As farmers are getting to work on harvest, many are using desiccants to spray down crops to get them to dry out quicker.
Those chemicals come with a bevy of rules and regulations, explains Saskatchewan Ministry of Agriculture Crop Extension Specialist Mackenzie Haldun.
"There is a minimum number of days that must pass after applying a product, such as a desiccant before a crop can be swapped or straight cut, and this is known as a pre-harvest interval. These pre-harvest intervals, also known as PHIs, are in place to ensure that the levels of chemical residue on the harvested crop are within acceptable limits.”
"This is important to protect both Canadian grain markets as well as any animals and livestock that ingest the harvested grain. Following the PHIs will ensure that chemical residues do not go over the maximum residue limits and are safe for consumption.”
Hladun says that people who want to learn more about PHIs or maximum residue limits (MRLS) can look to the Government of Canada's website or talk to their local crop expert.
Timing is one of the key considerations of desiccants, which can lead to issues if timed improperly.
“ Applying desiccants too early can interfere with seed fielding and can cause yield loss. Because desiccants do not accelerate crop maturity, only promote plant dry down, applications made too early can also promote green seed in the crop. Applications made too late may also not prevent shattering and could eliminate some benefits associated with desiccation.”
“Food, grain, and moisture should be less than 30% in the least ripe part of the field before a desiccant is applied. As a general rule, ensuring applicants are at the right crop stage, using recommended product rates, surfactants, and water volumes will go a very long way in achieving their desired results by using desiccation or using desiccants.”
All types of crops tend to have different times for desiccation, which can be found through labels and testing out the crop.
"As a rule of thumb, lentils, field peas, chickpeas, dry beans, faba beans, and soybeans, are not to apply before there has been a change in colour for approximately 80 per cent of the pods. For canola, different desiccants require application at different maturity stages, so it's important to read and follow the label. For wheat, utilizing a thumbnail test is a good strategy for timing. If you can leave a dent in the kernel without it splitting, it's time to apply a desiccant.
“Always check the product application timing prior to spraying texture and green seed as and harvesting the crop and proper dry down is achieved. Desiccated crops are generally harvested earlier if combines have started as soon as the crop dried out is completed. Earlier harvest reduces crop exposure to wet weather and eliminates the risk of swath movement from the wind and reduces the risk of post-swathing diseases. Desiccation may be a good option for those cooler and wetter falls.”