August 28, 2012

Agronomists Notes

Hello Reader,

I apologize for the tardiness of the newsletter this week as we were just finishing up peas. As you can see in the photo, the resident antelope herd kept me company while I travelled past at 2 mph every day. At least they kept to the tram lines, unless they were fighting, laying down, or snacking.

Producers are still busy swathing canola and pre-harvesting the later seeded wheat with more barley and wheat coming off. Yields are highly variable as was the rainfall this year. So far, yields in wheat have ranged from 35 bu/ac to 70 bu/ac with 50-60 bu/ac the norm. Malt barley has ranged from 70 to 90 bu/ac. Peas have averaged 40 to 70 bu/ac with most in the 50 bu/ac range. Overall, yields are not as good as they looked in the field. Temperatures in the low to mid-30’s throughout July took their toll. 2012 will shape up to be an average year with only select areas hitting bumper yields.

Protein premiums offered for wheat have also been variable, depending on which company you chose. Cargill and Viterra are not offering protein premiums past 13.5% while James Richardson is offering $8.00 tonne. The CWB currently has a $7.00 tonne premium for a 14.5% protein in its first PRO. There can be some serious money left on the table this year so make your deal wisely. I suspect protein levels will be above average given the lighter grain weights and drier finish during grain fill.

This week we’ll look at the effects of high temperature stress in wheat to make sense of what’s to come this fall. Next, I’ll recap my observations in disease control from this year to help with decisions in 2013. Next, I’ll briefly review my top canola varieties as they relate to standability and sclerotinia. I’ll discuss residue management and some tips to help you adjust choppers and residue spread. We’ll finish with technical grain market news.

Have a great week.

[ Beyond Agronomy News will be taking a two week break starting next week so I can finish off harvest and let the trial work come off before I post results. Have a safe and enjoyable harvest. We’ll see you back on September 18th, 2012. ]

Photo: Give me a home where the buffalo roam and the deer and the antelope play… only on the tram lines. Photo source: V. Larocque

Harvest Progress

(Calgary to Drumheller to Three Hills)

Wheat: 2%
Canola: 1%
Barley: 5%
Peas: 75%

Steve's tips and tricks for the week

Follow me on Twitter for in-season updates @BeyondAgronomy

Watch wheat and barley fields as they mature and watch for stripping. Now is the time to easily diagnose an unlevel air drill or improper air delivery system.
Pay close attention to residue management and set yourself up for proper establishment in 2013.

High temperature effects on wheat yield

One of the major limiting factors to achieving maximum yield in wheat is high temperature stress. It’s hard to believe that temperature would play a significant role in Prairie wheat production but wheat is a cool season crop that prefers temperatures below 20°C. To put it in perspective, head size in wheat is strongly affected by air temperature and to a lesser extent nitrogen and water. On our quest for high yielding wheat, I think it is important to understand what determines head size and what can be done and when to encourage it’s development. Today I’ll outline some key points on the effects of temperature on head development and outline potential management strategies to reduce heat stress.

The development of head size

The growing point of the plant is called the apex which quickly becomes the head (spike) of spring wheat.
The apex develops in two distinctive stages: 1) vegetative, 2) reproductive.
The first stage initiates the development of all 8 leaves that grow on a wheat plant.
The first stage occurs in the first 17 to 21 days after emergence.
At the 4 to 5 leaf stage (GS 14-15) wheat switches from the vegetative phase to the reproductive stage and seed-bearing spikelets form on the apex.
Each spikelet has a potential to produce 8 kernels.
Spring wheat can produce roughly 20-30 spikelets per head (20 x 8 = 160 kernels/head) depending on variety.
The terminal spikelet formation on the head ends at the 6-leaf stage, roughly 26 to 29 days after emergence.

The effects of temperature on head size

The critical period in determining the number of spikelets per head occurs during the 5 to 6-leaf stage (GS 15-16)
The number of spikelets formed on each head is strongly influenced by air temperatures above 20°C and to a lesser extent nitrogen and water.
As air temperature increased above 18°C during the 5 to 6-leaf stage, the number of spikelets per head decreased and resulted in lower grain yield potential.

The effects of temperature on kernel number and weight

Research has shown wheat grown at 25°C during flowering had only 40 percent of the kernel number in the main spike when compared with plants grown at 15°C.
Over the range of a 12° to 26°C increase in mean temperature during grain filling, grain weight is reduced at a rate of 4 to 8 percent/°C.

The reason why yield declines under heat stress is because of a hormone imbalance. When plants fall under heat stress the proteins inside hydrolyse to ammonia. The build up of ammonia is toxic and causes the plant to produce the hormone ethylene, which eats up cell wall tissue and causes premature ripening. The trick to managing heat stress is to reduce excessive ethylene production.

Two ways to reduce heat stress are direct seeding and early planting. Early planting allows the plants to reach tillering by the end of May or early-June before average temperatures above 20°C usually occur. Direct seeding uses residue cover to help reduce evaporation and help keep the soil cooler. The addition of soil moisture and reduction in soil temperature helps the plant buffer against temperatures above 20°C.

The next answer to managing heat stress, and one many product companies are working on, is the use of specific compounds and plant hormones. I haven’t used or recommended products for reducing heat stress but I have found a few to try:

Fulvic acid reduces heat stress. Fulvic acid was sprayed on plants just before head development, and allowed to grow to maturity over time when hot, dry winds are prevalent. It was found that grain yield increased by 7% to 18% over the untreated controls. Xudan (1986)
BioForge by Stoller is used in the US to treat excessive ethylene production.
Action 5X sold by Stoller in Canada is said to maintain fertile pollen and ovaries under high temperatures during head development and ripening.

Some research suggests that strobilurin fungicides do little to reduce ethylene production when plants are under heat stress. Products like Headline, Quilt and Stratego which claim to reduce ethylene should be used with caution as they work best when disease is present.

Managing heat stress in the future will not only remain in the hands of genetics, it will come from the timely application of products that allow plants to tolerate heat stress. In the mean time, we can do our best to seed early and maintain residue to help keep plants cool but we can’t plant everything early and the evenness of our residue spread leaves little to be desired.

When you look at the genetic potential of 160 kernels per head in HRS wheat and the 25 to 32 kernels we achieve today, we have a long way to go. The subsequent 4% to 8% yield loss each time the temperature climbs 1°C during grain fill has me wondering what we can do to help protect yield during grain fill when temperatures typically hover between 20°C and 30°C. With nitrogen and water availability second to the importance of air temperature, I’d say it’s worth finding ways to reduce heat stress throughout the growing season. SL

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Photo source: S. Larocque

Disease management in hindsight

Product reviews and tips

After reviewing disease pressure in cereals 30-45 days after application, I thought I’d provide a review of the observations I made to help with decisions for fungicide use in 2013. Here they are in no particular order:

Barley

Stratego (trifloxystrobin+propiconazole) at $6.50/ac provided similar control of net-spot blotch and scald control as Twinline (metconazole+pyraclostrobin) at $9.00/ac.
From my side by side trials, the most long lasting fungicide on the market to control key barley diseases (net-spot blotch, scald) is Prosaro (tebuconazole+protioconazole) at $13.50/ac.
Quilt (azoxystrobin+propiconazole) at the 150 ml/ac rate which is the ¾ rate provided better control of net/spot blotch and scald than Stratego (trifloxystrobin+propiconazole) or Twinline (metconazole+pyraclostrobin).
For the money on high value feed or malt barley, Quilt at 200 ml/ac or Prosaro at 320 ml/ac are top choices.

Wheat

When controlling stripe rust already present as well for prevention, it’s hard to beat Folicur or generic tebuconazole for the $10.80/ac.
If you have stripe rust present, fungicides that contain strobilurin only actives (Headline- pyraclostrobin and Acapela-picoxystrobin) are a last option. They will stop stripe rust from progressing but will do nothing to control the disease that is already present.
When it comes to eradicating stripe rust, products containing triazole fungicides like Folicur (tebuconazole), Prosaro (tebuconazole+prothioconazole) and Quilt (azoxystrobin+propiconazole) are excellent.
When comparing all the strobilurin fungicides on the market (Quilt, Headline, Stratego), Quilt (azoxystrobin) has the slowest mobility inside the leaf which means it stays concentrated longer and adds to its length of protection. Quilt is my preferred choice given the two modes of action.
Tilt (propiconazole) moves from the point of contact to the leaf tip quickly, which means the concentration breaks down quickly and the reason is provides such a short window of protection, 7 to 14 days. I only recommend Tilt at herbicide timing in some cases, rarely at flag leaf or heading. The window of protection is too short for the money spent.
If I had to rank my favorite all around fungicides for leaf spot diseases and stripe rust it would be Folicur, Quilt, Prosaro, Twinline, Tilt, Stratego.

Canola

In Australia, Bayer is seeking registration for use of Prosaro to control blackleg in canola. It is not registered in Canada but may have a future if blackleg resistance breaks down as we’ve seen in the last two years. To give you an example, a 576 ml/ac rate of Prosaro has the same amount of prothioconazole as a 150 ml/ac rate of Proline plus an additional 288 ml/ac of tebuconazole for the same price as Proline at 150 ml/ac. Again, not registered in Canada!
Blackleg presence increased dramatically this year with much of it going un-noticed I’m sure. I can see fungicide applications of Tilt and Headline at 2-6 leaf stage occurring in tight canola rotations next year. SL

Top canola varieties for standability

Stand up for yield

One of the biggest tools we can use to reduce sclerotinia infections besides rotation and fungicides in canola is standability. A canola plant that stands erect provides more protection against sclerotinia because it leaves fewer main stems exposed to petal drop, the point where infection begins. If you have plants that begin to lodge, the main stems become more prone to petal capture and more prone to main stem infections. As we know, if you shut down the main stem, you shut down the grain filling potential of the entire plant. A plant that stands erect is still susceptible to sclerotinia but you will find more infections on the branches so only a portion of the plant dies off.

With that, I’ve reviewed a number of plots and client fields this fall prior to look at standability only. If you match the yield and quality parameters you look for in your area, you may come up with a winning combination. Here are my top canola picks for standability, in no particular order:

InVigor 5440: This variety is very well suited to my clients in the west who border the Highway 2 corridor. It has the potential to hit 90 bu/ac and higher if you push the agronomy in the right growing season. The standability of this variety is second to none (I use it as a benchmark) and the only other variety that compares is a RR variety called VT 500.
VT500: This variety sold by Viterra was a bit of a surprise. For a RR variety it stands extremely well, in fact, probably as well as 5440 under high fertility or irrigation. I’d rate this variety the number one RR variety for standability. Now, VT500 would be great if you have serious lodging issues but it yields between 5 and 10% less than 5440 or L130.
InVigor L130: This variety yields extremely well and stands very well, but a little less than 5440. It is a high yielder and one I recommended heavily in 2012. It's a solid variety.
InVigor L159: This variety is similar in yield as L150 but has the standability of L130 or close to 5440. This variety is only sold through Viterra. I’ve only seen this variety in this year’s plots.
Dekalb 7444: This RR variety looks very solid in the test plots this year. I think Dekalb is getting close to having better standability in their varieties which was not always the case.

Photo source: S. Larocque

Proper residue management key to higher yields and maturity

One of the biggest yield and maturity robbers in our production system is poor residue management. Every year I see poor emergence in canola and cereals from uneven, heavy residue levels. Unfortunately, we are coming into another harvest with heavy residues and higher humidity levels than normal. This creates a recipe for disaster in 2013 as residue spread is reduced and residue loads from multiple years increase.

Now the majority of producers use heavy harrows to manage straw and they do a decent job behind conventional combines. Where I see the biggest issue of poor residue management is behind rotary combines. Heavy harrows can actually move conventional straw around because it is typically longer compared to rotary combines that leave very short residue. Today’s fine cut choppers do a great job of turning straw into chaff or very small pieces but it makes it impossible to manage properly after harvest.

Before you get too heavy into harvest I’ve listed a few changes that can be made to either shorten straw and spread it more evenly or increase straw length so it can be managed with heavy harrows. Hopefully you can avoid the hangover that will come with heavy residue in 2013:

You can adjust the length of the straw by adjusting the rotor speed of chopper. Some have two or more speeds.
The length of the chopped straw is controlled by the stationary knife which can be adjusted to different depths. An optional controller bar is also available to inhibit flow.
Some combines allow you to adjust deflectors individually both in front and rear side. There are deflectors behind the discharge beater that can be adjusted to redistribute the straw mats into chopper.
The rear side veins on some fine cut choppers are the only ones that are adjustable.
The spreading width can also be set by adjusting spreading hood up and down.
Deflectors can be adjusted for side wind compensation on the John Deere power cast system and Lexion combines.

Now, I’m not recommending we move back to conventional combines, nor am I giving you an exhaustive review of chopper settings on all makes and models of combines. I’m only suggesting we don’t need to turn straw into chaff with fine cut straw choppers. If you do have fine cut choppers behind a rotary combine, take the time to fine tune the width of the spread and the size of the straw. There’s too much money at stake to ignore one of the biggest yield and maturity robbers in our system today. SL

Setting residue managers

The goal: to send residue flying across the width of your cut. Photo source: S. Larocque