FORMULATION OF AN ENDOPARASITIC NEMATODE, SUBANGUINA-PICRIDIS BRZESKI, A BIOLOGICAL-CONTROL AGENT FOR RUSSIAN KNAPWEED, ACROPTILON-REPENS (L)DC

Subanguina (Paranguina) picridis is the only plant pathogen, along wit h the fungus Puccinia acroptili, known to be effective as a biological control agent against Russian knapweed, Acroptilon repens (L.)DC. The nematode causes galls on stems and leaves of knapweed which considera bly weaken and stunt the plants. A formulation technique for long-term storage of the nematode has been developed for nematodes extracted fr om galls and for those in galls. The nematodes were encapsulated in ca lcium alginate granules, coated with a unique inverting oil followed b y an oil absorbent, and then dried. Survival of the nematodes in whole galls from infected Russian knapweed plants was assessed at two tempe ratures (4 and -20 degrees C) after drying at room temperature, with o r without a coating of inverting oil plus adsorbent. Less than 50% of the nematodes survived for 1 month when coated or uncoated whole galls were stored at 4 or -20 degrees C, with viability declining rapidly t hereafter. Nematodes extracted from galls and formulated in calcium al ginate survived in dry granules for up to 9 months at -20 degrees C wi th no significant loss of infectivity. (C) 1995 Academic Press, Inc.