Four pathogenic fungal isolates belonging to different genera including Alternaria, Fusarium and Curvularia were isolated from selected diseased weeds growing in the fields in Dakahalia district. The inoculum of these pathogenic fungi specific to weeds were cultured, standardized and formulated as alginate pellets containing mycelium plus culture filtrate. These mycoherbicides were evaluated for disease severity (DS). Maximum DS was obtained with the alginate pellets of mycelium filtrate Fusarium solani. Physiological changes of the treated weed were determined 5 and 10 days after treatments. As compared to the healthy weeds, all mycoherbicide formulations significantly decreased the amount of photosynthetic pigments and subsequently soluble and insoluble sugars in the infected weeds. The mycoherbicide formulation of F. solani had the greatest effect on lowering to the abovementioned amount in the leaves of Chenopodium murale. Generally, treatment of weed leaves with the specific mycoherbicide led to a highly significant increase in total phenol content when compared to the healthy control weed. C. murale infected with the mycoherbicide formulation of F. solani had higher levels of phenolic compounds than those other treated weeds particularly after 10 days of inoculation.
KEYWORD: Carbohydrates, Disease severity, Mycoherbicide, Phenolic compounds, WeedsWeeds in Dakahlia district are a major problem in agriculture. Most economic plants are lost every year due to damage done by weeds to various agricultural crops. Mechanical and chemical control methods, which are most commonly used, are not completely satisfactory (Sonawane and Ambekar, 1999). Biological control of weeds using plant pathogens is a practical and environmentally sound method of weed management. A variety of herbaceous, woody, climbing, aquatic, and parasitic weeds have been shown to be capable of being controlled by plant pathogens (Charudattan, 1991). Many examples of weed control with pathogens exist, such as the control of hamakua pamakani weed (Ageratina riparia by the Entyloma compositarum; Trujillo et al., 1988), milkweed vine or strangler vine (Morrenia odorata by DeVine [Phytopthora palmivora]; Kenney, 1968), musk thistle (Carduus nutans by Puccinia carduorum; Baudoin et al., 1993), sicklepod (Cassia obtusifolia by Alternaria cassiae; Walker and Riley, 1982;Charudattan et al., 1986), silverleaf nightshade (Solanum elaeagnifolium by the nematode Orrina phyllobia; Parker, 1991), skeletonweed (Chondrilla juncea by Puccinia chondrillina; Supkoff et al., 1988), yellow nutsedge (Cyperus esculentus by Puccinia canaliculata; Phatak et al., 1987), and wild persimmon (Diospyros virginiana by Cephalosporium diospyri; Griffith, 1970).Biological control with plant pathogens is an effective, safe, selective and practical means of weed management that has gained considerable importance (Charudattan, 1986;Flint and Thomson, 2000;Pemberton and Strong, 2000;Bouda et al., 2001). Despite considerable success with biological and integrated control methods in t...