BIOLOGICAL-CONTROL OF BOTRYTIS-CINEREA ON TOMATO STEM WOUNDS WITH TRICHODERMA-HARZIANUM

The effectiveness of Trichoderma harzianum in suppression of tomato st em rot caused by Botrytis cinerea was examined on tomato stem pieces a nd on whole plants. Ten days after simultanous inoculation with B. cin erea and T. harzianum, the incidence of infected stem pieces was reduc ed by 62-84%, the severity of infection by 68-71% and the intensity of sporulation by 87%. Seventeen days after inoculation of wounds on who le plants, the incidence of stem rot was reduced by 50 and 33% at 15 a nd 26 degrees C, respectively, and the incidence of rot at leaf scar s ites on the main stem was reduced by 60 and 50%, respectively. Simulta nous inoculation and pre-inoculation with I: harzianum gave good contr ol of B. cinerea (50 and 90% disease reduction, 10 days after inoculat ion). The rate of rotting was not reduced by the biocontrol agent once infection was established. However, sporulation by B. cinerea was spe cifically reduced on these rotting stem pieces. Temperature had a grea ter effect than vapour pressure deficit (VPD) on the efficacy of bioco ntrol. Suppression of B. cinerea incidence by T. harzianum on stem pie ces was significant at 10 OC and higher temperatures up to 26 degrees C. Control of infection was significantly lower at a VPD of 1.3 kPa (6 0% reduction), than at VPD < 1.06 kPa (90-100% control). Reductions in the severity of stem rotting and the sporulation intensity of grey mo uld were generally not affected by VPD in the range 0.59-1.06 kPa. Sur vival of T. harzianum on stems was affected by both temperature and VP D and was greatest at 10 OC at a low VPD and at 26 degrees C at a high VPD.