Protecting Fall Pansies

Production of pansies for the fall market begins during late summer, when insect and disease pressure is high. Knowing the key disease and insect problems you may encounter can help you be prepared with preventive and corrective measures to help ensure success of a high quality crop.

Foliar Diseases

Cercospora leafspot

  • Infections begin as small, purple-black spots on the older leaves.
  • As spots enlarge, they will develop brown-tan centers with dark, purple margins that have a distinct feathery appearance.
  • Infected leaves will turn yellow, shrivel and drop as the disease progresses.

Anthracnose

  • Infections begin as small, tan spots with a solid dark, thick border, often along the leaf margin.
  • A concentric ring pattern may develop creating light tan colored spots with papery centers which are slightly sunken appearance.
  • Spots may coalesce creating blighted areas of tissue.
  • Under humid conditions, reproductive structures of the fungus will form and appear as tiny, black, pepper-like spots scattered throughout the papery lesion.
  • This disease also can progress to petioles and stems, resulting in plant death.

Botrytis

  • Pansy blooms are highly susceptible to infection.
  • Initial infections will cause small, white spots or flecking on flower petals.
  • Under extended periods of cool temperatures and high humidity, the disease can quickly progress, destroying blooms and other parts of the plant.

Foliar Disease Management Strategy

Cultural tactics that help minimize leaf wetness, along with proper sanitation practices and preventive fungicides are all important for controlling these foliar diseases. The following fungicides can be used in a preventive rotation on a 14 day interval to protect against the diseases described above:

  •  Daconil Ultrex® fungicide 1.4 lbs/100 gal
  •  Mural® fungicide 4-6 oz/100 gal
  •  Palladium® fungicide 4-6 oz/100 gal


Once blooms are present, do not use Daconil Ultrex as this can damage flowers, but Mural and Palladium will continue to provide effective control of foliar diseases and Botrytis.

 

Root & Stem Rots

Infections by these pathogens generally results in plants that are stunted, wilt during the heat of the day and exhibit signs of nutritional deficiencies. These infections may result in the death of the plant. Reducing the chance of infections starts with a clean growing area, utilizing good cultural and sanitation practices and reducing heat stress on the plants. A laboratory confirmation of root and stem diseases is always advised because symptoms are often indistinguishable.

Rhizoctonia Root & Stem Rot

  • Infections commonly start at the soil line causing a dark brown discoloration of the lower stem.
  • As the disease progresses, the stem will become girdled, causing the plant to wilt and collapse.
  • Rooted liners that are planted too deeply are more prone to infection.
  • High temperatures and saturated media conditions can also promote disease.
  • Drench with Medallion® WDG fungicide at 1 oz/100 gal. Reapply after 21 days or rotate with a Thiophanate-methyl product such as Cleary's 3336® WP fungicide at 1 lb/100 gal if needed.

Pythium Root & Stem Rot

  • Roots that are stressed and damaged are highly susceptible to infections.
  • Avoid injury to roots through oversaturated media, heat stress, high salts/EC in planting media or a combination of these conditions.
  • Drench applications of Subdue Maxx® fungicide 1 oz/100 gal and Truban® WP 8 oz/100 gal can be rotated and used on a 4 week interval to prevent Pythium infections.

If growers have a history of fungal root rot problems early in the season, tank mixes of the various products above to give broad spectrum preventative control.

Black Root Rot (Thielaviopsis basicola)

  • Tends to be more of a problem when cooler temperatures are prevalent.
  • Plants will be stunted and have yellow lower foliage.
  • Roots will have dark lesions or black in appearance and remain intact.
  • Alkaline soil conditions favor disease development.
  • Maintaining a lower pH of 5.5-5.8 can help suppress this disease.

Preventive drench rotations using Thiophante methyl based products such as Cleary's 3336® WP at 1 lb/100 gal, Medallion® WDG at 1-2oz/100 gal and Terraguard® 75 WP fungicide at 4-6 oz/100 gal on a 21-day interval are used to prevent this disease.

Pest Problems

  • Aphids and Whitefly are the primary pests that occur during fall pansy production.
  • Periodically check the undersides of the leaves where these pests can hide.
  • Spray applications of Endeavor® insecticide at 5oz/100 gal or Mainspring® GNL insecticide at 4 oz/100 gal can be used to control both insect pests and will provide 2-3 weeks of control.
  • Thrips can also injure pansies late in production when blooms are present.
  • Use yellow or blue sticky cards to monitor activity along with general scouting.
  • Spray applications of Mainspring GNL at 4 oz/100 gal or Avid® 0.15 EC miticide at 8 oz/100 gal can be used to control these pests.
  • Black and variegated cutworms can occasionally cause problems in outdoor production, feeding at night on stems near the soil line.
  • Watch for moth activity in the productions areas, this can be an indication that young caterpillars will be present soon.
  • Mainspring GNL can be used to control various caterpillars in outdoor production.

All photos are the property of Syngenta unless otherwise noted.

2017 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local extension service to ensure registration and proper use. The trademarks displayed or otherwise used herein are trademarks of a Syngenta Group Company or third parties.

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