VOLATILES FROM GERMINATING CANADA THISTLE SEED AND ROOT CUTTINGS THATSTIMULATE GERMINATION OF TELIOSPORES OF THE CANADA THISTLE RUST FUNGUS, PUCCINIA-PUNCTIFORMIS

Volatiles collected from germinating Canada thistle, (Cirsium arvense L.) seeds stimulated germination of the teliospores of the Canada this tle rust organism, Puccinia punctiformis. As thistle seed germination increased to 92% in 7 days, germination of teliospores on 1% agar test plates exposed to the volatiles in the germination chamber increased from 0% to 50%. Seedling volatiles collected on Tenax columns increase d germination up to 31% after 7 days. Volatiles from undamaged germina ting seeds represent normal, endogenous products. Two tridecylpolyacet ylene compounds isolated from safflower (Binder et al., 1977) stimulat ed germination of the teliospores of P. punctiformis. Volatiles collec ted from root cuttings of Canada thistle, which may become infected wh en root buds are inoculated with teliospores (French and Lightfield, 1 990), also stimulated teliospore germination. Secondary shoots from se ed inoculated with teliospores were systemically; infected after 5 wee ks. This information may be useful in manipulating the Canada thistle rust fungus for use as a biocontrol agent.