Blackwelder column: Quince rust a problem for Bradford pears

The disease makes its mark on leaves, twigs and fruit. Photo by Darrell Blackwelder, for the Salisbury Post.

Quince rust produces ugly orange pustules on fruit and the adjacent twigs and leaves. Photo by Darrell Blackwelder, for the Salisbury Post.

Bradford pears with quince rust will show discolored leaves. Photo by Darrell Blackwelder, Salisbury Post.

Many have called from all over the county over the past few weeks concerned about their Bradford pears.

Bradford pears and flowering cherry trees are having problems. Generally the only real problems with Bradford pears is limb breakage during wind and ice or an occasional problem with fire blight.

Fire blight is a bacterial disease on pear and apple trees that manifests itself with scotched or burned twig tips. It's a common problem with both ornamental and fruiting pear trees. There have been a few cases reported this spring, but it is not as widespread as it has been in past seasons.

On the contrary, quince rust has been a problem on the tree this spring. This is a fungus that produces orange pustules on fruit and the twigs adjacent to the infected fruit.

Newly formed leaves in the area of the fruit become discolored and die, producing a scattering of dead leaves throughout the tree. Even though this rust is not a new disease, it seems to be rampant this spring.

This disease has an alternate host, juniper (red cedar) that is also infected but is rarely noticed. Quince rust can be a problem when weather is extremely moist and warm as experienced earlier this season. Applications of fungicides may help the following year, but generally it is not warranted since the disease is not often fatal.

Another more serious problem with Bradford pears and other ornamental trees is stress. Many people called earlier this spring complaining their ornamental flowering cherry trees bloomed as normal and then suddenly died for no apparent reason.

Many ornamental cherry trees were severely stressed by the sudden cold snap from the unseasonably warm weather followed by the snow and then frigid blast. This may have been a major factor in the decline. Stress to flowering cherries and Bradford pears was also induced by the drought in 2007.

Stress induced deaths and decline are difficult to diagnose. Droughts, temperature extremes and excessive moisture are all factors contributing to the decline and eventual death of many trees. Flowering cherry and now Bradford pears seem to have fallen victim to seasons of unpredictable weather conditions.

Unfortunately, stressed trees are easy targets for insects and disease — nature's way of expediting death. Often, insects and diseases are blamed for these deaths, but often the real culprit is stress. Unfortunately, when trees become stressed and start to decline, they almost never recover.

Darrell Blackwelder is an extension agent in horticulture at the Rowan County North Carolina Cooperative Extension. Call him at 704-216-8970.

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