A single lime application of 5.4 t/ha per 20 cm increment of soil to a depth of 60 cm controlled bacterial wilt (Psendomonas solanacearum E. Smith) up to 2 years in tomato (Lycopersicon esculentum Mill.) growing in a naturally infested soil. `Sunny' with 64% disease incidence, was the most susceptible, `Capitan' (20%) was intermediate, and `Caraibo' (5%) and `Hawaii 7997' (2%) were the least susceptible. Incorporation of lime 40 to 60 cm deep reduced bacterial wilt incidence in 'Capitan' by 75%, and 60% in `Sunny'. The number of bacteria in the soil was not affected by lime treatment. Soil pH and total Caincreased linearly with time and with depth of lime incorporation. Bacterial wilt control in `Sunny' and `Capitan' was associated with an increase in pH. Liming to 40 or 60 cm generally increased leaf Ca and decreased Mn, Zn, and Cu. `Hawaii 7997' contained significantly higher concentrations of Ca, Mg, and K, and lower Cu compared to 'Sunny'. `Hawaii 7997' produced significantly higher yields than the other cultivars. Deep lime incorporation increased fruit weight of `Sunny' by 184% and 'Capitan' by 79% as compared with 0 lime.
R. Ssonkko, S.J. Locascio, R.E. Stall, and D.N. Maynard
S.J. Locascio, A.G. Smajstsrla, D.H. Hensel, and D.P. Weigartner
Growth and production uniformity of potato (Solanum tuberosum L.) as influenced by conventional seepage irrigation and by subsurface drip irrigation was evaluated in field studies during two seasons in plots 16 rows (18.3 m) wide and 183 m long. Seepage irrigation water was supplied through ditches located on each side of each plot. Drip irrigation water was distributed through buried tubes placed under the beds 6.1 m apart extending the length of the rows. Water application throughout the plots was accomplished more rapidly with the subsurface drip system and water use during the two seasons was 33% less than with the conventional seepage system. Tuber yield during the first season was similar with the two irrigation systems. During the second season, plant growth, tuber development, and tuber yield were sampled on alternate rows beginning on each outside bed, at each end of each plot, and in the middle of the plots. Irrigation method and bed location among the 16 beds had little influence of potato growth and development. With water flow from north to south, plant growth, and tuber yield were significantly higher from potatoes growing at the north end, lowest in the plot center, and intermediate from potatoes growing at the south end. These data indicate that potato production with the two irrigation systems was similar.
M.E. Elkashif, S.J. Locascio, and D.R. Hensel
Isobutylidene diurea (IBDU) and sulfur-coated urea (SCU) alone or in combinations with NH4NO3 were evaluated as N sources for potatoes (Solanum tuberosum L.) on 2 sandy soils. Nitrogen was applied either all preplant or in split application at 134 or 201 kg N/ha. Tuber yields were highest with NH4NO3 alone or with NH4NO3 combined with IBDU or SCU, and were lowest with 100% IBDU and SCU. Marketable yields obtained with NH4NO3 were 25% and 27% higher than with 100% IBDU and SCU, respectively. Marketable and total yields increased and tuber specific gravity decreased slightly with increased N. Split applications of N increased marketable and total yields at one location. Leaf N, Mg, and Ca concentrations were higher and K was lower with NH4NO3 alone or with NH4NO3 with IBDU or SCU than with IBDU and SCU. Nitrogen sources had no significant effect on soil total soluble salts, NO3-N, or NH4-N, 7 and 12 weeks after fertilization.
Peter J. Stoffella, Salvador J. Locascio, Teresa K. Howe, Steve M. Olson, Kenneth D. Shuler, and Charles S. Vavrina
Bell pepper (Capsicum annuum L.) cultivars were grown in nine Florida environments to evaluate phenotypic stability of marketable fruit yield (t-ha-') and mean fruit size (g/fruit). A stable cultivar excelled for a particular trait when grown in either favorable or unfavorable environments. A stable cultivar for a given trait was defined as one with an individual mean greater than the grand mean (mean of all cultivars) (x > X), a regression coefficient (b1) ≤ 1 (individual genotypic mean regressed against environmental means), nonsignificant deviation mean squares from regression (S2d), coefficient of linear determination (R2) > 0.50, and coefficient of variation (cv) < the pooled cv. `Ssupersweet 860', `Whopper Improved', and `Ranger' were stable for mean marketable fruit weights and fruit size, and `Ssupersweet 860' and `Whopper Improved' were stable for mean fruit size. Bell pepper cultivars were differentiated for phenotypic stability of yield and fruit size or adaptability to diverse environments. Therefore, through stability analyses, bell pepper plant breeders can identify cultivars or select advanced breeding lines that express adaptability for fruit yields or size to diverse environmental conditions or cultural practices.
G. J. Hochmuth, S. J. Locascio, T.E. Crocker, C.D. Stanley, G.A. Clark, and L.R Parsons
The Florida horticulture industry (vegetables, ornamentals, citrus, and deciduous fruit), valued at $4.5 billion, has widely adopted microirrigation techniques to use water and fertilizer more efficiently. A broad array of microirrigation systems is available, and benefits of microirrigation go beyond water conservation. The potential for more-efficient agricultural chemical (pesticides and fertilizer) application is especially important in today's environmentally conscious society. Microirrigation is a tool providing growers with the power to better manage costly inputs, minimize environmental impact, and still produce high-quality products at a profit.
S.J. Locascio, J.G.A. Fiskell, D.A. Graetz, and R.D. Hauck
Peppers (Capsicum annuum L.) were grown during 2 seasons on Blichton fine sand (Arenic Plinthic Paleaquult) to evaluate the effects of black polyethylene mulch and timing of N application on accumulation of applied N by the shoots and fruit. Nitrogen was applied at 224 kg/ha as 15-N depleted (NH4)2SO4 in a split application or in a single application with and without mulch. During a relatively dry season, total fruit yields and N accumulation were not influenced by treatment. At the end of the crop season, N accumulation from the 224 kg N/ha averaged 16.5% in the shoots, 2.2% in the immature fruit, and 15.8% removed in the harvested fruit for a total utilization of 34.5% (77 kg/ha). The soil supplied about 43 kg N/ha. During an extremely wet season, fruit yields and N uptake were influenced significantly by treatments. Fruit yields were 25.1, 5.5, and 17.5 T/ha with the mulch, no-mulch single, and the no mulch split application treatments, respectively. Total N utilizations by plant shoots, immature fruit, and harvested fruit were 41.8% (94 kg/ha), 7.6% (17 kg/ha), and 23.9% (54 kg/ha) of the applied N with the 3 treatments, respectively. Nitrogen quantities utilized from the soil with the 3 treatments were 27, 11, and 15 kg N/ha, respectively.
L.A. Risse, J.K. Brecht, S.A. Sargent, S.J. Locascio, J.M. Crall, G.W. Elmstrom, and D.N. Maynard
Two newly released cultivars of small watermelons [Citrullus lunatus (Thumb.) Matsum and Naki], `Mickylee' and `Minilee', plus two other cultivars, Baby Fun and Sugar Baby, were stored at various temperatures from 1 to 21C for up to 4 weeks plus 1 week at 21C over two seasons. All cultivars were susceptible to chilling injury (CI) when stored below 7C; however, `Minilee' was less susceptible than the other cultivars tested. Chilling injury increased with storage length. Conditioning at 26C for 3 days before storage at 1C reduced CI and increased the percentage of marketable watermelons after storage. Decay percentage increased with storage time and was highest on fruit held at 1C where CI led to decay. The flesh of `Mickylee' and `Minilee' was firmer than that of the other cultivars tested and `Mickylee' and Minilee' retained their firmness better during storage. Total soluble solids concentration decreased with increased storage temperature. `Minilee' watermelons were superior to the other three cultivars in postharvest storage potential and exhibited the least CI and decay.
D. W. Sweeney, D. A. Graetz, A. B. Bottcher, S. J. Locascio, and K. L. Campbell
Factorial combinations of trickle or overhead irrigation, polyethylene mulch or no mulch, and 100% NH4NO3 or 50% sulfur-coated urea (SCU) and 50% NH4NO3 were evaluated for their effects on yield and N recovery by tomatoes (Lycopersicon esculentum Mill). In treatments using 100% NH4NO3, 15N-depleted NH4NO3 was applied. Neither tomato yield nor N uptake were affected by irrigation method but both were increased by the use of polyethylene mulch. Higher yields were obtained with NH4NO3 than with 50% NH4NO3 and 50% SCU. An average of 65% of the N in the plant and fruit originated from fertilizer N. Nitrogen recovery from plants and soil at the end of the season in treatments using 15N-depleted fertilizer ranged from 52% to 95%. Highest recovery was obtained with mulch plus overhead irrigation. With this system, 53% of the added N was recovered by the plant and 42% remained in the soil. Only 5% of the added N was lost from the system. All of the other treatments resulted in loss of an average of 46% of the added N.