Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 19, 1997
Publication Date: N/A
Interpretive Summary: The cost to our society resulting from the illegal use of cocaine is staggering. Bioherbicides are being considered as alternatives to chemical herbicides for the control of coca, the source of cocaine. Bioherbicidal formulations of Fusarium oxysporum, a pathogen of coca, were tested in greenhouse and field studies. The bioherbicide consistently introduced large populations of the coca pathogen into the soil which persisted for u to 7 months. The bioherbicide increased the kill of coca in three separate field tests. These studies indicate a bioherbicide for the control of coca can be produced using established methods. It may be possible to reduce production of cocaine by killing coca plants in the field using a bioherbicide. Control of cocaine production could reduce many of the ills of our society which result from the illegal use of this drug and would be of benefit to not only citizens of the United States but also to the world. .
Technical Abstract: A rice alginate prill formulation of isolate EN-4 of F. oxysporum Schlechtend:Fr. f. sp. erythroxyli, pathogenic to Erythroxylum coca var. coca (coca) was evaluated in greenhouse and field studies to determine its ability to enhance pathogen populations in the soil and cause disease in coca. The formulation was applied to 4 different soil types in the greenhouse at 5.5 kg/ha. The formulation enhanced the population of EN-4 in each soil and most (>90%) of the fungul population remained in the upper 5 cm of soil during the 49 day experiments. When applied in field experiments, the formulation enhanced the population of EN-4 in each soil,type. EN-4 was present in the upper 7.6 cm of soil 28 days after application at populations similar to those in the greenhouse studies (1 x 10**3 to 1 x 10**4 cfu g**-1 soil). Elevated populations of the pathogen (1 x 10**2 cfu g**-1 soil) were still present in treated soils 229 days after application of the formulation. The areas used for field studies were already infested with the pathogen and typically developed high levels of fusarium wilt within 2 years of planting with coca. The formulated F. oxysporum began having a significant effect on plant death 100 to 200 days after application based on repeated measures analysis. These data suggest a formulation of Fusarium oxysporum f. sp. erythroxyli which enhances the incidence of fusarium wilt in coca fields can be produced using established techniques.