MANAGING FIELD CROP DISEASES AGRONOMY UPDATE Lethbridge, Alberta, January 16, 2013

Michael Harding Research Scientist, Alberta Agriculture and Rural Development

ACKNOWLEDGEMENTS

R.J. HOWARD – Alberta Agriculture & Rural Development, Brooks, AB

T.K. TURKINGTON – Agriculture & Agri-Food Canada, Lacombe, AB

H.R. KUTCHER – University of Saskatchewan, Saskatoon, SK

P. LAFLAMME – Alberta Agriculture & Rural Development, Edmonton, AB

OVERVIEW

• Back to the basics: fundamentals of disease management – Farm Management Decisions – Crop Input Decisions

• Fungicides: risks and rewards

• Top 5 reasons why fungicide applications may give unexpected results

Parker (1915) “.…Crop rotation in itself is not the cure-all for unproductive land or the absolute key to profits from high priced agricultural land. But crop rotation is the chief factor in a combination of good farming practices that will maintain the productivity of the soil, and around which intensive systems of farming may be developed that will yield the maximum crop value per acre at the minimum of expense. Crop rotation is to general field agriculture what the foundation is to the house, the solid base on which we may successfully rear a permanent superstructure designed in a hundred different ways according to our individual requirements and desires.”

FARM MANAGEMENT DECISIONS • Crop rotation

– Can ensure sustainable crop production – Will help maximize land use and profitability – Can help minimize inputs

Moore (1921)

“Rotations need to be based on crops that are profitable for the producer, otherwise the benefit in terms of disease management is rendered use-less”

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Blackleg severity

(0-5)

Cont C w-C w-p-C w-p-w-CRotation

Blackleg RBlackleg S

R. Kutcher, AAFC Melfort

Influence of rotation length on severity of blackleg of canola

[14 site-years - Scott and Melfort, 2000-06]

• Tillage – Handling of crop residues

• Seeding – Seeding depth – Seeding date – (Seeding rate) – (Seed quality) – (Seed treatments)

FARM MANAGEMENT DECISIONS

FARM MANAGEMENT DECISIONS • Irrigation

– Avoid over-irrigation – Avoid irrigation at critical points of the disease cycle

• Weed and volunteer management – Minimize disease reservoirs

• Utilize disease resistance or tolerance – www.seed.ab.ca

CROP INPUT DECISIONS • Seed quality

– Seed testing – Seed cleaning – Seed treatment

• Fertility and nutrition

– A healthy crop J – Lush growth and dense canopies L

• Fungicides

Photos courtesy of M. Burrows

1. Should I spray? Yes No 2. When Should I spray?

a) Threshold b) Calendar c) When there are lots of planes in the sky 3. What Should I spray? a) Registered product b) FRAC groupings c) Management of multiple diseases, cost of

product, tank mix options, flexibility, etc

FUNGICIDES: RISK VS. REWARD

FUNGICIDES: RISK VS. REWARD

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Application consideration

Too spray or not to spray Timing Which product to use

Incr

easi

ng im

pact

(G. Hollaway, DPI Victoria, Australia)

WHY DON’T FUNGICIDE APPLICATIONS ALWAYS PRODUCE EXPECTED RESULTS?

..

TOP FIVE REASONS 1. Application Problems

a) Timing: correct alignment of fungicide with disease progress • Infrequent scouting • Incomplete understanding of pathogen biology and disease cycle

Photo courtesy of M. Burrows b) Failure to hit the target (groundspeed, boom height, water volume, nozzle type, environment)

Correct Timing of Fungicide Application

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Amount of Disease

Economic Threshold

Correct Timing of Fungicide Application

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Fungicide application

Untreated

Treated

Correct Timing of Fungicide Application

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Amount of Disease

Weather C

hange

TOP FIVE REASONS

2. Product incompatibilities and limitations a) Tank contamination b) Intentional mixing of incompatible products c) Product not stored within acceptable limits, or past expiry

TOP FIVE 3. MISDIAGNOSIS

a) Physiological disorder b) Insect damage c) Herbicide injury

PLS Septoria Stripe rust Cereal leaf beetle Surfactant burn

MISDIAGNOSIS d) Non-fungal pathogens

TOP FIVE

Aster yellows Bacterial leaf blight Barley yellow dwarf

ALBERTA PLANT HEALTH LABORATORY

• Located at the Crop Diversification Centre North (Edmonton, AB)

• Diagnostic support and pathology expertise

• Fee-for-service (partial cost recovery)

• Plans to be open for sample receipt in Spring or Summer of 2013

• More details to be made available soon

A correct diagnosis can be made in hindsight, but its usually much better to have a correct diagnosis before disease severity becomes too great to allow successful treatment.

4. Environmental effects – temperature, precipitation, relative humidity, wind, etc.

TOP FIVE

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1998 1999 2000Unsprayed Ronilan Benlate

Stem Rot Incidence (%) on canola at Melfort Kutcher and Wolf. 2006. Crop Prot. 25: 640-646

TOP FIVE 5. Limitations of the fungicide

– Protectant vs. curative

• Contact fungicides

• Translaminar fungicides

• Xylem mobile (apoplastic, acropetal)

• Truly systemic (symplastic, amphimobile)

– Registered for “CONTROL” or “SUPPRESSION” – Disease pressure is too high, or too advanced to allow a response

Fungicide movement in wheat leaves and control of powdery mildew

Bartlett, et al., 2002, Pest Management Science 58:649-662 Plate 1. Redistribution of strobilurins in wheat to control powdery mildew (Source: Syngenta)

Additional reasons Varietal effects Fungicide Resistance Rotation Registered for control or suppression Water quality Duration of product activity Improper rates, mixing and sprayer calibration SUGGESTION:

-----------------------------LEAVE A CHECK STRIP-------------------------------- And avoid comparing fungicide performances from different (multivariate) fields

Photos courtesy of M. Burrows

Conclusions

• Farm Management Decisions (rotation, tillage, cultivar selection, irrigation scheduling) can provide a foundation for successful crop production and pest management

• Crop Input Decisions (fertility, seed quality and seeding rate, fungicides) can help push crop productivity/quality to capacity and may help, or complicate, disease management

• There are risks associated with fungicide use, but there are rewards when best practices are used, and the environment cooperates

• There are limitations to what fungicides can provide, and many reasons why a fungicide application may not give expected results.