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Asian Pear Diseases

By Cayden Conor ; Updated September 21, 2017
Healthy pears hang on the tree, ready for picking.
Pears on a tree image by walentyna from Fotolia.com

The Asian pear is crispy and is good to eat as soon as it is harvested. It lasts for months, if kept in cold storage immediately after picking. The Asian pear retains its crispy features--it does not soften like European or Bartlett pears. They are often called "apple pears" because of this feature. While Asian pears have been cultivated for years in Japan, they have only been cultivated in the United States since 1984, according to Purdue University. They are mostly grown in California, with a few plantings in Washington and Oregon.

Fire Blight

Fire blight (Erwinia amylovora) is the same disease that affects apples. It is often known as apple blight or pear blight. Fire blight commonly affects Bartlett, Bosc and D'Anjou pears. According to West Virginia University, all Asian pears, except the cultivars Seuri, Singo and Shinko, are extremely susceptible to fire blight. Fire blight can be controlled with streptomycin sprays, but are only effective if applied on the day of the infection, or the day before. To determine when an infection might take place, monitor the temperature. If you have more than 200 hours at more than 65 degrees F, then a rain or heavy dew, a blossom infection could be triggered.

Bacterial Leaf Spot

Two types of bacteria cause bacterial leaf spot: Pseudomonas causes reddish-brown spots and Xanthomonas causes brown spots. Pseudomonas causes the pear leaves to distort and Xanthomonas' spots are angular or circular and have yellow halos. Both types of bacteria can cause dead spots in the foliage and fruit, and both are capable of causing cankers on the stems. Both types of bacteria enter the tree via an injury to the tree. The injury could be from tools, insects or another disease. The only control of bacterial leaf spot is sanitation. Remove dead and decaying branches and other foliage from the tree. Remove fallen foliage and fruit from under and around the tree. Be careful when working near the trees, so that weed eaters, ladders and other equipment does not damage the tree.

Pear Scab

Pear scab is another disease that commonly affects both pears and apples. Sometimes known as apple scab, it is caused by the Venturia pirina fungus. The disease overwinters in infected plant debris, so all pruning and fallen debris must be cleared from under the tree. Pear scab symptoms include sooty spots that have a velvet look on early fruit, stems and flower petals. The fruit drops or is misshapen. It causes older fruit to crack. Pear scab continues to grow until dry weather or fungicides are sprayed. According to Oregon State University Extension, applying dolomitic lime after the leaves drop in the fall helps to control a spring outbreak of pear scab.


About the Author


Cayden Conor has been writing since 1996. She has been published on several websites and in the winter 1996 issue of "QECE." Conor specializes in home and garden, dogs, legal, automotive and business subjects, with years of hands-on experience in these areas. She has an Associate of Science (paralegal) from Manchester Community College and studied computer science, criminology and education at University of Tampa.