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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #246940
Title: WEED COMMUNITY COMPOSITION IN TREE FRUIT NURSERIES TREATED WITH METHYL BROMIDE AND ALTERNATIVE FUMIGANTS

Author
item SHRESTHA, ANIL - University Of California
item Browne, Greg
item LAMPINEN, BRUCE - University Of California
item Schneider, Sally
item Trout, Thomas

Submitted to: International Journal of Fruit Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2009
Publication Date: 1/1/2009
Citation: Shrestha, A., Browne, G.T., Lampinen, B.D., Schneider, S.M., Trout, T.J. 2009. WEED COMMUNITY COMPOSITION IN TREE FRUIT NURSERIES TREATED WITH METHYL BROMIDE AND ALTERNATIVE FUMIGANTS. International Journal of Fruit Science. 9(1):78-91.

Interpretive Summary: Several agricultural cropping systems, for decades, have relied on methyl bromide (MeBr) for pest control including weeds. Alternative fumigants are being sought worldwide because MeBr has been identified as an ozone-depleting substance in the stratosphere. Ozone is needed in this outer region of the earth’s atmosphere to prevent excessive entry of ultraviolet radiation. Weed communities can respond dynamically to alterations in management systems. Thus, transition from MeBr to alternative fumigants may cause shifts in weed communities. This hypothesis was tested in four commercial fruit nurseries in California, USA. Treatments included a non-fumigated control, MeBr (98%), iodomethane (50%) + chloropicrin (50%), 1,3-dichloropropene (1,3-D), 1,3-D (61%) + chloropicrin (35%), and 1,3-D (62%) + chloropicrin (35%) applied sub-surface. All the fumigants reduced the population of common major weed species and had similar species composition as MeBr. None of the fumigants, including MeBr, controlled species such as Medicago polymorpha, Lotus purshianus, Malva parviflora, Conyza sp., Senecio vulgaris, and Sonchus oleraceus. This study suggested that, fruit nurseries transitioning from MeBr to alternatives may not see an immediate shift in weed communities. Additional weed control measures, however, will be required to manage weed species of the Asteraceae, Fabaceae, and Malvaceae family that are not controlled by either MeBr or the alternate fumigants.

Technical Abstract: Several agricultural cropping systems, for decades, have relied on methyl bromide (MeBr) for pest control including weeds. Alternative fumigants are being sought worldwide because MeBr has been identified as an ozone-layer depleting substance. Weed communities respond dynamically to alterations in management systems. Thus, transition from MeBr to alternative fumigants may cause shifts in weed communities. This hypothesis was tested in four commercial fruit nurseries in California, USA. Treatments included non-fumigated control, MeBr (98%), iodomethane (50%) + chloropicrin (50%), 1,3-dichloropropene (1,3-D), 1,3-D (61%) + chloropicrin (35%), and 1,3-D (62%) + chloropicrin (35%) applied sub-surface. All the fumigants reduced the population of common major weed species and had similar species composition as MeBr. None of the fumigants, including MeBr, controlled species such as Medicago polymorpha, Lotus purshianus, Malva parviflora, Conyza sp., Senecio vulgaris, and Sonchus oleraceus. This study suggested that, fruit nurseries transitioning from MeBr to alternatives may not see an immediate shift in weed communities. Additional weed control measures, however, will be required to manage weed species of the Asteraceae, Fabaceae, and Malvaceae family that are not controlled by either MeBr or the alternate fumigants.