LETHBRIDGE – One of the many weather related records being set this year is the amount of summerfallow that producers have during the 2010 growing season.For many producers, chemical fallowing over a whole growing season is reserved for years when a crop is lost to frost, hail or water.“Luckily, most farmers have limited experience with chemfallow over a large area or a full season,” said Clark Brenzil of Saskatchewan Agriculture.“And while I’m not going to say these moisture conditions have been good for farmers’ incomes, there is a silver lining when it comes to weed control.”We have the opportunity to get a handle on some nasty weeds and improve margins in the future,” said the provincial weed specialist.Perennials that have escaped control due to poor harvest season conditions that didn’t allow for fall spraying, and those annuals that are persistently a problem due to large weed seed populations in the soil, will be getting the chance to flourish in unseeded acres this summer and fall.“And we’ve had the moisture to ensure germination and lots of lush, green growth making them vulnerable to herbicide control,” said Brenzil.He said producers don’t have to be vigilant about spraying every time it rains because most nutrients the weeds take up will be put back into the soil when they die.In some cases, the water they remove may make field traffic possible.“That will help keep application costs down, however you don’t want to keep letting things get away to the point where (weeds) get into a position to be setting seed either,” he said.Jon Gough of DuPont said the timing for herbicide applications has been tough due to the relentless showers.“There is a place for systemic herbicides in this scenario,” he said.Agrologists say glyphosate will likely be the most commonly used product.Brenzil said there are new chemical combinations that have been added to the chemfallow arsenal that provide extra punch and residual weed control.“Prepass (Dow) and Heat (BASF) can be safely used, however not later in summer or in the fall as they can cause some injury in sensitive crops next season. Or Express (DuPont) can also be used this way,” he said.“Where you have established dandelion, narrow-leaved hawk’s-beard, flixweed, stinkweed, wild buckwheat, those sorts of weeds, adding one of these products makes sense.”Mark Oostlander of BASF said Heat can be effective on the larger, tougher to control weeds in a chemfallow situation.“But you want to use it earlier and then move to other products later in the season. You can’t be using it over and over again like a straight glyphosate,” he said.Brian Wintonyk of Dow said when using products that have a residual control aspect or if tank mixing herbicides with staying power, producers need to watch their timing and plan for next year’s cropping to avoid residue issues in sensitive crops.Prepass, Heat and Express products have re-cropping guidelines for some crops.Sean Dilk of Monsanto said producers might think they are saving money going with lower rates of glyphosate.They will find that with well established weeds that are at or near the flowering stage, rates of 1–1.33 litres per acre of 540 gram active ingredient or 1.5–2 litre rates of 360 gram product will be needed.Agronomists recommend the addition of dicamba or 2,4-D to the glyphosate to control herbicide tolerant canola.“If the weeds are growing well, you will get excellent control, but if they are suffering moisture stress, they won’t take up the herbicide that well. You have to consider the conditions,” said Dilk.Ed Thiesen of Syngenta said producers that are facing tall, heavy weed stands due to saturated fields shouldn’t scrimp on the water along with full rates of herbicide.“We need that extra water, 10 gallons (per acre) to ensure good canopy penetration. If weeds are growing well, they’ll take that herbicide and move it to the roots,” he said.Weeds such as Canada thistle are susceptible to herbicides at the bud stage. Grasses like green foxtail, and barnyard grass can be controlled during the season while they are green and lush.Brenzil said weeds dandelion and boxtail barley are best controlled in August or later.
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