CHARACTERISTICS OF SERIALLY PRODUCED ZOOSPORE SUSPENSIONS OF POLYMYXA-BETAE FOR TRANSMISSION OF BEET NECROTIC YELLOW VEIN VIRUS

Zoospore suspensions of Polymyxa betae were analysed for their potenti al as inocula to infect sugar beet plants with beet necrotic yellow ve in furovirus. The infectivity could be maintained when zoospore suspen sions were serially transferred. When zoospore-producing seedlings wer e individually transferred some of these seedlings lost their infectiv ity after several passages. Infectivity was first detected in suspensi ons within 1 day after inoculation of the plant by zoospores. The susp ensions remained infectious for at least 10 h after removal of the pla nts producing viruliferous zoospores. Both the number of test plants i nfected and the concentration of virus that developed were greater at 25 degrees C than at 20 degrees C.