Biological control of phytophthora by trichoderma

DETAILED DESCRIPTION We claim: 1.
A biocontrol agent effective against Phytophthora cactorum selected from the group consisting of: Gliocladium virens, 031 (ATCC 20903); Gliocladium virens, 035 (ATCC 20904); and Gliocladium virens, 041 (ATCC 20906).
2.
The biocontrol agent of claim 1 which is Gliocladium virens, 031 (ATCC 20903).
3.
The biocontrol agent of claim 1 which is Gliocladium virens, 035 (ATCC 20904).
4.
The biocontrol agent of claim 1 which is Gliocladium virens, 041 (ATCC 20906).
5.
A method of controlling Phytophthora cactorum caused plant diseased which comprises applying to the plant root biosphere of the plant to be protected a biosphere colonizing amount of a biocontrol agent selected from the group consisting of: Gliocladium virens, 031 (ATCC 20903); Gliocladium virens, 035 (ATCC 20904); and Gliocladium virens, 041 (ATCC 20906).




Description:
BACKGROUND OF THE INVENTION Crown and collar rot, caused by at least four Phytophthora spp.
(Jeffers et al, 1982, Phytopathology, 72:533-538) is a widespread and economically serious problem of apples throughout the Northeast U.
S.
In New York State, this disease appears to be the most common biological cause of premature tree decline and death, and in Pennsylvania, many growers have abandoned the horticulturally-desirable MM 106 rootstock because of high crown rot incidence or its perceived threat.
Because no single approach to the control of Phytophthora crown rot has proved reliable, growers have been advised to adopt an integrated or additive disease management strategy, utilizing a combination of site selection, site modification, rootstock selection, and chemical treatments where appropriate (Wilcox, In: 1987 New York State Pesticide Recommendations.
Cornell University, Ithaca, N.
Y.
533 pp).
However, the possibility of introducing a biological control agent as an additional component of such a program has heretofore been largely ignored.
Species of Trichoderma and Gliocladium have been shown to provide varying levels of biological control of a number of important soil-borne plant pathogens, including Sclerotium cepivorum (Abd-el Moity et al, 1982, Phytopathology, 72:396-400; Abd-el Moity et al, 1981,, Phytopath