Intercropping of seedless watermelon [Citrullus lanatus (Thumb.) Matsum. & Nak.] and cotton [Gossypium hirsutum (L.)] in the eastern geographical area of South Carolina requires changes in normal crop-management programs but has the potential to improve grower profits compared with typical production of each crop separately. The alteration and timing of several normal crop-production practices for both crops can present challenges and must be well-defined for successful intercropping of watermelon and cotton in the region. Notable adjustments in production for watermelon are delayed planting date, reduced row spacing and bed width, and modification of herbicide applications. Significant changes in normal cotton production also include modification of herbicide applications, but additional considerations, such as temporal limits on side-dressed fertilizer and insecticide applications, are needed because of the raised beds and plasticulture used for watermelons and also because of labeling restrictions for pesticides across crops. Research was conducted to 1) identify modifications in standard crop-management procedures for watermelon and cotton intercropping; and 2) determine the feasibility and profitability of intercropping the crops. Although there was a slight numerical reduction in intercropped watermelon yield each year, there were no significant differences in total watermelon yield between intercropping and watermelon monoculture in any of the years. There were also no significant differences in watermelon fruit quality parameters (size, brix, hard seed, hollow heart) in any of the years. Intercropped cotton yield was significantly less than monoculture cotton yields in each of the three years. The net income from intercropping in each year was slightly less than the net income from watermelon monoculture.
Gilbert Miller and Jeremy Greene
Jonathan R. Schultheis*, Richard L. Hassell*, Wilfred “Bill” R. Jester, Donald N. Maynard, and Gilbert A. Miller
Demand for triploid watermelons has outpaced the demand for diploid watermelons in the United States in recent years. The size of most triploid watermelons sold in U.S. markets is from 6 to 9 kg. Recently, a new produce item, seedless watermelons weighing about 1.8 to 3.6 kg, have been introduced and created excitement in the produce industry. Several vegetable seed companies have developed proprietary miniwatermelon hybrids. Syngenta Seeds and Seminis Vegetable Seeds have received the most publicity, with the PureHeart and Bambino brands being featured in the 15 June 2003 New York Times. The 2003 season was the first year that cultigens (cultivars and advanced lines) were generally available. At least four trials were conducted in the southeastern United States to evaluate yields and quality of mini-watermelons; Bradenton, Fla., Ediston, S.C., Charleston, S.C., and Kinston, N.C. Cultural practices and the number of cultigens varied among locations (9 to 17). Fruit less than 3.6 kg that yielded best in all locations were `Petite Perfection' (Syngenta) and RWT 8149 (Syngenta). Other cultigens that yielded well in at least one location were; `Precious Petite' (Syngenta), `Vanessa' (Sunseeds), ZG 8905 (Zeraim Gedera), SR 8103 WM (Sunseeds), SW 8002 (Southwestern), and HA 5130 (Hazera). Rind thickness varied from 6 to 25 mm and soluble solids ranged from 10 to 13%, depending on location and cultigen. New cultivars will be made available in 2004. Key characteristics that seem important to overall success in the market of the triploid miniwatermelon is consistent quality. This includes high yields of uniform sized fruit from about 1.6 to 3.8 kg; high soluble sugars (11% to 13%); and fruit with bright red, crisp flesh with a thin rind that endures shipping.
Richard L. Hassell, Jonathan R. Schultheis, Wilfred R. Jester, Stephen M. Olson, and Gilbert A. Miller
The goals of these studies were to determine how miniwatermelon (Citrullus lanatus) cultivars differed and responded to plant in-row spacing in terms of percentage of marketable fruit and yields, and if plant spacing impacted internal fruit quality. Three genetically diverse triploid miniwatermelon cultivars (Mohican, Petite Perfection, and Xite) were selected. These cultivars were evaluated in field locations at northern Florida (Quincy), central South Carolina (Blackville), coastal South Carolina (Charleston), and eastern North Carolina (Kinston) at five within-row distances. Within-row distance included 9, 12, 15, 18, and 21 inches. All plots were15 ft long with row middles 9 ft apart. Fruit were categorized as marketable if they weighed between 3.1 and 9.0 lb per fruit. Within this range further categories were divided as follows: ≤3.0 lb (cull), 3.1 to 5.0 lb (small), 5.1 to 7.0 lb (average), 7.1 to 9.0 lb (large), and ≥9.1 lb (cull). There was a cultivar by location interaction, suggesting that the three cultivars responded differently at each of the four locations. ‘Petite Perfection’ was among the highest yielding at all locations except Quincy, where it was the lowest yielding cultivar. As with total yields, the percentage of marketable fruit was similar for some cultivars across locations. Cultivar Petite Perfection produced the highest percentage of marketable fruit at three of the four locations. The exception was the Quincy site where ‘Xite’ had the highest percentage of marketable fruit. Within-row plant distances and populations affected total marketable yield, both for fruit weight and number per plant, regardless of cultivar and location. As the plant population increased from eight plants per plot (21-inch in-row spacing) to 12 plants per plot (15-inch in-row spacing), total marketable miniwatermelon fruit yields increased in total fruit number as well as total weight. There was a cultivar by location interaction for the percentage of soluble solids and the rind thickness measurements, suggesting that some cultivars responded differently at each of the four locations. Quality effects were more apparent with ‘Mohican’ and ‘Xite’, as they were more responsive to location than ‘Petite Perfection’.
Gilbert Miller, Ahmad Khalilian, Jeffrey W. Adelberg, Hamid J. Farahani, Richard L. Hassell, and Christina E. Wells
Delineating the depth and extent of the watermelon [Citrullus lanatus (Thumb.) Matsum. & Nak.] root zone assists with proper irrigation management and minimizes nutrient leaching. The objective of this 3-year field study was to measure root distribution and root length density of watermelon (cv. Wrigley) grafted on two different rootstocks (Lagenaria siceraria cv. ‘FR Strong’ and Cucurbita moschata × Cucurbita maxima cv. Chilsung Shintoza) and grown under three soil moisture treatments. Irrigation treatments tested were: no irrigation (NI), briefly irrigated for fertigation and early-season plant establishment; minimally irrigated (MI), irrigated when soil moisture in top 0.30 m of soil fell below 50% available water capacity (AWC); well irrigated (WI), irrigated when soil moisture in top 0.30 m of soil fell below 15% (AWC). Root length density (RLD) was measured from 75-cm-deep soil cores at two locations three times per growing season and a third location at the end of the season. Cores 1 and 2 sample locations were 15 cm to the side of each plant: Core 1 on the same side as the drip tape and Core 2 on the opposite side. At the end of the season, Core 3 was taken 15 cm outside of the bed in bare ground. RLD was significantly greater in the 0- to 30-cm soil depth and dropped dramatically below 30 cm; it was not significantly affected by irrigation treatment or rootstock. Core 1, next to the drip tape, had greater RLD than Core 2, 30 cm from drip tape, but only at the later sampling dates. Roots were found in Core 3 at all depths, but the RLD was significantly less than that measured in Cores 1 and 2. These findings suggest that the effective root zone depth for watermelon is 0 to 30 cm and that the particular scion/rootstock combinations tested in this study do not differ in root system size or location.
Judy A. Thies, Richard L. Fery, John D. Mueller, Gilbert Miller, and Joseph Varne
Resistance of two sets of bell pepper [(Capsicum annuum L. var. annuum (Grossum Group)] cultivars near-isogenic for the N gene that conditions resistance to root-knot nematodes [Meloidogyne incognita (Chitwood) Kofoid and White, M. arenaria (Neal) Chitwood races 1 and 2, and M. javanica (Treub) Chitwood] was evaluated in field tests at Blackville, S.C. and Charleston, S.C. The isogenic bell pepper sets were `Charleston Belle' (NN) and `Keystone Resistant Giant' (nn), and `Carolina Wonder' (NN) and `Yolo Wonder B' (nn). The resistant cultivars Charleston Belle and Carolina Wonder were highly resistant; root galling was minimal for both cultivars at both test sites. The susceptible cultivars Keystone Resistant Giant and Yolo Wonder B were highly susceptible; root galling was severe at both test sites. `Charleston Belle' had 96.9% fewer eggs per g fresh root than `Keystone Resistant Giant', and `Carolina Wonder' had 98.3% fewer eggs per g fresh root than `Yolo Wonder B' (averaged over both test sites). `Charleston Belle' and `Carolina Wonder' exhibited a high level of resistance in field studies at both sites. These results demonstrate that resistance conferred by the N gene for root-knot nematode resistance is effective in field-planted bell pepper. Root-knot nematode resistant bell peppers should provide economical and environmentally compatible alternatives to methyl bromide and other nematicides for managing M. incognita.
Richard L. Hassell, Jonathan R. Schultheis, Wilfred (Bill) R. Jester, Stephen M. Olson, Donald N. Maynard, and Gilbert A. Miller
The goal of this study was to evaluate miniwatermelon (Citrullus lanatus) cultivars/experimental hybrids (cultigens) for yield, quality, and adaptability in various growing environments. Eighteen cultigens were evaluated in field locations at southern Florida (Bradenton), northern Florida (Quincy), central South Carolina (Blackville), coastal South Carolina (Charleston), and eastern North Carolina (Kinston). Fruit at each site were harvested when watermelons in several plots were at market maturity. Fruit were categorized as marketable if they weighed between 3.0 and 9.0 lb. Fruit were categorized by size as follows: ≤3.0 lb (cull), 3.1–5.0 lb, 5.1–7.0 lb, 7.1–9.0 lb, and ≥9.1 lb (cull). Fruit were graded according to U.S. Department of Agriculture (USDA) grading standards for all watermelon fruit. We found that eight cultigens (Meilhart, Petite Perfection, Precious Petite, Little Deuce Coupe, RWT 8162, Master, Bibo, and Vanessa) were consistently among the top yielding and four cultigens (HA 5138, HA 5117, Petite Treat, and Valdoria) were consistently among the lowest yielding. These had a consistent yield response regardless of location. Within the small marketable melon category (3.1–5.0 lb), ‘Bibo’, ‘Precious Petite’, and RWT 8162 produced a uniform fruit over the five locations. Within the medium marketable melon category (5.1–7.0 lb) ‘Meilhart’, ‘Little Deuce Coupe’, HA 5109, ‘Xite’, ‘Mohican’, SR 8101, and ‘Vanessa’ produced uniform fruit size over the five locations. HA 5117, HA 5109, ‘Extazy’, ‘Mohican’, ‘Petite Treat’, and ‘Valdoria’ produced more fruit in the larger category. Those cultigens that produced melons that were consistently >9.0 lb were HA 5138, HA 5117, Bobbie, and Valdoria. The larger USDA marketable class (7.1–9.0 lb) was considered too large to be in the miniwatermelon market. We found five cultigens that provided consistently high soluble solids readings at each location: Master, RWT 8162, Betsy, Bobbie, and Bibo. We sampled only five fruit at each location for internal quality, and found dark seeds in all of the cultigens in at least one of the locations. Rind thickness and fruit shape did not appear to be influenced by test site location.
Judy A. Thies, Richard F. Davis, John D. Mueller, Richard L. Fery, David B. Langston, and Gilbert Miller
Root-knot nematode-resistant `Charleston Belle' bell pepper (Capsicum annuum L. var. annuum) and metam sodium treatment were evaluated for managing the southern root-knot nematode [Meloidogyne incognita (Chitwood) Kofoid and White] in fall-cropped cucumber (Cucumis sativus L.). `Charleston Belle' and its susceptible recurrent parent, `Keystone Resistant Giant', were planted as spring crops at Blackville, S.C., and Tifton, Ga. `Charleston Belle' exhibited high resistance and `Keystone Resistant Giant' was susceptible at both locations. After termination of the bell pepper crop, one-half of the plots were treated with metam sodium delivered through the drip irrigation system. Cucumber yields and numbers of fruit were highest for cucumber grown in plots treated with metam sodium following either `Charleston Belle' or `Keystone Resistant Giant'; however, root gall severity and numbers of M. incognita eggs in the roots were lowest for cucumber grown in plots treated with metam sodium following `Charleston Belle'. Conversely, root gall severity and nematode reproduction were highest for cucumber grown in plots following `Keystone Resistant Giant' without metam sodium treatment. Application of metam sodium through the drip irrigation system following a spring crop of root-knot nematode-resistant bell pepper should reduce severity of root galling and reproduction of M. incognita as well as increase fruit yield of fall-cropped cucumber.