Hot Acidified Cupric Acetate Soaks for Eradication of Xanthomonas campestris from Crucifer Seeds

Abstract

Acidified cupric acetate soaks were tested for eradication of Xanthomonas campestris from naturally infected crucifer seeds. The pathogen was eradicated from seeds by soaking in 0.5% cupric acetate dissolved in 0.005 N acetic acid for 20 min at 35, 40, 45, and 500C but not 250C. Moreover, normal bacterial flora of crucifer seeds and the seed-borne Phoma lingam and Alternaria spp. were reduced by 95, 92, and 81%, respectively, after the cupric acetate treatment at 400C. The seed germination percentage was generally reduced, but the amount of reduction depended upon the treatment temperature and plant cultivar. At 500C, less than 50% of the seed of all 12 cultivars tested germinated, whereas at 40°C more than 50% of the seeds of most cultivars germinated. Treating seeds in cupric acetate at 400C should prove useful for eradicating X. campestris from seeds of breeding lines and stock seed used for hybrid seed production. Furthermore, a significant reduction in total bacterial flora and seed-borne fungi suggests the usefulness of the treatment for other microorganisms associated with other seeds or foodstuffs.

Identification of Bacteria Infecting Seedlings of Mung Bean Used in Rooting Bioassays

“…Seeds of 'Berken' mung bean were purchased from a commercial distributor; damaged seeds were dis- carded before treatment. Seeds were surface-sterilized with 0.5% NaOCl for 10 min and either: 1) rinsed with tap water and aerated 24 h in tap water before sowing, 2) rinsed with sterile distilled water and sown immediately, or 3) rinsed with sterile water, soaked for 20 min at 52C in a solution containing 0.25% (w/v) cupric acetate dissolved in 0.005 N acetic acid (Schaad et al, 1980), rinsed, placed in a sterile solution of the antibiotics tetracycline (10 mg•liter -1 ) and cephalexin (10 mg•liter -1 ) for 30 rein, rinsed, and sown immediately. Only sterilized distilled water was used in treatments 2 and 3.…”

Opportunities for developing value-added brassica seed

“…The use of disease-free seed is critical in the control of the disease as seeds are the most important source of inoculum and the pathogen can persist for several years in seed as a surface contaminant or internal infection (Schaad et al 1980a). Seed treatments involving hot water, hot air, ultraviolet light, chemicals and antibiotics have been evaluated for pathogen removal (Clayton 1924;Klisiewicz & Pound 1961;Humaydan et al 1980;Schaad et al 1980b;Harman et al 1987;Shiomi 1992;Brown et al 2001). These treatments rarely completely remove the pathogen and often reduce seed germination and vigour.…”