Abstract
The spread of arbuscular mycorrhizal (AM) fungi and infection rates in five legume cover crops [Chinese milk vetch (Astragalus sinicus L.), hairy vetch (Vicia villosa Roth), white clover (Trifolium repens L.), red clover (Trifolium pratense L.) and narrow-leaf vetch (Vicia angustifolia L.)] were studied over one season. The legumes were sown between rows of five-year-old grapevines (4.0m by 4.5m). Mycorrhizal infection varied with the season and was highest in March when vegetative growth was most vigorous. Numerous arbuscules were observed in the intra-radical spaces of both legume and indigenous weed species. Spore populations were higher in May 2001 than in October 2000 in the cover crop plots as compared with clean cultivated control plots. Peach (Prunus persica Batsch) seedlings were readily infected when planted in soils collected from cover crop plots, but infection was significantly lower when seedlings were planted in soils from control plots. All surveyed legumes were found to be highly susceptible to mycorrhizal infection and potentially capable of maintaining high AM inoculum levels in the vineyard.
