SURFACE STERILIZATION OF GOURD (Cucurbita pepo) SEED FOR CONTROL OF BACTERIAL FRUIT SPOT (Xanthomonas campestris pv cucurbitae):

R. S. Lyon and R. M. Riedel
Plant Pathology Dept., Ohio State Univ.,
Columbus, OH 43210

Gourd seed lots used in this study, identified as B6 and B9, were from seed lots naturally contaminated with X. campestris pv cucurbitae. Seeds in one pound lots were treated with either 6% hydrochloric acid (HCl), 10% or 30% commercial bleach (Chlorox), or 3% hydrogen peroxide (H2O2) for 10 min with agitation. Treated seeds were immediately rinsed in large quantities of cold tap water for 5 min. Rinsed seeds were blotted dry and allowed to dry slowly to storage moisture at room temperature. Fifteen seeds from each treatment were placed 3 to the petri dish on nutrient agar to test for bacterial contaminants. One hundred seeds from each treatment were placed on moisture filter paper to test for germination. Ten pounds of seed treated with 30% chlorox were planted to test for occurrence of Bacterial Fruit Spot under grower conditions.

Germination of all treatments was relatively high (Table 1). H2O2 and Hcl treatments did not reduce bacterial contamination effectively. Chlorox at 10% was more effective than acid or peroxide treatments. Chlorox at 30% decreased bacterial contamination to undetectable levels for seed lot B6 and 20% for B9. Field planted gourds did not develop Bacterial Fruit Spot although the disease was common in surrounding fields planted with untreated seeds.

* 10 min soak; tap water rinse; dried for storage; treated with Captan before planting

** Xanthomonas campestris pv. cucurbitae