Seeds from 19 selfed plants of watermelon PI 271778 were field-planted with seven cultivars in July 1997. Two weeks after planting, one seedling per plot was inoculated on 15 July by spraying to runoff (24 × 104 conidia/mL in water) a mixture of indigenous isolates of Didymella bryoniae. Plants were inoculated again on 31 July. On 7 Aug., plants with at least one stem lesion ranged from 0% to 96% (mean = 22%) for selections from PI 271778, while cultivars ranged from 3% to 71% (mean = 24%). On 19 Aug., plants with at least one stem lesion ranged from 12% to 100% (mean = 74%) for selections and 94% to 100% (mean = 97%) for cultivars. These differences were further reflected in average dead canopy of 25% for selections and 80% for cultivars on 3 Sept. By 17 Sept., dead canopy averaged 47% for selections and 100% for cultivars. Fruit harvested per plant averaged 2.5 for selections and 0.8 for cultivars. By harvest, vines were totally collapsed on all cultivars and on some selections, while stems of most selections were still vigorous but leaves exhibited significant necrosis.
Melvin R. Hall and Donald R. Sumner
Suhas R. Ghate, Donald R. Sumner, and Sharad C. Phatak
Cucumber crop was established in conservation tillage from gel-sown germinated seed. Fungicides (flutolanil + metalaxyl) were mixed with gel or applied as a drench after seeding to control Rhizoctonia and Pythium seedling diseases. The benefit of mixing fungicides with gel was similar to drenching the seeded area with fungicides. There was no added advantage of using germinated seed for cucumber production in conservation tillage. In fact, germinated seed was more susceptible to fungal diseases in the absence of fungicides. Crop yield was greater in conventionally-prepared soil than in conservation tillage.
Kathryn E. Brunson, Sharad C. Phatak, J. Danny Gay, and Donald R. Sumner
Velvetbean (Mucuna deeringiana L.) has been used as part of the crop rotation in low-input vegetable production in southern Georgia to help suppress populations of root-knot nematode (Meloidogyne incognita) for the past 2 years. Over-wintering cover crops of crimson and subterranean clovers were used the low-input plots and rye was the plow-down cover crop in the conventional plots. Tomatoes, peppers, and eggplant were the vegetable crops grown in these production systems. Following the final harvest in 1992, use of nematicides in the low-input plots was discontinued and velvetbean was then planted into the low-input plots and disked in after 90 days. Results from the 1993–94 soil samples taken before and after velvetbean showed a continuing trend of reduced nematode numbers where velvetbean had been, while most conventional plots that had nematicides applied resulted in increases in nematode populations.