As field peas are beginning to dry down in the lower canopy, the time for desiccation is near. Desiccation is the chemical termination of plant growth at the stage when seed size and yield have been set. Benefits of desiccation include: earlier maturity (can advance pea harvest by 10 days), even ripening of the crop, reduced lodging and increased harvest speed, and reduced weed seed set and growth late in the season.
The optimal time for field pea desiccation is when seed moisture is < 30%. It is recommended to begin monitoring the crop for pod colour and developmental changes approximately 20 days after flowering. Field peas are at 30% seed moisture when the lower 75% of pods are brown, and seeds are firm, rubbery and split when they are squeezed (R7). The tops of plants may still be green and middle pods may be shrunken and leathery at this stage. Examine 10-20 seeds from random plants across the field for splitting.
Both early and late desiccation can have negative effects. Early desiccation can reduce yield and lock in the green colour of yellow peas prior to colour change. Conversely, late desiccation can reduce quality and cause seed bleaching.
It is important to be aware of maximum residue levels of products and the potential market restrictions they can impose. Glyphosate, saflufenacil (Heat) and flumioxazin (Valtera) are registered field pea desiccants that do not cause market restrictions. However, glyphosate should not be used if peas are grown for seed due to the risk of reduced seed viability.
Click here for information on maximum residue levels of desiccation products in pulse crops.