A Consistent Method for Producing Gram Quantities of Typical Bipolaris Zeicola and B. Maydis Conidia

ABSTRACT

A consistent method was developed to economically produce gram quantities of typical Bipolaris zeicola and B. maydis conidia that are viable, uniform, morphologically normal, and free from other fungi and bacteria. Such conidia were produced on a lima bean agar (LBA) consisting of 20 g/liter finely ground dry baby lima bean seed and 7.5 g/liter USP crude agar. Plates of LBA were inoculated with conidia, incubated at 25 C in the dark or under fluorescent light (continuous 100–200 lux) for 14 days, and dried at 32–35 C to a thin film. Conidia were aseptically vacuumed at 200 mm Hg from the dried medium with a cyclone spore collector. We obtained 25 g of phragmoconidia of each species from 300 LBA petri dish cultures (~82 mg conidia/plate culture). Cultures on the LBA medium produced four to six times more conidia than on potato dextrose agar medium and at the lowest practical cost of any of several substrates tried.

Key Words:

• Bipolaris
• sporulation
• LBA medium