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Bielinski M. Santos

The effects of early pruning on the growth and yield of ‘Florida-47’ and ‘Sungard’ tomato (Solanum lycopersicum) were assessed in west-central Florida. Each cultivar was established in separate experiments. The four pruning treatments consisted of leaving one, two, and three main stems in the tomato plants below the first flower cluster, and a nonpruned control. Pruning shoots had significant effects on the plant height of ‘Sungard’ and ‘Florida-47’ at 4 and 3 weeks after transplanting, respectively. Tomato plants with a single stem were 13% and 10% taller than the ones in the nonpruned control, respectively. However, this effect disappeared 1 and 2 weeks later in both cultivars. Regardless of the cultivar, early pruning did not influence foliar disease incidence or early and total tomato marketable yield. This cultural practice did not affect the partitioning to different fruit categories in either cultivars. This data showed that early pruning can temporarily change the plant architecture of ‘Sungard’ and ‘Florida-47’ tomato, explaining the perceived increased plant vigor in comparison with the nonpruned control. However, the effect disappeared during the growing season and did not reflect on marketable yields of either tomato cultivars. If no pruning were performed in these cultivars, growers would be able to save an estimated $40/acre of tomato.

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Bielinski M. Santos

Research was conducted to determine appropriate in-row spacing for eggplant (Solanum melongena) and to determine the best economic returns of this practice. ‘Classic’ eggplant seedlings were transplanted at in-row distances of 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 ft. Eggplant height decreased linearly as in-row spacing increased. In-row spacing affected total eggplant fruit number, with no fruit number differences among 1.0, 1.5, 2.0, and 2.5 ft, averaging ≈46,800 fruit/acre. Total fruit weight followed a trend similar to that for total fruit number and there were no differences among 1.0, 1.5, 2.0, and 2.5 ft (ranging between 18.2 and 19.9 tons/acre). From an economical standpoint, the comparison between 2.0 and 2.5 ft resulted in the former spacing having a marginal return rate of 8.03% in relation to an in-row spacing of 2.5 ft, which indicated that growers would earn $0.08 extra for each $1.00 of net profit by switching from 2.5 to 2.0 ft in-row plant spacing.

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Bielinski M. Santos

Field studies were conducted to determine effects of preplant nitrogen (N) and sulfur (S) sources on ‘Strawberry Festival’ strawberry (Fragaria ×ananassa) growth and yield. Six treatments resulted from the preplant application of ammonium nitrate [AN (34% N)], ammonium sulfate [AS (21% N and 24% S)], ammonium sulfate nitrate [ASN (26% N and 14% S)], polymer-coated AS [PCAS (20% N and 23% S)], and elemental S (90% S). A nontreated control was added. The N was fixed at 50 lb/acre for AN, AS, ASN, and PCAS, which resulted in S rates of 0, 57, 27, and 57 lb/acre, respectively. The S rate of the elemental S treatment was set at 57 lb/acre. For early fruit number, the highest values were found in plots treated with AS and elemental S, while the highest total fruit numbers were obtained in plots treated with AS, ASN, PCAS, and elemental S. There was no difference in total fruit numbers between the nontreated control and AN. Plots treated with elemental S, PCAS, ASN, and AS had the highest early marketable fruit weights, whereas the lowest early marketable fruit weight was found in the nontreated plots. In comparison with the nontreated control plots, all the preplant fertilization programs improved early marketable fruit weight, with AN, AS, ASN, PCAS, and elemental S. Total marketable fruit weights were maximized in plots treated with preplant AS, ASN, PCAS, or elemental S. There was no difference between the total fruit weights obtained in the control and AN-treated plots. The data indicated that the strawberry total yield increases can be attributed to the use of preplant fertilizer sources containing S. This research may lead to a more appropriate use of N for strawberry production in Florida, minimizing the nitrate-leaching potential in high sandy soils by eliminating N sources from preplant fertilization programs.

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Bielinski M. Santos

Two field studies were conducted to compare the effects of preplant nitrogen (N) rates and irrigation programs on tomato (Solanum lycopersicum) growth and yields. Irrigation programs were seepage (subsurface) irrigation alone at a water volume of 28 acre-inches/acre per season and seepage plus drip irrigation at a volume of 28 and 14 acre-inches/acre per season, respectively. Preplant N fertilization rates were 200, 250, and 300 lb/acre, using ammonium nitrate as the N source. There were significant irrigation program by N rate interactions for nitrate (NO3 ) petiole concentrations at 8 weeks after transplanting (WAT), and yield of extra-large fruit and total marketable fruit, but not for plant height at 5 and 7 WAT. The highest NO3-N petiole concentrations were found in plots treated with 200, 250, and 300 lb/acre for N and seepage plus drip irrigation, and with 300 lb/acre N under seepage irrigation alone. For the total marketable fruit weight, there were no differences among N rates in those plots irrigated with the seepage plus drip combination, ranging between 23.8 and 25.9 tons/acre. However, there was a significant N effect in plots receiving only seepage irrigation with marketable fruit weight almost doubling from 12.0 to 22.7 tons/acre when applying 200 and 300 lb/acre N, respectively. Both irrigation programs had equivalent performance when 300 lb/acre N were applied.

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Bielinski M. Santos

Selecting the “right” nutrient rate for fertilization programs is one of the most important decisions growers face. On one hand, increasing fertilizer prices and environmental concerns have increased the awareness of accurately managing fertilization programs, thus reducing fertilizer amounts during cropping seasons. By contrast, many growers fear not obtaining the desired crop performance and economic returns, especially when fertilization is assumed as “inexpensive insurance” to improve yields, thus leading to overfertilization. The objective of this paper was to provide general principles for selecting and monitoring the right nutrient rate within the framework of the “4R” nutrient management concept (right rate, right source, right placement, and right timing) to protect environmental quality while maintaining productivity. Some methodologies to determine, apply, and adjust fertilization rates during the growing season were discussed, including in-season monitoring procedures, such as petiole sap testing, plant diagnostic analysis, leaf color evaluation, and plant growth index.

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Bielinski M. Santos

A two-season study was conducted to assess the effects of preplant potassium (K) fertilization rates and sources on the growth and yield of beefsteak tomato (Solanum lycopersicum). Fourteen treatments resulted from the combination of two K sources: sulfate of potash [SOP (0N–0P–42K)] and muriate of potash [MOP (potassium chloride, 0N–0P–50K)] and seven preplant K rates (0, 50, 100, 200, 300, 400, and 500 lb/acre). Soil electrical conductivity (EC) at 4 weeks after transplanting was influenced by the interaction between preplant K rates and sources. When SOP was applied, soil EC increased from 0.4 dS·m−1 with no preplant K application to ≈1.3 dS·m−1 with a rate of 500 lb/acre of preplant K. However, the soil EC steadily increased from 0.4 to 3.0 dS·m−1 as preplant K rates increased from 0 to 500 lb/acre when MOP was used as the nutrient source. The combined effect of the preplant application of K rates and sources influenced the seasonal extra-large and total marketable fruit weight, which increased steadily with K rates, regardless of the sources, from 0 to 300 lb/acre. At K rates between 300 and 500 lb/acre, there were no extra-large and total fruit weight differences among rates when SOP was applied. In contrast, extra-large and total marketable fruit weight declined when rates increased from 300 to 500 lb/acre of K and MOP was applied to the soil. Data demonstrated that plots treated with MOP at rates higher than 300 lb/acre of K increased soil EC and caused a decline on extra-large and total marketable fruit weight of tomato.

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James P. Gilreath and Bielinski M. Santos

Two independent field studies were conducted to determine the efficacy of methyl iodide (MI) formulations and rates on mixed nutsedge [purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus)] stands and their effects on tomato (Solanum lycopersicum) yields. In both studies, treatments were rates of two formulations of MI + chloropicrin (Pic) at the 98:2 (v/v) and 50:50 (v/v) proportions. In the MI + Pic 98:2 study, the fumigant rates were 0, 100, 125, 150, 175, and 200 lb/acre in Spring 2004 and 0, 125, 150, 175, and 200 lb/acre in Fall 2004. In the MI + Pic 50:50 study, the rates were 0, 200, 250, 300, 350, and 400 lb/acre during both seasons. Additionally, a grower standard was included in each study, which consisted of plots fumigated with methyl bromide (MBr) + Pic 67:33 (v/v) at a rate of 350 lb/acre. Higher rates of MI + Pic 98:2 and 50:50 significantly reduced mixed nutsedge densities and increased relative marketable fruit weight of tomato. Plots fumigated with MBr + Pic were weed-free at the sampling times during both studies. Data from both studies indicated that MI + Pic 98:2 and 50:50 rates of 125 and 200 lb/acre, respectively, consistently provided the highest marketable fruit weights and mixed nutsedge control, which were similar to those obtained in plots treated with MBr + Pic.

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Gary E. Vallad and Bielinski M. Santos

Field studies were conducted in Florida to determine the effect of early shoot pruning on the severity of bacterial spot, and on the growth and yield of different tomato (Solanum lycopersicum) cultivars. Two tomato cultivars, two inoculation regimes of bacterial spot pathogen (Xanthomonas perforans), and three shoot pruning programs were arranged in a split-split plot design. The tomato cultivars were Tygress and Security-28; shoot pruning included none, light, and heavy; and X. perforans treatments consisted of non-inoculated plots and plots inoculated with a suspension of the pathogen. Tomato plant height was not influenced by any of the three factors or their interactions, whereas the disease severity was higher in inoculated plots versus non-inoculated plants. Early extra-large fruit weight was affected by tomato cultivars and the inoculation with the bacterial spot pathogen, but not by pruning programs or the interaction among factors. Tomato plants inoculated with X. perforans reduced their extra-large fruit weight by 31% in comparison with non-inoculated plants. There were no differences on early marketable fruit weight among the combinations of each cultivar and the three pruning programs. All three factors individually influenced the seasonal marketable fruit weight of tomato, with no difference between light-pruned plants and the non-pruned control for seasonal marketable fruit weight, regardless of tomato cultivars. However, heavy pruning did reduce seasonal yields by 10% in comparison with the non-pruned control. These results indicated that light shoot pruning, which is the standard grower practice in Florida, did not improve bacterial spot control or tomato yields of total and extra-large marketable fruit, which might save up to $50/acre in reduced labor costs for Florida tomato growers.

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Bielinski M. Santos and Teresa P. Salame-Donoso

A study was conducted over two southern highbush blueberry (Vaccinium corymbosum × Vaccinium darrowi) seasons in a grower field in Florida. The objective was to compare the early fruit weight of southern highbush blueberry cultivars in high tunnels and in open fields. Four treatments were tested using combinations of two southern highbush blueberry cultivars (Snow Chaser and Springhigh) and two production systems (open fields and 18-ft-high tunnels). The results indicated that there was a significant effect of the production systems on the number of days with air temperatures at or near freezing (≤34 °F), and maximum and minimum air temperatures. The minimum air temperature in open-field plots reached ≈19 and 21 °F (61 freezing or near-freezing events) in the 2009–10 and 2010–11 seasons, respectively, whereas the minimum air temperatures inside the high tunnels were ≈32 and 33 °F, respectively, during the same seasons (only 3 days at ≤34 °F). This indicated that using high tunnels was an effective means to avoid freezing air temperatures in blueberries. In the first season, the cumulative early fruit weight was the highest in plots planted with ‘Snow Chaser’ inside the high tunnels (≈10 tons/acre), while the combined production of the two cultivars in the open fields did not reach 1 ton/acre until the end of the early harvests. The following year, there were no differences in the cumulative early fruit weight of both cultivars when planted in the open fields (2.2 tons/acre) and the cumulative fruit yields of ‘Springhigh’ and ‘Snow Chaser’ growing inside the high tunnels was twice and four times higher, respectively, than the early fruit production obtained in the open fields. These data showed the profound effect of high tunnels on flower protection and fruit set. High tunnels reduced water use for freeze protection. The total volume used in the open fields during the freezing or near-freezing days was ≈2.5 acre-inch/acre per 8 hours of freeze protection, whereas only 1/10 of that volume was applied inside the structures.