Ec. Tjamos et Dr. Fravel, DETRIMENTAL EFFECTS OF SUBLETHAL HEATING AND TALAROMYCES-FLAVUS ON MICROSCLEROTIA OF VERTICILLIUM-DAHLIAE, Phytopathology, 85(4), 1995, pp. 388-392
Microsclerotia of Verticillium dahliae were not heated or heated in wa
ter with one of three regimes to simulate soil solarization. Regime 1
consisted of 31 C for 10 h followed by 35 C for 14 h. Regime 2 consist
ed of 33 C for 10 h followed by 36 C for 14 h. Regime 3 consisted of 3
5 C for 10 h followed by 38 C for 14 h. Heating for 1-5 days with regi
me 1 did not affect the final number of microsclerotia that germinated
but did affect the rate at which they germinated. Additional days of
heating with regime 2 or 3 affected both the number of germinated micr
osclerotia and the rate at which they germinated. Of the microscleroti
a that germinated, colonies arising from heated microsclerotia formed
significantly fewer melanized microsclerotia and melanization of these
new microsclerotia was significantly slower than for those originatin
g from the nonheated microsclerotia. When microsclerotia were heated a
s above, placed in nylon mesh envelopes, and buried in raw soil with o
r without the biocontrol agent Talaromyces flavus, there was a synergi
stic interaction between the heating and T. flavus resulting in increa
sed mortality of the microsclerotia. Colonies arising from surviving,
previously heated microsclerotia were slower growing than colonies fro
m nonheated microsclerotia and were slower to form melanized microscle
rotia. Sublethal heating and T. flavus acted additively to suppress Ve
rticillium wilt of eggplant. Opportunities for combining sublethal hea
ting with thermophilic biocontrol agents are discussed.