Plant ProtectionPosted in: Farming By Bill Strautman June 1 2009
Research news you can use
Camelina appears less salt tolerant than canola
Preliminary results of an Ag Canada study suggest camelina is somewhat less salt tolerant than canola.
Camelina, a new oilseed crop, is generating interest in the brown and dark brown soil zones. The crop is adapted to the cool, semiarid growing conditions and has some potential to replace canola as a biodiesel feedstock in the brown soil zone.
Certain canola varieties continue to be productive under slightly and moderately saline fields in western Canada. This research, lead by K.G. Wall from the Ag Canada research station in Swift Current, is comparing the salinity tolerance of InVigor 9590 canola to that of CS15 camelina.
At 20dS/m, camelina emergence was reduced to 30 percent of control. Canola managed a survival rate of 78 percent at 27 dS/m. The point where seed yield was reduced by 50 percent in canola was 16.91 dS/m, while with camelina it was 6.78 dS/m.Using hydroponic sand tanks calibrated for various levels of salinity, researchers studied emergence, seed yield, oil content and composition for the two crops. Conductivities of less than four dS/m are considered negligible, four to eight dS/m slightly saline, eight to 16 dS/m moderately saline and greater than 16 dS/m are considered severely saline.
And the point where oil content takes a big drop in canola was 27 dS/m, while with camelina it was 15 dS/m.
The research is continuing, but the conclusion so far is that even under slightly saline conditions, canola would be the better cropping option for grain yield. Under moderate salinity conditions, emergence and survival of camelina begins to be affected as well, making canola again a better cropping option than camelina.
Control of Canada _ eabane
While no glyphosate-resistant weeds are currently present in Canada, at least 15 weed species in other parts of the world are now known to have resistance to glyphosate. One Canadian species, Canada fleabane, has developed resistance in countries such as Brazil, China, Spain, Czech Republic and USA.
Researchers from the University of Saskatchewan, Ag Canada and Monsanto established a trial, lead by Ken Sapsford from the U of S Department of Plant Sciences, to evaluate herbicide options available to control Canada fleabane in western Canada.
Ten separate treatments were spring applied to Canada fleabane weeds under non-crop conditions. Products tested, at varying rates, included: dicamba, 2,4-D ester, clopyralid, amitrol, florasulam, pyrasulfotole + bromoxynil and BAS 800.
All treatments controlled Canada fleabane greater than 70 percent. Certain treatments were rated at greater than 80 percent and greater than 90 percent control, at 16 to 28 days after application.
The study concluded that there are alternative herbicides that will suppress or control Canada fleabane if glyphosate-resistant biotypes appear in western Canada. It suggested that future work should be considered to evaluate these products with crop competition and in-crop herbicides.
Hemp response to N and P
Increasing consumer demand for hemp seed and hemp oil products spurred a group of Saskatchewan researchers to develop nitrogen and phosphorus response curves for industrial grain hemp.
Ag Canada and Saskatchewan Ministry of Agriculture researchers, lead by C.L. Vera from the Melfort Research farm, treated the hemp varieties Finola and Crag with a range of N and P rates, then compared those results to untreated controls. The hemp responded well to applied nitrogen fertilizer. The response of hemp seed yield to additional P was minimal.
The study concluded that hemp seed yield was maximized at rates of around 150 kg/ha of nitrogen
Control of group 2 resistant kochia in spring wheat
Since the discovery of group 2 resistant kochia more than 20 years ago, the resistant biotype has spread from the brown and dark brown soil zones into the black soil zone, as well.
An Alberta-based Ag Canada survey in 2007 revealed that about 90 percent of the fields contained group 2 resistant kochia. Similar results were found in Manitoba.
The rapid spread of this resistant kochia is the result of several factors. At least three different mutations in kochia confer resistance to these herbicides. Kochia is an out-crossing species, so the dominant resistance gene can spread through a population quickly. And with prolific seed production, a low level of seed dormancy and a tumbleweed seed dispersal mechanism, resistant kochia is able to spread rapidly.
Ag Canada and University of Saskatchewan researchers, lead by Ken Sapsford at the U of S Department of Plant Science, established trials with both group 2 resistant and group 2 susceptible kochia populations. Fifteen treatments were applied when kochia plants were less than 10 cm tall, with visual ratings taken at 7 to 14 days and 21 to 28 days after application.
The researchers concluded that group 4 herbicides that control susceptible kochia will control group 2 resistant biotypes equally well. But herbicide products that contain group 2 and 4 modes of action may not contain enough of the group 4 component to control kochia.
Two herbicides that contain group 2 and 4 modes of action and that do control group 2 resistant kochia are Triton K and GF 184. Infinity, a group 6 and 28 mode of action herbicide, controls group 2 resistant kochia.
The group also concluded that unless you know otherwise, assume kochia infestations on the prairies contain group 2 resistant biotypes.
Managing leaf spot diseases of winter wheat
Leaf spot diseases, including tan spot, septoria and spot blotch, are frequently observed in western Canadian winter wheat crops. While disease impact and management practices have been evaluated in spring wheat, little research has occurred in winter wheat.
A group of Ag Canada researchers from Lacombe and Brandon, led by C.L. Kirkham from the Melfort Research Station, established a study to determine the benefits of variety selection and fungicide treatments to control leaf spot diseases in winter wheat, to improve disease control strategies and recommendations.
Two varieties were chosen – Osprey as a susceptible and McClintock as less susceptible. Fungicides were applied at stem elongation, full flag leaf emergence, or both.
Eight treatment were established using Headline, Stratego, Dithane and Tilt, along with a control. Leaf spotting over the trials was almost three times greater, at 16.1 percent, on the Osprey, compared to 5.1 percent on the McClintock.
The less susceptible McClintock did not benefit in terms of symptom reduction from fungicide treatment, or fewer of the treatments were effective. But at the locations with the greatest leaf spotting disease severity, yield increases of 21 and 26 percent were detected when averaged over varieties and fungicide treatments.
Application of Headline, Stratego and Tilt, at recommended rates, all reduced leaf spot symptoms over the unsprayed control.
In general, split applications of fungicide did not greatly enhance disease control or increase yieldover a full rate application at the flag leaf stage.
The study concluded that variety selection is an important leaf spot disease management practice in western Canadian winter wheat production. Fungicides were effective in decreasing disease severity and increasing yield. Little reduction in leaf spot severity or increase in yield was observed with split applications of fungicide, compared to the recommended rate application at the flag leaf stage.
Biocontrol of clubroot in canola
Clubroot, first confirmed in canola near Edmonton in 2003, constitutes a serious threat to canola production in western Canada. Current canola varieties are highly susceptible and breeding in disease resistance may not be possible.
A team of researchers from Edmonton, Guelph and Japan, lead by Gary Peng from Ag Canada in Saskatoon, is looking at possible biocontrol solutions to reduce clubroot severity.
Previous studies have shown that a beneficial fungus can reduce clubroot on Chinese cabbage.
The fungus forms a symbiotic relationship with the Chinese cabbage roots and induces plant resistance to clubroot and other soil-borne diseases. The team has shown this same process can reduce clubroot on canola. They have also evaluated several commercial biofungicides, with three showing promise.
Studies to develop practical methods to deliver these agents into canola fields, such as formulations for seed treatment and in-furrow applications, are in progress.
Studies are also underway to isolate and screen soil microorganisms as effective biocontrol candidates. The goal is to use effective microbial agents in combination with resistant cultivars and good agronomic practices, for long-term management of clubroot.
Winter annual cleavers control
In Saskatchewan, cleavers has generally been a spring germinating annual weed. With more acres under direct seeding systems and better snow cover, it is starting to exhibit winter annual growth behavior, with over-wintered plants at the 8 to 10 whorl stage when spring burnoff applications are made.
Because this is past the growth stage specified on herbicide labels, researchers at the Department of Plant Sciences at the U of S in Saskatoon conducted a trial at two dark brown soil locations to evaluate the effectiveness of several pre-seed burnoff treatments.
Quick burndown of winter annual cleavers was observed with CleanStart, glyphosate + Attain and glyphosate + UAP 0401, at nine days after application.Ken Sapsford and Rick Holm applied various combinations of glyphosate, Attain, UAP 0401, CleanStart, Express and PrePass to cleavers plants that were up to 20 cm tall and had nine whorls. The treatments were made May 24.
By 19 days after application, all treatments controlled the cleavers, but cleavers treated with CleanStart showed signs of regrowth. The researchers suspect that the rapid contact injury caused by the carfentrazone may have reduced thetranslocation of the glyphosate, allowing more regrowth to occur.
They concluded that winter annual cleavers should not be a major problem weed as it was controlled with most of the burnoff treatments currently in use.
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