2012 Disease Management Update by Michael Wunsch

Disease management update -
lentils, chickpeas, and field peas
Michael Wunsch, PhD
plant pathologist
NDSU Carrington Research Extension Center

Ascochyta blight
Caused by the fungal pathogen
Ascochyta rabiei
CHICKPEAS

CHICKPEAS
Ascochyta blight – management
Use clean seed:
• Ascochyta blight is seed-borne and seed-transmitted.
• Seed should be tested for Ascochyta. Only use seed with 0% or < 0.3% incidence
of Ascochyta.
Always treat seed with thiabendazole (Mertect).
• Even if seed test indicates 0% Ascochyta infection

CHICKPEAS
Ascochyta blight – management
Make timely fungicide applications:
• Apply preventatively; cannot eradicate Ascochyta blight once it has developed.
• First application – 7 to 10 days before bloom (if wet), bloom initiation (if dry).
• One or more applications may be necessary during pod-fill
- Diseased pods often fail to produce seed
- Even low levels of foliar disease during bloom can lead to high levels of pod infections

CHICKPEAS
Ascochyta blight – management
Fungicide resistance management is critical:
• When canopy is open, tank-mix with chlorothalonil (Bravo WS, Echo 720, etc.)
• Rotate Proline (DMI fungicide, FRAC 3) with a carboxamide (FRAC 7):
Endura (boscalid)
Priaxor (pyraclostrobin + fluxapyroxad)
Vertisan (penthiopyrad)
Note that ProPulse is a premix of Proline and a carboxamide: If you apply Priaxor
or Vertisan after ProPulse, you will not be rotating fungicide chemistries.

CHICKPEAS
Fungicide efficacy:
Endura
CARRINGTON 2011:
Chickpea cultivar: Xena
Planting date: May 25
Fungicide timing:
A = June 23, B = July 6, C = July 18, D = July 29
MINOT 2011:
Chickpea cultivar: Xena
Planting date: May 19
Fungicide timing:
A = July 2, B = July 15, C = July 29, D = Aug. 12
Carrington
(2011)
Minot
(2011)

Fungicide efficacy:
Endura
CHICKPEAS
CARRINGTON 2009:
Chickpea cultivar: Sierra
Planting date: May 22
Fungicide timing, Carrington:
A = June 30, B = July 13, C = July 28
Carr. 2011 Minot 2011 Carrington 2009

CHICKPEAS
Fungicide efficacy: Vertisan
CARRINGTON 2011:
Chickpea cultivar: Xena
Planting date: May 25
Fungicide timing:
A = June 23, B = July 6, C = July 18
Carrington 2011 Williston 2011
WILLISTON 2011:
Chickpea cultivar: Dylan
Planting date: May 26
Fungicide timing:
A = June 28, B = July 7, C = July 21

Fungicide efficacy: Priaxor
CHICKPEAS
CARRINGTON 2011:
Chickpea cultivar: Xena
Planting date: May 25
Fungicide timing: A = June 23, B = July 6, C = July 18, D = July 29, E = Aug. 10

LENTILS
There are five major foliar disease of lentils in ND
ANTHRACNOSE – caused by Colletotrichum truncatum
ASCOCHYTA – caused by Ascochyta lentis
BOTRYTIS GRAY MOLD – caused by Botrytis cinerea and B. fabae
SCLEROTINIA STEM ROT (WHITE MOLD) – Sclerotinia sclerotiorum
STEMPHYLIUM BLIGHT – caused by Stemphylium botryosum

Lentil anthracnose
Foliar lesions: A
Stem lesions: B
Much more
damaging than
Ascochyta.
LENTILS

Lentil anthracnose
LENTILS
• Lesions girdle stems, killing plants
• Causes dead spots within fields
• Infected seeds are discolored

LENTILS
Lentil anthracnose - distribution
Widespread in northwest, west-central, and east-central North Dakota
2011 survey: WILLIAMS COUNTY – 11 of 13 fields
MOUNTRAIL, McLEAN, and WARD COUNTIES – 5 of 9 fields
FOSTER and SHERIDAN COUNTIES – 2 of 2 fields

Anthracnose -
Partial host resistance
LENTILS

LENTILS
Lentil anthracnose – partial host resistance

LENTILS
Anthracnose – fungicide efficacy
Fungicide timing:
A = 3 to 4 days after bloom initiation (June 28)
B = July 9
Location: Carrington, ND
Seeding date: May 3, 2010
Variety: Pennel

Anthracnose
Fungicide timing:
A = Bloom initiation (June 30)
B = Canopy closure (July 11)
C = July 13, D = July 20, E = July 27
ANTHRACNOSE SEVERITY RATING SCALE:
0 = no disease
1 = incidence low; infected plants generally have 1 lesion/stem
2 = incidence low; infected plants generally have 2 lesions/stem
LENTILS
Location: Carrington, ND
Variety: CDC Maxim CL
Planting date: May 17, 2011
3 = incidence moderate; infected plants have 2 to 3 lesions/stem
4 = incidence moderate to high; infected plants have ≥4 lesions/stem
5 = incidence severe; plant mortality high

Ascochyta blight
Easily confused with anthracnose.
Anthracnose: A,C
Ascochyta: B,D,E
E
LENTILS

Ascochyta blight
LENTILS
Widespread but generally well managed.
In 2011, at trace levels in all regions surveyed except northeastern Montana.

Ascochyta blight
Small green lentils:
CDC Viceroy – good resistance
Medium green lentils:
CDC Improve CL – fair resistance
CDC Greenland – good resistance
CDC Meteor – good resistance
CDC Richlea – very poor resistance
Extra small red lentils:
CDC Impala CL – good resistance
CDC Rosetown – good resistance
Small red lentils:
CDC Maxim CL – good resistance
CDC Redberry – good resistance
CDC Red Rider– good resistance
CDC Rouleau– good resistance
LENTILS
SOURCE: Saskatchewan Ministry of Agriculture “Varieties of Grain Crops 2011”

Ascochyta blight
LENTILS
Fungicide efficacy: no data available
• Other crops: Headline, Priaxor, and Proline effective
Fungicide timing: bloom initiation or canopy closure

Botrytis
LENTILS
Distinctive sporulation
found in early morning
and/or after rains until
disease kills plant.

Botrytis gray mold
LENTILS
At a field level, symptoms are very similar to Sclerotinia:
Initially, chlorosis of upper leaves
Later, necrosis

LENTILS
Botrytis gray mold - distribution
A severe problem in west-central ND in 2011.

Fungicide timing:
A = Pre-bloom/bloom initiation, canopy open (July 1)
B = Mid-bloom, canopy closure (July 11)
C = End of bloom (July 15)
D = Early pod set (July 29)
LENTILS
Botrytis gray mold - management
Location: Minot, ND
Variety: CDC Richlea
Planting date: May 19, 2011

LENTILS
Botrytis gray mold - management
Relative susceptibility of commercial lentil varieties: unknown
Fungicide efficacy: no data available
• Other crops: Headline and Endura are effective
• very high-risk for the development of fungicide resistance
Fungicide timing: canopy closure
Seed-borne: Do not save seed from an infested field.

LENTILS
Sclerotinia stem rot (white mold)

LENTILS
Sclerotinia stem rot (white mold)
At a field level, symptoms are very similar to Botrytis:
Initially, chlorosis of upper leaves
Later, necrosis

LENTILS
Sclerotinia stem rot (white mold): distribution
Widespread in central and west-central ND.
In northwestern ND, a problem in acreage with irrigation capabilities
(including fields that were not irrigated this season).

LENTILS
Sclerotinia stem rot (white mold): management
Relative susceptibility of commercial lentil varieties: unknown
Fungicide efficacy: no data available for lentils
• Other crops: Endura and Proline are effective
Fungicide timing: canopy closure

Stemphylium blight
LENTILS
A problem when rains occur at mid- to late-bloom

Stemphylium blight
LENTILS

Stemphylium blight
LENTILS

Stemphylium blight
Widespread
LENTILS
Only a problem where late rains occurred while lentils in pod-fill stage.

LENTILS
Stemphylium blight
Lentil varieties
differ in susceptibility
F: 15.63,
P > F: < 0.0001
CV: 63.05
Lentil variety trial, Hettinger, ND (August 1, 2011):

Stemphylium blight
Susceptibility, Clearfield lentils:
Disease ratings taken
August 21
Clearfield lentil variety trial, Minot, ND (August 21, 2011):
LENTILS

Stemphylium blight
Common fungicide strategies
(products and/or application timing)
may not be effective.
Location: Buchanan, ND
Variety: CDC Impala
Fungicide timing:
A = Three days prior to bloom initiation (June 30)
B = Full bloom (July 11)
C = Full bloom (July 20)
D = July 20, E = July 24
LENTILS

Mycosphaerella blight
FIELD PEAS
Caused by three fungal pathogens:
Ascochyta pinodes (Mycosphaerella pinodes)
Ascochyta pisi
Phoma medicaginis var. pinodella

Fungicide efficacy –
Mycosphaerella blight
FIELD PEAS

Fungicide efficacy –
Mycosphaerella blight
FIELD PEAS

Fungicide efficacy –
Mycosphaerella blight
FIELD PEAS

Thank you!