Author
|
Submitted to: Georgia Fruit & Vegetable Growers Association Winter Conference Proceedings
Publication Type: Abstract Only Publication Acceptance Date: 12/1/2003 Publication Date: 9/1/2004 Citation: Johnson, III, W.C. 2004. Weed control with organic production [abstract]. In: Proceedings of the Southeast Regional Fruit and Vegetable Conference, Georgia Fruit and Vegetable Growers Association, January 9-11, 2004, Savannah, Georgia. p. 13-14. Interpretive Summary: Technical Abstract: Weed management in organic crop production systems requires an integration of cultural and mechanical controls, augmented with thermal and biological tactics. Successful weed control depends on careful integration of these tactics, tailored to the crop, weed species composition, and tillage system. Unfortunately, there is little research information on non-chemical weed control on crops grown in the southeastern coastal plain. Therefore, research projects were initiated in 2003 to evaluate nonchemical weed controls in leguminous vegetables, peanut, and turnip green. Trials at the Coastal Plain Experiment Station in Tifton, GA were initiated in 2003 to evaluate systems of weed management without using herbicides in snapbean, lima bean, southern pea, and peanut. Depending on the specific trial, treatments included early season propane flaming at differing intervals, stale seedbed tillage, cultivation, row patterns, and tillage sytems. Across all trials, propane flaming provided acceptable control of small broadleaf weeds, however annual grasses were not controlled by propane flaming. Peanut was very tolerant to over-the-top propane flaming, while snapbean, lima bean, and southern pea needed directed propane flaming to avoid unacceptable injury. These trials clearly showed the value of mechanical weed control, using stale seedbed tillage before planting and cultivation. Both forms of mechanical weed control significantly improved overall weed management in these trials. Peanut seeded in narrow rows partially suppressed weed growth compared to peanut seeded in wide rows, greatly improving overall weed management. In these trials, weeds were not adequately controlled in strip-tillage cropping systems due to the inability to cultivate. In addition, cover crop biomass insulated annual weeds from control with propane flaming. Based on these preliminary results, mechanical weed control should be strongly considered in organic crop production, along with cultural controls using modified row patterns. Propane flaming is not a stand-alone practice for non-chemical weed control, but offers potential when carefully integrated with other strategies. Solarization is a proven means of weed control in regions of intense solarization, i.e. the Middle East. In these regions, sunlight is intense enought to heat soil covered by clear plastic to temperatures lethal to weed seed and other propagules. Previous research in the southeastern U.S. has shown unsatisfactory weed control by short-term solarization. It is hypothesized that sacrificing the use of field for an entire summer for solarization and repeated fallow tillage may help reduce densities of yellow nutsedge in future crops. Therefore, trials were initiated in Tifton, GA in 2003 to determine if combinations of summer solarization and frequent fallow tillage deplete populations of yellow nutsedge and provide acceptable non-chemical weed control in fall seeded turnip green. This trial was conducted in a field with heavy infestation of yellow nutsedge (>50 plants/m2). Treatments included all possible combinations of solarization (beginning in May, July, September, and nonsolarized) and frequency of shallow tillage (weekly, monthly, and nontilled). Plots were solarized using clear plastic, spread over moist clean seedbeds at the designated times and remaining covered for the remainder of the summer. Plots were shallow tilled to a depth of 7.6 cm at the appropriate times using a power tiller. Preliminary data analysis showed that weekly tillage and solarization beginning in May reduced the number of yellow nutsedge tubers in the soil and numbers of yellow nutsedge plants in direct seeded turnip green compared to the nontilled and nonsolarized controls. While the economic considerations of these practices have not been fully analyzed, the preliminary analysis o |
