Abstract
In in vitro biological control of charcoal rot disease of sunflower (caused by 31. ohaseolina), Trichoderma harzianum, Arachniotus sp. and Penicillium sp. provided 93, 100 and 50 per cent disease control respectively. Trichoderma harzianum significantly promoted vigour and dry stein weight where as Arachniotus sp. increased vigour,dry stein weight, plant yield and dry root weight over the non infected healthy plants. Penicillium sp. did not affect vigour but significantly decreased plant yield and dry stem weight. In in vivo control Trichoderma harzianum, Arachniotus sp. and Penicillium sp. provided 85, 91 and 60 per cent disease control. Trichoderma harzianum and Arachniotus sp. increased plant vigour and head size of the sunflower. The three antagonists also signifi-cantly reduced extent of linear stem infection of the diseased plants.
INTRODUCTION
In Pakistan sunflower (Helianthus annuu8 L.) is known to suffer from root and stein rot disorder called charcoal rot disease (Anonymous, 1980). The disease is caused by a soil borne pathogen, ifacrophomina phaseoiina (Ilyas et al., 1981). Symptoms of the disease (wilting, flagging, defoliation and loss of plant vigour) become prominent just prior to crop maturity and the disease causes 20.50 per cent yield losses. (Acirnovic, 1962; Ilyas et aI., 1981). Commer-cial cultivars lack resistance against .M, pha8eolina (Anonymous, 1980) and chemical control of the pathogen is too expansive to be practicable (Watanabe et al., 1970 Ilyas et al., 1975). The biological control involving the use of antagonistic microorganisms appears to be feasible and an economical control measure (Dhingra, 1973; Ghaffar, 1982). This paper reports on the in vitro and in vivo control of charcoal rot of sunflower by antagonistic soil fungi.
*Department of Plant Pathology, University of Agriculture, Faisalabad.
