Website: pddc.wisc.edu

Brian Hudelson reported a surge in diagnostic activity over the past two weeks, with a wide range of diseases affecting herbaceous ornamentals, woody plants, fruits, and vegetables. Below is a categorized summary of notable diagnoses:

Herbaceous Ornamentals

• Hosta, Heuchera, Phlox: Diagnosed with Anthracnose (Colletotrichum spp.), characterized by (at the microscopic level) ruptured epidermis and spore masses with black “eyelash” hairs.
• Phlox: Also showed Powdery Mildew.
• Amaranth: Diagnosed with Pythium root rot; grown as a fresh cut flower by organic producers.
• Zinnia: Confirmed Bacterial Leaf Spot (Xanthomonas sp.).
• Iris (German Bearded): Soft rot suspected to be initiated by Iris borer, though no larvae were found.
• Hosta (additional case): Southern Blight (Agroathelia rolfsii).

Conifers and Needled Ornamentals

• Larch: Diagnosed with Larch Needle Cast (Mycosphaerella laricina).
• Various conifers: Browning of needles possibly due to root rot or water stress.

Deciduous Trees and Shrubs

• Oak:
  • Smooth Patch (Aleurodiscus oakesii): Non-pathogenic bark disorder.
  • Anthracnose, Tubakia Leaf Spot, Monochaetia Leaf Spot: Common foliar diseases.
  • Two-lined Chestnut Borer: Insect damage misdiagnosed as oak wilt.
  • Chlorosis: Widespread, especially in stressed trees.
• Lilac, Smokebush: Diagnosed with Verticillium Wilt.
• Redbud: Suspected cold injury; no disease confirmed.
• Birch, Beech, Serviceberry: Chlorosis observed; soil testing recommended.
• Catalpa: Under investigation for Verticillium Wilt.
• Ohio Buckeye: Orange bumps on fruit diagnosed as Edema, not rust.
• Callery Pear: Confirmed Fire Blight (Erwinia amylovora).

Vegetables and Fruit Crops

• Grapes:
  • Black Rot (Phyllosticta ampelicida): Leaf spots and shriveled fruit with fruiting bodies.
  • Sour Rot: Caused by yeasts and certain fungi; noted for fermented odor.
• Plum: Diagnosed with Black Knot.
• Strawberries: Root and Crown Rots (Phytophthora, Rhizoctonia); commercial grower affected.
• Asparagus: Diagnosed with Phomopsis stem blight; stems covered in fruiting bodies.
• Cucumbers: Anthracnose (Colletotrichum orbiculare) with irregularly-shaped lesions.
• Pumpkins: Confirmed Bacterial Wilt (Erwinia tracheiphila) via molecular testing.
• Snap Beans: Confirmed Halo Blight (Pseudomonas savastanoi pv. phaseolicola), despite resistant variety.
• Cole Crops: Multiple Root and Crown Rots (Phytophthora, Pythium, Rhizoctonia, Fusarium) in low-lying areas of fields.