Black Knot Disease Still Rampant But City Has Found a Promising Preventative

According to Jim Hole's newsletter, Reflect, Relax, Reconnect; the City of St. Albert has found a method which seems to be effective in preventing black knot disease.

Black knot disease has been responsible for killing many trees in the Prunus family, namely Schubert Chokecherry, Mayday, Cherry and Plum.  The disease appears as a black mass on the branches of any of the aforementioned trees and, if left unchecked, will spread through the tree.  If it girdles a branch, or worse yet the trunk, it will kill the branch/tree, respectively.  

As mentioned in my post, Fungal Alert - Black Knot on Local Schubert Chokecherries, if you find this disease on your tree, you must trim the branch back at least one foot below the infected area.  Then destroy the affected trimmings as the disease is air born and spreads easily.  Disinfect your pruning equipment thoroughly afterwards.

The city tree care team has been out trimming the Prunus trees and applying a dormant spray.  Why, you wonder?  According to Kevin Veenstra (City of St. Albert and a certified arborist), a spray of a combination of lime sulphur and horticultural oil helps protect the trees from the disease, stating that the trees they've sprayed remain disease free.

What wonderful news!  I wish I'd known or thought of this years ago when my Schubert Chokecherry had the disease.  Since we have moved, I no longer have that particular tree to care for, but you, my readers, can certainly benefit from this development!!

Please, give it a try.  Spray when there is no wind and the temperature is above zero but before the leaf buds begin to swell.  Let me know if you feel this makes a difference for your trees, please.  

*Warning, the lime sulphur does indeed smell like sulphur but the odour dissipates in time and exposure to fresh air.  ;}

**photos taken by myself and previously posted at Fungal Alert - Black Knot on Local Schubert Chokecherries.

Re: Black Knot Disease

black knot on local Schubert Chokecherry Trees

As per my previous post regarding Black Knot on Schubert Chokecherry Trees (prunus), I have confirmed with a horticulturist that it is not necessary to wait until the trees are dormant to prune out the disease.  Please, do it now.  Cut at least 8 inches below visible signs of infection, disinfecting your tools between each cut.  A 10% bleach or alcohol solution will kill traces of the disease.

For photos and more information on Black Knot see
http://shirley-agardenerslife.blogspot.com/search/label/black%20knot%20disease

If you see this in your municipality, feel free to contact the horticulture department so they may address the problem.

Fungal Alert - Black Knot on Local Schubert Chokecherries

To my dismay, my beloved Bailey's Schubert Chokecherry tree once again has evidence of black knot.  It is unfortunate that I have had to deal with this same fungus the previous two years, but it is now rampant throughout the neighborhood, including the trees planted by the city along the walkways.  Black knot presents itself as a black, crackled mass on a twig or branch.  It is a fungus, and, if left untreated, can girdle the branch or twig causing its demise.  Basically it strangles it.  The only way to treat this, is to remove the afftected limb by cutting about a foot below the diseased area and disposing of it in the garbage.  DO NOT compost it!  It is necessary to cut well below the infected area because the fungus can spread through the tissue beyond what is visible to the eye.  Be sure to use sharp tools, ie. pruners, lopper or saw,  and disinfect with a 10% bleach solution between each cut.

That is my task of the day, to remove and destroy and to contact the city and neighbours regarding their trees.