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Common Diseases in Field Peas



North Central IPM Center
Ascochyta Blight

Mycosphaerella pinodes (Anamorph: Ascochyta pinodes)

Symptoms:
Symptoms may appear at any time after plants emergence. On leaves, the disease starts as small purple flecks, developing to dark brown lesion that could dry out the leaves. On stems, lesions are more elongated than on leaves and could potentially girdle the stems. Pods may also be affected later in the season infecting the seeds. Infected seeds may present either no symptoms or shrinkage and dark brown discoloration. Infected seeds can cause foot rot resulting in girdled stems, stunted plants, or plant death.

Factors favoring:
Moist weather conditions, rain splash, wind, and sprinkler irrigation. Moderate temperatures with daily highs less than 25 °C (77 °C). Leaf wetness for 18 to 24 hours. Dense stands of field peas.

 
Root Rots

Fusarium solani f.sp. pisi and/or F. avenaceum;  Aphanomyces euteiches

Fusarium Root Rot

Symptoms:
Reddish brown to black streaks appear on primary and secondary roots. These streaks coalesce at later stages, lower stem is often girdled. Red discoloration of the vascular system can be seen, especially near cotyledon attachment. Stunted growth, yellowing and necrosis appear on the basal foliage.

Factors Favoring:
Soilborne fungi. Cool, wet weather condition before seedling and hot, dry weather after seedling.
 
Field Pea crop affected by Fusarium Root Rot

Aphanomyces Root Rot

Symptoms:
Initial symptoms are often seen on the first primary and lateral roots as honey brown discolorations. As the disease progresses the infected tissues often become soft and darker in color. Plants are easily pulled out of the ground, the cortex often sloughs off and remains behind in the soil leaving the vascular tissue strand attached to the plant. Stunting and wilting plants, yellowing from the bottom upward, and premature death can occur in severe cases.

Factors Favoring:
Favored by poorly drained soil. Often severe when cool wet spring is followed by warm weather.
 
Field peas affected with Aphanomyces root rot. Aphanomyces root rot samples: first four rows toward front of picture are non-inoculated pea plants; the last four rows are inoculated with Aphanomyces.
Powdery Mildew

Erysiphe pisi  (syn. E. polygoni ),Erysiphe trifolii

Symptoms:
Leaves turn light grayish, and powdery on the upper surface of lowest and oldest leaves. Pods are often malformed, small, poorly filled and fall off before they mature. Pod and & stems may turn purplish color. Small black specks, which are fruiting bodies of the fungus, develop in older lesions.

Factors favoring:
Warm temperature 20-25°C (68-75°F) and humid over 70% relative humidity with overnight dew.  Late season or in low, wet areas with high soil moisture. Overwinter on debris and spread by wind.
 


Bacterial Blight

Pseudomonas syringae pv. pisi and/or Pseudomonas syringae pv. syringae

Symptoms:
Small,dark-green water soaked lesions on leaves and stipules. Leaflets turn yellowish and later brown and papery. Lesions on the pods are sunken and turn olive-brown. Discoloration in heavily infected seed.

Factory Favoring:
High rainfals, hail, strong wind and low temperature.  Overwinter in debris and is seedborne.  Spread through rain-splash or wind-borne water droplets.
 
 


White Mold-Sclerotia

Causal Organism: Sclerotinia sclerotiorum

Symptoms:
White cottony growth(mycelium) forms on stems and pods. This affected tissue may soften and become slimy. Low areas with increased moisture are often seen affected first. Lodging and bleaching of stems is common. Black hard bodies(sclerotia) are present within the mycelium, stem cavities, pods, and in or on the soil. Affected plants may wilt and die prematurely and contaminated crops could be rejected.

Factors Favoring:
Conditions that favor infection include temperatures of 20-25˚C, moisture, excessive soil nitrogen, heavy seeding rates, planting close together, infected seeds or soil, and using cultivars that produce large amounts of foliage. Also, infected debris and infected fields nearby will increase inoculum source for infection.



 
For More Information

Links to other websites with information about field pea diseases some of which have been included here:

http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm7819
http://vegdis.cas.psu.edu/VegDisases/Identification_files/peas.html
http://www.extension.umn.edu/yardandgarden/ygbriefs/p231peadiseases.html
http://www.apsnet.org/publications/commonnames/Pages/Pea.aspx
http://www.agric.wa.gov.au/PC_92119.html?s=1001
http://vegetablemdonline.ppath.cornell.edu/factsheets/Viruses_Peas.htm

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