agronomy update - alberta agriculture and forestry peas and lentils • pulse crops grown for feed,...

Robyne Bowness

Alberta Agriculture and Rural DevelopmentLacombe, AB

Agronomy UpdateJanuary 18th, 2011

Field Peas and Lentils• Pulse crops grown for feed, food, and ingredients• Valuable in crop rotation (N2 fixation)• Important crops globally Demand is increasing every year Canada is second largest exporter

In 2010• Over 895,000 acres of peas harvested

• Over 135, 000 acres of lentils harvested

Source: Alberta Agriculture and Rural Development

Ascochyta Blight of Field Pea• Common disease• Complex of three pathogens Mycosphaerella pinodes ( )

White mould of Lentil• Not so common Sclerotinia sclerotiorum

Caused by fungal pathogens

Can attack the crop at any growth stage

Prefer cool, wet, shadier conditions

Problematic in Alberta during summer 2010

Most serious foliar disease of field pea in Western Canada

Found in all commercial pea fields

Interferes with photosynthesis

Crop lodges

Reduces seed weight, number and quality

Yield losses range from 20-50%• In wet years even higher

Symptoms

• Appear within 2-4 days of infection• Small purple to brown lesions on leaves, stems and pods• Pinpoint lesions on the flowers• Breakdown stem strength – crop lodges• Seeds smaller with dark brown discoloration

Survives in seed, in the soil and on plant debris

Two types of spores - spread by wind or rain splash

Infections early and repeatedly throughout the season

Most critical factor is leaf wetness

Spores

Strategies include• Crop rotation• Disease free seed• Seed treatment• Cultural practices

No cultivars resistant to this pathogen

Most effective strategy is repeated application of fungicides

Fungicide options include:• Bravo 500 ®

• Headline EC ®

• Lance ®

• Quadris ®

Timing is critical

Considerations• Protectants – won’t kill the pathogen• Crop Canopy – dense Before canopy closes

• Level disease• Yield increase is expected

Is yield loss higher than cost of application?

Crop Canopy• Thin, moderate, or thick

Leaf wetness (at noon)• None, low, moderate, or high

Percent of plants showing symptoms• None, low (<20%), moderate (20-50%) or high (50-100%)

5 day weather forecast• Dry, unsettled, showers, wet

Source: Lopetinsky and Hoy, 2008

%

Field inspections should be done twice a week (June)

Add up score for each factor• 1+2+3+4 = ?


Estimation Risk Scale Score

Crop CanopyThin

0Moderate

10Mod/ Thick

15Thick

30 30

Leaf wetness/ humidity

None0

Low10

Moderate20

High40 10

Percentage of plants with symptoms

None

0

Low(<20%)

15

Moderate(20-50%)

25

High(50-100%)

4025

5 day weatherforecast

Dry0

Unsettled10

Showers15

Wet20 15

Total --- --- --- --- 1+2+3+4


Estimation Risk Scale Score

Crop CanopyThin

0Moderate

10Mod/ Thick

15Thick

30 30

Leaf wetness/ humidity

None0

Low10

Moderate20

High40 10

Percentage of plants with symptoms

None

0

Low(<20%)

15

Moderate(20-50%)

25

High(50-100%)

4025

5 day weatherforecast

Dry0

Unsettled10

Showers15

Wet20 15

Total --- --- --- --- 80


Field inspections should be done twice a week (June)

Add up score for each factor• 1+2+3+4 = ?

Magic number is 65

Score above 65 points.. • Fungicide application is recommended

Score below 65 points..• Fungicide applications not necessary at this time• Field inspections should continue


Prediction system is a tool..

May help making the decision as to whether to spray or not easier

Must be starting with a healthy crop!

No disease, don’t spray!

Caused by Sclerotinia sclerotiorum• Serious foliar disease of many crops• Plant parts - high water content• Losses can be great

On lentil• Usually not of economic importance Lentils better suited to drier areas

• Except in wet years Affects yield and quality

Photos : Faye Dokken – Bouchard and Sabbine Banniza

Symptoms

• Appear late in the season - from flowering to pod set• Stems appear bleached• Leaves and stems turn brown, plants wilt• Plant become covered with white cottony mould• Black sclerotia develop inside and outside of the plant

Photos : Faye Dokken – Bouchard and Sabbine Banniza Photo: Ontario Ministry of Agriculture

Sclerotia survive in the soil

Sclerotia germinate and release spores

Lots of moisture / plants are stressed / conditions are right

Infection occurs• Most critical factor is canopy wetness

Spor

es

Very difficult pathogen to control

Most economic option is cultivar resistance• There are none available

Common strategy is application of fungicides

Not always recommended

Issues:• Not the same as canola• Infects late in the season• Spraying at flowering not effective• Can’t get effective delivery after canopy close

Timing is critical

Only fungicide option available is Lance®

Considerations• Temperature and leaf wetness are favorable• History of Sclerotinia in the field• Before canopy closes

• Spray to protect the crop• Before you see any disease

Is yield loss higher than cost of application?

Strategies include

• Crop rotation with cereal crops• Clean seed – no sclerotia• Wide row spacing / plant densities• Cultural practices• Fields with good drainage

Good news is it only show up once in a while!

Start with a healthy crop

Scout your fields often

Familiarize yourself with the disease

Familiarize yourself with the chemical

Consider the economics of spraying

Good luck!

Faye Dokken-Bouchard, Saskatchewan Agriculture

Sabinne Banniza, University of Saskatchewan

Mark Olson, Alberta Agriculture and Rural Development

agronomy update - alberta agriculture and forestry peas and lentils • pulse crops grown for feed,...

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