Fireblight Causes Problems with Fruit Trees if Missed Earlier

 Q. I came back from vacation and my ‘Gala’ apple tree branch was dead.  The tree also has some black spotting under the bark. I'm hoping it's not damage from fire blight. 

Both pictures are fire blight in 'Gala' apple tree with an older infection. As this reader suggested, the earlier symptoms were not noticed and the bacterial disease has now invaded the trunk. Most likely the trees will either die or may serve as a host for further infection of trees. 

A.  I looked at the picture you sent of your fruit tree, and it looks like older fire blight disease that escaped earlier detection and is now in the trunk of your tree.

Fire blight is a serious disease that is highly contagious for many apples. It’s more damaging to some apples like ‘Pink Lady’ than others such as your ‘Gala’.  It’s particularly damaging to all Asian pears.  It can be damaging to some European pears, like ‘Bartlett’ and others, such as ‘Keiffer’, it doesn’t seem to affect much here.

This is fire blight disease on a recently planted 'Bartlett' pear. Sometimes this disease can come in on nursery plants from "dirty" growers.

It is damaging to some ornamentals like pyracantha and some cotoneasters in the rose family. The varieties of these plants may show differences. It just depends on the genetics of the plant combined with the genetics of the disease.

When I saw this disease in the spring it was heavily into Asian pears, some European pears and many apples and quince. What gave it away then was the early spring growth, which was black, hooked and had the presence of sap.

Fire Blight control is normally through removal of the infected limbs 10 to 12 inches below where the infection is seen.

What gave it away to me now are the dark cankers (black spotting) on the trunks of your trees and also the presence of sap.  The “sap” is what is contagious and can cause it to spread.  The dark cankers are probably from earlier fireblight infestations. Once this particular disease gets into the trunk the tree usually dies.

If the tree continues to look bad or worsens, I would cut these trees down and get the pruning off of the property. You cannot use this wood for wood chips or anything near plants or it can reinfest susceptible plants.