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- Author or Editor: Donald R. Sumner x
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.
Abstract
Nitrogen did not influence the severity of leafspots (Cercospora cruenta and C. canescens) or rust (Uromyces phaseoli var. vigna), but these foliage disease were more severe on southernpea plants grown in disk-harrowed treatments than in treatments deep-turned with a moldboard plow. Three applications of chlorothalonil reduced the severity of Cercospora leafspots and rust, but did not effectively control the diseases in all tests. Foliage diseases were less severe on ‘White Acre’ than on ‘Purpose Hull Pinkeye’ southernpea. ‘White Acre’ produced the most foliage in disk-harrowed treatments, and ‘Purple Hull Pinkeye’ was superior in deepturned treatments.
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.
Winter cover crops were evaluated to determine their influence on yield, nematodes, and soil-borne pathogens in sustainable cantaloupe production during a two year period. Six cover-cropping regimes, including a weedy fallow control, were tested in a replicated trial. Pesticide and commercial fertilizer inputs were significantly reduced in the cover crop treatments. No insecticides were needed throughout the study due to high populations of beneficial insects. Fertilizer inputs were only one-fourth the recommended rate used for conventional cantaloupe production. Populations of southern root-knot nematode (Meloidogyne incognita) and soil-borne pathogens Rhizoctonia solani and Pythium spp. were significantly higher in crimson clover and subterranean clover cover crops, yet yields were greater following crimson clover. Lowest yields and highest number of worm-damaged fruit occurred in the weedy control.