Search Results
Abstract
To determine whether cold hardiness of peach [Prunus persica (L.) Batsch] is affected by cultural practices, 2-year-old ‘Coronet’ trees growing in a peach tree short-life site were treated by soil fumigation with 1,2-dibromo-3-chloropropane (DBCP) late fall application of nitrogen, combination of fumigation and fall applied nitrogen, fall pruning (November), or usual grower practices (control). Cold hardiness was measured by determining the leakage of electrolytes from dormant terminal twig sections exposed to low temperatures, and visually by oxidative browning and ease of phloem-xylem separation. Fall-pruned trees were lower in cold hardiness and survival than controls. Nitrogen applied alone or in combination with fumigation reduced cold hardiness in early winter but increased vigor and survival. Trees grown in fumigated soil and winter-pruned were hardier than control trees and fall-pruned trees in nonfumigated soil. Differences in hardiness were greatest near bloom time. Cultural practices strongly affected cold hardiness of xylem, phloem, and cambium of treated trees, and cold hardiness was associated with tree longevity.
Abstract
Disc tillage of turnip greens (Brassica campestris L. Rapifera group) caused an abrupt increase in soil strength below tillage depth, which in turn prevented turnip root penetration. Soil strength of 85 N/cm2 on Lakeland sand and 100 N/cm2 on Tifton sandy loam prevented penetration of turnip roots. In general, root fresh and dry weights were unaffected by tillage treatments. Turnip root growth with the disc treatment was shallow, whereas turnips grown with subsoil-bed and subsoil-plant tillages developed deeper root systems. Balanced downward and horizontal turnip root systems were developed with mold-board plow preplant tillage.
Abstract
Preplant tillage treatments influenced growth and yield of turnip greens (Brassica campestris L. Rapifera group). Yields in response to moldboard plow, subsoil-bed and subsoil-plant treatments were not significantly different on either Tifton sandy loam or Lakeland sand. Yields with the above tillage treatments were significantly greater than with disc treatments on Lakeland sand. However, on Tifton sandy loam, only moldboard plow treatment resulted in higher yields than with disc treatments. Plants with higher top fresh and dry weights were obtained with moldboard plow treatment on Tifton sandy loam but not on Lakeland sand. Disc treatment increased soil strength and decreased root length.
Abstract
During winter months, concentrations of K, Ca, Al, Sr, B and Zn were significantly greater in twigs of apparently healthy, dormant peach (Prunus persica (L.) Batsch) trees grown on old peach orchard sites than in twigs of apparently healthy trees on adjacent new sites in Georgia. Later in the spring, tree mortality and injury from cold and bacterial canker caused by Pseudomonas syringae Van Hall were also much greater on the old sites than the new sites. Differences in elemental concentrations in roots and 2-year-old shoots were not significant when trees on old and new orchard sites were compared. In a short life site in South Carolina, pruning trees in November greatly increased tree mortality compared to fumigated or nonfumigated trees pruned in February. Concentrations of K, Mg, Fe, and Al were also significantly greater in the November-pruned trees than in the February-pruned trees. Accumulation during dormancy of certain elements in peach twigs may be an indicator that the trees have been predisposed to short life.
Abstract
This study was designed to determine the effect of pest control intensity on net returns in multiple cropping systems. The study is tempered with an evaluation of risk. The cropping system encompasses: turnip greens (Brassica rapa L.) for processing, field corn (Zea mays L.), and southern peas [Vigna unguiculata (L.) Walp. ssp. unguiculata] for processing. Within the ranges of pest control intensities studied, less intensive control resulted in higher net returns. Further, the level of greatest pest control intensity consistently yielded negative net returns. This level, however, was less risky in terms of gross returns. Risk did not differ significantly between the other levels of pest control.