An-Najah Staff

An invert emulsion (water-in-oil formulation) based on coconut and soybean oils provided the most stable emulsion layer (93% V/V) and lowest viscosity (27±0.81 cps), suitable for a formulation of Trichoderma harzianum conidia. Conidia remained viable for 36 months (shelf-life) with 50% reduction in viability (half-life) after 5.3 months at 20±1°C., compared with 2.7 and 0.7 months, respectively, for dry non-formulated conidia. Stability and viscosity of the formulation remained constant during the time period of viability study. Bio-assay tests on wounded apple fruit indicated the presence of significant preventive effect of formulatedTrichoderma conidia against the causative organism of apple gray mold Botrytis cinerea. The diameter ofBotrytis lesions was significantly reduced (P<0.05) 5 days after inoculation and treatment with formulatedTrichoderma conidia. Botrytis sporulation on the lesion surface was also inhibited 10 days after inoculation. These results were confirmed under simulated natural conditions by spraying a Botrytis conidial suspension on microwounded apple fruit following treatment by dipping fruit. Treatment of healthy non-wounded apple fruits resulted in protection from Botrytis infections for >2 months following inoculation and treatment.

Control of primary postharvest diseases caused by Rhizopus stolonifer, Botrytis cinerea, and Penicillium expansum on a variety of fresh fruit was evaluated with an invert emulsion formulation of Trichoderma harzianum. Diseases evaluated were quantified by the period of protection conferred by the antagonist and the diameter of decay lesions. Treatment of the various fruit species with formulated T. harzianum conidia in an invert emulsion significantly (P ≤ 0.05) reduced the mean lesion diameters of R. stolonifer on apple, pear, peach and strawberry, B. cinerea on grape, pear, strawberry, and kiwifruit, and P. expansum on grape, pear, and kiwifruit in comparison with the control treatment. Significant differences (P ≤ 0.05) were obtained in the mean percent reduction in lesion diameter caused by the same postharvest pathogens on the same fruit species due to the treatment with the formulated T. harzianum conidia relative to control treatment. The greatest mean percent reduction (86.7%) was obtained on apple fruit for the infection with R. stolonifer. Significant differences (P ≤ 0.05) were also obtained in the mean durations of the minimum protection period due to treatment with the formulated T. harzianum against the infection with the same postharvest pathogens on the same fruit species. The longest mean duration of the minimum protection period (up to 59 days) was obtained for unwounded apple fruit against the infection with R. stolonifer. Overall, the results indicate that the treatment with the invert emulsion formulation of T. harzianum protected fruit from infection by the primary postharvest pathogens of the fruit tested for up to 2 months and reduced the diameters of decay lesion up to 86% and is a promising treatment to prolong the postharvest shelf-life of fresh fruit.