Streaky field patterns usually come down to one thing: sprayer trouble.
At the latest Farming Smarter Field School, one of the demonstrations provided a look at how active a herbicide can be at very low concentrations, due to varying thoroughness of sprayer tank clean-out.
Kara Oosterhuis caught up with Mark Oostlander, herbicide lead with BASF, to talk tips on sprayer tank clean-out in this episode of Canola School. (Story continues below video)
The demo used a few different chemical groups, commonly used in a pre-seed burn down, then sprayed canola with simulated tank contamination. Canola is a good example because it is sensitive to a lot of different herbicides, so it really shows those effects of low doses on the crop.
“When we apply a herbicide we have a labelled rate, but we’re trying to control a very specific weed or a number of weeds, so we have a recommended rate,” says Oostlander. “But when we take that same tank that we sprayed the herbicide and go into a sensitive crop, at very minute rates, you know 1/10,000s of a rate, you can still see plant injury if you have contamination in the tank.”
Proper tank clean-out is a dirty, time consuming job, but is absolutely critical. The first thing Oostlander recommends is to “leave the chemical in the field,” — avoid letting chemical sit in the tank overnight. Products will fall out of suspension, adhere to tank walls, and gum up hoses. So the less time a product spends in the tank, the easier it is to clean out later.
His advice is to follow these three steps:
- Rinse. Try to remove as much product as you can
- Clean. Use a good tank cleaner, or the recommended tank cleaner based on the label. Ideally, let it sit overnight, says Oostlander.
- Final rinse. Remove whatever’s left in there.
It’s important to use the recommended tank cleaner from the label, according to the product you used. Different types of tank cleaners do different things. Ammonia water for example is a solubilizer and certain chemistries are more soluble at higher pHs, so using ammonia water will increase the pH of the solution. Consult your label as a starting point, advises Oostlander.
The most common mistakes are missing a part of the sprayer while cleaning it out— whether it’s a filter or a screen—using the wrong tank cleaner, or not allowing enough time letting that tank cleaner sit for a thorough clean-out.