Hello ReaderWe’ve hit the 90% complete mark with most farms just finishing by the end of the week. We may have had a late start but early seeded wheat and barley is now in the two-leaf stage, peas hitting 2nd node and canola popping its first true leaf. We are right on schedule with the five-year average.
This week we’ll take a look at the impact of residues on germination and emergence. Next, I’ll provide a handy tank mixing reference to help you remember mixing order. Next, I’ve also included a handy chart you can keep to help you remember optimal water rates and droplet sizes to help achieve optimal performance of our most common herbicides. Last, we'll review the importance of water vapour on germination and checking problem wild oat fields early. We’ll finish with technical grain market news.
Have a great week.
Pictured above: Hi Heat Ltd seeding canola in front of a classic Alberta back drop of pump jacks.
Crop Staging(Calgary to Drumheller to Three Hills)
Seeded May 1-7 May 8-15 May 16-22
Wheat 2-leaf 1-leaf Emerging
Canola 1-leaf cotyledon Emerging
Barley 2-leaf 1-leaf Emerging
Peas 2nd node 1st node Emerging
Steve's tips and tricks of the week
Follow me on Twitter for in-season updates @BeyondAgronomy
- Now is the time to look for emergence patterns. Is residue management causing emergence delays? Is seeding depth highly variable? What is causing crop emergence variability?
- Continue checking for wireworm damage and look out for cutworm and flea beetle damage as well. Look closer at fields that don’t seem to be advancing as fast as others.
- Be mindful of overnight temperatures when spraying. To avoid crop damage do not spray herbicides when temperatures are dipping down to 5 degrees over night.
- Do not spray ‘imi’ herbicides a like Odyssey or Viper ADV during cold weather as their effectiveness is dramatically reduced.
- Monitor volunteer canola in wheat and barley fields. The 2012 wind storm created a large seed bank of volunteer canola. It can get out of control fast with warm temperatures.
- Be sure to measure plant stand densities during weed scouting this week. This will help you understand seedling mortality and help fine tune seeding rates next year. SL
Residues in furrow toxic to young seedlingsHave you ever looked at a cultivated field and admired how even the crop staging and plant densities are? Nice, uniform rows where each plant has the same advantage as its neighbor. In high residue fields, I typically see up to 30 and 40% of the plants emerge late, they aren’t as vigorous and from the start do not have the same yield advantage as the plants that emerge earlier. The issue in large part is the phytotoxic effects of residues left on the soil under direct seeding systems.
I came across research from Australia in the early 80’s that looked at wheat emergence under wheat, sorghum, canola and pea residue at high 24C and low 8C temperatures. Here is a summary of the research:
- The rates of seedling emergence and early growth of wheat were severely depressed by crop residues.
- In general the residues induced similar negative effects on the rate of emergence and shoot length at both high and low temperatures.
- The results suggest that the effects were due to phytotoxin production during the decay of the residue material, although the exact cause and effect relationship will require further study.
- Under low temperatures (8C), wheat seedling emergence compared to control (no residue) was depressed by 71% under a wheat residue, by 57% under a sorghum residue and by less than 50% under pea and canola residues.
I think intuitively we’ve always known that residue hinders germination and emergence but have always chalked it up to differences in soil moisture, depth and temperature. This research points to the phytotoxic effect of residues laying on the surface, something we’ve been battling for a long time. At the same time we can’t ignore the positive effects that high residue systems have garnered with improved moisture, nutrient use efficiency and ultimately yield.
We’ve made significant yield gains through direct seeding and I see so many people going backward by reintroducing excessive tillage. Instead of going back to full tillage systems or band-aid vertical tillage systems, we should be looking to a solution that maintains residue cover and standing stubble but removes or pushes residue away from the furrow.
Here are a few examples of what some producers including myself are doing to keep standing stubble but remove it from the furrow.
- Two pass inter-row seeding system. First pass helps incorporate residue between the rows while second pass pushes residue out of the way.
- One pass inter-row seeding system leaving tall standing stubble. Effective on wheat and barley but not on canola residue.
- Strip till system ahead of canola to incorporate residue, fertilize and even up soil temperatures. Only useful when seeding canola.
- Striper headers and disk drills with the intent of leaving as much stubble standing as possible.
Photo credit: S. Larocque
Herbicide mixing order refresherOne of the most frequent questions I get asked is how to mix herbicides and in what order to mix them. In fact, I had a quick reference app made to streamline the process for us in Western Canada. See here. Another way to remember proper mixing order is to remember the acronym WALES. Here are some basic rules that I've adapted from a recent DuPont bulletin to help guide you.
WALES = Wettables, Agitate, Liquids, EC’s, Surfactants
• Dry products (SG, WG, DF, WP) in the tank first, always, followed by
• SL products, then SC products, then EC or OD products,
• then surfactants (exception with Liberty® and clethodim)
• Additives where required (exception is pH adjuster added before Assert®)
The reason you add wettable agents like granulars and powders is to make sure they disperse and dissolve in water before they become coated with oil from soluble liquids, which is next on the list. Then you add liquid products that are the most compatible with water followed by the least compatible. Last, you add surfactants and anti-foaming agents.
Good luck this spring! SL
Optimize performance of herbicides
Water volume and droplet sizeSpray specialist and nozzle guru Dr. Tom Wolf shared a handy little chart showing the optimal water volumes and droplet sizes we need to maximize the efficacy of common herbicides. Have a look at the chart and be sure to maintain the optimal speed and pressure to achieve proper water volumes and droplet sizes.
Link to chart here
Source: Dr. Tom Wolf
Water vapour versus seed to soil contactIn a recent article, I discussed the importance of water vapour and its role in germination versus the commonly held belief that seed to soil contact is most important. Further to that, Daryl Chubb of DeNovo Ag sent me a photo illustrating the role water vapour plays in seed germination.
Daryl’s photo shows a wheat seed laying on the soil surface with just 20% of its surface area touching the soil. With recent rains and high humidity levels this seedling has established nicely in spite of being stranded on the soil surface.
When it comes to packing systems, it’s important to understand that over packing has created more problems with germination and emergence than under packing. Creating a firm layer of soil above the seed is paramount to capturing the small amount of water vapour needed to trigger germination. SL
Photo credit: Daryl Chubb
Check problem wild oat fields earlyThere were a few fields with patchy wild oat pressure in my travels last week and it prompted some spot spraying in a few areas. The plants were at the one-leaf stage, the perfect time to catch them before they start to rob yield. Leaving those areas for 10 days to reach the normal in-crop herbicide timing could have created a small disaster.
Research by Alberta Agriculture suggests when wild oats exceed 20 plants per ft2, tillering in wheat can be reduced by 50%. Remember that tillers account for 50% of your yield in spring wheat. Research by Arysta LifeScience pegs nitrogen loss at 1.2 lbs/ac when wild oats are at the 1-leaf stage. If you wait until the 6-leaf stage to control wild oats, you’re looking at a nitrogen loss of 16 lbs/ac in the affected areas.
There are several grassy herbicides on the market that can be used at the 1-leaf stage in wheat, barley, canola or peas:
Wheat: Axial (pinoxaden), Achieve Liquid (tralkoxydim), Traxos (clodinofop/pinoxaden), Horizon (clodinofop), Everest (flucarbazone), Assert (imazamethbenz), Velocity (thiencarbazone-methyl), Varro (thiencarbazone-methyl)
Barley: Axial (pinoxaden), Achieve Liquid (trakoxydim), Puma Advance (fenoxaprop-p-ethyl), Assert (imazamethabenz)
Peas and canola: Centurion (clethodim), Equinox (tepraloxydim), Assure II (quizalofop-p-ethyl)
NOTE: Be sure that temperatures don’t fall below 5 degrees Celsius the night before spraying to avoid crop injury. SL
The charts I use take a short and long term look at whether the market is oversold, neutral or overbought. I use charts as a way to pull the trigger, not to determine the best price.
Canola Nov 14: The long term trend is down and the short term trend is up.
HRS Wheat: Dec 14: The short and long term trends are down.
Corn Dec 13: The short and long term trends are down.
Soybeans: Nov 14: The short and long term trends are down.
Canadian $: Jun 14: The short term trend is up and the long term trend is down.