The Bean Report - August 14, 2024

Soybeans range from R4 (full pod) to R5 (beginning seed).

• Some fields are showing signs of moisture stress and a rain would be welcome in several areas as seeds are developing and filling.
• Soybean aphids have been low overall across the province, with few fields reporting ‘sticky’ soybean leaves which are a result of honeydew from soybean aphids.
• Stem diseases are occurring in several fields, typically in the headlands. Pod and stem blight, northern stem canker, white mold and Phytophthora root rot have been more common to spot this year due to previous moisture and humidity in the crop canopy.
• Patches of potassium (K) deficiency may occur in soybeans growing on sandier soils during pod filling stages. Symptoms are chlorosis of the leaf margins are soybeans are moving K from the leaves to the seeds. In previous research in Manitoba, soybean yields have not responded to K fertilizer treatments at low-K sites. Soybeans remove large amounts of K in the seed (1.1 – 1.4 lbs K2O/bu) so it is important to balance K fertility throughout the rotation to support yields of other crops.

Field peas range from R5 to R7 (full maturity). Pea harvest has started on earlier-seeded fields with yields ranging from 45-80 bu/ac.

• Peas have lodged in some fields due to strong winds. In some fields, stems have also been weakened by Mycosphaerella blight stem infections. Peas will lodge more often with wet weather and taller crop canopies. Vine lifters and pick up reels aid in harvesting lodged crops by lifting the canopy up over the cutting bar. Vine lifters have been found to reduce harvest losses from 5% to 1.5% of crop yield, decrease plugging and allow for faster harvest speeds (PAMI, 1990). Lifters spaced at 9-12 inches intervals were found to work best.
• Peas are ready for harvest when overall seed moisture is 18 to 20%. The maximum safe storage moisture for peas is 16%. Aeration in the bin is typically used to reach this safe storage moisture. Pea Desiccation and Harvest Guide →
• Peas usually sweat after going in the bin, so monitor for moisture build-up or spoilage post-harvest.

Dry beans range from R6 to R7 (full seed).

• White mould is prevalent in several fields, especially those that did not receive a fungicide application. Orange larvae may be found feeding on the tufts of white mould, these are the larvae of the white mould gall midge and they are not a pest.
• Grasshoppers have been causing defoliation around field edges, but below thresholds.

Faba beans range from R5(full seed) to R6 (beginning maturity).

• Foliar and stem diseases in faba beans have been low overall, with some symptoms of white mould, anthracnose and chocolate spot occurring.
• Lygus bugs cause perforation damage in faba beans, reducing seed quality. Faba beans are susceptible to lygus damage until seeds and pods are firm enough that lygus cannot penetrate them any longer. 

Desiccation Decisions

Crop desiccation has become an increasingly hot topic. In part due to consumer demand for pesticide-free products, variable maximum residue limits (MRLs) across export markets and the negative spotlight on glyphosate. It doesn’t mean desiccation is off-limits. But we need to understand the limitations of late-season herbicide. Especially when it comes to crops destined for human consumption, including field peas and dry edible beans.

Some questions to ask before applying that late-season herbicide:

• Is it a stagey crop with areas maturing at different rates?
• How far away from harvest is the majority of the crop?
• Are there weeds that need to be controlled?
• What are the weather conditions like during maturity?
• What grade are you targeting?
• What crop are you planning to grow after?