UC Garden Blogs
I was forwarded this great article by Barry Tickes, an Area Agricultural Agent with the Yuma Ag Center and part of the University of Arizona and Arizona Agricultural Experiment Station.
With Barry's permission, I've posted his explanation of "lift off" or "codistillation" of herbicides. The article and other is in that issue of Vegetable IPM Updates can be found HERE.
Goal “Lift Off”
Codistillation is when a herbicide evaporates or changes from a liquid to a vapor with water. This can occur from soil, water or plant surfaces and can be responsible for substantial loss of some herbicides. When codistillation occurs with Oxyflurofen (GoalTender, Goal 2XL and others), the concern is not herbicide loss but crop injury. Codistillation can occur with several herbicides. It is affected by many factors including temperature, moisture, organic matter, soil pH and other variables.
In general, codisillation is greatest when temperatures, moisture and pH are high and organic matter is low. One of the herbicides used in this region that is most affected by codistillation is Eptam (EPTC). A study conducted several years ago in Brawley California found that more than 80% of the Eptam that was applied in irrigation water was lost by codistillation. Most of this was from the soil after it had reached the field. In our trials, we have found that codistillation may help GoalTender and Goal 2XL (oxyfluorfen, also sold as Galligan, Oxi Flo and others) kill weeds but it also can increase crop injury. Goal can move into plants in the vapor phase once it has lifted off and both weed control and crop injury are enhanced. We have seen this when Goal is Chemigated through sprinklers. Goal is primarily a contact type herbicide and moves little in the plant. It works preemergence by killing weeds as they emergence from the soil and contact the herbicide. It is rare for contact type herbicides to work better when overhead water is applied but this seems to be the case with this herbicide.
Lift-Off or codistillation of Goal lift off injury seems to be worse this season because of rain. In many cases this potential is exaggerated. Lift-Off of Goal differs from the usual off target drift that can occur with other herbicides. In this case it is movement of the herbicide with water vapor. Moisture must be present and this moisture must evaporate. The vapor normally stays in the field and it is common for a band application to the furrows, for instance, to move across the bed top. Significant movement out of the field normally only occurs with wind. GoalTender is not as volatile as Goal 2XL and is less prone to codistillation but it occurs with both. The picture below is of GoalTender that was applied to the furrows only but it lifted off and covered the entire bed. The crop grew out of this in 2 weeks.
Barry knowledgeable, Barry helpful….
A plant's ultimate goal is to self-perpetuate in some way by making more of itself. Their life cycle, be it short or long, consists of building up vegetative growth, which in turn supports seed development and other methods of self-propagation (runners,...
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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.
It may have flown hundreds of miles from the Pacific Northwest, and Washington State University entomologist David James is eager to know where you found it.
James, an associate professor at Washington State University, studies the migration routes and overwintering sites of the Pacific Northwest Monarch population, which are thought to overwinter primarily in coastal California but also in central Mexico. He spearheads a Monarch-tagging project in which volunteers--primarily inmates at the Washington State Penitentiary, Walla Walla--rear and release the butterflies.
“There are currently more than 2000 monarchs (Danaus plexippus) in the Northwest that are carrying tags and many of these I have good reason to believe are in the general Sacramento to San Francisco area," James said this week.
“Last Friday, Oct. 10, one of our tagged Monarchs was seen near San Mateo--this one was tagged 10 days earlier in Applegate, southern Oregon. It had flown 330 miles! Then a few weeks ago (Sept. 27) another was seen at Glen Ellen, Calif. This one had flown a whopping 600-plus miles from Yakima in central Washington."
James explained that “we have very little data to support the notion that they all fly to coastal California for overwintering. Before our project there was just a single tagged Monarch from Washington recovered in California. Recent observational evidence suggests that some PNW Monarchs fly in a more southerly-south-easterly direction, away from California and we speculate these may end up in Mexico! We have had one tag to date that supports this idea...a monarch released at Walla Walla turned up at Brigham City in Utah.”
Because the summer Monarch population in Washington, Oregon, British Columbia and Idaho is so small, James and his team have had to resort to mass breeding of Monarchs for tagging.
“We obtain wild females in Washington and rear their progeny,” the entomologist said. “Much of the rearing is done by inmates at Walla Walla Penitentiary.” He described it as “a very successful program for the butterflies and the prisoners! “
James is also increasingly using citizen scientists to rear and tag as well. See more details of recent recoveries and information about the program at the program's Facebook page.
You don't need a professional camera to capture an image. James said that "the two California recoveries we have had so far were both confirmed by cell phones or regular cameras! This technology definitely aids recoveries. It's so easy to take a high quality 'snap' that can be used to determine the tag details."
“I am confident there are a number of tagged Monarchs currently in your area," James told us. "We are actually still releasing them here in Washington, so the opportunity to see one will persist for a few weeks yet. “
He figures they are "likely heading to the overwintering sites at Bolinas, Santa Cruz and Pacific Grove--maybe further south as well.”
For more information about the project, see WSU's Monarch Butterfly news story.
Close-up of a tagged Monarch butterfly. (Photo by David James, entomologist at Washington State University, Pullman, Wash.)
Entomologist David James demonstrates how to tag a Monarch. This image was taken at a meeting of the Washington Butterfly Association at a Monarch breeding site near Vantage in central Washington on Aug. 23 2014.
Inmates at the Washington State Penitentiary, Walla Walla, rear most of the Monarchs. The photo, taken during a WSU Media Day, shows the release of the butterflies. (Photo by David James)
This Monarch butterfly, reared by inmates at the Washington State Penitentiary, heads for freedom. (Photo by David James)