Question: My large plant of pyracantha has fire blight. My plant is flaring up, one branch at a time. Nothing I have tried stops it. I cut off the affected branch, but the disease recurs. The leaves turn an odd red-brown and dry up on the plant. I have seen the same thing on azaleas here and on other broad leaf evergreens. Won’t you suggest treatment? R.J., Kentucky.
Answer: Fire blight is a bacterial disease indigenous to this country affecting plants of the rose family, and especially damaging to apple and pear trees. The pyracantha is likewise susceptible to this disease. The parasitical bacteria probably enter the stem through the flower at blooming time, being carried there by insects from diseased tissue. The bacteria moves along the stem with the sap stream killing the branch. If the destruction is extensive, cankers develop. The bacteria live over winter in these cankers from which they are liberated early in the spring. They are then picked up by the insects and introduced into the flowers. It would seem that the only effective remedy is the complete destruction of all diseased tissue. Not only should the diseased branches of the pyracantha be destroyed, but an examination of all adjoining plantings should be made to locate any source of infection from other shrubs or trees.
