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See Dry Weather Weed Control on Manitoba Agriculture website for more details and complete recommendations and cautions.
Dry weather means both weeds and crops shift gears. Weed spectrums can be different, post-emergent herbicides can be less effective because weeds may have smaller leaves and/or thicker cuticles (waxy layer) that slows the penetration of herbicides.
Some herbicides withstand dry weather better than others so choose your product carefully. Here are some general guidelines on weed control during a dry period.
1. Remove weeds early.
2. Know your crop stage.
3. Review the “Effects of Growing Conditions” section of each product in the Manitoba Agriculture Guide to Field Crop Protection to determine likely outcomes.
4. High Daytime temperatures can trigger crop injury in some herbicides.
5. Use full rates of herbicide.
6. Use higher water volumes.
7. Use split applications of broadleaf and grassy herbicides rather than tank mixing if the Guide to Field Crop Protection warns that antagonism can occur.
8. Check the forecast for rain – shallow, stressed crops roots may be impacted by herbicides moving into the root zone.
9. Compare the risk of crop injury to the risk of yield loss due to weed pressure.
Registration is now open for the 2018 Crop Diagnostic School in Carman, MB.
School dates are July 10-13 and 17-19.
Topics this year will include insect scouting, dicamba drift, pea disease & soil erosion damage mitigation and others.
For more information see Crop Diagnostic School webpage
Registration can be called into 204-745-5663.
As of August 1, 2018, 25 Canada Western Red Spring (CWRS) varieties and 4 Canada Prairie Spring Red (CPSR) varieties will be moved into the Canada Northern Hard Red (CNHR) class. Prior to putting seed in the ground, consult the Canadian Grain Commission’s variety designation list to see if the variety you are planning to grow will be changing classes before harvest. The complete list of varieties transitioning to CNHR is available at: https://www.grainscanada.gc.ca/consultations/classes-en.htm
The modernization of the wheat class system revised the parameters of the CWRS and CPSR classes to ensure that wheat varieties in these classes met strict quality guidelines. The varieties transitioning from CWRS and CPSR to CNHR do not meet the quality parameters of their current class. The CNHR wheat class was created to allow farmers more flexibility in the wheat varieties they grow while preserving the quality of the CWRS class. Wheat varieties in the CNHR class such as Faller, Prosper, and Elgin ND, have slightly lower protein than CWRS wheats but are higher yielding.
Submitted by: Anne Kirk, Cereal Crops Specialist, Manitoba Agriculture
Despite rainy and windy conditions, early post-emergent herbicide applications are nearing completion in most crops. Emergence of cool season annual weeds was relatively unaffected by earlier cool, dry conditions while emergence of warm season annual weeds was delayed, resulting in herbicide staging issues for some producers. Emergence of warm season annuals, like redroot pigweed and barnyard grass, is now well underway due to recent rainfall.
Weed identification form: www.gov.mb.ca/agriculture/crops/crop-diagnostic-services/. Weeds submitted to Manitoba Agriculture for identification in the previous week include:
Black nightshade (Solanum nigrum) is a warm season annual problematic in potato, dry bean and soybean production. What to look for: small seedlings with pointed ovate cotyledons, currently in the cotyledon to early true leaf stage (see picture submitted to MB Ag).
Hairy galinsoga (Galinsoga quadriradiata) and smallflower galinsoga (Galinsoga parviflora) are annual species also referred to as ‘quickweed’ based on their ability to set seed within only weeks after emerging. What to look for: toothed, opposite leaves and ‘club’ shaped cotyledons (see picture submitted to MB Ag).
Of the various goosefoot species coming in for identification, oak-leaved goosefoot (Chenopodium glaucum) has been the most common. What to look for: goosefoot shaped leaf, often with distinct yellow-green veins. Stems may be red and green to red. Typically grows more prostrate than lamb’s-quarters. Oak-leaved goosefoot does especially well in wet and/or saline areas.
Weed Management Issues:
Manitoba Agriculture staff have begun to receive herbicide drift complaints and are providing advice accordingly. Talking to the applicator should always be the first step in a suspected drift incident. Herbicides involved in the drift complaints to date include glyphosate, group 2 and group 4 herbicides.
If malathion is in your shed, it may be time to revisit your inventory. According to a recent advisory issued by Health Canada (http://healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2017/63150a-eng.php), Malathion products purchased prior to June 2016 should not be used. This advisory applies to all products including agricultural and mosquito control products containing malathion. The advisory was issued because over an extended period of time, malathion can convert into a toxic metabolite called isomalathion. This conversion can be faster if label directions for storage are not followed properly. If you are purchasing malathion products in 2017, be sure to check expiry date on the packaging.
What to do with old/obsolete inventory of malathion products?
Steps to consider for safe use of pesticide products
Additional questions can be directed to Health Canada (613) 957-2991, 1866-225-0709
Manitoba Agriculture has a number of weather stations across the province that measure air/soil temperature, soil moisture, wind direction and speed. For local information please visit
Central/East/Interlake Regions: http://www.gov.mb.ca/agriculture/weather/current-conditions-summary1.html
Southwest/Northwest Regions: http://www.gov.mb.ca/agriculture/weather/current-conditions-summary2.html
Previous Day on Highs/Lows and Average Soil Temperature at:
Central/Easter/Interlake:http://www.gov.mb.ca/agriculture/weather/yesterdays-summary1.html Southwest/Northwest: http://www.gov.mb.ca/agriculture/weather/yesterdays-summary2.html
Another useful application of the data gathered by the network for rainfall can be found at Rain Watch http://www.gov.mb.ca/agriculture/weather/rain-watch.html
Seed can be an expensive input, but a poor crop stand can be lost profit. To maximize your seed, still get the stand needed to optimize yield, start calculating the real seeding rate needed for the plant stand desired and not gauging seeding rate by lbs/ac or bu/ac.
The following are the standard recommendations for FINAL plant stand, not what you are putting in the ground. Germination, TKW and mortality are very important to use in the equation to determine actual seeds/ac to plant. For example, if you assume your germination is 96% and its only 85% and conditions turn cold and wet (increasing mortality), you may have a lot thinner stand than you anticipated (which could mean a harder time controlling weeds).
|Grain Crops||Oilseed Crops||Pulse Crops|
|Mortality Rates (%)||10-15||10-15||10-15||10-15||20-60||10||40-50||5-15||5-10||5-10|
*Navy Bean = pinto beans on lower end and navy bean require higher plant stands
Source: Manitoba Agriculture, Canola Council of Canada, Flax Council of Canada, Ontario Ministry of Agriculture, Food and Rural Affairs
Seeding Rate (lbs/ac) = target plant stand/ft2 x TKW (g) / % expected seed survival x 10
e.g. FLAX Seeding Rate= 45 plants/ft2 x 5g (TKW) / ((88% germination x (1- 40% mortality)) X 10 = 43 lbs/ac
Using 1000 Kernel Weight for Calculating Seeding Rates – http://www1.agric.gov.ab.ca/%24department/deptdocs.nsf/all/agdex81
Optimizing Plant Establishment – http://www.gov.mb.ca/agriculture/crops/production/pubs/optimizing-stand-establishment-in-less-than-optimal-conditions.pdf
Can you identify the plants in the two pots below?
The plants on the right are redroot pigweed (Amaranthus retroflexus); the plants on the left are waterhemp (Amaranthus tuberculatus).
Unfortunately, the need to distinguish between these closely related weed species has become a reality for Manitoba producers and agronomists since waterhemp was found in the province in the fall of 2016. Suspect plant specimen collected from a soybean field in the RM of Taché was verified as waterhemp by staff with the Agriculture and Agri-Food Canada Collection of Vascular plants in Ottawa. Waterhemp occurs in neighbouring states and provinces, including Minnesota, North Dakota and Ontario.
Both species thrive in agricultural fields where they compete with crops for nutrients, moisture and light. Waterhemp has no hairs on its stem or leaves, which can be used to distinguish it from redroot pigweed when plants are small. The lack of hairs give waterhemp leaves a ‘glossy’ look unlike that of the ‘dull’ green leaves of redroot pigweed. Also, waterhemp leaves are lanceolate in shape (longer than they are wide) compared to the more ovate leaves of redroot pigweed. Colour is not a reliable identifying characteristic since both species can be green, red or variations of the two colours.
Mature waterhemp plants tend to be more branched than redroot pigweed. And unlike redroot pigweed, which has male and female flowers on the same plant, waterhemp has separate male and female plants. Waterhemp inflorescence are long, slender and vary in colour compared with the compact, prickly inflorescence of redroot pigweed. Like most pigweeds, waterhemp is a prolific seed producer with up to a million seeds per plant (under ideal conditions).
Waterhemp populations resistant to group 2, group 9 (glyphosate) and group 2+9 exist throughout the US, including Minnesota and North Dakota, and in Ontario. Seed from one of the plants found in Manitoba have been sent to Ontario for resistance testing.
Information on waterhemp will be added to Manitoba Agriculture’s weeds webpage shortly (http://www.gov.mb.ca/agriculture/crops/weeds/) and will be included at the Weed Seedling Identification Day (hosted by the Manitoba Weed Supervisors Association). Manitoba Agriculture staff will conduct a waterhemp surveillance program in and around the RM of Taché in 2017.
Additional information on waterhemp is available at: http://www.extension.purdue.edu/extmedia/BP/gwc-13.pdf (excluding herbicide recommendations).
Photo: Waterhemp in Manitoba, Tone Ag Consulting
Submitted by: Jeanette Gaultier, Provincial Weed Specialist, Manitoba Agriculture