A factorial experiment begun in 1980 included `Hamlin' and `Valencia' sweet-orange scions [Citrus sinensis (L.) Osb.], and Milam lemon (C. jambhiri Lush) and Rusk citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] rootstocks, tree topping heights of 3.7 and 5.5 m, between-row spacings of 4.5 and 6.0 m, and in-row spacings of 2.5 and 4.5 m. The spacing combinations provided tree densities of 370, 494, 667, and 889 trees ha. Yield increased with increasing tree density during the early years of production. For tree ages 9 to 13 years, however, there was no consistent relationship between yield and tree density. Rusk citrange, a rootstock of moderate vigor, produced smaller trees and better yield, fruit quality, and economic returns than Milam lemon, a vigorous rootstock. After filling their allocated space, yield and fruit quality of trees on Milam rootstock declined with increasing tree density at the lower topping height. Cumulative economic returns at year 13 were not related to tree density.
T.A. Wheaton, J.D. Whitney, W.S. Castle, R.P. Muraro, H.W. Browning and D.P.H. Tucker
James E. Brown, Daniel W. Porch, Ronald L. Shumack, Charles H. Gilliam and Larry Curtis
In sweet corn field plots in Alabama, urea-ammonia nitrogen was applied to the soil through underground and aboveground drip fertigation systems. Dry nitrogen in the form of ammonium nitrate was surface band-applied as a control. Nitrogen rates of 67 kg/ha and 135 kg/ha were applied in either 2 or 4 applications by each of the 3 methods. P and K fertilizers were applied to all treatments in a dry form according to soil test recommendations. The underground drip pipe was placed 23 cm beneath the soil surface in each row. Nitrogen (wet or dry) rate of 135 kg/ha produced greater sweet corn yield than the 67 kg/ha rate with no effect of application number on yield in 1988, when rainfall was less than adequate. In 1987 and 1989, when rainfall was adequate, no differences occurred in yields regardless of number, rate, or method of application of nitrogen.
James E. Brown, Charles H. Gilliam, Ronald L. Shumack and Daniel W. Porch
Commercial snap bean (Phaseolus vulguris L.) yields in spring were similar when comparing a commercial fertilizer standard based on soil test recommendations to three application rates of broiler litter. Snap bean yields in the fall were higher on plots that received spring-applied broiler litter than on those receiving the commercial fertilizer standard in the fall. Increasing the application rate of broiler litter generally resulted in a linear yield response during both seasons.
D.S. Lawson, S.K. Brown, J.P. Nyrop and W.H. Reissig
A barrier system for pest control consisting of insect-exclusionary cages covered with three types of mesh material was placed over columnar apple (Malus domestica Borkh.) trees. This system has been shown to provide arthropod control equivalent to insecticides. Light intensity, evaporation, and air and soil temperature were reduced inside the cages. Shoot elongation of columnar apple trees grown inside insect-exclusionary cages was significantly greater than that of trees grown outside the cages. However, this increased shoot growth was not due to etiolation. Tree performance was unaffected by insect-exclusionary cages. Fruit set and fruit soluble solids concentration were not reduced by the cages; however, fruit color intensity was reduced as the degree of shading from the mesh increased. These findings, in conjunction with high levels of arthropod control by insect-exclusionary cages, may allow insect-exclusionary cages to be used for evaluating integrated pest management thresholds, predator-prey relationships, and apple production without insecticides.
S.S. Miller, R.W. McNew, B.H. Barritt, L. Berkett, S.K. Brown, J.A. Cline, J.M. Clements, W.P. Cowgill, R.M. Crassweller, M.E. Garcia, D.W. Greene, G.M. Greene, C.R. Hampson, I. Merwin, D.D. Miller, R.E. Moran, C.R. Rom, T.R. Roper, J.R. Schupp and E. Stover
Cultivar and planting site are two factors that often receive minimal attention, but can have a significant impact on the quality of apple (Malus ×domestica) produced. A regional project, NE-183 The Multidisciplinary Evaluation of New Apple Cultivars, was initiated in 1995 to systematically evaluate 20 newer apple cultivars on Malling.9 (M.9) rootstock across 19 sites in North America. This paper describes the effect of cultivar and site on fruit quality and sensory attributes at a number of the planting sites for the 1998 through 2000 growing seasons. Fruit quality attributes measured included fruit weight, length: diameter ratio, soluble solids concentration (SSC), titratable acidity (TA), flesh firmness, red overcolor, and russet. Fruit sensory characteristics rated included crispness, sweetness, and juiciness, based on a unipolar intensity scale (where 1 = least and 5 = most), and acidity, flavor, attractiveness, and desirability based on a bipolar hedonic scale (where 1 = dislike and 5 = like extremely). All fruit quality and sensory variables measured were affected by cultivar. The two-way interaction of cultivar and planting site was significant for all response variables except SSC, TA, russet, crispness, and sweetness ratings. The SSC: TA ratio was strongly correlated with sweetness and acidity sensory rating, but was weakly correlated with flavor rating. The results demonstrate that no one cultivar is ideally suited for all planting sites and no planting site is ideal for maximizing the quality of all apple cultivars.