Strawberry and Bramble Disease Management

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					Strawberry and Bramble
 Disease Management

          Anne DeMarsay
 Regional Specialist, Fruit Pathology
  Maryland Cooperative Extension
        Upper Marlboro, MD
                 In this talk . . .
• Diseases of
  – Strawberries in matted-row production systems
  – Red raspberries in outdoor production
• Management tools
  – Cultural practices and sanitation
  – When to use fungicides
       A Family Resemblance?

• Strawberries and brambles (raspberries and
  blackberries) are relatives
  – Members of the same branch of the rose family
  – Roses are a close relative
• Brambles (genus Rubus) are woody plants with
  a perennial crown and biennial shoots
  – 1st year primocanes grow vegetatively
  – 2nd year floricanes bear fruit and die
              Red Raspberries
• New shoots grow from root system, not crown
• May be grown as a hedgerow or in “hills”
  (individual plants)
• Most cold-tolerant bramble, but can suffer heat
• Two types
  – Floricane-bearing (summer) raspberries bear fruit on
    2nd year canes
  – Primocane-bearing (fall or everbearing) raspberries
    bear fruit on 1st year canes
• Herbaceous, short-lived perennial (genus
  Fragaria) with a crown (compressed stem) that
  may branch
• Propagate by runners to produce daughter
• Two types
  – June-bearing (short-day) varieties initiate flowers in
    the fall and bear from May-June in the mid-Atlantic
  – Day-neutral varieties produce flowers throughout the
    season and typically bear three crops between mid-
    May and frost
                 Diseases to Avoid

                          • Viral and bacterial
                             – Clean, virus-indexed
                             – Avoid injury to plants
ringspot virus
                             – Control insects,
on strawberry                  including nematodes
(above) and
             Diseases to Avoid
• Soilborne fungal diseases
  – Verticillium wilt
  – Phythophthora diseases
     • Raspberry: Phytophthora root rot
     • Strawberry: Red stele, Phytophthora crown rot
  – Strawberry: Black root rot complex


Verticillium Wilt (V. dahliae)
Phytophthora Root
Rot – Raspberry
(6 species)

               Phytophthora Crown Rot – Strawberry
               (P. cactorum)

   Phytophthora Diseases
Red Stele – Strawberry
(P. fragariae)

                   Phytophthora Diseases
  Black Root Rot Complex – Strawberry

• Causes
  – Root-rotting soil fungi (Rhizoctonia,
  – Nematodes
  – Physiological stressors
     •   Soil compaction
     •   Drought
     •   Excess salt or water
     •   Improper soil pH
     •   Herbicide damage
     •   Fertilizer burn
     •   Winter injury
  Avoiding Soilborne Fungal Diseases
• Choose a favorable site
  – Excellent drainage, full sun, good air circulation, good
    soil structure (tilth), no frost pockets
  – No history of Verticillium wilt (5–10 yrs) or recent
    planting of susceptible crops (brambles, strawberries,
    tomatoes, peppers, eggplant, potatoes)
  – No history of Phytophthora or other root-rotting
  – No harmful nematodes or residual herbicides
  Avoiding Soilborne Fungal Diseases
• Construct raised beds to improve drainage
• Choose disease-resistant varieties where
   – Resistance to red stele and Verticillium wilt are
     available in commercial strawberry varieties
• Buy clean plants and inspect them before
• Avoid injury to plants and control insects that
  can cause wounds
  Avoiding Soilborne Fungal Diseases
• Test soil regularly for pH and salt levels
• When replanting strawberries or brambles, use
  crop rotation or fumigation to reduce populations
  of harmful nematodes and soilborne pathogens
• For established strawberry or bramble plantings,
  Ridomil Gold, Aliette, or phosphite fungicides will
  suppress Phytophthora diseases, but drainage
  improvement will be necessary for permanent
      Fungal Diseases to Manage
• Cane and foliar diseases
   – Powdery mildew
   – Raspberry: spur blight
   – Strawberry: leaf spot, leaf scorch, leaf blight
• Fruit rots
   – Botrytis fruit rot (also cane blight on raspberry and
     crown rot on strawberry)
   – Raspberry: late leaf rust
   – Strawberry: leather rot, anthracnose fruit rot


      Powdery Mildew (Sphaerotheca macularis)
                        Botrytis Cane Blight
                        (Botrytis cinerea)

Spur Blight
(Didymella applanata)

Cane and Foliar Diseases - Raspberry
Common Leaf Spot and              Leaf Scorch (Diplocarpon earlianum)
“Black Seed”
(Mycosphaerella fragariae)

                             Leaf Blight

               Foliar Diseases – Strawberry
  Managing Cane and Foliar Diseases
• Choose disease-resistant varieties
  – Resistance to powdery mildew and leaf diseases is
    available in commercial strawberry varieties
• Remove any wild brambles and wild (multiflora)
  roses within 500 to 1000 feet
• Promote rapid drying of plants
  – Plant rows in the direction of prevailing winds if
  – For raspberry, manage the canopy density (plant
    spacing, row width, and cane length) to speed drying
  Managing Cane and Foliar Diseases
• Avoid excessive nitrogen application
• Control weeds in the planting
  – Remove pest and disease reservoirs
  – Reduce drying time for plants
• If disease appears, use fungicides to stop
  spread and protect healthy plants
  Managing Cane and Foliar Diseases
            on Strawberry
• For carryover plantings, renovate beds after
  – Inspect and remove diseased plants
  – Remove leftover fruit and dead leaves
  – Mow leaves without injuring crowns
  – Bury or burn all plant debris
  Managing Cane and Foliar Diseases
            on Raspberry
• Prune only when necessary and in dry weather
• Practice good sanitation after harvest
  – For floricane-bearing (summer) varieties
     • Remove and destroy old fruiting canes and any diseased
     • In the spring, apply a delayed-dormant spray of lime sulfur at
       budbreak (no more than ¼” green)
     • When new growth begins, scout for and remove any
       diseased or winter injured canes
  – For primocane-bearing (fall) varieties, mow and
    remove all canes
      Fungal Diseases to Manage
• Cane and foliar diseases
   – Powdery mildew
   – Raspberry: spur blight
   – Strawberry: leaf spot, leaf scorch, leaf blight
• Fruit rots
   – Botrytis fruit rot (also cane blight on raspberry and
     crown rot on strawberry)
   – Raspberry: late leaf rust
   – Strawberry: anthracnose fruit rot, leather rot

     Botrytis Fruit Rot or Gray Mold (B. cinerea)
                                             Symptoms on
Galls on white spruce                        raspberry leaf
needles                                      and fruit

                Late Leaf Rust – Raspberry
                (Pucciniastrum americanum)
Anthracnose Fruit Rot
(Colletotrichum acutatum)
                                         Leather Rot
                                         (Phytophthora cactorum)

                    Fruit Rots – Strawberry
             Managing Fruit Rots
• Botrytis fruit rot (gray mold)
   – Sanitation!
      • Remove diseased raspberry canes and leaves in the fall
      • Remove all dead leaves and fruit from strawberry plants after

   – Avoid injuring plants, especially strawberry crowns
   – Apply fungicides to protect plants at critical periods:
     during bloom and before harvest
      • Start sprays at 5–10% bloom
      • In wet years, apply fungicides starting at 3–5 days preharvest
        on raspberry and from pink fruit onward on strawberry
           Managing Fruit Rots
• Raspberry – Late leaf rust
  – Remove wild brambles in 500–1000 feet, especially
    wild red raspberry
  – If early symptoms appear, apply fungicides (Rally 40
    WSP; alternate with Cabrio or Pristine)
• Strawberry – Anthracnose fruit rot
  – Buy clean, disease-free plants
  – Rogue infected plants promptly and remove all fruit
    after harvest
  – If anthracnose appears in a planting, apply protectant
    fungicides to healthy plants
           Managing Fruit Rots
• Strawberry – Leather rot
  – Choose a favorable site: excellent drainage and no
    history of Phytophthora diseases
  – Maintain a thick layer of clean straw between fruit and
  – Apply Ridomil Gold, Aliette, or phosphite fungicides
    only if disease is present
            Got a Question?

        Anne DeMarsay, Ph.D.
        Maryland Cooperative Extension
        2005 Largo Road
        Upper Marlboro, MD 20774-8508
        Phone: (301) 627-8440
Photo credits
APS Digital Image Collection, Diseases of Small Fruits
Dr. William Turecheck, USDA-ARS

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