Biology of Subanguina picridis, a Potential Biological Control Agent of Russian Knapweed

A. K. Watson

Abstract


The knapweed nematode, Subanguina picridis, forms galls on the leaves, stems, and root collar of Russian knapweed, Acroptilon repens. After being revived from a dormant, cryptobiotic state, second-stage juveniles required at least 1 month in a free-living state before becoming infective. Galls were induced on relatively slow-growing host plants that retained their apical meristems at or near the soil surface for 2-5 weeks. Galls developed extensive areas of nutritive tissue. The nematode was introduced from the Soviet Union and released in Canada for the biological control of Russian knapweed. Key words: Acroptilon repens (Russian knapweed), biological weed control, gall, histopathogenesis, host specificity, physiological sink, Subanguina picridis (knapweed nematode).

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