A Plan Of Attack For Unplanned Summerfallow – for Jul. 23, 2010

Farmers love to talk about the weather, though this year it might be a more somber conversation than most. The weather has been bizarre and unco-operative through the spring and continuing to stretch into the summer. Heads start to shake in an unbelieving way as tales are shared of just how wet it is, how much the water is running again, how much has been lost to flooding and how much never got seeded.

All areas of the Prairies are dealing with a management issue that we as farmers don’t often spend a lot of time thinking about — unplanned summerfallow. Due to the persisting weather many farmers will be forced to put chemfallow into their plans this year. Most farms operate on the assumption of cropping the entire land base and hope to make a return on those acres. The tables have been turned and now we will have to begin managing these unseeded acres to minimize the negative effect they will have on our farms for not only this year, but into the years ahead.

As we drive down the highway we will all see chemfallow fields that exhibit varying levels of management. Some farmers will choose to actively treat their chemfallow to minimize the effects of weeds, while others will simply let the management slip while the negative effect of the weed growth accumulates throughout the year.

For many of us who weren’t planning on chemfallow, management will be critical. Managing the chemfallow (or making the best of the situation dealt to us) can help minimize the negative long term effect of not cropping the land and help us set it up for next year’s production. Poorly managed chemfallow will hurt us more, as not only are we losing this year’s productivity but we’re also potentially leaving the land in worse shape with more obstacles against us for setting up a good start for 2011.


The timing and frequency of treatment on chemfallow will greatly depend on the weeds present, their rate of growth and the continuing frequency of rainfall throughout the summer. It is not uncommon for many fields to be treated two or three times throughout the summer. Weed staging is an important consideration, as when weeds get larger it takes a proportionally higher rate of glyphosate to control them.

Chemfallow is also a good opportunity to strike aim at any perennial weed populations in the field. An early spray application followed by a time of growth, allowing the perennial weed to grow into a rosette stage, sets that weed up for excellent control. A glyphosate application during the rosette stage is particularly effective as the plant is actively growing, readily absorbing the chemical and translocating it through the root system. An application of 360 to 540 active equivalent grams of glyphosate (0.66 to one litre of 540 g glyphosate) will provide good control of Canada thistle, perennial sow thistle and dandelions. This will be the most cost effective control for perennial weeds due to the high level of control that we should expect with the relative cost effectiveness of glyphosate this year.

While growing weeds will use up excess moisture, they’re inefficient users of nutrients and will gobble up a lot of costly fertilizer that may have been put down last year. If you choose to let weeds use up moisture, control should be timed to kill off weeds prior to seed set.


Farmers this year may look at the option of seeding winter wheat into unseeded fields. This may be an option for many farmers, but it could also come with some risk as there will be reduced amounts of stubble. Poor stubble means poor snow trapping and an increased risk of winterkill. Soil testing is also recommended as it is hard to determine the amount of mineralization of nitrogen that occurred during the period of chemfallow. This uncertainty can make the plant use requirements of all nutrients, but especially nitrogen, hard to determine.


Glyphosate is the number one go-to, cost-effective chemfallow option, but it’s important to dip into the array of other tank-mix partners that can be used on chemfallow to help address particular weed problems. If volunteer Roundup Ready canola is present it will be imperative to use another product along with glyphosate to obtain control.

Due to the price of glyphosate (in comparison to these other chemicals) it may be just as advantageous for farmers to look at using higher rates of glyphosate for weed control. In many cases an extra 180 to 360 active-equivalent grams of glyphosate (0.33-0.66 L/ac of a 540 g glyphosate) will be the same price or less than some of the additional partners to glyphosate. But some products, such as DuPont’s Express offer a level of residual control, and this may be beneficial for some weeds that will continue to germinate in many flushes. Keep chemical groups in mind, however, as an application of these herbicides does not allow for a farmer to count the chemfallow as a “free” year.


Although this chemfallow was unplanned, it does give us the ability to plan for next year. Well-managed chemfallow will help to dry out the saturated moisture conditions for next spring as well as help us to address some persistent weed concerns. It will be imperative to have soil testing on chemfallow fields as the amount of nitrogen mineralization can be largely variable between fields. The availability of many nutrients, especially nitrogen, will be much more difficult to predict coming off of a chemfallow field than a cropped field. Having a field in chemfallow will also give farmers a chance to reset rotations and that helps many of us who are pushing both pulse and oilseed rotations on our farms.

Making the best management decisions on all of our land whether it is going according to our plan or not is all that we as farmers can do. Managing our chemfallow situation well will help us set up for a profitable year next year, we hope, rather than continuing the detrimental effects of the weather that we have experienced this spring.

BobbieBratrudfarmswithherhusbandMark nearWeyburn,Sask.TheyalsorunBratrud AgAdvisoryServices( www.bratrudag.ca).








Glyphosate +Heat


Glyphosate+bromoxynil Increased control of RR canola volunteers

Glyphosate+2,4-D Most cost effective. Can vary the rate depending on individual needs

Increased control of RR canola volunteers, dandelions, kochia

Increased control of RR canola volunteers and dandelions. Flushing control on some weeds for up to two weeks

Very fast control. Does control RR canola volunteers

Increased control of all canola volunteers and annual and perennial sow thistle

Increased control of RR canola Doesn’t control RR canola volunteers

Slightly more expensive. Can only vary the rate of glyphosate by adding, can’t vary the rate of dicamba

Cost. Doesn’t help to increase control of kochia

More expensive option

More expensive option

Slower activity on some weeds


Although this chemfallow was unplanned, it does give us the ability to plan for next year. Well-managed chemfallow will help to dry out the saturated moisture conditions for next spring as well as help us to address some persistent weed concerns.

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