Three years of trials in Mississippi have led to the naming of a Mississippi Medallion vegetable award winner for 2007, the fourth vegetable winner in the program's history. The Medallion program looks for garden crops that will perform throughout the state of Mississippi and help improve sales of plant materials to gardeners at retail. The Medallion selection process illustrates how growers and marketers, not just gardeners, can select specialty vegetables and cultivars for production and sale. Between 2003 and 2005, the Mississippi Medallion trials evaluated 11 sweet peppers with no green fruit stage for ornamental and yield value. Each site had three or four replications of all cultivars under evaluation annually with four plants per plot set out on raised beds with drip irrigation. Objective evaluation included total yield, marketable yield, fruit size, and days to harvest. Subjective evaluation included crop uniformity, pest tolerance, and appearance of the fruit based on color, uniformity, and shape. After nine trials, four cultivars were among the highest-yielding group in most trials: Mavras, Tequilla, Blushing Beauty, and Gypsy. The Medallion winner, to be announced in Fall 2006, was selected in part because it was within or near the top-yielding group, by least significant difference, in most trials. The perceived attractiveness of the mature fruit to the evaluating team and the perceived potential marketability of the cultivar moved it above the others under consideration. The reasons for not selecting other cultivars as the winner are as important as the reasons for selecting the winning cultivar. In the Medallion pepper case, these were mostly marketability concerns with the other cultivars, not yield issues, relative to that of the winner.
William B. Evans, Christine E. Coker, Kent E. Cushman, Thomas E. Horgan, and Keri L. Paridon
Russell T. Nagata, Kenneth L. Pernezny, Darrin M. Parmenter, Eugene McAvoy, and Kent E. Cushman
Twenty-five varieties of bell peppers (Capsicum annuum) were transplanted in commercial pepper fields in Immokalee and Delray Beach, Fla., to evaluate horticultural characteristics and resistance to race 3 bacterial spot of peppers caused by Xanthomonascampestris pv. vesicatoria. All cultural and management procedures were based on commercial best management practices. Eighty to 90% of marketable fruits had three or four lobes. Total marketable fruit yield from three harvests ranged from 4596 to 7089 kg·ha-1 and marketable fruit number ranged from 20,571 to 31,224 fruit/ha. Most fruit were slightly elongated with length to diameter ratios between 1.1 and 1.2. Seminis 7602 had a ratio of one, while lines ACR 252, PRO2R-3, and PR99R-16 had ratios of 1.40, 1.36, and 1.28, respectively. Significant differences were observed for fruit wall thickness, with those grown in Delray Beach having thicker fruit walls that averaged 7.5 mm vs. 5.3 mm for the Immokalee site. Bacterial spot infection at both sites did not affect yield, due to late natural infection of the field. Susceptible control `Jupiter' had a mean foliage disease incident rating of 26% after the final harvest and was surpassed only by 7682 and 8328 from Enza. The most resistant lines with disease ratings of <3% were 5776, 7141, and 8302 from Seminis, and Telstar from Hazera.
Kent Cushman, Muhammad Maqbool, Ebru Bedir, Hemant Lata, Ikhlas Khan, and Rita Moraes
Podophyllotoxin is a pharmaceutical compound extracted from rhizomes of Indian mayapple (Podophyllumemodi). Leaves of American mayapple (P. peltatum) also contain podophyllotoxin, and the species is being investigated as a domestic, renewable, and alternative source of the compound. The objective of this study was to explore strategies of leaf removal that would not adversely affect regrowth of American mayapple shoots in subsequent years. Plots were established in two locations among naturally occurring populations in the wild, one in full sun and one in partial shade. Plots were 1.0 m2 and leaves were removed from plants every spring, every other spring, or every third spring. In addition, leaves were removed in early spring, soon after shoots emerged and leaves had fully expanded, or in late spring, when leaves first showed evidence of yellowing and beginning to senesce. Sexual and asexual leaves were harvested separately. Leaf number, leaf area, and dry weight were recorded. Subsamples of leaf material were extracted to determine podophyllotoxin, α-peltatin, and β-peltatin contents. Results clearly showed that leaf removal every year, in combination with early harvest, was too severe and plants lost vigor over the 4-year period of this study. Plants subjected to this treatment combination produced significantly less leaf area and dry weight than any of the other treatment combinations. Results were similar for both sun and shade locations. Lignan content was not affected by treatment. Our results indicate that leaves can be removed from mayapple plants as often as every year provided harvests are not scheduled too soon after shoot emergence.
Kent E. Cushman, Muhammad Maqbool, Hemant Lata, Ebru Bedir, Ikhlas A. Khan, and Rita M. Moraes
Four levels of shade (0%, 30%, 55%, and 80%) were used to determine their effect on growth and lignan content of american mayapple (Podophyllum peltatum L.). Mayapple rhizomes were harvested from the wild and transplanted into plant beds on 20 Dec. 2001 using a randomized complete block design with four blocks. Growth and lignan content were recorded during spring of 2002 and 2003. Leaf samples were analyzed for the following lignans: podophyllotoxin, alpha-peltatin, and beta-peltatin. Increasing levels of shade increased shoot longevity, leaf area per plant (cm2/plant), and shoot height. Shade did not affect shoot emergence, total leaf area (cm2·m-2), or leaf dry mass (g·m-2 or g/plant). Regardless of year, podophyllotoxin and total lignan contents at 0% shade were significantly greater than those at 80% shade, and the overall trend was for decreasing contents with increasing shade. Shade did not affect alpha-peltatin content. Content of beta-peltatin was greatest at 0% shade compared to the other three shade treatments. Year affected alpha-peltatin and beta-peltatin contents, with less content of each in 2003 than in 2002. There were large numerical decreases in podophyllotoxin yield (podophyllotoxin content per unit area, mg·m-2) as shade increased from 0% to 80%, but these differences were only marginally significant (P = 0.0897). In contrast, podophyllotoxin yield was significantly greater in 2003 than in 2002 as total leaf area and dry mass significantly increased. Increasing levels of shade slightly decreased air and soil temperatures. Our results indicate that american mayapple is not a shade-requiring species. Under full sun (0% shade) shoots did not persist as long as under shade and leaves were smaller and thicker, but total lignan content was significantly greater than under shade. It appears that growers of specialty crops serving the pharmaceutical industry can establish and cultivate american mayapple under full sun, thus providing leaf biomass with high podophyllotoxin content while avoiding the cost of expensive shade structures.
Gregory S. Hendricks, Sanjay Shukla, Kent E. Cushman, Thomas A. Obreza, Fritz M. Roka, Kenneth M. Portier, and Eugene J. McAvoy
Watermelon (Citrullus lanatus) production is concentrated in southern Florida where growers often use seepage irrigation. According to a recent survey, growers believe that nitrogen (N), phosphorus (P), and potassium (K) rates recommended by the University of Florida Institute of Food and Agricultural Sciences (UF-IFAS) are low. A study was conducted during Spring 2004 and 2005 at a UF-IFAS research farm to compare three nutrient and water management systems: high rate [HR (265, 74, and 381 lb/acre N, P, and K, respectively)], recommended rate [RR (150, 44, and 125 lb/acre N, P, and K, respectively)], and recommended rate with subsurface irrigation (RR-S). Irrigation was managed to keep soil moisture content at 16% to 20% for HR and 8% to 12% for RR and RR-S. The experimental design was a randomized complete block design with two replications and three subsample areas within each 0.25-acre plot. The HR management approach produced ≈60% to 80% higher yields (cwt/acre) during 2005 than RR or RR-S. The HR treatment produced larger watermelons than RR or RR-S in 2005. Triploid watermelon prices had to be at least $3.74/cwt to cover all costs associated with HR. The HR approach increased the grower net returns by $590/acre and $1764/acre under conservative and higher yield and price expectations, respectively. Soluble solids content and hollowheart ratings were unaffected by treatment. Total biomass, recorded during 2005, followed a similar trend as yield, with HR producing 105% and 125% greater total dry weight than RR and RR-S, respectively. Total N content of HR biomass was 56% higher than that of RR and RR-S. Total P content was 29% and 50% higher than that of RR and RR-S, respectively. Leaf and petiole tissue from the HR treatment exhibited consistently higher N and K leaf tissue values during 2005 than RR and RR-S. In conclusion, trends in the data consistently showed greater plant performance with higher rates of fertilizer and soil moisture content. Our ability to detect differences in 2005 was probably enhanced by higher rainfall during 2005 compared with 2004.
Kent E. Cushman, William B. Evans, David M. Ingram, Patrick D. Gerard, R. Allen Straw, Craig H. Canaday, Jim E. Wyatt, and Michael M. Kenty
Small- and large-scale farmers must often decide when to begin application of fungicides, either before the onset of disease as a preventative treatment or after disease becomes evident in the field. Growers also must decide about products that claim to enhance fungicide efficacy when added to the spray mixture. A study was conducted during the summer of 2002 to investigate control of foliar diseases of vine crops (Cucurbita spp.) with low-input (LI) or high-input (HI) management approaches and six fungicide/spray combinations at four locations in southeastern United States. Fungicide applications began for LI when leaf disease first became evident and for HI about 20 days after seeding. Both approaches continued applications at 7- to 10-day intervals until harvest. Spray treatments consisted of a water-only control or one of six combinations of azoxystrobin/chlorothalonil alone or in combination with potassium bicarbonate, foliar phosphite (0N–12.2P–21.6K), or foliar nitrogen (25N–0P–0K). Azoxystrobin was applied in rotation with chlorothalonil for all treatments except the control. Seeds of ‘Lil’ Goblin’ pumpkin (Cucurbita pepo) were planted July to August and fruit harvested October to November, depending on location. Plants were rated twice for powdery mildew (Sphaerotheca fuliginea and Erysiphe cichoracearum) and downy mildew (Pseudoperonospora cubensis). HI did not significantly increase yield compared with LI. All fungicide treatments significantly increased yield and reduced foliar diseases compared with the water-only control. The simplest of treatments, the azoxystrobin/chlorothalonil rotation without any other chemicals, can be recommended for general use where strobilurin resistance has not been documented.
Monica Ozores-Hampton, Eric Simonne, Eugene McAvoy, Phil Stansly, Sanjay Shukla, Fritz Roka, Tom Obreza, Kent Cushman, Phyllis Gilreath, and Darrin Parmenter
Florida tomato growers generate about $600 million of annual farm gate sales. The Florida Vegetable and Agronomic Crop Water Quality/Quantity Best Management Practices Manual was adopted by rule in the Florida Administrative Code in 2006 and describes cultural practices available to tomato growers that have the potential to improve water quality. By definition, BMPs are specific cultural practices that are proven to optimize yield while minimizing pollution. BMPs must be technically feasible, economically viable, socially acceptable, and based on sound science. The BMP manual for vegetables endorses UF-IFAS recommendations, including those for fertilization and irrigation. Current statewide N fertilizer recommendations for tomato provide for a base rate of 224 kg/ha plus provisions for supplemental fertilizer applications 1) after a leaching rain, 2) under extended harvest season, and 3) when plant nutrient levels (leaf or petiole) fall below the sufficiency range. An on-farm project in seven commercial fields was conducted in 2004 under cool and dry growing conditions, to compare grower practices (ranging from 264 to 468 kg/ha of N) to the recommended rate. Early and total extra-large yields tended to be higher with growers' rate than with the recommended rate, but these differences were significant only in one trial. The first-year results illustrated the need for recommendations to be tested for several years and to provide flexibility to account for the reality of local growing conditions. Working one-on-one with commercial growers provided an opportunity to focus on each farm`s educational needs and to identify specific improvements in nutrient and irrigation management.