Producers of organic vegetables often report that weeds are a troublesome production problem. It has been documented that corn gluten meal (CGM), a by-product of the wet-milling process of corn, is phytotoxic. As a preemergence or preplant-incorporated herbicide, CGM inhibits root development, decreases shoot length, and reduces plant survival of weed or crop seedlings. The development of a mechanized application method for CGM and the ability to apply the material in a banded pattern would increase its potential use in organic vegetable production, especially in direct-seeded vegetables. Therefore, the objective of this research was to develop a mechanized method to uniformly apply CGM to the soil surface in either a broadcast or banded pattern. An applicator was assembled using various machinery components (fertilizer box, rotating agitator blades, 12-volt motor, and fan shaped gravity-fed row banding applicators). The equipment was evaluated for the application of two CGM formulations (powdered and granulated), three application rates (250, 500, and 750 g·m–2), and two application configurations (solid and banded). Field evaluations were conducted during Summer 2004 on 81-cm-wide raised beds at Lane, Okla. Differences between CGM formulations affected the flow rate within and between application configurations. The granulated formulation flowed at a faster rate, without clumping, compared to the powdered formulation. While the CGM in the banded configuration flowed faster than the solid application. It was determined that the CGM powder used with the solid application configuration was inconsistent, unreliable, and thus not feasible for use with this equipment without further modifications. These evaluations demonstrated the feasibility of using equipment, rather than manual applications, to apply CGM to raised beds for organic weed control purposes. Several design alterations may increase the efficiency and potential usefulness of this equipment. If research determines equivalent weed control efficacy between the two CGM formulations, the granulated formulation would be the preferred formulation for use in this equipment. This equipment would be useful for evaluating the benefits of banded applications of CGM for weed control efficacy and crop safety for direct seeded vegetables.
James W. Shrefler, Charles L. Webber III, and Otis L. Faulkenberry III
Lewis W. Jett, Ronald D. Morse, and Charles R. O'Dell
Consumer attitudes and preferences towards fresh market broccoli (Brassica oleracea L. Group Italica) are changing. Consumers desire large-head broccoli with more florets per unit weight, which we term single unit broccoli. Single unit broccoli could be field established by transplanting, alleviating the problems of poor stand establishment encountered with direct-seeded broccoli in the Southeast. The objectives of this research were to determine the feasibility of producing single unit broccoli and the optimal plant arrangement and spacing to maximize the yield of single unit broccoli. Two spatial arrangements (single vs. twin row) and five plant densities (10.8, 7.2, 5.4, 4.3 and 3.6 plants/m2) were examined in 1990 and 1991 for production of single unit broccoli. Spatial arrangement had no significant effect on any measured variable, although the twin row arrangement resulted in less plant damage with each multiple harvest. For exclusive production of high quality, single unit broccoli with high yields of marketable florets, a planting density of 3.6 plants/m2 (46 cm within row spacing) should be used in a twin row arrangement.
John T. A. Proctor
American ginseng is propagated by seed. In commercial practice ginseng seed is harvested in August or September, placed in a stratification box for about 12 months, and then direct seeded into raised beds. Germination takes place the following spring, some 18 to 22 months after seed harvest. Little is known about the dormancy-controlling mechanisms of ginseng seed. The objective of this study was to investigate seed development and temperature in the stratification box until it was removed 12 months later and seeded in the field. During stratification 3 embryo growth stages were identified. In Stage I of 250 days (September to mid-May) embryo length increased from about 0.5 to 1.0 mm, in Stage II of 100 days (mid-May to late August) length increased to 2.0 mm and in Stage III (late August to late November) length increased to 5.3 mm. Exocarp split width could also be placed in 3 stages. Changes in embryo length correlated with values for embryo: endosperm length ratio. The stratification box temperatures at all depths never exceeded -2°C even when the air temperatures dropped to -13°C and, therefore, were not damaging to the seeds.
Teresa Olczyk, Kent Cushman, and Waldemar Klassen
Okra (Abelmoschus esculentus) is grown as a direct-seeded cash crop at high plant populations (>87,000 plants/acre) on calcareous soils in Homestead, south Florida. A study was established in a commercial field in May 2005 to evaluate if high populations translated to higher yields. Seedlings were thinned to within-row spacings of 2, 4, 6, 8, and 10 inches in rows set 3 ft apart (87120, 43560, 29040, 21780, and 17420 plants/acre). Harvest data was collected from 29 July to 30 Sept. 2005 (26 harvests) from 10 ft of the center row within plots 15 ft long and 3 rows wide. Decreasing plant density resulted in decreasing plant height early in the season and increasing height late in the season. Density affected stem caliper with a clear trend of decreasing density and increasing caliper. Early, mid-, and total yields by weight (boxes/acre) were not affected by density, but plants at the lowest density produced 55% more late yield than plants at the highest density. Plants at the lowest density produced 30% fewer early pods and 31% more late pods than plants at the highest density. Decreasing plant density resulted in increasing average pod weight for early, late, and total harvests by as much as 14% to 18%. With inexpensive open pollinated cultivars such as `Clemson Spineless 80', there seems little economic incentive to reduce plant populations below what is commonly used in the Homestead area. Growers should not be alarmed, however, if plant stands are reduced to some extent after seeding.
Kevin L. Cook and Leonard M. Pike
An `intermediate leaf' hybrid pickling cucumber (TAMU 884304 X ARK H-19 `little leaf') was direct-seeded at four plant densities (94,570; 48,440; 32,290; 25,375 plants/ha) using four within-row spacings (15, 30, 45, 60cm) at two locations and two seasons. Optimum yield based on marketable fruit number, grade distribution and fruit quality occurred with 94,570 plants/ha. Optimum harvest time depended on location and season. Delayed harvest times were also evaluated. Harvests with fruit >5.1cm in diameter had severely reduced brining quality. Fruit did not enlarge or enlarged slowly to oversize. This resulted in a mixture of fruit ages within the largest marketable fruit grades. It is recommended that `little leaf' lines and their hybrids such as `intermediate leaf' be harvested when fruit 3.8 to 5.1cm in diameter appear and before oversize fruit are produced. Spacing did not significantly effect length/diameter ratio(LDR) but LDR was significantly greater for delayed harvests.
R.M. Wheeler, C.L. Mackowiak, J.C. Sager, B. Vieux, and W.M. Knott
Lettuce (Lactuca sativa cv. Waldmann's Green) plants were grown in a large, tightly sealed chamber for NASA's Controlled Ecological Life Support Systems (CELSS) program. Plants were started by direct seeding and grown in 64 0.25-m2 trays (six plants per tray) using nutrient film technique. Environmental conditions included: 23°C, 75% relative humidity, 1000 ubar (ppm) CO2, a 16/8 photoperiod, and 300 umol m-2 s-1 PPF from metal halide lamps. Although the chamber was typically opened once each day for cultural activities, atmospheric ethylene levels (measured with GC/PID) increased from near 15 ppb at 23 days after planting (DAP) to 47 ppb at 28 DAP. At harvest (28 DAP), heads averaged 129 g FW or 6.8 g DW per plant, and roots averaged 0.6 g DW per plant. Some tipburn injury was apparent on most of the plants at harvest. By 28 DAP, stand photosynthesis rates for the entire chamber (approx. 20 m2) reached 17.4 umol CO2 m-2 s-1, while dark-period respiration rates reached 5.5 umol CO2 m-2 s-1. Results suggest that good yields can be obtained from lettuce grown in a tightly sealed environment.
Paul W. Teague and Tina Gray Teague
spring field trials conducted over 2 years were used to determine differences in net returns using “cut” (harvested by removing the whole plant near the ground level for a one time over harvest) and “shucked” collards (harvested by removing marketable sized individual leaves using multiple harvests). 'Blue Max' transplants were set 11 March 1991 and 11 Feb 1992 in rows spaced 25.4cm apart on raised beds spaced 1m apart. Four spacing treatments were evaluated (7.62, 15.24, 22.86, and 30.48 cm between plants) in a RCB with 4 replications. Plants were harvested beginning 25 April 1991 and 28 April 1992 once (cut) or over 5 wks (shucked). Yields were higher for shucked collards spaced 15.24cm in both years, but no differences Were observed in cut collards. cut collards provided a higher 1st harvest yield. A system analysis to provide 1000 boxes (9.lkg) of collards/wk was imposed to determine the economics of harvest method. Cost differences Were considered to reflect differences in hectareage required, transplant cost for 4 densities, and a 25% higher harvest cost/box for shucked collards. The shuck harvest method provided an economic advantage over cutting of $9853 and $1671 in 1991 and 1992, respectively, where all production was assumed to come from transplanted collards. when a combination of transplanting and direct seeding was assumed, results indicate an economic advantage to cutting of $680 for the system using 1992 yield data.
Warren Roberts and Julia Whitworth
A factorial experiment with four mulch treatments (clear, black, or IRT plastic, and a non-mulched control), two planting types (seed vs. transplants), and two row cover treatments (with and without) was initiated to determine the harvest date of watermelon with these treatments. Experiments were planted in the field April 7. Row covers (Kimberly Farms, spunbonded polypropylene, 20 g·m-2) were suspended on wire hoops above selected plots. Soil temperatures at 5 cm, measured at noon, were lower in plots with row covers. On May 13, the row covers were in the process of being removed when a thunderstorm developed. One guard row remained covered during the storm. Hail ranging from 1.3 to 2.5 cm in diameter fell for 30 minutes, with a final accumulation of 5 cm of hail and 10 cm of rain. There was no noticeable difference between transplants and direct seeded plants, or among the different types of mulch, on resistance to hail damage. All plots that were not covered with row covers were totally destroyed. However, the area on which row covers had not been removed received only minor damage.
J.R. Dunlap, S.J. Maas, J.F. Gomez, and R. LaGrange
Two muskmelon (Cucumis melo L.) cultivars, Mission and Laguna, were direct-seeded in spring plantings separated by 30 days at the TAES farm in Weslaco. Females were tagged each morning for 8 consecutive days beginning on the first day of flowering and evaluated for fruit set 15 to 20 days later. Mean numbers of flowers and fruits produced on individual plants were compared across cultivars and planting dates. The flowering patterns appear to be bimodal with the majority of blooms occurring during the first 5 days followed by a sharp decline on day 6 and gradual increase, thereafter. The majority of the fruit is set during the first 5 days of flowering and failed to increase with the subsequent rise in flowering. Mission produced approximately 30% more female flowers per plant than Laguna; however, fruit numbers were the same for both cultivars. The environmental conditions associated with earlier plantings suppressed flowering in Laguna but had no effect on the daily rate of fruit-set. Fertilization and fruit set appear to be relatively unaffected by the population dynamics of female flowering.
H.Y. Hanna, P.D. Colyer, T.L. Kirkpatrick, D.J. Romaine, and P.R. Vernon
Studies were conducted for 2 years in root-knot-nematode-infested soils to determine growth and yield response of `Dasher II' cucumbers (Cucumis sativus L.) to double-cropping with nematode-resistant tomatoes (Lycopersicon esculentum Mill.), using nematode-free cucumber transplants and preplant treatment with ethoprop nematicide. Cucumbers grown following the nematode-resistant `Celebrity' tomato during the same season produced significantly more plant dry weight, more fruit per plant, and higher premium and total yields than did cucumbers double-cropped with the nematode-susceptible `Heatwave' tomato in both years. The cucumber produced longer stems in 1992 and fewer culls in 1993 following resistant tomatoes. Cucumber plants raised in nematode-free soilless mix for 3 weeks before transplanting produced significantly longer stems and more plant dry weight than did direct-seeded cucumbers in 1992, but not in 1993; however, they produced significantly higher premium yield in both years, and higher total yield, more fruit per plant, and fewer culls in 1993. Preplant treatment with ethoprop significantly increased cucumber stem length, dry weight, premium and total yield, and number of fruit per plant in 1992 but not in 1993. Ethoprop treatment had no effect on the percentage of culls in either year. Chemical name used: O-ethyl S,S-dipropyl phosphorodithioate (ethoprop).