June 25, 2013

Agronomist Notes

Hello Reader

Another week of cooler weather goes by with rainfall tallying 8 to 10 inches in many areas not to mention extreme flooding throughout High River and downtown Calgary and other communities. Out in the fields, the ruts are deep as producers push to finish herbicide spraying before fungicide timing.

In spite of the cool weather, crop staging has progressed nicely with early-May seeded wheat and barley at flag leaf. The 14-day forecast calls for temps in the high 20’s by early July then drops back down to low 20’s.

This week we’ll focus on timing flag leaf emergence to help you stage fungicides. Next, we’ll look at a list of top tips for fungicide applications. I’ll also include yield loss potential from leaf diseases with fungicide rates and prices. I'll also include some handy info on fungicides and stripe rust. We’ll finish with technical grain market news.

Above: Sprayers making ruts in many areas while trying to finish in-crop herbicide. We’ll be dealing with those in the fall. SL

Crop Staging

(Calgary to Drumheller to Three Hills)

Seeded    May 1-7 May 8-15        May 15-22
Wheat flag emerging 1st node 5-leaf, 2 tiller
Canola     bud stage            6 leaf 5-leaf
Barley      flag emerging 2nd node 5 leaf, 3 tiller
Peas        start of flower      12th node        10th node

Steve's tips & tricks of the week

Follow me on Twitter for in-season updates @BeyondAgronomy

Continue post-herbicide checks to make sure herbicides performed well. If not, you have an opportunity to correct the problem with a re-spray.
If spraying by air, book the plane to get on the list. It’s going to be a busy season.
Book your fungicides now to make sure you get what you want and not what’s left.
Time to stage flag leaf emergence so you can prepare for fungicide timing.
I’m seeing some crop shortening from 2,4-D applications prior to cool evenings. Watch the overnight temperatures while spraying.
Expect some leaf bronzing in Liberty Link canola from high humidity levels. You may see some phytotoxicity with contact herbicides.
Check sandy or coarse textured soils for signs of sulphate or nitrate leaching, especially in canola. SL

Predicting flag leaf emergence in barley

Fungicide timing

Barley (2-row)
When the third node is about half an inch above the ground, the penultimate leaf (one just below the flag) is visible, and the next leaf to appear is the flag. If only one node is visible, then it will be about 10-14 days till flag leaf; if two nodes are visible it will be about 5-7 days until the flag leaf is out.

Barley (6-row) & wheat
When the second node is half an inch above the ground, the penultimate is visible and the next leaf is the flag. Rule of thumb, if you can see the second node toward the base of the stem, the flag leaf is emerging. If only 1 node is visible, the flag leaf will start emerging in about 5-7 days.

The flag leaf is usually the seventh leaf in cereals. In wheat, the flag leaf is large and contributes to 45% of the yield. The penultimate leaf contributes another 10%. In a barley crop, the flag leaf is smaller so the penultimate and flag together contribute 65% of the yield.

Source: Syngenta

Disease yield loss potential & fungicide costs

Top 4 diseases in wheat and barley

The following list will give you an idea of yield loss from common wheat and barley diseases along with approximate fungicide costs.

Losses
Tan spot: 3% to 15%
Septoria: 1% to 25%
Net blotch: 1% to 40%
Scald: 10% to 50%

Registered fungicides
Acapela: (picoxystrobin) 192 ml/ac = $10.90/ac
Bumper: (propiconazole) 120 ml/ac = $6.50/ac
Caramba: (metconazole) 280 ml/ac = $10.95/ac (405 ml/ac rate for fusarium)
Folicur EW: (tebuconazole) 200 ml/ac = $12.25/ac
Fuse: (tebuconazole) 118 ml/ac = $13.45/ac
Headline: (pyraclostrobin) 120 ml/ac = $10.80/ac (160 ml/ac rate for stripe rust)
Pivot: (propiconazole) 120 ml/ac = $6.50/ac
Prosaro: (tebuconazole + prothioconazole) 320 ml/ac = $17.10/ac
Quilt: (propiconazole + azoxystrobin) 405 ml/ac = $11.40/ac
Stratego: (propiconazole + trifloxystrobin) 200 ml/ac = $7.50/ac
Tilt: (propiconazole) 202 ml/ac = $7.50/ac

Top tips for applying fungicides

In order to get the volume, method and speed of fungicide application right for the full benefit of a spray application, follow these simple guidelines:

Have an understanding of how the fungicide you’re going to apply works on the plant. Most fungicides have limited translocation potential or move upwards and outwards only, meaning sprayers need to target the spray to hit the plant exactly where it’s needed. If the source of the infection is lower in the plant, more water may be required if the product has curative properties.
Ensure adequate volume (e.g. 7.5-10 US/gallons per acre for cereals and 10-15 gallons/US acre for pulses).
Try to limit application speeds to less than 12mph— any faster and most of the droplets will hit only one side of the plant.
Select a nozzle to give medium spray quality. Fine droplets won’t penetrate dense crop canopies and coarse ones may not give enough retention on waxy surfaces or when using an oil-based wetter.
Select nozzle sizes and volumes that will run the nozzle with adequate pressure (e.g. more than 35 psi for fan type and low drift and more than 50 psi for low-pressure air induction) and don’t use air induction with oil-based products.
Consider using narrower nozzle spacing such as 10 inches if you can. For those on wider spacing (e.g. 20 inch) twin jets or twin caps may improve coverage but should only be used at ground speeds of up to 10 mph.
Use the minimum hold setting on the controller to ensure you don’t lose pressure and under-dose or increase droplet size when you slow down at the end of rows.
Run the controller with total flow (gallons per minute for the whole boom) on the display when spraying and know what the pressure and flow rate should be when delivering the correct number of gallons per acre so that checks can be made as you go. For example, if pressure increases and flow remains the same, check for blockages. If flow increases or pressure drops check for leaks, if flow reduces and pressure stays the same, check that all sections are engaged.
Wind speeds should always be above 3-4 km/h and less than 20 km/h for in-crop spraying unless the label specifies otherwise.

Reference: Bill Gordon, spray consultant, NSW, AUS

The quick n’ dirty on stripe rust & fungicides

There are reports of stripe rust showing up in northern Washington and Idaho, which means we’ll likely see it here at some point. Those who sprayed a fungicide in 2011 enjoyed an 8-15 bu/ac response from adequate leaf disease protection when stripe rust showed up early. This year more producers are on the alert and asking questions so I thought I’d give you a quick update on stripe rust and fungicide applications:

With ground application, the boom must be high enough so that the spray fans overlap on the uppermost leaves.
Fungicides will only move from the droplet on the leaf surface towards the leaf tips, they do not move from lower leaves to upper leaves or the head.
Try to allow the majority of flag leaves to emerge. Portions of leaves, whole leaves and heads that develop after spraying will not be protected.
Tilt (propiconazole) moves towards the leaf tips quickly so the concentration drops and stops protecting after about 3 weeks.
Folicur (tebuconazole) and Prosaro (tebuconazole + proth ioconazole) move more slowly toward the leaf tip and give 4 weeks protection.
The strobi portion of Quilt (azoxystrobin + propiconazole) is more immobile in the plant and can give up to 5 weeks protection.
Triazoles (Folicur, Twinline, Prosaro) are the only products that can cure an early infection of stripe rust (less than 7 days old).
If you have stripe rust already, a triazole is preferable because of its curative properties. Again, so long as the infection is less than 7 days old.
A stripe rust infection can restart once the fungicide applied breaks down. This is called ‘kick back’.
Fungicides containing strobi’s (Quilt, Twinline, Headline, Stratego) can only be applied up to heads half emerged versus triazoles (Folicur, Prosaro) which can be applied from flag and up through flowering.
Once the effectiveness of the fungicides declines after 3 to 5 weeks depending on the product, stripe rust will start developing again from the ends of old stripes and from new infections. A second application of fungicide may then be needed. SL