AUGUST 21, 2019

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Crop Update

Soybeans across Manitoba are at or approaching R6. Premature drying is occurring in many regions, though some regions have been hit harder than others. Soybeans in dry or sandy regions are showing patches of dry down/color change and are progressing towards leaf drop, while soybeans in regions with more moisture are still green and trying to fill pods.

The late-season, R6 rating of the 2019 National Soybean Survey is wrapping up this week. Disease levels in soybean crops were relatively low this year, with low levels of bacterial blight, downy mildew and Septoria brown spot found in soybean fields throughout the province. White mould risk was very low this season and no white mould has been found in soybeans or other pulse crops in this survey.

Dry beans are beginning to dry down and are at R8.5 to R9 in eastern Manitoba. Desiccation has begun in the central region this week. Dry beans are also showing signs of premature dry-down.

Field pea harvest is underway in most regions across Manitoba and is nearing completion in some of those regions. Later seeded peas range from R6 to R8, while earlier seeded peas have already been harvested. Yields so far have been variable and typically depend on crop moisture throughout the growing season.

Faba beans are approaching R8 in eastern Manitoba. Plants appear to be short in stature with some pod splitting or seed drop occurring in the driest areas.

Precipitation is still below average in most regions and is still needed. Although it is too late for early-maturing crops, soybean and dry bean crops that aren’t yet at full maturity could use some rain to maintain yield at this point.

Soybeans at R6 on August 15.

Dry Beans on August 15.

Field Peas on August 16.

Faba Beans at R8 on August 15.

Insect Update

Grasshoppers are still present in low to moderate levels and have been moving from harvested crops into green ones (e.g. soybeans, dry beans). Farmers should continue scouting and should consider both the economics and pre-harvest intervals (PHIs) of certain insecticide products (Matador/Silencer PHI: 21 days, Coragen PHI: 1 day) before deciding whether to spray or not. Find more information on Manitoba Agriculture’s Manitoba Grasshopper Forecast for 2019

What to look for:

Round to ragged holes in the leaves – holes may extend in from leaf margins and between veins.
Damaged soybean pods – grasshoppers may chew through the pod tissue into the seed. Once the seeds harden and pods mature, less damage to seeds and pods is expected.
Edge effects – grasshoppers move into new fields from more preferred plants that may be maturing or being harvested.

Scouting for Soybean Cyst Nematode

Add soybean cyst nematode (SCN) to your scouting watch list at this stage in the growing season. It can be tricky to scout for since symptoms of SCN may resemble other plant stressors, such as nutrient deficiencies and drought stress. To make it even trickier, plants may still appear healthy at low levels of infection. Our best recommendation is to dig and investigate soybean roots in suspect areas (field approaches, low spots, high pH spots) for the tiny, white, lemon-shaped cysts of SCN. Note that these cysts are much smaller than root nodules.

Read more about soybean cyst nematode to equip yourself for scouting, identification, prevention and management. Visit the link for an extensive list of available resources.

Dry Bean Desiccation and Harvest Tips

Desiccation

Proper desiccation timing should be based on the least mature part of the field. Dry beans are ready for desiccation at:

- <30% seed moisture
- 80% pod colour change
- 80 to 90% leaf drop

Products available for desiccation in dry beans include Heat (saflufenacil), Reglone (diquat) and Valtera (flumioxazin). Check out the 2019 Grower Advisory on keepingitclean.ca and consult your buyer before selecting a desiccation product, to avoid market risks.

Harvest

Combining in dry beans can begin at 16 – 22% seed moisture, when some pods are brown, but most pods are still yellow. Read more about the risks and benefits associated with different harvest methods available to edible bean growers.

Tall Waterhemp

Tall waterhemp is a tier 1 noxious weed that has been detected in at least three municipalities in Manitoba in 2019. Previous discoveries of waterhemp in Manitoba were of only small patches or individual plants. In 2019, more significant and concerning discoveries have been made. This weed is of particular concern as it is a prolific seed producer, it has documented resistance in the U.S. to at least seven herbicide classes (2, 4, 5, 9, 14, 15 and 27) and its seeds remain viable in the soil for several years.

Photo: Ohio State

Photo: Tammy Jones

The following resources have been developed by Manitoba Agriculture to help identify and manage this aggressive pest species:

Crop Talk Webinar on tall waterhemp by Tammy Jones, Manitoba Agriculture Weeds Specialist
Fact Sheet on tall waterhemp
Video on identifying tall waterhemp vs. redroot pigweed