Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Pea (Pisum sativum) -- Powdery Mildew
 
Cause: Erysiphe pisi, a fungus that can be seedborne but usually survives as conidia on living plants. Normally the disease does not cause serious losses if peas are planted in spring or an early-maturing cultivar is planted. When peas are recropped on the same ground, the fall planting sometimes develops problems.
Symptoms: The first symptom is powdery white mycelium and spores on leaf and stem surfaces. On some cultivars, affected areas may die. All cultivars are dwarfed if infested early. Affected pods of some cultivars, including 'Oregon Sugar Pod', develop small brown to black necrotic spots.

Note the white colonies on the leaves.

 
Cultural control:
  1. Plant early-maturing cultivars.
  2. Many resistant cultivars are available.
  3. Plant early in the growing season.
  4. Rotate plantings at least 1 year.
Chemical control:
  1. Cuprofix Ultra 40D at 1 to 2 lb/A on 7- day intervals. 12-hr reentry.
  2. Endura at 8 to 11 oz/A on 5- to 14-day intervals. Do not feed treated pea commodities to livestock. Preharvest interval is 21 days for dried peas and 7 days for succulent peas. 12-hr reentry.
  3. Kaligreen at 2.5 to 3 lb/A on 7- to 10-day intervals. Might supplement a normal program when powdery mildew is first observed. May be applied up to the day before harvest. 4-hr reentry.
  4. Kocide 2000 at 1 to 2.25 lb/A or Kocide 3000 at 0.5 to 1.25 lb/A on 7-day intervals. 24-hr reentry.
  5. Microthiol Disperss at 7 lb/A on 14-day intervals. 24-hr reentry.
  6. MilStop (85% potassium bicarbonate) at 2 to 5 lb/A. 1-hr reentry.
  7. Nu Cop 50 WP at 1.5 to 3 lb/A on weekly intervals. Do not apply within 1 day of harvest. 24-hr reentry.
  8. Sulfur 6L (52% sulfur) at 3 to 7 pints/A. 24-hr reentry.
  9. Thiolux Jet (80% sulfur) at 3 to 10 lb/A. Do not apply if temperatures are high or leaves may burn. Do not allow spray drift to sensitive plants (spinach, etc.). Do not use within 2 weeks of an oil treatment. 24-hr reentry.
Biological control:
  1. Sonata at 2 to 4 qt/A on 7- to 14-day intervals. Can be applied up to and on the day of harvest. 4-hr reentry.
Content edited by: Cynthia M. Ocamb on January 1, 2010
 
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