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  • Author or Editor: D.J. Mills x
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In the production of fresh-market vegetables, off-farm inputs, such as, plastic, nitrogen fertilizer, fungicides, insecticides, and herbicides are routinely used. One aim of the sustainable agriculture program at the Beltsville Agricultural Research Center is to develop systems that reduce these inputs. We have completed the second year of a study designed to examine foliar disease progress, foliar disease management, and marketable fruit yield in staked fresh-market tomatoes grown in low- and high-input production systems. Specifically, four culture practices (black plastic mulch, hairy vetch mulch, dairy manure compost, and bare ground) were compared in conjunction with three foliar disease management treatments (no fungicide, weekly fungicide, and a foliar disease forecasting model, TOMCAST). Within all culture practices, use of the TOMCAST model reduced fungicide input nearly 50%, compared with the weekly fungicide treatment, without compromising productivity or disease management. With regard to disease level, a significant reduction of early blight disease severity within the hairy vetch mulch was observed in 1997 in relation to the other culture practices. Early blight disease severity within the black plastic and hairy vetch mulches was significantly less than that observed in the bare ground and compost treatments in 1998. In addition, despite a 50 % reduction in synthetic nitrogen input, the hairy vetch mulch generated yields of marketable fruit comparable to or greater than the other culture practices. It appears that low-input, sustainable, production systems can be developed that reduce the dependence on off-farm inputs of plastic, nitrogen fertilizer, and pesticides, yet generate competitive yields.

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Abstract

A shift in the form of Ν in the nutrient solution to all NH4 after initial bloom significantly reduced pod yield as much as 50%, depending on the prebloom NO3/NH4 ratio. Pod yield was unaffected by prebloom NO3/NH4 ratio if at least half of the Ν in the nutrient solution was NO3, or if NO3 supplied all of the Ν during postbloom development. Therefore, for maximum pod yield, NO3 should be the primary Ν form supplied to snapbean plants after bloom. Kjeldahl Ν values were consistently high in the vegetative tissue with NH4 as the predominant Ν form, indicating that the use of Kjeldahl Ν values as an indicator of the Ν status of the plant in relationship to pod yield would be a misuse of this diagnostic tool without knowing the predominant Ν form being absorbed by the plant. The NO3 content in upper mature leaves at pod maturity was significantly correlated (r = 0.88***) to NO3 level applied, with a value of 7000 ppm in the leaves associated with highest pod yield. Total Ν (Kjeldahl Ν + NO3) of at least 5.50% in upper mature leaves at pod maturity was associated with highest pod yield.

Open Access

Root growth of `Penncross' creeping bentgrass (Agrostis palustris Huds.) plugs sodded into a sandy loam soil and fertilized with five 1:1, 1:3, and 0:1) were evaluated. Root growth and root: shoot ratios were higher with as the predominant N form. Results from this study indicate should be the predominant N form when rapid and extensive root development is desired for the establishment of sodded bentgrass.

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Experiments were conducted to compare changes in quality of slices of red tomato (Lycopersicon esculentum Mill., cv. Sunbeam) fruit from plants grown using black polyethylene or hairy vetch mulches under various foliar disease management systems including: no fungicide applications (NF), a disease forecasting model (Tom-Cast), and weekly fungicide applications (WF), during storage at 5 °C under a modified atmosphere. In this study, we used the fourth uniform slice from the stem end and analyzed for firmness, soluble solids content (SSC), titratable acidity (TA), pH, electrolyte leakage, molds, yeasts and occurrence of water-soaked areas. With both NF and Tom-Cast fungicide treatments, slices from tomato fruit grown with hairy vetch mulch showed greater firmness than those from tomato fruit grown with black polyethylene mulch after 12 d of storage. Ethylene production of slices from tomato fruit grown using hairy vetch mulch under Tom-Cast was about 1.5- and 5-fold higher than that of slices from tomato fruit grown under the WF and NF fungicide treatments after 12 d, respectively. Within each fungicide treatment, slices from tomato fruit grown using hairy vetch mulch showed less chilling injury (water-soaked areas) than those from tomatoes grown using black polyethylene mulch. The percentage of water-soaked areas for slices from tomato fruit grown using black polyethylene mulch under NF was over 7-fold that of slices from tomato fruit grown using hairy vetch under Tom-Cast. These results suggest that, under our conditions, fruit from plants grown using hairy vetch mulch may be more suitable for fresh-cut slices than those grown using black polyethylene mulch.

Free access

Experiments were conducted to compare changes in quality of slices of red tomato (Lycopersicon esculentum Mill. `Sunbeam') fruit from plants grown using black polyethylene or hairy vetch mulches under various foliar disease management systems including: no fungicide applications (NF), a disease forecasting model (Tom-Cast), and weekly fungicide applications (WF), during storage at 5 °C under a modified atmosphere. Slices were analyzed for firmness, soluble solids content (SSC), titratable acidity (TA), pH, electrolyte leakage, fungi, yeasts, and chilling injury. With both NF and Tom-Cast fungicide treatments, slices from tomatoes grown with hairy vetch (Vicia villosa Roth) mulch were firmer than those from tomatoes grown with black polyethylene mulch after 12 days storage. Ethylene production of slices from fruit grown using hairy vetch mulch under Tom-Cast was ≈1.5- and 5-fold higher than that of slices from WF and NF fungicide treatments after 12 days, respectively. The percentage of water-soaked areas (chilling injury) for slices from tomatoes grown using black polyethylene mulch under NF was over 7-fold that of slices from tomatoes grown using hairy vetch under Tom-Cast. When stored at 20 °C, slices from light-red tomatoes grown with black polyethylene or hairy vetch mulches both showed a rapid increase in electrolyte leakage beginning 6 hours after slicing. However, slices from tomatoes grown using the hairy vetch mulch tended to have lower electrolyte leakage than those grown with black polyethylene mulch. These results suggest that tomatoes from plants grown using hairy vetch mulch may be more suitable for fresh-cut slices than those grown using black polyethylene mulch. Also, use of the disease forecasting model Tom-Cast, which can result in lower fungicide application than is currently used commercially, resulted in high quality fruit for fresh-cut processing.

Free access