Editor’s note: This column was written prior to BASF releasing its message to Growers found here.
An array of unusual considerations will go into next year’s crop rotations and there will be some atypical choices.
One big consideration for many growers will be herbicide residue. In a dry year, many herbicides with residual activity persist much longer than intended. In this record drought year, it’s reasonable to expect more problems than ever.
Even in relatively normal years, growers have been reporting problems with Group 2 carryover, specifically with imazamox and imazethapyr. Although a number of companies have developed generic products, BASF is the leader with brand names that include Solo, Viper, Odyssey and Pursuit.
Imazamox by itself is used mainly for weed control in Clearfield lentils. According to the label, a wide range of crops can be seeded the year following application including cereals, non-Clearfield canola and flax. The only listed restriction is tame mustard, which shouldn’t be seeded until the second year after application.
Despite this, many growers have been reporting crop injury on canola and even cereals. Some have received a limited amount of compensation from BASF. This usually involves a non-disclosure agreement, and, as with any company, this means take what we’re offering and shut up about it.
Odyssey, which contains both imazamox and imazethapyr, has more cropping restrictions listed on the label. Flax and canola are not to be seeded the year after application. Saskatchewan’s Guide to Crop Protection contains an extra note about how environmental conditions such as drought slow the breakdown and may result in injury to rotational crops.
Hopefully, the companies selling residual herbicides will mount an information campaign to inform growers of the risks to 2022 crops given the abnormal weather this year. Since breakdown depends upon both moisture and time, the late season rains enjoyed in some regions may not be enough to alleviate problems. Provincial agriculture departments should also start disseminating information and guidance and the sooner the better.
Let’s consider a Clearfield lentil grower who used imazamox this year. The residue could potentially hurt next year’s canola and it may even be a problem on cereals in regions that remain very dry. So what do you seed to avoid a residue issue?
One answer is to seed field peas or go back to lentils on those fields. Back-to-back lentils are never recommended and neither are peas following lentils due to the fear of aphanomyces root rot and other diseases. However, with this year being so dry, crop diseases were not a big issue.
And there’s another reason why some growers may want to seed consecutive pulse crops — nitrogen levels in the soil.
If you are in an area with dismal yields on canola, wheat, durum and barley and those crops had a significant amount of nitrogen fertilizer applied, chances are a lot of that nitrogen remains in the soil. It’s especially important this fall to do soil tests to know what you have for residual nutrients.
Seeding lentils or peas that fix their own nitrogen is a waste if the soil already has high levels of nitrogen. Fertilizer prices have spiked. No one wants to waste nutrients. Besides, with adequate rain, lentils on high nitrogen ground could become vegetative with lots of growth but disappointing seed set.
So even though it departs from the normal rules of crop rotation, to deal with Group 2 herbicide residue and to avoid fields with high nitrogen levels, some producers may decide back-to-back pulse crops are the least bad decision. Abnormal weather leads to abnormal actions.
Kevin Hursh is an agricultural journalist, consultant and farmer. He can be reached by e-mail at email@example.com.