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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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A clear polyester plastic was evaluated to determine if its physical properties were suitable for vegetable plasticulture. Integrity of the clear plastic was greatly reduced if edges were damaged or torn, resulting in ripping during the mulch lading process. All six punching devices evaluated for planting holes performed well on the black plastic. Flame burner rated highest for the clear plastic and the lowest rating was achieved with the standard transplanter wheel punch. Clear plastic deteriorated quickly and by 78 days after laying was brittle. Where paint treatments provided adequate coverage, deterioration was greatly reduced. Weed growth under clear plastic was a problem early, but weeds soon died due to heat accumulation under the clear plastic. Despite a lower cost, limited agricultural use could be made of this material.

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Best management practices (BMPs) for vegetable crops are under development nationwide and in Florida. One goal of the Florida BMP program is to minimize the possible movement of nitrate-nitrogen from potato (Solanum tuberosum) production to surface water in the St. Johns River watershed without negatively impacting potato yields or quality. Current fertilizer BMPs developed for the area focus on fertilizer rate. Controlled-release fertilizers (CRF) have long been a part of nutrient management in greenhouse and nursery crops. However, CRFs have been seldom used in field-vegetable production because of their cost and release characteristics. Nutrient release curves for CRFs are not available for the soil moisture and temperature conditions prevailing in the seepage-irrigated soils of northern Florida. Controlled-leaching studies (pot-in-pot) in 2000 and 2001 have shown that plant-available nitrogen (N) was significantly higher early in the season from ammonium nitrate, calcium nitrate and urea compared to selected CRFs. However, N release from off-the-shelf and experimental CRFs was too slow, resulting in N recoveries ranging from 13% to 51%. Cost increase due to the use of CRFs for potato production ranged from $71.66 to $158.14/ha ($29 to $64 per acre) based on cost of material and N application rate. This higher cost may be offset by reduced application cost and cost-share pro-grams. Adoption of CRF programs by the potato (and vegetable) industry in Florida will depend on the accuracy and predictability of N release, state agencies' commitment to cost-share programs, and CRFs manufacturers' marketing strategies. All interested parties would benefit in the development of BMPs for CRFs.

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With the development and implementation of best management practices (BMP), extension educators are facing a new and unexpected combination of challenges and opportunities. Because the BMP mandate requires a combination of research, demonstration, and outreach, it may affirm the relevance of the land grant mission in the 21st century, engage universities in interagency alliances, and help rediscover the wonders of the proven extension method. The extension approach to water and nutrient management needs to shift from “pollute less by applying less fertilizer” to “pollute less by better managing water.” Applied research is leading to advances in areas such as nutrient cycles and controlled-release fertilizers. At the same time, universities need to walk a fine line between education and regulation, address perennial issues of overfertilization, and consider the reformulation of recommendations that are now used in a quasi-regulatory environment. A combination of education, consensus, and novel approaches is needed to adapt the rigor of research to a multitude of growing conditions and risks of nutrient discharge in order to comply with U.S. federal laws and restore water quality.

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Most bell peppers produced and consumed in the United States are green in color. However, red, yellow, orange, brown, white, black, and purple bell pepper are also available. While bell pepper consumption has been increasing in the past 10 years, limited information is available on how color, retail price, and vitamin C influence consumer behavior. A conjoint analysis of 436 consumer responses showed that color (75%) and retail price (23%) were more important than vitamin C (3%) in shaping consumer purchase decision. Six consumer segments were identified. Segments II to V preferred green bell pepper, while segments I and VI favored the orange and brown color, respectively. Demographic variables were not good predictors of segment membership. However, previous purchases of bell pepper significantly affected the probability of membership in at least one segment. These results suggest that while green is the preferred color, a market exists for orange, red, and yellow peppers. Results on price sensitivity suggest that profits at the retail level are likely to increase by increasing the price of green peppers, and decresing that of the colored ones.

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Lettuce (Lactuca sativa) production historically has been limited in the southeastern United States because of the risk of early bolting and unacceptable bitterness. Small-scale vegetable growers may be able to include lettuce in their production through selection of bolt tolerant and nonbitter varieties. The objectives of this research were to evaluate earliness, bitterness, vitamin E, ascorbic acid, folate, β-carotene, and lutein content in 17 lettuce varieties. Significant difference were found among varieties for days to harvest (DTH) (47 DTH for `Epic' to 37 DTH for `Big Curly'). Observed DTH in this study was consistently 7 to 10 days less than commercial descriptions of the lettuce varieties, due to the use of transplants. Only `Slobolt' and `Greengo' bolted before reaching marketable size. Panelists found that the bitterness was acceptable for most varieties, but not for `Nancy,' `Big Curly,' and `Slobolt'. Significant differences among varieties were also found in vitamin E, ascorbic acid, folate, β-carotene, and lutein. `Redprize' and `Nevada' were the best varieties overall, while `Salinas 88 Supreme,' `Epic,' `Legacy,' `Big Curly,' `Slobolt,' and `Greengo' were unacceptable.

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Sweet corn (Zea mays) is a major cash crop produced on calcareous soils in Miami–Dade County. Applications of large amounts of phosphorus (P) fertilizer for many years resulted in the accumulation of high levels of P in these soils. Accumulated P is slowly released into the soil solution to become available for plant roots. Previous studies conducted in this area showed little or no yield and crop quality response to P fertilizer applications. Large-scale field trials with reduced P applications were conducted in a grower's field. The treatments were: 1) no P; 2) 50% grower's rate; and 3) 100% grower's rate with six repilications. The data collected included: plant stand, height, nutrient concentrations in leaf tissue, leaf chlorophyll, tip fill, number, and weight of marketable ears/acre. Reduced rates of P fertilizer did not significantly reduce yield and quality of sweet corn.

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Petiole sap testing using ion-specific electrodes is a simple method that can be used to guide in-season applications of N and K to vegetable crops. This method requires petiole sampling and sap extraction using a sap press. Because some vegetables are grown with foliar applications of N and/or K and because some crops have large petioles, petioles may need to be washed and/or cut before being pressed. Because limited information is available on the effect of washing/cutting on sap testing results, muskmelon, bell pepper and tomato petioles were used to test if washing/cutting reduced NO3-N and K concentrations and changed the subsequent interpretation of plant nutritional status. Washing for 30, 60, or 120 seconds in distilled water and cutting petioles before or after washing significantly reduced sap concentrations (p = 0.01 and p = 0.04 for NO3-N and K, respectively) in 7 of 12 tests when compared to the control method (petioles cut and not washed). The average concentration reductions between the control and the lowest value among all the washing/cutting treatments were 30% for NO3-N and 19% for K. These losses due to washing/cutting are likely to change the diagnosis of nutritional status from “sufficient” to “less than sufficient” and therefore may suggest the need for unnecessary fertilizer applications.

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