INTERACTIONS BETWEEN PYTHIUM-OLIGANDRUM AND THE FUNGAL FOOTROT PATHOGENS OF PEAS

Pythium oligandrum was shown to antagonize Fusarium solani f. sp. pisi, Phoma medicaginis var. pinodella and Mycosphaerella pinodes, the three major footrot pathogens of peas, under a range of in vitro conditions. Interactions on dual plate cultures and on filter papers demonstrated the varying antagonistic performance of P. oligandrum under different nutritional conditions. Using cellophane, interactions between the pathogens and P. oligandrum were observed directly, and necrotophic parasitism by P. oligandrum was recorded. The mycoparasite produced a volatile antibiotic that reduced the growth rate of P. medicaginis and M. pinodes. The mechanism of parasitism employed by P. oligandrum and the effect of nutrient stress on its antagonistic performance are discussed.