegetation (Shearer and Nelson, 2002).…”

The impact of temperature on the production and fitness of microsclerotia of the fungal bioherbicideMycoleptodiscus terrestris

“…Within 8 days, hydrilla tissues were completely colonized by the pathogen. Subsequent hydrilla collections in Texas resulted in the isolation of a very aggressive strain of M. terrestris that demonstrated excellent potential for hydrilla control alone or in combination with chemical herbicides (Netherland and Shearer 1996;Shearer 1997Shearer , 1998Nelson, Shearer, and Netherland 1998;Shearer and Nelson 2002).…”