Biological soil treatment with Trichoderma harzianum to control root rot disease of grapevine (Vitis vinifera L.) in newly reclaimed lands in Nobaria province

Abstract

Augmentation of soil with different biological treatments i.e., Trichoderma harzianum cultured on sugar cane bagasse, Trichoderma harzianum (spore suspension 5 × 106 cfu/ml) and plant guard (biocide), successfully controlled Fusarium solani, F. oxysporium and Macrophomina phaseolina, the main pathogens of root rot disease on grapevines in Nobaria province. Complete reduction of these pathogens was recorded at 4 ml/l of plant Guard. Meanwhile, T. harzianum caused a reduction of 80.0, 84.4 and 88.9% of linear growth of the same pathogens respectively. In greenhouse trials, artificially infested soil treated with bio-enhancing bagasse at rate of 10% (w/w) of soil, plant guard 4 g/l and T. harzianum 100 ml/l treatments showed a large effect in decreasing percentages of infection and severity of root rot disease on grapevine seedlings. These treatments caused a reduction in root rot infection caused by M. phaseolina, F. oxysporum and F. solani reach 100, 100, 80% and 80, 60, 60% and 60, 40, 40%, respectively, with two soil applications. Also, the percentage reduction in disease severity reach 100, 100 and 88.2%; 69.2, 57.1 and 52.9%; 46.2, 42.8 and 41.2% respectively. Meanwhile, one soil application with the same treatments caused a moderate effect in decreasing both disease infection and severity. Two soil applications with bio-enhancing bagasse 10% and plant Guard 4 ml/l treatments caused significantly reduced numbers of infested vines as well as percentage of disease severity of these vines after 30, 60 and 120 days from application. Moreover, these treatments cause an increasing population density of Trichoderma spp., wherever it decreases in the rhizosphere soil of untreated vines (control). The large increase in yield/vine was recorded on vines treated with bio-enhancing bagasse 10% (51.2% increase over control) and Plant Guard 4 ml/l (48.8% increase over control) in two applications. Through these results it can be suggested that manipulating soil by biocontrol agent formulation on agricultural wastes or as biocides such as plant guard may be safely used commercially as a substitute for traditional fungicidal treatments for controlling soil borne plant pathogens.