Education & Awareness
BLACK KNOT OF CHERRY
"Inspect your trees"
Black Knot occurs naturally and is caused by a fungus, Dibotryon morbosum. It is a widespread and serious problem in this area. The disease infects Mayday, Chokecherry, Pin Cherry and members of the Prunus family, and can lead to the eventual death of the tree if proper control measures are not taken. The disease becomes more serious with each growing season.
The disease is very visible this time of year. Thickened, black knotty material is seen on twigs, branches, fruit spurs, and occasionally on the trunk. These knots continue to grow each season, eventually killing the branch, by restricting water and nutrient flow.
The best defence is to begin with resistant varieties. Check your local garden centre for recommendations. The first step in disease control is eradication. Prune out all knots and signs of infection as soon as they are 
noticed. Make pruning cuts at least 8 inches below the swollen, black area. To prevent spreading of the fungus, dip pruning tools in a 10 percent bleach solution between cuts. Destroy infected branches by burning or complete disposal. Trees that are completely infected should be removed and burned to avoid spreading infection. Keep trees healthy by providing adequate moisture and nutrients.
Do not place infected plant material in the yard waste pickup, composter or use as mulch or firewood.