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Sodium alginate was used to prepare pelletized formulations for each of five fungi. Aqueous mixtures of 1.0% (w/v) sodium alginate and homogenized mycelia ofAlternaria cassiaeJurair & Khan,Alternaria macrosporaZimm.,Fusarium lateritiumNees ex Fr.,Colletotrichum malvarum(A. Braun & Casp.) Southworth, or aPhyllostictasp. were pelletized by dropwise additions of each mycelial-alginate mixture into 0.25 M CaCl2. Abundant conidia were produced on the pellets 24 to 48 h after the pellets were spread into trays and exposed 10 min/12 h to 275-W sunlamps. These conidia germinated readily (90 to 100%) and readily infected the respective host plants. Each liter of mycelium plus growth medium from submerged liquid cultures produced 4 L of the mycelial-alginate mixture. Each liter of the mycelial-alginate mixture produced approximately 18 g of air-dried formulation. When 10% (w/v) clay was incorporated into the pellets, each liter of the mycelial-alginate mixture produced approximately 118 g of air-dried formulation. The pelletized fungi sporulated readily following storage at 4 or 25 C for 6 to 8 months. This method of pelletization is potentially useful for the formulation of inoculum of fungi used as mycoherbicides, for the mass production of pycnidium-forming fungi, and for the production of inoculum for host-plant resistance studies.

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A method is described to produce inoculum ofAlternaria cassiaeJurair and Khan for biocontrol studies. Approximately 8 g of a conidial preparation containing 1 × 108conidia/g were produced per liter of growth medium. In greenhouse studies the effectiveness ofA. cassiaeas a biocontrol agent for sicklepod (Cassia obtusifoliaL.) was affected by dew-period temperature, dew-period duration, inoculum concentration, and the stage of growth of sicklepod seedlings at the time of inoculation. Optimum environmental conditions included at least 8 h of free moisture at 20 to 30C. Spray mixtures containing approximately 5 × 104or more conidia/ml gave maximum control when sicklepod seedlings were sprayed to runoff. Sicklepod seedlings in the cotyledon to first-leaf stage were most susceptible to the pathogen.

An isolate of the fungus Myrothecium verrucaria (MV) was evaluated for biocontrol potential against kudzu (Pueraria lobata). In greenhouse tests, MV was highly virulent against kudzu in the absence of dew when conidia were formulated in 0.2% Silwet L-77 surfactant (SW). Inoculum concentrations > 2 3 10 7 conidia ml 2 1 were required to satisfactorily control plants in the third leaf stage and larger. In controlled environment experiments, kudzu mortality was greater at higher temperatures (25-40ë C) than at lower temperatures (10-20ë C), although pathogenesis and mortality occurred at all temperatures tested. In Weld tests, transplanted kudzu seedlings in the 2-3 leaf growth stage treated with MV at 2 3 10 7 conidia ml 2 1 in 0.2% SW, exhibited leaf and stem necrosis within 24 h following inoculation, with mortality occurring within 96 h. After 7 days, 100% of inoculated kudzu plants were killed in plots treated with the fungus/surfactant mixtures. Similar results were observed in a naturally occurring kudzu population , where 100% control occurred within 14 days after inoculatio n with 2 3 10 7 conidia ml 2 1 in 0.2% SW. In summary, MV eVectively controlled kudzu in the absence of dew over a wide range of physical and environmental conditions and under Weld conditions. These results indicate that, when properly formulated, MV has potential as a valuable bioherbicid e for controlling kudzu.