Abstract

Chickpea (Cicer arietinum L.) is a major source of human and animal food and the world’s third most important pulse crop after beans and peas. In Pakistan, it is one of the most prominent rabi crop mostly cultivated in Thal region of Punjab, areas which are totally dependent on rainfall for water requirements. Along with these drought conditions prevailing in this region, some biotic factors also contribute in low yield of this crop. Considering the current situation, it was necessary to find the exact cause of Gram wilt and to develop sustainable management strategies. This study was planned with the aim of determining the different fungal isolates associated with this wilt problem and its long term management strategies. To achieve the goal of this study, a comprehensive survey of Thal areas including districts of Layyah, Jhang, Bhakkar, Khushab and Mianwali was conducted with the aims to collect the diseased samples from and checked the incidence and severity of disease in this region. Maximum disease incidence (83.88±4.14) and disease severity (7.12±0.51) was observed in five locations of district Layyah which was followed by five locations of district Bhakkar showed disease incidence (81.06±3.52) and disease severity (6.52±0.57). Intermediate result of district Khushab was observed in which DI and DS was (79.58±4.54) and (6.3±0.64) respectively. District Jhang showed DI (76.24±3.12) and DS (5.26±0.71). Minimum disease incidence (73.34±4.12) and disease severity (4.44±0.55) was observed in district Mianwali. Pathogenicity test was demonstrated by fulfilling Koch's postulates in which most virulent isolates were further studied. Morphological studies showed purplish white to brownish white and fluffy and cottony texture of Fusarium spp. was founded. Sizes of microconidia (2.0-3.5 × 6-12.5) with 0-2 septations and macroconidia (3.5-5.5 × 13-30) with 1-5 septations were recorded under microscope. Physiological parameters included optimum pH 7.0, optimum temperature 30ºC and 10 days after optimum sowing time gave maximum disease and inoculation after 40 days of sowing gave maximum growth.  Molecular characterization of fungal isolate(s) was done in which Fusarium oxysporum, Fusarium solani and Gibberella moniliformis was founded two strains of Fusarium oxysporum species and one strain Gibberella moniliformis, was present in the isolates of Layyah. Two Fusarium oxysporum species were founded from Bhakkar. One Fusarium oxysporum strain and one Fusarium solani was obtained from Khushab. One Fusarium oxysporum strain was founded from Jhang. One Fusarium solani strain was present in the isolates of Mianwali. Three fungal antagonists (Trichoderma harzianum, Trichoderma viride and Trichoderma virens) were evaluated against virulent pathogens in which Trichoderma harzianum showed maximum inhibition under lab and field conditions. Ten fungicides (Score, Topsin M, Baviston, Cholorothalonil, Stump, Big Time, Champion, Velvet, Curzate M8 and Co-oxy) were evaluated against virulent pathogens in which Score showed maximum inhibition of isolates of Fusarium spp. which were followed by Topsin M and Baviston under lab conditions while on the other hand Score showed maximum disease reduction under field conditions.