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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #152014
Title: WEED CONTROL AND COVER CROP MANAGEMENT AFFECT MYCORRHIZAL COLONIZATION OF GRAPEVINE ROOTS AND ARBUSCULAR MYCORRHIZAL FUNGAL SPORE POPULATIONS IN A CALIFORNIA VINEYARD

Author
item Baumgartner, Kendra
item SMITH, RICHARD - UC COOP EXT. MONTEREY CA
item BETTIGA, LARRY - UC COOP EXT. MONTEREY CA

Submitted to: Mycorrhiza
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2004
Publication Date: 1/1/2005
Citation: Baumgartner, K., Smith, R.F., Bettiga, L. 2004. Weed control practices and cover crop management affect mycorrhizal colonization of grapevine roots and arbuscular mycorrhizal fungal spore populations in a California vineyard. Mycorrhiza 15:111-119

Interpretive Summary: We examined the effects of chemical (preemergence herbicides, postemergence herbicides) and non-chemical (mechanical cultivation) weed control practices and three cover crop treatments (bare ground, Secale cereale cv. 'Merced rye', and X Triticosecale cv.'Trios 102') on arbuscular mycorrhizal (AM) fungi in a vineyard in California's Central Coast. We examined AM fungi in grapevine roots and cover crop roots and in vineyard soil on a seasonal basis, while measuring the efficacy of the weed control practices on weeds that also host AM fungi. Weed control had a significant effect on AM fungi in grapevine roots and vineyard soil. Grapevines in rows treated with preemergence herbicides had significantly lower mycorrhizal colonization than that of cultivated rows. Mycorrhizal colonization of grapevine roots corresponded with weed frequency in two of three weed control treatments, suggesting that weed control effect may be a function of weed suppression. Neither cover crop had an effect on colonization of grapevine roots, despite higher spore populations in spring in cover cropped middles. Cover crops were mycorrhizal and shared four AM fungal species in common with grapevines. However, we found no contact between grapevine roots and cover crop roots in the vineyard we examined. There was a significant effect of season on mycorrhizal colonization of grapevine roots and spore populations. Low mycorrhizal colonization of grapevine roots in spring, which coincided with early bloom, may be due to slow internal fungal growth relative to root growth. Seasonal changes in mycorrhizal colonization of grapevine roots did not correspond to that of spore populations, suggesting that spores may not be the primary means of colonization of grapevine roots.

Technical Abstract: We examined the effects of three vineyard weed control treatments (preemergence herbicides, postemergence herbicides, and mechanical cultivation) and three cover crop treatments (bare ground, Secale cereale cv. 'Merced rye', and X Triticosecale cv.'Trios 102') on arbuscular mycorrhizal (AM) fungi in a vineyard in California's Central Coast. We quantified mycorrhizal colonization of grapevine roots and cover crop roots, AM fungal spore production, and weed frequency on a seasonal basis in an attempt to determine how different sources of AM fungal propagules contribute to the AM fungal community. Weed control had a significant effect on mycorrhizal colonization of grapevines. Grapevines in rows treated with preemergence herbicides had significantly lower mycorrhizal colonization than that of cultivated rows. Mycorrhizal colonization of grapevine roots corresponded with weed frequency in two of three weed control treatments, suggesting that weed control effect may be a function of weed suppression. Neither cover crop had an effect on colonization of grapevine roots, despite higher spore populations in spring in cover cropped middles. Cover crops were mycorrhizal and shared four AM fungal species, Glomus aggregatum, G. etunicatum, G. mosseae, and G. scintillans, in common with grapevines. However, we found no contact between grapevine roots and cover crop roots in the vineyard we examined. There was a significant effect of season on mycorrhizal colonization of grapevine roots and spore populations. Low mycorrhizal colonization of grapevine roots in spring, which coincided with early bloom, may be due to slow internal fungal growth relative to root growth. Seasonal changes in mycorrhizal colonization of grapevine roots did not correspond to that of spore populations, suggesting that spores may not be the primary means of colonization of grapevine roots.