Organic weed control in direct seeded vegetables depends on management strategies that control weed germination or growth which depletes the weed seedbank. In 2004, a randomized complete-block experiment conducted on land transitioning to organic production examined the effects of tillage and control treatments on weed pressure in sweet corn [Zeamays (L.) cv. Silver Queen]. The two tillage treatments consisted of conventional (moldboard and rototill) and spader tillage. Weed control treatments included a weed free control, a spring-tine weeder, rolling cultivator, row flamer, stale seedbed, and corn gluten meal. In August, the weed infestation was primarily goose grass [Eleusineindica (L.) Gaertn.], crab grass [Digitariasanguinalis (L.) Scop.], giant foxtail (Setariafaberi Herrm.), and smooth pigweed [Amaranthushybridus (L.)] species. Dried weed weights indicated that smooth pigweed constituted about 80% of the total weed biomass in all but the control and flamer treatments. Plots managed with the spring-tine weeder or corn gluten had twice the weed biomass of those managed with the rolling cultivator and flamer. The rolling cultivator and control treatments produced equivalent husked corn yields (6.9 t·ha-1); yields were reduced by the other weed control methods. At 5.4 t·ha-1, yields in the flamer treatment were the lowest among all weed control methods. The flamer suppressed both weeds and the crop, which may preclude its utility for sweet corn production. Results demonstrated that the rolling cultivator provided the best weed control without negatively affecting potential yields.
Meriam Karlsson and Jeffrey Werner
Flowering in response to day length was identified for sunflower (Helianthus annuus L. `Pacino Gold'). Germination and seedling development occurred at 20 °C and long days (ld, 16 hours) following direct seeding into 10-cm pots. Sixteen days after seeding, plants were placed at ld or short days (sd, 8 hours), 20 °C and 8 mol·d-1·m-2. Flowering was recorded at the stage of reflexed petals after 48 sd. At the time of flowering in sd, flower buds were of minute size under ld. Plants started at ld, and moved to sd after 1, 2, or 3 weeks, flowered at similar times as those grown under uninterrupted sd conditions. Four initial weeks of ld delayed flower development with 7 days, compared to a continuous sd environment. On the other hand, 2 to 3 weeks of initial sd followed by ld hastened flowering with 5 to 10 days. With increasing number of early ld from 1 to 4 weeks, plant height at flowering doubled from 20 to 40 cm. Average plant height in continuous sd was 18 cm. Plants grown exclusively or moved to ld after 1 to 4 weeks of sd were similar in height to plants finished at sd with 4 initial weeks of ld. Combinations of sd and ld may be used to manage height and rate of development in the sunflower `Pacino Gold'.
Dru Bernthal*, Elsa Sánchez, and Kathleen Kelley
A field trial investigating the use of living mulches for weed management in edamame (Glycine max), also known as vegetable soybean, was conducted in 2003 at the Russell E. Larson Agricultural Research Center, Rock Springs, Pa. Edamame was direct seeded on 24-25 June 2003. Seven weeks later, the living mulch treatments were broadcast seeded. The living mulch species were white clover (Trifolium repens), buckwheat (Fagopyrum esculentum) and a control with no living mulch (bare ground). Each living mulch plot was divided into a weeded and non-weeded subplot. Weed pressure was evaluated every 2 weeks from the time living mulches were sown. Data collected included the total number of weeds present, number of different species present, number of broadleaf and grass species and number of annual and perennial species. The total number of weeds in weeded and non-weeded subplots was lowest in the buckwheat and highest in the clover. Species diversity in weeded subplots was lowest for the control and highest in clover while species diversity in non-weeded subplots was lowest in buckwheat and highest in the control. Overall, most weeds present were broadleaf annuals including pigweeds (Amaranthus spp.), shepard's purse (Capsella bursa-pastoris), common lambsquarters (Cheno-podium album) and common purslane (Portulaca oleracea). Based on this 1-year study, which will be repeated in 2004, the buckwheat treatment is likely the most effective in managing weeds in edamame field production for consideration by Pennsylvania growers.
Paul W. Bosland
Chile pepper (Capsicum spp.) hybrids are normally produced by hand-emasculating the female parent and then pollinating the emasculated flower by hand. Increased yield has occurred with F1 hybrid seed, but the seed is considered too expensive by growers to be direct-seeded, a common production practice in the southwestern U.S. chile pepper industry. In ornamental flowers, when F2 hybrid seed is available, it is cheaper than F1 hybrid seed. If F2 hybrid chile pepper cultivars could manifest heterosis, and produce fruit quality acceptable to the chile pepper industry, then a less-costly alternative would be available to growers. A series of field trials with jalapeños was conducted to test F1 hybrid cultivars to their F2 progeny for yield and fruit quality. The results indicated that in some instances the F2 progeny can yield as well as the F1 hybrid parent. Therefore, F2 hybrid cultivars can be used in a commercial production system. However, if a male-sterility system is used to produce the F1 hybrid cultivar, the F2 progeny will have significantly lower yield than the F1 hybrid parent, as was the case in one accession in this trial. Nevertheless, F2 hybrid cultivars are an additional way to supply high yielding hybrid cultivars to growers.
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.
Michelle Le Strange
In recent years, an estimated 65% of processing tomato acreage has converted from direct seeding to transplanting the crop. Growers have been switching to transplants for a number of reasons, including land use efficiency, water conservation, and weed management. Field studies investigating plant spacing and multiple plants per transplant plug (cell) were initiated when observations by growers indicated that there were seemingly decreased fruit yields from transplanted crops. A transplant density experiment was established in 2004 in a commercial field of processing tomatoes grown on the west side of Fresno County in the San Joaquin Valley, the major tomato production area in California. The field trial investigated in-row spacing (37.5 cm and 75 cm), the number of plants per transplant plug (1, 2, or 3), on a medium vine size variety (Halley 3155) and a large vine size variety (AB2). Individual plots were large enough for mechanical harvest. Yield results indicate that these two varieties responded similarly to increasing plant density. In general, a spacing of 37.5 cm with 2 or 3 plants per plug yielded significantly more than 1 plant per plug, regardless of variety. There was no yield advantage in seeding 3 plants per plug when compared to yields with 2 plants per plug, regardless of variety or in-row plant spacing. A plant spacing of 75 cm with only 1 plant per plug yielded the least.
Craig R Andersen and Danielle B. Williams
Pumpkin cultivar trials were held in 2003 and 2004 at the Agricultural Experiment Station Fayetteville, AR. 18 cultivars were direct seeded the 4th week of June. Plots 8 plants each, spaced 3 ft apart, 12 ft between rows were randomly replicated 6 times. Pumpkin fruit were harvested October 1 and evaluated for number, size shape, and quality. Plots were irrigated by drip irrigation and standard production practices were followed. During 2004 the same practices were followed except plots were planted during the second week of July. In 2003 large fruited pumpkins yielded 700 to 1950 fruit per acre. Howden, the industry standard yielded 700 fruit, averaging 16 lb each, with a gross return of $700/acre. Cultivar fruit size ranged from 15 to 27 lb, and yields ranged from 10200 to 52000 lbs to the acre. Based on the 1 Oct. 2003 prices from USDA AMS, gross returns ranged from $744 to $1760 per acre. Specialty types Jack be Quick, Rouge, and Long Island Cheese yielded 15700, 1800, and 1470 fruit per acre valued at $2100, 1950, and 3400 respectively. Excessive rain in June 2004, and cooler that normal weather during July and early August significantly affected quality and yields of pumpkin fruit. Fruit number and size per plot were reduced up to 75%. Yields ranged from 10% to 20% of 2003 yields. Fruit quality was significantly affected making most of the fruit harvest unmarketable due to immaturity and size.
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.
J.E. Warren and M.A. Bennett
Improved germination under unfavorable soil conditions is an important safeguard against yield losses in direct-seeded crops. Osmoprimed seed has been shown to provide earlier and more uniform germination as well as improve low temperature germination. These attributes combined with the reduced rates of damping-off associated with Pseudomonas aureofaciens AB254 creates a bioosmopriming seed treatment that provides rapid germination under a wider range of soil temperatures while exhibiting the disease resistance and improved growth associated with bacterial coatings. The objective of this work is to combine biopriming and osmopriming into one procedure, thus creating an environment for adequate seed hydration and rapid multiplication of beneficial bacteria which will thoroughly colonize the seed surface. Processing tomato seeds (Lycopersicon esculentum Mill. `OH8245') were bio-osmoprimed in aerated –0.8 MPa NaNO3 at 20°C for 4 days. On the fourth day, a mixture of nutrient broth, a defoaming agent, and bacteria that have been adjusted to the same osmotic potential is added. This is done so that the removal of seeds from the tank at the end of the 7-day treatment coincides with peak populations of bacteria. Pseudomonas aureofaciens AB254 multiplies very rapidly in this environment, with colony forming units for tomato averaging 4 × 105/seed. Results will also be reported for cucumber seed (Cucumis sativus L. `Score'), which were treated using a similar procedure. Bacterial populations per seed, germination characteristics and pathogen control will be discussed.
S. Alan Walters and Jeffrey D. Kindhart
Various tillage systems were evaluated in summer squash (Cucurbita pepo) production in southern Illinois to observe the influence of these systems on yellow and zucchini squash production during 1998, 1999, and 2000. For squash production, suppression of a cover crop such as tall fescue (Festuca arundinacea) or winter ryegrass (Secale cereale) must be accomplished to obtain the greatest possible yields. However, once the cover crop is killed via herbicides, squash yields tend to be similar among tillage, strip tillage, and no-tillage treatments. Previous studies indicated that early yields may be reduced when using a no-tillage production system, especially if direct seeding is the method of planting and would not be beneficial to growers seeking early production. This study found that squash growers can use transplants in a no-tillage system and not compromise early yields. No differences were observed for soil bulk densities between tillage and no-tillage treatments and may partially explain why similar yields were obtained between these treatments. Effective systems for weed control must be developed in no-tillage squash production before wide acceptance will occur. Observations from this study indicated that the success of no-tillage squash production depends on the availability of effective herbicides; however, few herbicides are currently labeled for use in summer squash. Future studies need to address the problem of weed control in no-tillage squash production.