Weed control strategies need to be adjusted every year on every farm, but this year across the Prairies, adjustments may have to be large and wide-ranging.
In addition to limited residual moisture to get the crop going ahead of weed competition in most areas, there are unprecedented herbicide shortages. Growers will therefore need to make the best use of what’s available, and leverage every other weed management tool in the tool box to keep them under control, says Ashton Thomas, a certified crop advisor with Parrish & Heimbecker Ltd.
“Having a reliable retail or agronomist in your operations corner is critical in 2022. The herbicide options — new products, label changes, product availability — are always changing but that’s true this year more than ever.”
Ashton Thomas, Parrish & Heimbecker
“We’re at the time of year when all our winter weed control planning strategies are being implemented, but for many of us, particularly in southern Alberta, there’s a lot of revision going on,” she says. “We’re coming off an extremely dry 2021 growing season, followed by very little moisture over the fall and winter. Where I’m located near Milk River, we’ve had multiple days in March over 15 C. The sun has been shining and the spring precipitation has not been falling. Lack of moisture is a factor that we can’t ignore.”
On top of the lack of moisture in most parts of the Prairies, product shortages are unprecedented. The situation is changing for the worse by the day, with many products already allocated or sold out. Expected delivery amounts for later in the season are much lower than normal.
“So, growers this year need to focus on weed control strategy planning more than ever before,” says Thomas. “To succeed, you have to put more time and thinking into how you’re going to protect each of your crops in the serious circumstances we’re facing. Doing what you’ve done for the last 10 years just isn’t going to cut it this year. You have to adapt, which means changing your typical habits. Be ready to do things you’ve never done before.”
Ashton Thomas is a CSR with P&H and farms with her husband just outside Warner, Alberta.Strategy: control what you can
Good weed control in any year includes enabling crops to outcompete weeds as best they can. This includes increased seeding rate, adjustments to row spacing, optimized crop rotation, using certified seed, wise fertilizer application and keeping excellent seeding and product application records. However, growers will need to decide carefully how to adjust the things they can, because all aspects of a cropping strategy can’t be changed in a given year.
“You can’t, for example, buy a new drill this year, and use different fertilizer placement options this year, and use different spacing, and buy brand-new seed for every acre of the farm, and, and, and,” Thomas says. “You have to work within the limits you have. You may have recently invested in new equipment, and it’s here to stay for the next few years. And maybe you’re going to rent some land for the first time this year, and the cropping history might be incomplete or completely unavailable. You may not be able to seed as early as you’d like due to cold temperatures.”
The costs of fertilizer and other inputs will also affect decisions this year on the type, how much to apply and the application strategy to aim for those higher yields while keeping costs down.
Strategy: scouting
To decide which herbicides to use for pre-seed burn-off and in-season control, Thomas strongly advises thorough scouting to get a complete understanding of your scenario. You need to know which weeds are growing at time of application, their growth stage, which weeds may have a second flush, your problem weed species, which crop will be seeded after burndown, and so on.
“After scouting, there’s always the possibility that what you planned on seeding on certain fields may need to be changed,” Thomas says. “Perhaps you discovered weed issues that would indicate that seeding a specific crop there, regardless of spray decision, may not be the best option. For example, you might discover the field has potential for being ‘dirtier’ and seeding a pulse crop there over a cereal would limit your in-crop spray options, so changing that acre away from a pulse to get a handle on the weeds may be your best management strategy.”
Strategy: product choice
After scouting comes the decision of what products to use. One big factor is whether a grower needs a contact-only product or one with a residual component. Obviously, for a residual product, the conditions must be in place for the product to work. Most residuals on the market need moisture to activate, and if no moisture follows application, the product will have no effect on weeds.
“I highly recommend that you go over all your options with your retailer or your operations agronomist of choice,” Thomas says. “Use their knowledge and expertise to the fullest extent this year. Having a reliable retail or agronomist in your operations corner is critical in 2022. The herbicide options — new products, label changes, product availability — are always changing but that’s true this year more than ever.”
Strategy: rates and mixing
Tank mixing is a very important consideration this year, due to both the high cost and low availability of glyphosate.
“As 2022 moves forward, glyphosate is running at over $10 a litre,” Thomas says. “So, instead of pushing up its rate, we should look hard at tank-mix options. This way we add other options into the tank and end up paying roughly the same cost per acre as we would using a higher rate of glyphosate alone. I come from the area in Alberta where glyphosate-tolerant kochia was first discovered and tank mixes have been essential. There are lots of options for tank mixes which allow the glyphosate to control a broad spectrum of weeds and another product in the tank targets those harder-to-control weeds or specific weed issues in particular fields.”
In addition, because glyphosate is in short supply this season, using a tank mix at a 0.5-0.75 litres per acre instead of relying on glyphosate by itself at high rates will help alleviate some of the supply chain issue pressure while maintaining effective weed control.
Thomas also reminds growers that glyphosate-only applications or using increased rates of glyphosate alone obviously brings serious risks of promoting herbicide resistance. “It’s really important to combat your resistance issues — and they exist and are growing on every farm — by maintaining effective glyphosate rates in a tank mix with other products, to target specific issues. That’s on top of rotating crops and so on, on every acre of land.”
Use all tools and expertise
As parting advice, Thomas reiterates the need for a thorough look at your individual farm circumstances to decide what weed management strategies will be most beneficial in 2022.
“Using multiple options from the tool box will increase the efficiency and economical outcome of your strategy choices. Also be sure to lean on the expertise of your trusted retailer and/or agronomist as you plan out not only your 2022 growing season, but as you pick tools that will benefit you in future growing seasons.”
