Legumes (pulses) are more susceptible to weather damage than cereals, so a delay in harvesting can lead to loss of yield and deterioration of quality. To reduce the time from maturity to combining, field crops may be desiccated. Desiccation is the chemical termination of plant growth at the stage when all growth functions, seed size and yield have been set. It helps to minimize late disease development and harvest problems caused by late weed growth, uneven ripening of crops and crop lodging. It also makes for better control of harvest timing.
What are desiccants?
Desiccants are contact herbicides which are designed to quickly dry down the crop. They interfere with photosynthesis, causing plant cells to break down and release their liquid contents so they can dry down more rapidly than would have happened naturally. It is important to note that although glyphosate can desiccate a crop, it is not a true desiccant. It is a systemic herbicide which must be absorbed and translocated to growing points to kill plants, and therefore takes longer to dry the crop. Glyphosate is useful as a pre-harvest herbicide for weed control but when its application is incorrectly timed, there is a danger of herbicide residue ending up in the seed and exceeding maximum residue limits. Moreover, it should not be used on pulse crops destined for planting seed because of an increased risk of poor emergence.
When to apply desiccants
When applying desiccants, timing is important. Incorrect timing of pre-harvest herbicides can negatively affect crop maturity. Desiccants applied too early can interfere with the process of seed filling, resulting in yield loss. Research suggests that the best time to desiccate is when the seed has less than 30% moisture.
The decision to use a desiccant depends on the risk of the crop losing quality if left to dry down naturally in the field, and whether a producer needs to manage harvest workload and timing. Individual circumstances will determine if desiccation will provide financial and operational benefits. Your SynergyAG rep can guide you in making that call.