Hamman says that while some may be tempted to go at or just after seeding with a burnoff to get as many weeds as possible, it can prove risky. “The issue there is if you run into bad weather, you may miss your window entirely.”
compare glyphosate concentrations
No matter what name is on the label, any glyphosate product contains the same active ingredient, expressed as acid equivalent. Each product, however, is not the same. The glyphosate molecule is mixed with various different salts in varying concentrations, depending on the product. The salts may or may not make a difference (you’ll have to run your own evaluation of that), however it is useful to compare active ingredient concentrations when determining price.
Grab your provincial guide to crop protection and jot down the grams per litre of active ingredient (acid equivalent) then compare that to price to determine a cost per unit of active ingredient. Because of availability, personal preference and differing prices, the following is just an example. Sketch out or create your own comparison spreadsheet to compare. A higher concentration means less volume necessary for the same rate per acre and can result in a cost savings.
The following shows the grams per litre of active ingredient for a few glyphosate products. This is just an example. It is by no means the whole list of glyphosate products:
Credit 356 Credit Plus 360 Glyfos 356 Touchdown iQ 360 Touchdown Total 500 Vantage Plus Max 480 If Glyfos at 356 grams per litre
is used as a benchmark (given a value of 1), then Touchdown Total has a value of 1.4.
No matter how competitive a crop, knocking out competition early in the growing season protects yield potential and saves moisture and money. Fall control is the ideal first step to a clean spring seed bed, but it doesn’t always happen, especially when harvest is stretched until November.
Bill Hamman runs Hamman Ag Research out of Lethbridge. Between his past research plots and current consulting, he’s put together some key recommendations for spring burnoff. Whether you managed to control perennials or winter annuals in the fall or not, it’s time to tackle what’s out there now. Pre-seed burndown is a must for most fields, but the effectiveness of glyphosate and other products is largely affected by growing conditions, rates and tank mixes.
The first thing you need to do in the spring, Hamman says, is to get low and take a close look. Winter annuals and annuals can be tiny but plentiful. It’s a good idea to start out by knowing what weeds are out there, how big the plants are and at what concentration — all things that aren’t apparent a few yards out.
Of course, if you can see big weeds out there you might need to go in with some extra juice to take them out. Often the solution to big weeds is big rates, especially with dandelions, wild buckwheat and other aggressive growers, Hamman says. Sometimes all you need is a higher rate of glyphosate to get good control, he says, but a higher rate may only be half a litre per acre, depending on the weed type. Big dandelions may need as high as 1.5 litres per acre.
Glyphosate and other contact herbicides need an actively growing plant to move the chemical in the plant and kill it. “If it’s a good day for growing, it’s a good
day for spraying,” Hamman says. A hard frost will set growth back, at least for 24 hours. “If you can, wait a day after a hard frost before spraying,” he says. At a minimum, he recommends waiting until the end of the day to give the plant a chance to get its system running again.
Products with some residual, such as PrePass and Express Pro, can be part of the solution to this problem, however any product with a residual component requires a closer inspection of the label. Areas with sandy soils or low organic matter should pay particular attention, especially if planning on seeding a pulse on these fields.
CleanStart has proven a good fit for specialty crop, pulse and oilseed growers looking for a safe pre-seed burnoff. Hamman says good water volume (10 gallons per acre) and good weather are key to making this product work best, as it also works through contact. He says growers
can expect some re-growth, but with good control, and can safely seed within two days of spraying.
Western Canada, as yet, does not have a glyphosate-resistant weed problem, but by including any Roundup Ready crops in rotation, there is a need to tank mix or switch out products to control volunteers. Any of the above products will help, as will older products, such as 2,4-D. There are also a few new products awaiting registration (BASF’s Heat, for example) that could help, if approval is given.
Good quality water does have an effect on glyphosate effectiveness. Hard water can cause problems, but pH isn’t an issue, Hamman says. Hard water is easily dealt with by adding ammonium sulfate or a water conditioner.
Hamman says that while some may be tempted to go at or just after seeding with a burnoff to get as many weeds as possible, it can prove risky. “The issue there is if you run into bad weather, you may miss your window entirely,” he says.
Spraying earlier gives you more time to get the job done and hits weeds when they’re smaller and more vulnerable, however waiting may mean hitting more weeds in total. Hamman adds that because burnoff products work through contact there is also added concern of soil and dust covering weeds during the seeding process. That could decrease effectiveness of the spray.
Products such as CleanStart do address one last thing to consider with spring burnoff — herbicide group rotation. Hamman says it’s important to not only consider residual effects or cropping options after applications, but also to think ahead and look at fall, spring and in-crop control. “It’s important to not just plan herbicide rotations but to plan group rotations between preseed and in-crop products, as well,” he says.
Lyndsey Smith is a Grainews field editor based in Lumsden, Sask. She takes over as editor starting with the March 22 issue. You can reach her at [email protected]or 306-731-3637.
The 5 steps
1. Target perennial and winter annual weeds in fall
2. Increase glyphosate rates on dandelion and wild buckwheat, especially if controlling in the spring
3. Spray with the weather. If it’s a good day for growing, it’s a good day for spraying
4. Use a tank mix to control volunteer Roundup Ready canola
5. Plan herbicide group rotations between fall, spring and in-crop herbicides