The benefits of pre-harvest.
There are two primary reasons to apply a pre-harvest herbicide. The first is for weed control. Hard-to-control perennials such as Canada Thistle and Quackgrass are best controlled during the fall when leaf area is at is maximum. This is the primary reason pre-harvest should be considered in crops such as cereals with crop staging being critical. For wheat, preharvest application can only occur when the crop is at 30% or less moisture content. At this stage, if you press the kernel with your nail it will leave a dent in it.
The second reason to apply pre-harvest herbicide is for crop dry down. Certain pre-harvest products like diquat and HeatLQ will help dry out the plant and accelerate the overall maturity and harvesting process. It can also help mitigate uneven crop growth and control weeds. It’s important to note that glyphosate is not to be used for desiccating purposes. Not only is it ineffective, (takes over two weeks to dry down) but it gets absorbed by an immature crop which leads to residues in the grain.
Where are pre-harvest products allowed?
Glyphosate | Heat LQ | Diquat | |
Canola | Yes | Yes | Yes |
Wheat | Yes | Yes | No |
Barley | Yes | Malt – Consult with grain company Feed – Yes |
No |
Oats | Consult with grain company |
No | No |
Peas | Yes | Yes | Yes |
Soybeans | Yes | Yes | Yes |
Chickpeas | Yes (WeatherMax, Transorb) |
Yes | Yes |
Potatoes | No | No | Yes |
Flax | Yes | Yes | Yes |
Lentils | Yes | Yes (Red lentils only) |
Yes |
Fababeans | Yes | No | Yes |
Dry bean | Yes | Yes | Yes |
Cereal Seed Crops | No | No | No |
Talk to your Grain Buyer
When considering pre-harvest products like glyphosate, heat or diquat, it is important to pinpoint what exactly you are trying to accomplish, and in which crops. It is very important to check the declarations of grain buyers to see if they will accept grain treated with certain products. P&H will work with you through these considerations and help you pick a product that will meet your operation’s needs.
For complete details on pre-harvest products by crop, visit Keep it Clean.