Effect of Osmopriming Sugar Beet Seed on Germination Rate and Incidence of Pythium ultimum Damping-off. R. M. Osburn, Former Graduate Research Assistant, Department of Plant Pathology, University of California, Berkeley 94720. M. N. Schroth, Professor, Department of Plant Pathology, University of California, Berkeley 94720. Plant Dis. 73:21-24. Accepted for publication 28 June 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0021.

Osmopriming sugar beet seed in NaCl or polyethylene glycol (PEG) solutions reduced Pythium ultimum preemergence damping-off by 50 and 65%, respectively, compared with nontreated seed when planted in naturally infested field soil. Disease control was comparable to or better than that provided by metalaxyl-treated seed. Addition of metalaxyl to NaCl or PEG osmoprimed seed resulted, in an additive increase of disease control greater than any of the treatments alone. Damping-off was reduced 24.8 and 12.6% with NaCl and PEG osmoprimed seed treatments, respectively, compared with nontreated seed in one of two field trials. Seedling fresh weight was increased an average of 57.1 and 39.2%, respectively, in the two trials. The germination rate of both osmoprimed seed treatments was greater than that of nontreated seed at temperatures ranging from 9 to 27 C in petri dish assay. Similarly, seedling emergence rate was improved at 16–21 C in fumigated field soil. The viability and faster germination rate of osmoprimed seed were maintained at least 6 mo when stored at 21–24 C.