BIOASSAY TO ASSESS ROOT-ROT IN PEA AND EFFECT OF ROOT-ROT ON YIELD

Infection of pea roots by soil-borne pathogens causes foot and root ro t. In 1985 research was started to develop a method to predict the roo t rot likely to occur in prospective pea fields. In a bioassay the pea cultivar Finale was sown in a composite soil sample from each field i n pots under standardized conditions in the greenhouse. The plants wer e removed at the green bud stage and the severity of root rot recorded . Between 1985 and 1988 approximately 200 field pea crops were monitor ed for root rot development. Forty-eight fields were bioassayed in 198 6, 51 in 1987 and 30 in 1988. Each year, root rot readings in the bioa ssay and disease severity readings at field sampled plants at flowerin g and green pod were linearly correlated (P < 0.001). As the degree of root rot in the field crop increased, there was a proportional lower yield. In heavily infested fields, up to a 50% yield reduction occurre d. The bioassay in pots proved to be a reliable method for predicting root rot severity in sampled pea fields.