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Winter Wheat AAFC

Project Contact: Ken Coles

 

 

Abstract

The overall objective of this project was to overcome the obstacles in the adoption of winter wheat in western Canada. We decided to take a two-fold approach to achieve such. We established studies to broaden the stubble acreage available in the late summer for seeding winter wheat. We did this by using alternate stubble types, managing said types and using seed treatments. The other half of the project revolved around the use of several pest and nutrient management strategies to promote winter wheat plant heath, growth and yield stability.

We theorized that improving these components of winter wheat would allow for producers to widen the length of the seeding window or seeding into less optimum conditions and still see reasonable success.

 

Dr. Brian Beres discusses winter wheat trials during a Farming Smarter Crop Walk in 2012.

Dr. Brian Beres discusses winter wheat trials during a Farming Smarter Crop Walk in 2012.

 

Seeding

A total of 20 sites were established over the course of two growing seasons (2010-2011 and 2011-2012).

Seed treatment:

  • Imidacloprid insecticide
  • Tebuconazole + Metalxyl fungicides + Imidacloprid insecticide (Raxil WW)
  • Foliar fungicide (Prothioconazole – ‘proline’)

We found plant stand was not affected by the treatments even though the treatment visibly seemed to have affected winter wheat stand and growth in the early growing seasons. Grain yield was improved relative to the untreated check, especially under the application of foliar fungicide. This is surprising as the fungicide application created a favourable physiological response even in the absence of symptoms from foliar pathogens. This result was only significant when paired with Imidacloprid.

Crop

One of the main facets of our project was to successfully grow winter wheat in stubble other than canola. We believed that Barley would a reasonable substitute, particularly in shorter season areas. We wanted to see what management strategies would be needed to control volunteer barley. However, volunteer barley was suppressed by the winter wheat at all locations in 2010. We then shifted our objective to determine the efficacy of novel herbicides in control weeds in sub-optimal and optimal stands of winter wheat.

We realized that weeds like wild oats and cleavers can be problematic if the winter wheat stands are thin. We tried Pyroxasulfone – an experimental herbicide that has activity on wild oat, cleavers and other broadleaf weeds – but noted that it’s efficacy is inconsistent as it is a soil applied herbicide that relies on soil moisture for activation. Pyroxasulfone was applied pre-seed at rates of 100, 150, 200 and 250 hi/ha-1 to winter wheat seeded at 450 and 150 seeds/m2 .

This was compared to two post-emergence commercial standards.

The herbicide did not affect emergence and visual tolerance of winter wheat was generally low and considered acceptable. It is speculated that spring application may have resulted in some crop injury – which is an effect sometimes observed with ALS inhibitor herbicides. Winter wheat yield was increased by 5 per cent when seeding rate was increased from 150 – 450 seeds/m2 . Herbicide did not affect the yield due to the low weed densities and the competitiveness of winter wheat.

Managing Nitrogen

We also wanted to see if and how the nitrogen management recommendations needed to be altered when planting winter wheat into barley stubble. We were especially concerned that heavy trash left after barley is harvested could lead to N immobilizations and cause deficiencies in winter wheat.

Treatments:

  • Factorial combination of Four N rates
    1. 0 Kg N ha-1
    2. 40 Kg N ha-1
    3. 80 Kg N ha-1
    4. 120 Kg N ha-1
  • Six N application/straw treatments
    1. Urea banded at seeding, straw on surface
    2. Urea banded at seeding, straw removed
    3. ESN banded at seeding, straw on surface
    4. Super U banded at seeding, straw on surface
    5. UAN dribble band in spring, straw on surface
    6. Super U broadcast in sprint, straw on surface

N fertilizer rate increased most winter wheat responses, the exceptions being plant density and kernel/test wt. There were no significant interactions between N fertilizer rate and N straw treatment for any of the winter wheat responses. Nitrogen/Straw management alone did impact some winter wheat responses. Management did not affect plant density, grain quality and N uptake responses.

We found that midseason biomass yield at Lethbridge was greater when UAN was dribble-banded in the spring (with barley residue on the soil surface) compared to when urea was banded at seeding (with residue removed).

Winter wheat growth in May/June showed that NDVI was affected by N/straw treatment only for the initial three assessments in Brandon. The consistent difference was that urea banded at seeding (residue removed) always resulted in an NDVI equivalent to or greater than other N/straw treatments.

This trend was the same in Brandon and Fahler.

We didn’t observe any differences between the spring broadcast SuperU treatment and the remaining N/straw management treatments at Brandon as well as all the treatments at Lethbridge.

Crop Growth

Residue management strategies is something we looked at with a wide array of potential alternative stubbles, ranging from barley to camelina. Cop residue management is critical to successful winter wheat production on the Canadian prairies because it controls snow cover, which ultimately protects winter wheat from winterkill. The suitability of different stubble types for winter wheat is determined by the efficacy of stubble in trapping snow and the availability of stubble relative to the narrow window in which winter wheat can be seeded. We assessed the direct and indirect impacts of surface crop residues from a wide range of crops on growth, development, yield and quality of winter wheat.

Treatments:

  • Barley (swath removed)
  • Barley (swath removed, barley seeds broadcast at a rate of 400 seeds m-2)
  • Barley (combined to retain straw and chaff)
  • Canola (swathed and combined to retain straw and chaff)
  • Dry pea (desiccated and combined, with winter wheat seeded between stubble rows of the cereal crop proceeding the pea crop)
  • Dry pea (desiccated and peas pulled rather than cut, with winter wheat seeded between stubble rows of the cereal crop proceeding the pea crop)
  • Spring-seeded camelina (combined to retain straw and chaff)
  • Spring-seeded camelina (swath removed)
  • Fall-seeded camelina (swathed with residue removed)

We discovered that seeding winter wheat after canola reduced winter wheat stands compared to seeding winter wheat after barley, pea, or spring-seeded camelina. Seeding winter wheat after pea, but between the stubble rows from the cereal crop proceeding the pea crop, resulted in similar winter wheat stands and greater grain yields than seeding winter wheat after barley. Estimated grain N uptake was greater for winter wheat after pea than after barley suggesting that differences in available N supply may have contributed in part to observed yield differences.

To read more on this project, check out the full report

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