Pest Management

Insects

Monitor for wireworms, seedcorn maggot and cutworms from May to June. Insecticide seed treatment protects against wireworms and seedcorn maggot only. Assess the need for protection on a field-by-field basis. Scout weekly for soybean aphids from R1 to R5. See Soybean Aphids: Identification, Scouting and Management. Scout for leaf and pod feeding insects such as grasshoppers, green cloverworm and corn earworm from R1 to R6. See Soybean Insect and Disease Identification Guide.

Weeds

Soybean seedlings are poor competitors against weeds. Yield potential is maximized when weeds are controlled until at least the V3 stage.

Glyphosate-resistant kochia has been confirmed in several Manitoba municipalities. A proactive, integrated weed management strategy is recommended to prevent herbicide-resistant weeds. This may include diverse crop rotations, improved crop competition via narrower row spacing and higher plant populations, herbicide tank mixes, rotating modes of action and field or site-specific weed management. Herbicide options vary by production system and caution must be taken to prevent herbicide drift. Volunteer canola is the most abundant weed in soybean crops, according to the 2016 provincial weed survey. The action threshold (5% yield loss) for volunteer canola control is 2.5–3.2 plants/m2.

Diseases

Soybeans are susceptible to the root rot complex, including Fusarium spp., Rhizoctonia solani, Pythium spp. and Phytophthora root rot (PRR). Fungicide seed treatment can offer protection against these diseases for up to three weeks after seeding. Scout for early-season diseases in June. Fusarium spp. and PRR are the most common seedling diseases in Manitoba.

Scout for foliar and stem diseases from July to September. Common foliar diseases include bacterial blight, brown spot and downy mildew, although these are not generally of economic importance. Soybeans are susceptible to Sclerotinia (white mould), but are more tolerant than canola, dry beans and sunflowers.

The occurrence of stem rot, stem canker, anthracnose, frogeye leaf spot and bacterial pustule is being studied in Manitoba. Soybean cyst nematode (SCN) was first identified in Manitoba in 2019. Since SCN has only recently established itself in the province, cleaning the soil off of equipment, vehicles, soil sampling equipment and clothing will reduce the risk of introduction or spread.

DB Diseases, FP Diseases

2022 Disease Prevalence and Management Tools

2022 Update on Disease Surveillance in Soybeans, Peas and Dry Beans and On-Farm Fungicide Evaluation Results

Pulse Beat Individual Articles

Declining Sources of Resistance to Phytophthora Root Rot in Soybeans and How to Manage It

SINCE the mid-1950s, many soybean growers across Canada have struggled with Phytophthora root rot (PRR), caused by the oomycete Phytophthora sojae. Once the disease is present in their fields, farmers must deal with it for a long time as surviving spores will persist in the soil for approximately 10 years.

DB Insects

Assessing Grasshopper Damage

Pest Species in Manitoba There are 85 grasshopper species in Manitoba, but only four have the potential to become crop…

Pulse Beat Individual Articles

Insecticide Resistance in Soybean Aphids

John Gavloski, Entomologist, Manitoba Agriculture and Resource Development – Summer (June) 2021 Pulse Beat WITH ANY INSECT, pathogen or weed, repeated…

DB Weed Control, FP Weed Control, Pulse Beat Individual Articles

Late-Season Weed Scouting. So Many Questions.

It’s late summer. You’ve sprayed for weeds. Between now and harvest, there’s nothing left to watch for except insects and diseases, right? Not necessarily. Your weed control program doesn’t end when the sprayer pulls out of the last field.

DB Diseases, FP Diseases, Pulse Beat Individual Articles

2020 Foliar Disease Survey and On-Farm Fungicide Trial Results

Each year, a representative sample of soybean, field pea and dry bean fields are surveyed for root, foliar and stem diseases across Manitoba. Here are the results from the 2020 foliar and stem disease surveys and foliar fungicide results from the On-Farm Network.