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Potato (Solanum tuberosum L.) production best management practices (BMPs) are under development for the Tri-County Agricultural Area (TCAA; St. Johns, Putnam, and Flagler counties) near Hastings, Fla. BMPs are designed to reduce nitrate non-point pollution in the St. Johns River from the |8000 ha in potato production in the TCAA. Research to develop a controlled release fertilizer (CRF) program to help growers meet the current nitrogen rate BMPs was conducted during the 2003 season. A randomized complete block experiment with four replications was conducted at the Plant Science Research and Education Unit in Hastings, Fla. The treatments were no nitrogen control, ammonium nitrate (168 and 212 kg N/ha) and three CRF products blended at different ratios (168 kg N/ha). Total tuber yields for `Atlantic' for the no nitrogen, and 168 and 212 kg N/ha ammonium nitrate treatments were 11.5, 23.4, and 36.4 MT/ha. The best combination of the three CRF products were a ratio of 33:33:33 with a 40 day, 75 day, 120 day release period, respectively. Total yield for this blend was 42.2 MT/ha. Specific gravities for tubers in all four treatments were 1.060, 1.072, 1.078, and 1.082, respectively. Percent of tubers with hollow heart four all four treatment were 8.1, 18.2, 20.0, and 6.4% respectively. Percent of tubers with internal heat necrosis four all four treatments were 20.6, 8.1, 20.6, and 6.3%, respectively. The CRF treatment produced significantly more tubers than the ammonium nitrate treatment at the same nitrogen rate. Quality of the tubers in the CRF treatment was higher than tubers from the no nitrogen control and ammonium nitrate treatments. Research will continue to optimize the CRF program for potato production in Florida.

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Because deer pressure in Alabama is high, the efficacy of Garlic Barrier™ (GB) in controlling deer damage was evaluated with sweetpotato (SWP), southernpea (STP), sweet corn (SC), and zucchini squash (ZSQH). GB was applied on or around the plots at 10× the recommended rate. Damage was rated three times weekly on a 0 (0% damage) to 5 (100%) scale between 15 June and 18 Sept. All damage observed was unambiguously attributed to deer. GB on the plot significantly (P < 0.02) reduced grazing damage to SWP and STP, but not enough to prevent economical losses. Protection from GB around the plots was similar to the unsprayed control. Damage to SWP began 3 days after establishment. Damage to STP was limited to the developing pods. No damage was observed to SC and ZSQH (P > 0.37) during vegetative and reproductive stages. These results document scientifically the deer-repellent property of GB under natural conditions when applied directly on the plants. However, in its present formulation and under severe deer pressure, GB alone may not provide economical protection.

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Vegetable variety trials (VVT) are of interest to the entire vegetable industry from breeders, seed companies, growers, consultants, researchers, to Extension personnel. However, despite their importance VVT have always been given little-to-no scientific merit. In a period where resources are limited, regional VVT may provide a way for Land Grant institutions to include VTT as an entire part of their effort. This presentation will discuss the advantages (better use of resources, increased service to industry), challenges (credit given to VTT authors during tenure, timeliness of publication, uniformity of methods), and opportunities (publications in Hort Technology, regional publication, VTT web page, SR-IEG) associated with VVT. Participants will be given an opportunity to express their opinion through a questionnaire. Together with industry response, results will be used to inform the administration and work toward a regional VTT for the Southeast.

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Field performance, ear characteristics and sensory ratings were determined for `Even Sweeter,' `Fantasia', `Silver Queen', `Silverado', `Snow Belle', `Snow White', `Starshine', and `Treasure' sweet corn varieties. Yield (P = 0.60), ears per hectare (P = 0.77), and ear fill (P = 0.22) were not significantly affected by variety, whereas ear set height (P < 0.01), ear length (P < 0.01) and diameter (P < 0.01), tip cover (P < 0.01), eye appeal (P < 0.01), as well as sensory ratings of appearance (P < 0.01), sweetness (P < 0.01), and flavor (P < 0.01) after cooking were. None of the selected varieties was rated unacceptable. However, because mean separation tests at the 5% and 10% levels did not provide clear groupings and because all attributes have to be considered together in variety evaluation, a global performance index (GPI) was developed by adding the ranks of each variety for each attribute. GPI ranged between 28 for `Treasure' and 59 for `Snow White' on a 10 (best) to 80 (worse) scale. `Treasure', `Silver Queen', and `Even Sweeter' were above average. These varieties may be considered best performers for white sweet corn production in central Alabama.

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Visualizing the effect of irrigation volume on water movement in and below the root zone of strawberry (Fragaria ×ananassa) plants may be used to determine when to split irrigation. By injecting blue dye (Terramark SPI High Concentrate) during controlled irrigation events with several drip tapes commonly used by area growers, the objectives of this project were to: (1) determine vertical, lateral and longitudinal movements of wetted zones applied by drip irrigation on a Seffner fine sand soil; (2) describe the shape of the wetted zone for increasing irrigation volumes; and (3) determine the irrigation after which water moves below the root zone. Dye tests consisted in preparing mulched beds with different drip tapes (7 total), injecting dye, irrigating with the selected volume of water (V), digging longitudinal and transverse sections of the raised beds, and taking measurements of vertical (depth; D), lateral (width; W) and longitudinal (L) water movement. Increasing V from 279 to 3353 L/100 m, significantly increased D, W and L. Depth and W responses to V were D = 0.19 V + 26.1 (R 2 = 0.80), and W = 0.36 V + 13.5 (R 2 = 0.78). Emitter-to-emitter coverage occurred after 4 hours for 30-cm spacing. Based on expected root depths of 20 cm when the strawberry plants are young and 30 cm when they are fully grown, largest V before water moved below the root zone were 325 and 870 L/100 m, which corresponds to typical irrigation times of 1 and 3 hours, respectively. Greater irrigation volumes may reduce water use efficiency and increase the risk of nutrient leaching below the root zone.

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In 1999, two studies were conducted using bell pepper (Capsicum annuum L.) Study one evaluated the effect of three different mulch systems and bare soil (BS) on day and night temperatures encountered during the early growth, flowering, and fruit set period. Mulch systems were black plastic (BP), black plastic over white plastic (BOW), and minimum tilled rye (MTR). Study two evaluated the use of a 30% shade fabric on black plastic produced bell pepper. In study one, maximum daytime temperatures during the pre-flowering phase was significantly higher for MTR, 35.9 °C, compared to, 33.3, 32.5, and 32.1 °C for BOW, BP, and BS respectively. During early fruit set and fruit development, MTR was 36.9 °C, compared to 35.6, 34.9, 34.9 °C for BWP, BS, and BP respectively. Minimum nighttime temperatures were not significantly different between treatments. Bloom numbers and fruit set were adversely affected by MRT and were significantly lower than other treatments 23 and 15 days prior to harvest. Marketable weight and number of fruit per plot were significantly lower at harvest for MRT, 2.5 kg compared to 15.7, 14.5, and 11.6 kg for BWP, BP, and BS respectively. In study two, 30% shading 15 days prior to harvest resulted in 40% increase in number, 101 and 72, and weight, 21 and 15 kg, of marketable fruit for shaded area compared to nonshaded area respectively. Numbers of culls per plot, predominately sunburned fruit in non-shaded area, were reduced 72% by shading. The potential for developing systems to improve bell pepper production in Alabama are feasible based on these studies.

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Potato (Solanum tuberosum L.) is often produced as a nonirrigated crop in the southeastern United States. This practice makes tuber yields dependent on rainfall pattern and amount. An irrigation scheduling method based on a water balance and daily class A pan evaporation (Ep) was evaluated during 1996 and 1998 on a Hartsells fine sandy loam soil for `Red LaSoda' potatoes. Planting dates were 9 and 7 Apr. in 1996 and 1998, respectively, and standard production practices were followed each year. The model tested was (13 DAH + 191) * 0.5 ASW = D DAH-1 + [Ep * (0.12 + 0.023 DAH - 0.00019 DAH2) - RDAH - IDAH], where DAH was days after hilling, ASW was available soil water (0.13 mm/mm), D was soil water deficit (mm), R was rainfall (mm), and I was irrigation (mm). Controlled levels of water application ranging between 0% and 200% of the model rate were created with drip tapes. Four and seven irrigations were scheduled in 1996 and 1998, respectively. For both years, no interaction between irrigation regime and nitrogen rate was observed. Irrigation rate significantly influenced total yield and marketable yield (R 2 > 0.88, P < 0.01). Highest total yields occurred at 99% and 86% of the model rate in 1996 and 1998, respectively. These results show that supplementing rainfall with irrigation and controlling the amount of water applied by adjusting irrigation to actual weather conditions increased potato marketable yield. Over the 2-year period of the study, an average additional profit of $563/ha/year was calculated from costs and returns due to irrigation, suggesting that drip-irrigation may be economical for potato production.

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Because cucumber mosaic virus (CMV) affects southernpea (Vigna unguiculata) grown in the southeast, plants were preconditioned with different nutrient solutions from germination to the flowering stage, 24 DAT (days after transplanting) and rub inoculated with CMV. Symptoms were observed at a rate of 1/5, 1/5, 4/5, and 4/5 (observed infected plants/plants infected) in the Al, NH4, NO3, and Na treatments, respectively. At 67 DAT, ELISA detected CMV at a rate of 5/5, 5/5, 4/5, and 4/5 (detected infection/plants infected) of the Al, NH4, NO3, and Na treatments, respectively. The interaction of inoculation and preconditioning was nonsignificant for fresh or dry weight (P > 0.10); however, nutritional preconditioning significantly (P < 0.01) affected the fresh and dry weight. These preliminary data suggest that nutritional preconditioning affects southernpea plants' reaction to CMV.

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Sweetpotato (Ipomea batatas L.) is a drought-tolerant crop mostly produced without irrigation. Consequently, sweetpotato may be exposed to temporary water stress. In 1997, an irrigation scheduling model using a water balance and class A pan evaporation (Ep) was evaluated with `Beauregard' on a loam sandy soil. The model was (12.7 DAT + 76) 0.5 ASW = DDAT-1 + [Ep (0.12 + 0.023 DAT – 0.00019 DAT2) – RDAT – IDAT], where DAT is days after transplanting (DAT = 0 on 20 June), ASW is available soil water (15%), D is soil water deficit (mm), R is rainfall (mm), and I is irrigation (mm). Root depth expanded at a rate of 13 mm/day to a maximum depth of 305 mm. Irrigation rates ranging between 0 and 145% of the model rate were created with sprinklers. The model scheduled 10 irrigations between DAT = 26 and 116 (harvest). Irrigation did not alter storage root quality, but did influence all the marketable grades (P < 0.01; R2 > 0.87). However, between 0 and 129% yield increases were linear and small, suggesting that the model overestimated sweetpotato water use. Thus, deficit irrigation between 50% to 70% of the model would have a limited effect on sweetpotato yields.

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An irrigation scheduling model for turnip greens (Brassica rapa L.) was developed and validated.. The irrigation scheduling model is represented by the equation: 12.7 (i-3) * 0.5 ASW = 0i-1 + Ei(0.365+0.00154i+0.00011i2) - R - I where crop age is i; effective root depth is 12.7 * (i-3) with a maximum of 300 mm; usable water (cm/cm of soil) is 0.5 ASW; deficit on the previous day is Di-1 evapotranspiration; is pan evaporation (Ei) times 0.365+0.0154i+0.00011i2; rainfall (R) and irrigation (I) are in millimeters. Yield measured as leaf weight, and quality analyzed in terms of color (Gardner XL20 cronameter L, a, b), leaf blade and blade: stem weight ratio were determined. Leaf yield and quality responses were affected by both irrigation and fertilizer rates. Yield increased quadratically as irrigation rates increased from 0 to 190% of the model rate. Maximum leaf yields were produced by irrigations at 100% of the model rate. Leaf quality parameters also tended to change quadratically with irrigation rates. Leaf yield and quality changed quadratically as nitrogen fertilizer rates increased from 80 to 120% of the median recommended N rate for Georgia.

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