Pests & diseases › Black Knot
Black Knot
Distinctive black warty galls on plum and cherry branches. Looks like burned dog poo wrapped around the wood.
Symptoms
- Hard black corky swellings encircling branches
- Galls grow each year, eventually girdling and killing branches
- Spreads tree to tree on wind-blown spores
Lifecycle
Fungal — spores released in spring during wet weather.
What to do
- Prune out all galls 4+ inches below the gall, well into clean wood
- Disinfect tools between cuts
- Burn or bag prunings (NEVER compost)
- Copper sprays during dormancy
If it's bad
- Chlorothalonil during early shoot growth
Stop it coming back
- Remove wild plum, chokecherry trees within 500 feet (reservoirs)
- Resistant plum varieties: President, Shiro, Santa Rosa, Methley
- Annual inspection in late winter before leaves emerge
Crops it goes for
Plan the plot, track every sowing, cook the harvest
Sowing reminders and harvest forecasts for your own frost dates, the Seed Tin, Scan Centre for any label or packet, and the Potty Mouth Garden Club. Free to start.