A simulation model was built as a decision aid for management of five weed species in direct seeded irrigated onion (Allium cepa L.). The model uses the state variable approach and simulations are driven by temperature and sunlight as photosynthetically active radiation (PAR). It predicts yield reduction caused by competition for PAR according to the ratio of crop leaf area index (LAI) to weed LAI and respective light extinction coefficients (k). Input variables are plant density by species and average number of leaves by species. Number of leaves per plant is used by the model to provide an estimate of initial leaf area per plant. The model calculates initial species LAIs by multiplying species density times average leaf area per plant. The model accurately describes competitive interactions, taking into account respective plant densities, time of emergence, and time of weed removal. It permits economic evaluation of management factors such as handweeding, chemical weed control, herbicide phytotoxicity due to early application, and control of weed flushes during the season. The model is also used to evaluate mechanisms of plant competition for sunlight. In a sensitivity analysis, onion yield loss was more sensitive to weed PAR interception than to PAR use efficiency, the latter a species-dependent constant in the model.
Claudio M. Dunan, Philip Westra, and Frank D. Moore III
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.
Wayne C. Porter and Richard L. Parish
The initial investment of a precision seeder is cost prohibitive to many small vegetable growers. This study was initiated to evaluate the use of a relatively inexpensive bulk seeder to plant cabbage (Brassica oleracea L. Capitata). Cabbage was direct-seeded with a precision seeder or a relatively inexpensive bulk seeder. Treatments with the bulk seeder consisted of blending viable hybrid seed with nonviable, nonhybrid seed at several ratios to reduce hybrid seed cost and optimize plant spacing. Seed ratios represented 10, 20, 30, 40, 50, and 100% viable seed. Pre-thin plant stands of 30 and 40% hybrid seed treatments were similar to precision-seeded plant stands. Average head size was greatest with 10, 20, and 30% hybrid seed ratios. Marketable yields were similar for all hybrid seed ratios except the 10% ratio. Production costs per acre for the precision seeder were between that of the 40 and 50% ratios. Net income for 40% hybrid seed was similar to that of the precision seeder.
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.
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.
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.
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'.
T. Fujita, K. Kosuge, S. Miyoshi, and S. Shoji
Polyolefin-coated urea commercially called “MEISTER” was invented by T. Fujita and his co-workers. It shows primarily temperature-dependent dissolution and is divided into two groups of dissolution: ordinary (linear) and delayed (sigmoid). The dissolution of MEISTER in the soil is predicted easily with reasonable accuracy by a portable computer using temperature data. Thus, we can select kinds of MEISTER that can release N meeting the plant demand. It has been common knowledge that polymer-coated materials are used mainly on lawns, professional turf, and container-grown ornamental and horticultural plants and to a limited extent, in vegetable production. However, MEISTER is applied not only to high-value crops but also to low-value crops in Japan because this fertilizer can contribute to innovative fertilizer placement and farming systems (described later in this abstract), thereby the total farming cost can be notably reduced. Innovative fertilizer applications; co-situs placement and single basal application Innovative farming systems; paddy rice 1) no-till rice culture by direct-seeding and a single basal co-situs application and 2) no-till transplanting rice culture by single basal fertilization; and upland and horticultural crops 1) multi-cropping by a single basal fertilization and 2) no-till cropping by a single basal co-situs application.
Timothy L. Grey, David C. Bridges, and D. Scott NeSmith
Field studies were conducted in 1993, 1994, and 1995 to determine tolerance of seeded and transplanted watermelon [Citrullus lanatus (Thunb.) Matsum and Nak.] to clomazone, ethalfluralin, and pendimethalin using method of stand establishment (directseeded vs. transplanted) and time of herbicide application [preplant soil incorporated (PPI), preplant to the surface (PP), or postplant to the surface (POP)] as variables. Yield and average fruit weight in plots with clomazone were equal to or greater than those in control plots for the 3-year study regardless of method of application. Bleaching and stunting were evident with clomazone in early-season ratings, but injury was transient and did not affect quality or yield. Of the three herbicides, ethalfluralin PPI resulted in the greatest injury, stand reduction, and yield reduction of the three herbicides. Pendimethalin (PPI, PP, or POP) reduced yield of direct-seeded but not of transplanted watermelon. Chemical names used: 2-[(-2-chlorophenyl)methyl]-4, 4-dimethyl-3-isoxazolidinone (clomazone); N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) benzenamine (ethalfluralin); N-(1-ethylopropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).
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.