# Presentation: 076860

## Controlling Wild Oat in Tame Oat

- Steven Shirtliffe1, Chris Willenborg2 and Jeffrey Wildeman3, and Bill May4
- 1Department of Plant Sciences, University of Saskatchewan; 2Department of Plant Science, University of Manitoba, Winnipeg, MB; 3Cargill-AgHorizons, Regina, SK; 4AAFC Indian Head SK.

## Oat Agronomic Research at University of Saskatchewan

- begun in 1999
- focused on:
- managing wild oat in tame oat
- fertility management
- seed quality issues

## Introduction

**Introduction**

**Wild oat remains one of the most abundant and competitive weeds on the Canadian Prairies **
**#2 on surveys**
**Green foxtail also problem weed **
**#1 on surveys**
**No herbicides presently exist to selectively remove either of these weeds from tame oat**
**Oat producers must manage  both of these weeds using cultural control methods**
**wild oat is the bigger problem**
**early emergence and competition**

## Wild oat management in oat

- What agronomic methods can be used to reduce yield and quality losses from wild oat in tame oat?
- Do varieties differ in competitive ability?
- What should the seeding rate be?
- How does N fertilizer affect competition?
- Does seed size affect oat competition?
- What should a producer do when encountering a wild oat infestation in tame oat?
- What is the effect of wild oats emerging at different times on tame oat yield and quality?
- Can mechanical weed control reduce yield loss from wild oat?

## Experiment 1: The effect of oat genotype and seeding rate on competition with wild oat

- Genotypes
- AC Mustang		- OT 288
- CDC Bell		- Riel
- CDC Pacer		- Triple Crown
- Seeding rate
- 250 plants m-2
- 500 plants m-2

## Seeding rate effect

- Under wild oat competition increased seeding rate:
- Less yield loss
- Less wild oat contamination

## Yield loss of genotypes due to wild oat

- OT 288 was always the poorest competitor
- CDC Bell sometimes had good competitive ability
- was among the best
- however it has very poor absolute yield and very poor quality
- the other genotypes rarely differed in competitive ability

## Quality loss due to genotypes

- CDC Bell
- Consistently among the lowest % WO seed
- OT 288
- Significantly greater than all other genotypes

## Competitive/high quality oat?

## Comparison of “heritage”, modern and low input varieties under organic conditions

- SA98084 		nr
- SA98511 		nr
- CDC DANCER 	2000
- AC MORGAN 		1999
- AC ASSINIBOIA 	1995
- CALIBRE 		1983
- HARMON 		1965
- GARRY 			1948
- VICTORY 		1908

## Oat Yield under organic on-farm conditions (average of 6 site years).

- Morgan 	1978.6 a
- SA98084 	1898.5 ab
- Calibre 	1862.5 abc
- SA98511 	1750.5 bcd
- Dancer 	1700.1 cde
- Assiniboia 	1624.7 de
- Garry 	1611.1 de
- Harmon 	1542.6 de
- Victory 	1536.8 de

## Effect of Nitrogen Fertilizer on Oat/Wild Oat competition 

- In other cereals N fertilizer often affects competition with wild oat
- Results inconclusive
- Sometimes increases competition other times decreases
- Objective to determine the affect of nitrogen fertilizer on oat/wild oat competition

## Average effect of Nitrogen Fertilizer on Oat Yield at Sutherland and Goodale in 2005.

## Effect of Wild Oat Density on Oat Yield as affected by Nitrogen Fertilizer at Sutherland in 2005.

## Effect of Wild Oat Density on Oat Yield as affected by Nitrogen Fertilizer at Goodale in 2005.

## How does seed quality affect oat competition? 

- Large seed shown to be more competitive with wild oat in wheat
- Emergence time?
- Germination and emergence time does not appear to differ between genotypes tested and diff. seed sizes
- larger seed sizes have greater yield with or without wild oat competition in Greenhouse
- Objective
- Determine the effect of oat groat size on yield of oat with and without wild oat

## Effect of Oat groat size on Yield Density Relationship of Oat (no WO)

- XXXXX

- Indian Head 2005

- Saskatoon 2004

- Indian Head 2004

- Saskatoon 2005

## Effect of seeding denisty on yield in oat wild oat not pressent. Average of all seed sizes at 4 site years. 

## Effect of groat size on oat yield with and without wild oat

## Effect of groat size on wild oat contamination with and without wild oat

## Before seeding recommendations when wild oat is expected:

- Increase seeding rate
- Avoid semi-dwarf varieties (although we have never evaluated Ronald)
- Fertilize with N normally
- Plant with large groat seed

## Managing unexpected wild oat infestation in tame oat?

- What is a producer to do when wild oat comes up in a tame oat field?
- Depends on the relative time of emergence of the tame oat and wild oat

## Materials and Methods

**Materials and Methods**

**Location:  Indian Head, Saskatoon**
**looked at different densities of WO emerging before, with and after the oat crop**
**determined the yield loss and quality loss**

## Slide 24

## Effect of time of emergence on yield loss from wild oat

- 25 WO m-2 are needed to cause a 10% yield reduction when they emerge at the same time as the crop
- 85 WO m-2 are needed to cause the same yield reduction when the wild oats emerge 90 GDD after the crop
- one leaf stage in wild oat takes ~90 GDD
- second flushes not very important

## Management Implications

**Management Implications**

**TWO SOLUTIONS:**
**Apply glyphosate before oat emergence to kill emerged wild oats**
**live with later emerged wild oats**
**Destroy the crop and reseed**
**Delayed seeding reduces both yield and quality of tame oat**
**Producers must carefully assess wild oat populations before implementing a management strategy**
**Attempting to model the effect of destroying and then reseeding oat**

## Incrop harrowing

- not recommended
- according to organic “literature”

## Subcrown internode in wheat and oat (note position of crown and coleoptilar node)

## Burial of oat by in-crop harrowing and effect on yield

## Oat is as (or more) tollerent to in-crop harrowing as wheat

## Should producers use mechanical control? 

- Selectivity is low
- Difficult to control established wild oat
- Green foxtail control can be good
- However green foxtail usually emerges much later than tame oat

## Management of Wild oat in Oat

- It is possible
- Maximize competition of crop
- Minimize wild oat density
- Rotational concerns are issues as well

## Acknowledgements

**Acknowledgements**

- Technical Assistance:
- Shaun Campbell
- Aaron Miller
- Rachelle German

## Yield of genotypes under wild oat competition

## The effect of wild oat on tame oat yield and quality

- Oat physical oat quality is affected somewhat by wild competition
- Plumps and thins not usually affected
- thins sometimes increase
- Kernel weight can go down in some years
- Groat yield unaffected
- protein and fat unaffected

## Oat seeding rate recommendations

- if wild oat is present never seed oat under 250 seeds /m2 (25 seeds /ft2)
- for seed wt. of 35g/1000 seeds ~80 lbs./ac.
- when wild oat is present increase rate
- 120 lbs./ac not unreasonable
- don’t think of seeding in terms of bu./ac
- 25 WO/m2 at 50lbs/ac = 22% yield loss
- 25 WO/m2 at 120lbs/ac = 11% yield loss

## Oat Quality

- Increasing seeding rate:
- Plumps decrease in drier locations
- thins increase when there is a drought
- kernel wt. not affected
- test weight largely unaffected
- most potential agronomic method to enhance oat competition

## Agronomic methods to reduce wild oat damage

- Increase tame oat seeding density
- reduces yield losses
- yield advantages whenever wild oat are present
- reduces wild oat seed production and subsequent contamination

## Modelling the effect of reseeding oat on oat yield and quality

- model is in development
- must re-seed early or there is a heavy yield penalty
- wild oats can still grow after re-seeding
- goal is to have a simple fact sheet to aid producers and crop scouts in making re-seeding decisions

## Slide 41

## Slide 42

## Slide 43

## Materials and Methods

**Tame oats (AC Assiniboia) cross-seeded at right angles to wild oats at 100 GGD**
**2 m oat free check at the back of the plot to monitor wild oat emergence**

## The effect of wild oat density on tame oat yield and quality

- for every wild oat per square metre that is present oat yield is reduced ~.5%
- seeding ~250 oats/m2

## Other research

- Managing Crown rust in oat
- The effect of Sulphur on oat yield
- three field season done
- no effect on yield
- not done on low S soils