Botanic Garden >> Gardening > >> Question and Answer >> Plant Diseases

Black Knot on Plum: A Serious Fungal Disease

Hard Black Swellings on Plum Branches? It's Black Knot

Black knot forms rough, black galls that can girdle and kill branches. Prune 2–3 inches below galls during dormancy. Destroy prunings. Fungicides (lime sulfur, copper) help but sanitation is key. See Cornell resources.

Plant Diseases: Premature Fruit Ripening and Drop in Plum Trees: Environmental Causes; Plum Tree with Jelly-Like Sap: Borer Infestation; Victoria Plum Maggots: Plum Moth, Preventive Spraying Required; Plum Curculio and Codling Moth Control on Fruit Trees: Spinosad Option; Preventing Plum Tree Fruiting with Growth Regulators; Wild Persimmon Fruitlessness: Dioecious Nature and Late Frost; Stratifying Plum Seeds for Germination; Black Knot on Plum Trees: Fruit Safety and Disease Management; Preventing Fruit on Ornamental Plum Trees with Hormone Sprays; Plum/Cherry Black Knot: Prune Out Knots in Winter, Few Fungicides Work

Garden Articles

Bark Splitting and Sap Flow in Fruit Trees and Maples: Sunscald Management

Black Spots on Trees in Wet Area: Need Better Photo

Black Knot on Ornamental Plum: Organic Atomic Grow Treatment

Leaf Spots on Young Black Walnut: Harmless Fungi or Galls

Sooty Mold on Foxtail Palms: Caused by Scale or Aphids

Growing Tropical Fruit Trees from Seed in Canada – Challenges

Stop Purple Leaf Plum Fruit Production with Florel Spray

Plants

Ants on Cherry Trees: What They're Really After

Peach Tree Sudden Leaf Drop: Check for Cold Shock

Citrus Sooty Mold from Aphids: Indoor Winter Infestation Recovery

Filamentous Lichens on Trees in Western NC: Harmless Epiphytes

Blue Plum Fruit Rot: Brown Rot Disease

Plum Tree Brown Rot: Sanitation and Fungicide Timing

Plum Fruit Drop: Water, Pollination, or Fungus?