MANAGEMENT OF CHICKPEA WILT DISEASE CAUSED By Fusarium oxysporum f.sp.ciceri

Abstract

A series of laboratory and greenhouse experiments was conducted at the Department of Plants Protection at the College of Agricultural studies- Sudan University of Science and Technology (Shambat). The objective of the study was to work out a management strategy for chickpea Cicer arietinum wilt disease caused by Fusarium oxysporum f. sp ciceri. The disease is an important one it causes significant reductions in yield. In the present study, the pathogenic fungus was isolated from infected plant parts and soil. The fungus was identified based on morphological and cultural characters as Fusarium oxysporum In vitro studies were conducted to evaluate the effect of media, temperature and pH on mycelial growth of the fungus. The results showed that the fungus grew best on Potato Dextrose Agar (PDA) medium (86.7 mm) followed by Potato Sucrose Agar (PSA) (78.2 mm). Growth of F. oxysporum was maximum at 25 o C (84 mm) followed by 30 oC (46 mm). The maximum growth of the fungus was achieved at pH 7 followed by pH 6. The antifungal effects of the medicinal plant extracts Argel (Solenostemma argel), Ginger (Zingiber officinale) and Jatropha (Jatropha crucus) (seeds, stems, leaves and roots) were determined by in vitro study using aqueous and ethanolic extracts following the Poisoned Food Technique. The 11 extracts, undiluted and 2and 4–fold diluted were screened for antifungal activity using PDA medium. All extracts gave significant inhibition of growth of the pathogen. Among all plants Argel extracts was the mosst inhibitory. It was followed in descending order by Ginger and Jatropha. Furthermore, the ethanolic extracts of all plants was more suppressive to the fungal growth than their aqueous equivalents. Among the three Trichoderma spp. tested in vitro (T. harzianum, T. viride and T. koningii), for antagonistic potentials against the fungus T. harzianum showed the best performance (89.8% inhibition) followed by T. viride (85.7% inhibition), and T. koningii (53 % inhibition). The fungicides, Bayfedan, Abronstar, and Thiram each at three concentrations (25, 50 and 100 ppm) reduced mycelial growth of the fungus in a concentration dependent manner. Thiram was the most effective (95% inhibition) followed in descending order by Bayfidan (82 % inhibition) and Abronstar (77% inhibition). In the greenhouse experiments, powder of all plants and plants parts applied to soil, increased germination rate, height, dry weight (shoots and roots) and yield of chickpea and reduced disease incidence and disease severity. Among all plants tested Argel was the best as it effected the germination, height, dry weight (shoots and roots) and yield of chickpea and reduced disease incidence and disease severity. All Trichoderma spp tested reduced disease incidence. However, T. harzianum was the most effective (13.33 % reduction 4 weeks after planting and 20 % reduction 8 weeks after planting).Seed dressing by all fungicides resulted in reduced disease incidence, enhanced germination , height, dry weight (shoots and roots) and yield of chickpea. The maximum reduction in disease incidence was achieved with Thiram (20% reduction 8 weeks after planting). The chemical control method was found to be the best among all methods used against wilt disease of chickpea. Moreover, botanical and biological control methods were also promising. The overall results suggest the development of an integrated management strategy where chemicals could be 12 ‫‪decrease rates of the fungicides and consequently cost and increased‬‬ ‫.‪environmental safety‬‬