PRELIMINARY INVESTIGATIONS ON THE VIABILITY OF THE USE OF ABSCISIC-ACID (ABA) IN CRUCIFER SEED HEALTH TEST FOR DETECTING PHOMA-LINGAM

Phoma lingam, a seedborne fungal organism causes blackleg disease in c rucifer (Brassicaceae). The recommended International Seed Testing Ass ociation (ISTA) procedure for determining the incidence of P. lingam i n crucifer seed calls for examination of seed and blotters for typical pycnidia and conidial ooze, after 10-11 days of incubation at 20 degr ees C on blotters wetted with 0.2%, 2,4-D solution. The use of ABA at 100 mg/l is proposed as a new method for testing crucifer seed for P. lingam. The advantages of this seed assay are: a) ABA is totally solub le in water and using low concentration eliminates the risk of laborat ory contamination; b) Seed pretreatment with sodium hypoclorite to red uce saprophytic contaminating fungi is not necessary; c) ABA is not to xic to P. lingam, thus it does not affect seed health testing, and d) ABA is available world wide and there is no difference in formulations . Suggestions have been made to the working group on seed-borne diseas es of crucifer of the ISTA Plant Disease Commitee to compare this meth od with the presently recommended 2,4-D test.