Pulse Disease Concerns in Montana

Dr. Mary BurrowsMontana State University, Bozeman, MT

mburrows@montana.edu

406-994-7766

Top 4 tips for a healthy pulse crop

1. Start with high-germ, good quality seed of an adapted variety

– Ascochyta blight, bacterial blight, Anthracnose, and viruses can come in on seed

2. Use a fungicide seed treatment– Damping off, root rots

3. Good crop rotation practices– Root rots and foliar diseases

4. Scout crop on a regular basis- Foliar diseases and abiotic issues

Ascochyta blight• Three different species on Pea

• Ascochyta pisi, A. pinoides (Mycosphaerella pinoides), Phoma medicaginis var. pinodella (formerly A. pinodella)

• Different species on Lentils and Chickpeas

• Lentil = Ascochyta lentis• Chickpea = Ascochyta rabiei

• Spread by water splashing and wind• 60 – 75 F, humidity and rain

Montana Ascochyta seed testing

• Action threshold = 0% chickpea, 0.7% pea, 2% lentil• Where ‘action’ means seed treatment for ascochyta or not planting that seed• Action threshold is based on relative resistance of the crop to the disease

 

2009 2010 2011 (since Sept 2010)

Crop n Average

%

# of seed lots above

threshold n

Average %

# of seed lots above

thresholdn

Average %

# of seed lots above

threshold

Chickpea 2 0.00 0 4 0.75 1 7 0.17 2

Lentil 25 0.12 1 53 0.25 2 50 1.78 4

Pea 57 0.18 3 83 1.71 39 23 2.33 14

Ascochyta blight symptoms: chickpeaLeaf symptoms

Pycnidia (fungal spore structures)

Fungicide

No fungicide

Photo: Chengci Chen, Karnes Neill, MSU

Ascochyta blight symptoms: Pea, Lentil

Photo: S. Markell, NDSU

Photo: S. Markell, NDSU

Bacterial blight of Pea• Psedomonas syringae pv. pisi• Seedborne inoculum (persists 3 years)

– Also residue- and soil-borne• Local splash dispersal is the most

important for spread• Yield loss strongly correlated with leaf

area loss• No adapted cultivars with resistance

Bacterial blight of peaAngular lesions

Watersoaking and ooze

Hail damage

Use a fungicide seed treatment• Help manage root rots

– For a few weeks

• Aid emergence and stand establishment• Why is this important?

– Disease likely occurs early, shows up later

• Protect against seed-borne diseases– Use Mertect/LSP against Ascochyta in chickpea; Dynasty

(azoxystrobin) good for pea, lentil Ascochyta

Photo: S. Markell, NDSU

Seed treatment trials• Uniform pea seed treatment trials (ND, MT, WA)• 6 locations, 2008; 2 locations, 2010• Low disease severity in general• Agronomics were dependent on site and year

– In Montana:• Cruiser increased yield if there was pea weevil pressure• No one seed treatment stood out as better than the rest

• Chickpea seed treatments, 2007– Very wet site at Sidney, mefanoxam (metalaxyl) increased

stands and yield in kabuli chickpeas - Pythium

Seed Treatment• Will seed treatments always pay? NO• Questions to ask:

– How long have you been planting pulse crops?

– What’s you’re rotation?– Do you have stand establishment problems?– Have you seen problems in your fields?

Seed Treatments• Make sure your product has Fusarium and Rhizoc

control (True Fungi) in addition to Pythium (metalaxyl/mefanoxam)

• Examples: ApronMaxx, Trilex AL, Acquire + Acronis• 2009 ND field crop fungicide guide• Product labels• Use Mertect/LSP if you have Ascochyta in the seed;

Dynasty will also work but only for pea and lentil (chickpea Ascochyta is resistant to strobilurins)

Good crop rotation practices• 3-4 year rotation between legume crops

is recommended for disease management

• Should reduce root pathogen population: particularly the Fusarium species that attack pea

• Will also reduce inoculum for foliar pathogens

• Warm moist soil• Distinct chocolate brown to

dark red lesions• Often seen in association

with Fusarium

Fusarium Rhizoctonia Can be stress related Common in drought

years Dry rot with indistinct

brown lesions-occasional general browning

Few secondary roots

Photo: S. Mills, MSU

Lentil with root rot Healthy lentil

Fusarium wilt of pea

• Resistant varieties• Seed treatment• Rotation

Fusarium oxysporum f.sp. pisi

Scout crop on a regular basis• Foliar diseases

– Ascochyta blight– Powdery mildew

• Abiotic issues

Foliar Fungicides• Serious disease = serious yield reductions

– Fungicides can help prevent loss

• Fungicides will not always pay: beware the development of fungicide resistance!

• Scout for diseases• Consider climate

– Humid with rain in the forecast

• Early bloom is optimum time to spray• Late-season fungicides will not penetrate thick

powdery mildew (peas) – neither will dessicants

Fungicide Resistance in Chickpeas

• Fungicides Available before 2005– Chlorothalonil – Protectant (Bravo)– 2002: Azoxystrobin – QoI class (Quadris) – 2003: Pyraclostrobin – QoI class (Headline)

• Initially, QoI’s very effective, so effective that…• Growers were spraying multiple applications

• Resistance to Headline/Quadris identified in 2005

• Widespread resistance in 2006

Ascochyta resistance to Headline/Quadris (strobilurins)

Per

cent

of

Isol

ates

From K. Wise

2007 Chickpea Fungicide Trial- Minot

Yie

ld lb

/A

From K. McKay

Ascochyta Blight in Chickpeas• Ascochyta in chickpeas does not cause

disease in lentils or peas• Ascochyta population in chickpeas is

resistant to strobilurin fungicides– Headline and Quadris ineffective

• Still the case• Rotate chemicals

– Bravo, Proline, Endura, Proline

Preventing/Managing Fungicide Resistance

• Rotate FRAC groups! Not product• Follow the label

– Use appropriate timing• Don’t wait until epidemic is full force

– Use appropriate rate– Use appropriate technique (nozzles, water,

etc.)• Tank mixes

Thank you

• Sam Markell, Rubella Goswami, NDSU• Chengci Chen, Karnes Neill, Joyce

Eckoff, Rachel Leisso, Ken Baker, MSU• Northern Pulse Growers Association• USDA-Cool Season Food Legume

Program

ID# Treatment Name

Stand Count

(30 DAP, plants/ft2)

Root Rot Incidence

Root Rot severity

Yield(bu/A)

1 Untreated 5.5 30 ab 9 ab 12.9 a2 Tops 30 6.0 35 a 7 ab 12.8 a3 Trilex Concentrate 4.2 35 a 3 b 14.3 ab4 Trilex Concentrate +

Tops 30 6.0 30 ab 5 b 13.7 ab5 Trilex Concentrate +

Gaucho 600 5.5 13 b 5 b 15.1 b6 Apron MAXX 4.6 28 ab 5 b 12.5 a7 Cruiser MAXX 4.7 23 ab 5 b 15.7 b8 Mertec 5.4 18 ab 4 b 13.9 ab9 Acquire + Acronis 6.1 15 ab 9 ab 12.4 a

10 Tachigaren 5.3 20 ab 7 ab 12.7 aLSD(P=0.05) NS 22 8 2.1

CV 23.1 70 91 10.6

Moccasin, MT, 2008

ID# Treatment Name

Stand Count (30 DAP, plants/ft2)

Root RotIncidence

(%)

Root RotSeverity(% root)

Yield(bu/A)

1 Untreated 6.0 30 ab 9 ab 12.3 ab2 Tops 30 6.2 35 a 7 ab 10.4 a3 Trilex Concentrate 6.8 35 a 3 b 11.1 ab4 Trilex Concentrate +

Tops 30 7.0 30 ab 5 b 13.9 bcd5 Trilex Concentrate +

Gaucho 600 6.7 13 b 5 b 12.7 ab6 Apron MAXX 6.5 28 ab 5 b 15.9 cde7 Cruiser MAXX 6.8 23 ab 5 b 14.1 bcd8 Mertect 7.0 18 ab 4 b 16.6 de9 Acquire + Acronis 7.0 15 ab 9 ab 18.1 e

10 Tachigaren 6.4 20 ab 7 ab 13.2 abcLSD(P=0.05) NS 22 8 3.0

CV 15.2 71 91 12.8

Sidney, MT, 2008

Yield (lbs/a)Treatment n Yield stderr1. Control 4 2036.6 80.92. Trilex 2000 4 2143.3 110.63. Apron Maxx RTA 4 1999.5 67.94. Apron Maxx RTA + Mertec 4 2271.6 196.15. Nodulator granular 4 2344.2 118.16. Nitragen-C (peat) 4 2082.4 63.87. Trilex2000 + Nodulator granular 4 2327.3 189.88. Trilex2000 + Nitragen-C (peat) 4 2173.1 135.79. Apron Maxx + Nodulator granular 3 2236.0 70.110. Apron Maxx + Nitragen-C (peat) 4 2168.5 195.711. Apron Maxx + Mertect + Nodulator granular 4 2331.4 65.712. Apron Maxx + Mertect + Nitragen-C (peat) 4 2220.2 66.213. Stamina + Acquire + Nodulator Granular 4 2145.0 56.2

14. Stamina + Apron Maxx RTA + Nodulator Granular 4 2316.2 133.715. Rancona Summit + nodulator 3 2471.1 133.616. Vitaflo 280 + nodulator 4 2235.9 131.2

Mean 2214.6

R sq 0.6CV 8.4

p-value rep <.0001p-value treatment 0.1324

Moccassin, 2010

• Over 80% isolates from ND Survey were Fusarium species

• In MT, small chickpea survey in 2007: Fusarium, Pythium causing damping off of seed

• Rhizoctonia can also be important• Do all the Fusarium species cause disease,

equally?

What is causing our root rots?

18%

25%

20%

15%

19%

1% 2%

Rhizoctonia solani

Fusarium avenaceum

Fusarium oxysporum

Fusarium redolens

Fusarium graminearum

Fusarium acuminatum

Fusarium solani

Distribution of fungal isolates in field peas in 2008