ETIOLOGY AND BIOLOGICAL-CONTROL OF FUSARIUM-WILT OF PINKS (DIANTHUS-CARYOPHYLLUS) USING TRICHODERMA AUREOVIRIDE

Fusarium oxysporum f.sp. dianthi (F.o.d.) was the species isolated mos t frequently from wilted glasshouse-grown pinks in south-west England, whereas F. avenaceum was less prevalent and F. culmorum was not found . Although infections by F. avenaceum, via the roots or through a cut- stem wound, caused symptoms identical to those characterizing mild inf ections due to F.o.d., the former was always pathogenically weak relat ive to the latter. Of several organisms screened for potential antagon istic capacity towards F.o.d., using an in-vitro dual culture plate te chnique, Trichoderma aureoviride, isolated as an endophyte from health y pinks, proved most effective. Elevated temperatures substantially re duced the antagonistic capacity of micro-organisms in both in-vitro an d in-vivo screens, except in the case of T. aureoviride where maximum antagonism occurred at 28 degrees C, which was near the optimum for wi lt disease in pinks. The tolerance shown by T. aureoviride to a wide r ange of pesticides used in commercial production of pinks under cover indicated its potential in a proposed integrated disease control progr amme.