By John Ippolito, Regional Crop Specialist – Kindersley
With the ongoing decrease in summerfallow acres it is more difficult to find an opportunity for control of perennial weeds such as Canada thistle, quackgrass and dandelion. These weeds are often not at the proper stage for control by a pre-seed herbicide application. Depending on harvest conditions there may not be sufficient regrowth for a post-harvest application.
This is where the concept of pre-harvest weed control fits. Pre-harvest applications of glyphosate can be made to a number of registered crops when they are at 30% moisture and the weeds are still actively growing. This practice fits best in the cereal phase of the rotation as the crop is already well on its way to maturity and is not requiring herbicide application for harvest management.
Harvest management refers to rapid dry down of the crop to facilitate harvest of a quality crop in a timely manner. Pre-harvest glyphosate applications may provide some of this activity, but there are other herbicide options that are applied specifically for harvest management.
There are pre-cautions related to use of pre-harvest and harvest management herbicides that producers must be aware of. Buyers of crops such as malt barley may not purchase crops treated with pre-harvest glyphosate. Grain from crops treated in this manner should not be used for seed in following years.
For pulse crops such as lentils and field peas there are concerns about residues remaining in the seed from the pre-harvest application of herbicides. This has the potential to cause problems in marketing depending on the crop, the herbicide used and destination of the crop.
For more information on pre-harvest weed control refer to the factsheet – Herbicide Options in Enhance Harvesting – FAQ’s or the 2013 Guide to Crop Protection. Look under the News menu pick on www.saskpulse.com for the Grower Advisory regarding market implications of the various herbicides registered for use as pre-harvest weed control or harvest management.