Publication 360, Fruit Production Recommendations:
Plum Calendar - Popcorn (when blossoms show white)

Excerpt from Publication 360, Fruit Production Recommendations 2010-11,
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Table of Contents

1. Popcorn (when blossoms show white)
   • Brown rot
   • Black knot
   • Precautions
2. Other Plum Calendar Sections
   • Dormant (before bud break)
   • Green tip (just as buds are bursting)
   • Popcorn (when blossoms show white)
   • Bloom
   • Shuck (when most of the shucks are off)
   • First cover (12 days after Shuck)
   • Second cover
   • Prepick
   • Special sprays (when monitoring indicates the need)
   • Postharvest fruit treatment
3. Other Information on Plums
   • Notes on Tender Fruit Insects & Diseases
   • Table 7-10. Products Used on Plums
   • Table 7-11. Activity of Fungicides on Stone Fruit Diseases
   • Tender Fruit Nutrition
4. Plum Calendar (PDF 103 KB)
5. Chapter 7 - Tender Fruit Calendar PDF 401 KB
6. Related Links

Brown rot (Prebloom)

• Materials: Use one of:
  • Topas 250 E @ 500 mL/ha
    or Mission 418 EC @ 300 mL/ha
  • Indar 75 WSP @ 140 g/ha
  • Funginex DC @ 2.5 L/ha
  • Rovral @ 1.5 kg
  • Vangard 75 WG @ 370 g/ha
  • Lance WDG @ 370 g/ha
  • Pristine WG @ 750 g/ha
  • Supra Captan 80 WDG @ 4.5 kg/ha
    or Maestro 80 DF @ 4.5 kg/ha
  • Microscopic Sulphur - see label
• Comments: To help control brown rot, knock off fruit mummies when pruning. Cultivate entire orchard before bloom. Make two to three fungicide applications from early to full bloom. To avoid resistance, alternate among fungicide groups and do not use more than two applications of Rovral or Vangard per year.
  Topas, Mission and Indar: Do not alternate Topas or Mission and Indar.
  Pristine and Lance: Both products include active ingredients in the same fungicide group. Do not alternate Pristine with Lance.
  Sulphur: Helps control rust mites on European plums and prunes.
  Captan or Maestro: May cause injury under some circumstances. Injury has occurred on Grand Prize, Early Golden, Shiro, Burbank and Ozark Premier.
• Learn more:
  • Notes on Tender Fruit Insects & Diseases
    • Brown rot

Black knot (Prebloom)

• Materials: Use one of:
  • Supra Captan 80 WDG @ 4.5 kg/ha
    or Maestro 80 DF @ 4.5 kg/ha
  • Indar 75 WSP @ 140 g/ha
  • Topas 250 E @ 500 mL/ha
    or Mission 400 EC @ 300 mL/ha
• Comments: Fungicides will not provide adequate control of black knot without proper orchard sanitation (pruning, removal, and burning of black knots). Inspect all plums in early summer for new knots and those missed. Cut these out and burn them. European plums, prunes and Damsons are most susceptible. Apply fungicide sprays to protect the developing shoots between the popcorn stage (prebloom) and first cover every 3-5 days in wet weather. Spore release may be delayed in dry springs. Under these conditions extend fungicide coverage to Second cover. See OMAFRA Factsheet Black Knot of Plums, Order No. 05-017.
  Topas, Mission: Provide only suppression of black knot, see label.

Precautions:

Read the product label and follow all safety precautions. Consult the product label for suggested water volumes. Otherwise, use enough water to ensure thorough spray coverage. Where the product rate is listed in amount per 1,000 L and if a water volume is not provided on the label, use enough water to wet the foliage to the near drip point.

Products are listed by fungicide and insecticide group. Use products from different groups to prevent pest resistance. For resistance management refer to Pest Resistance to Insecticides, Fungicides, Miticides.

For preharvest interval, re-entry period, maximum number of applications and chemical group, see Table 7-10. Products Used on Plums.

Related Links

• Integrated Pest Management (IPM)
• Pesticide Application and Safety
• Pesticide Companies and Agents
• Search the PMRA website
• Ontario Minor Use Program
• OMAFRA Publication 505: Ontario Weeds
• OMAFRA Publication 360: Fruit Production Recommendations