For more information, click attachment below.
You say, it is a little late in the summer to be talking about using soil solarization for weed control because it works best in the summer when the days are long with high temperatures. Maybe we can learn some things from past situations where control has been marginal or poor.
I have seen some locations where results could have been more dramatic, if instructions were followed more closely (Figure 1). Most of the pertinent information for successful solarization can be obtained from the UC IPM Online called Soil Solarization for Gardens and Landscapes or the publication Soil Solarization: A Nonpesticidal Method for Controlling Disease, Nematodes and Weeds.
Four basics are needed for successful soil solarization: 1) a smooth, flat area preferably that has been cultivated; 2) a moist but not saturated soil; 3) 2 to 6 mil clear plastic covering the soil tightly; 4) and 4 to 6 weeks of clear (non-shade area) warm or hot weather. (Figure 2), Though solarization can give excellent weed control, it can also be less than outstanding under some circumstances.
Let's say you want to plant a fall garden. You can plant vegetables on flat soil, but what happens if we plant on beds? Is there something you can do to make solarization more effective? People are using “soil solarization” for turf grass and weed control prior to replanting to a more drought tolerant landscape. Can this be effective?
For fall vegetables, a late summer solarization in July or August can be excellent. Afterwards, remove the plastic and without cultivating the soil, either direct seed or transplant. If beds are used, prepare the beds before laying the plastic, not after. To optimize the increase of temperature in the beds, run beds north and south to increase uniform heating. This prevents a shaded “cool side” or open “hot side” of beds. Bed width should be a minimum of 2 feet to decrease the edge effect of cooler temperatures. For any cultivation before planting, make it very shallow, so no new weeds are brought to the soil surface to germinate (Figures 3 and 4.)
Remember, there is usually an increase in plant growth after solarization. There is a release of available nutrients and lack of competition with weeds, so the vegetables will be more vigorous (Figure 5).
If solarization is to be used around the landscape for turf grass control or for the control of all plants in the lawn area (Figure 6), the grass should be mowed as short as possible or preferably rototilled and the surface smoothed. Because the edges where the plastic is covered with soil will be cooler than in the center of the treated area, the edges should be extended beyond the edge of the grass. Often there is a lot of variation in the home turf areas. Sometimes they are on a slope or parts of the area are in shade of a tree or structure. Under these circumstances, unless the slope is facing south to the sun, decreased control will occur.
A rumor often heard is that solarization does not work for weed control in the coastal region of California. There are areas where many days have fog covers for much of the day, or heavy on-shore winds are a concern. In these areas, solarization may not be maximally effective in the mid-summer but would be more effective in the fall transition weather period. If you see a forecast of warm, clear, sunny days, “start” the solarization process. It is most critical for increased effectiveness that ‘heating' is started right after laying the plastic. If you start solarization with a few days of cool, foggy or cloudy weather, you find weeds germinating and thus reduce control. If one looks at the solar radiation measurements in the central valley and coastal areas they are reduced but still high enough for control of sensitive weeds (Table 1). The weed spectrum is different in many coastal areas compared to the hotter central valleys. Coastal areas often have high populations of annual bluegrass, other small grasses and common groundsel, prickly lettuce and annual sow thistle. These weeds are more easily controlled with solarization. Even cheeseweed is controlled in many locations.
Got a rather lengthy text from a colleague this afternoon concerning J rooting of strawberry plants - question was: does it really make a difference whether or not a strawberry transplant is J rooted?
Let's go to the Green Sheets, which have been a real treasure trove of information.
The one included in the link below was a summary of field work done by the late Warren Bendixen, who served as the Farm Advisor in Santa Maria for many, many years:
This work was done by Warren in response to a shift going at that time in Santa Maria from 40" inch beds with 5- 6" deep planting slots with very little J rooting to the 64" beds so familiar today, but with planting slots which would result in a lot of J- rooted plants.
Key takeaway from the paper, it's in bold because it's so important.
Plants with J roots reduced fresh fruit yields by 18.5%.
If this doesn't get your attention as to why we shouldn't be J rooting, I don't know what will.
Strawberry transplant showing correct positioning of the roots and depth of planting. UC Statewide IPM Program.
Planting into a slotted bed. UC Statewide IPM Program.
Interesting short piece on the potential to use "fruit flies" (these would actually be vinegar flies belonging to the family Drosophilidae, true fruit flies belong to the family Tephritidae - IBD needs a better science blurbist) to detect bombs and illicit drugs given that they can detect odor from these materials almost as well as wine odors.
I can believe it, I've seen work using electrodes on vinegar fly antennae showing highly selective sensitivity to certain volatiles given off from fruit in the air.
From a PRESS RELEASE from the USDA Office of Communications:
Release No. 0227.14
Contact: Brian Mabry (202)720-4623
USDA Announces Measures to Help Farmers Diversify Weed Control Efforts
WASHINGTON, Oct. 15, 2014 — Agriculture Secretary Tom Vilsack today announced several steps that the U.S. Department of Agriculture (USDA) is taking to address the increase of herbicide resistant weeds in U.S. agricultural systems.
"Weed control in major crops is almost entirely accomplished with herbicides today," said Vilsack. "USDA, working in collaboration with the Environmental Protection Agency, must continue to identify ways to encourage producers to adopt diverse tactics for weed management in addition to herbicide control. The actions we are taking today are part of this effort."
Today USDA is announcing several of the steps it is taking to help farmers manage their herbicide resistant weed problems in a more holistic and sustainable way:
- USDA's Natural Resource Conservation Service (NRCS) will offer financial assistance under its Environmental Quality Incentives Program (EQIP) for herbicide resistant weed control practices that utilize Integrated Pest Management plans and practices.
- Later this year NRCS will be soliciting proposals under the Conservation Innovation Grants (CIG) Program for innovative conservation systems that address herbicide resistant weeds.
- USDA's Animal and Plant Health Inspection Service (APHIS) will actively promote use of best management practices (BMPs) in design protocols for regulated authorized releases of genetically engineered (GE) crops and will include recommendations for BMPs with the authorization of field trials of HR crops.
- USDA is partnering with the Weed Science Society of America (WSSA) and is providing funds to develop education and outreach materials for various stakeholders on managing herbicide–resistant weeds. The Secretary has directed Dr. Sheryl Kunickis, Director of the USDA Office of Pest Management Policy, as the point person leading this effort with the USDA.
The issue of herbicide resistant weeds has become one of increasing importance for agriculture. When herbicides are repeatedly used to control weeds, the weeds that survive herbicide treatment can multiply and spread.
With EPA's announcement today on the registration of new uses for herbicide mixtures containing the herbicides 2,4-D and glyphosate (in the Enlist® formulation) in conjunction with new genetically engineered crop varieties, farmers are being offered one more new tool to better manage emerging populations of herbicide-resistant weeds in corn and soybeans crops. In its decision for 2,4-D use on genetically modified corn and soybean, EPA has outlined new requirements for registrants as part of a product stewardship program.
The USDA Office of Pest Management Policy worked with EPA to address the issue of herbicide resistance through appropriate label language that will require registrants to develop a stewardship program for the herbicide, develop training and education on proper use of the product that includes diversifying weed management, investigate and report nonperformance, and develop and implement a remediation plan for suspected herbicide resistant weeds.
EPA intends to require the same stewardship plans for all new applications for product registration on genetically modified crops with the goal being to encourage effective resistance management while maintaining needed flexibility for growers.
USDA recognizes that the problem of herbicide resistant weed control will not be solved solely through the application of new herbicides. USDA has worked with the Weed Science Society of America for a number of years on identifying best management practices for farmers and on addressing impediments to adoption of those practices.
USDA will continue to work to ensure that growers have the diverse tools they need to address the management of herbicide resistant weeds.