ALGINATE PRILL FORMULATIONS OF TALAROMYCES-FLAVUS WITH ORGANIC CARRIERS FOR BIOCONTROL OF VERTICILLIUM-DAHLIAE

Pyrophyllite clay (Pyrax), milled chitin, corn cobs, fish meal, neem c ake, peanut hulls, soy fiber, and wheat bran were used to make alginat e prill with or without ascospores of Talaromyces flavus. The formulat ions were compared for their ability to induce T. flavus to control Ve rticillium wilt of eggplant in the greenhouse in field soil and to inc rease populations of T. flavus in three field soils (two loamy sands, one silty clay). Survival of T. flavus in prill at 5 C or ambient temp erature (22-24 C), as well as the carbon (C) and nitrogen (N) contents of the prill, were also determined. Two formulations (corn cobs and p yrophyllite) consistently enhanced biocontrol activity. In treatments without T. flavus, half of all plants were wilted 59 days after transp lanting whereas more than half of the plants treated with T. flavus in either pyrophyllite or corn cob prill remained symptomless 90 days af ter transplanting. In some experiments, T. flavus in soy fiber prill d elayed the median time for symptom development by about 10 days. Exper iments on survival and proliferation in soils indicated that there wer e highly significant interactions among carrier, soil, and sampling ti me. These interactions indicate that the formulations performed differ ently in different soils. Populations of T. flavus from some prill X s oil X combinations increased during the 18-wk experiment while populat ions from other combinations remained constant or decreased. Populatio ns of T. flavus in two soils (Hatboro loamy sand, silty clay) amended with wheat-bran prill were greater than those with other formulations in the first 2 wk of assay in these two soils. Populations of T. flavu s in the loamy sand amended with peanut hull prill were greater than t hose from other prill at the 8- and 12-wk samplings in this soil. Pril l with pyrophyllite and corn cobs had significantly greater C/N ratios than prill with other carriers. Carriers significantly affected survi val of T. flavus at 5 C and at ambient temperature. Survival at both t emperatures was best in prill formulated with corn cobs, soy fiber and peanut hulls. Temperature did not alter the survival pattern during t he 18-wk sampling period.