Pear trees are cold tolerant, deciduous, fruit bearing plants native to Asia, Africa and Europe. Medium sized, growing 30 to 40 feet in height, pear trees produce oblong, green fruit, and pollinate and propagate in a very similar manner to that of apple trees. Pear tree diseases are either fungal, bacterial or viral in origin and can severally damage the tree's overall health and fruit bearing productivity.
Stony pit is a viral disease found in host scion wood and spread to other trees through grafting. Stony pit disease is identified by dark-green spots forming on the pear fruit. The dark green spots stop growing and the areas adjacent to the spots continue growing. This uneven growth causes a misshapen, tumor-ridden surface on the pear fruit. Infected trees should be removed. Prevention of stony pit requires grafting of disease free host trees.
Fire blight is a bacterial disease that can kill blossoms, limbs and entire pear trees. Outbreaks occur sporadically in the mid-Atlantic states and vary tremendously in intensity based on local environmental conditions and specific pear tree varieties. Fire blight is initially identified by dark, depressed areas of bark forming on the trunk. Smaller dark spots then form around buds, blossoms and branches. Removal of infected trees is the best way to prevent spreading.
Fabraea Leaf Spot
Fabraea leaf spot is caused by a fungal spore and manifests itself initially as small, round, purplish-black spots occurring on the fruit, leaves and shoots. The spots eventually cause the fruit, leaves and shoots to fall off prematurely. All pear trees of European descent are susceptible to Fabraea leaf spot. Preventive fungicides can be applied on pear trees in June and July in the eastern United States.
Pear scab is a fungal disease that causes brown lesions on the skin of pear tree fruit, ultimately making the fruit deformed and rotten. Pear scab is less common in the United States and more common in Europe and Japan, where the disease can spread quickly and ruin entire pear tree orchards. Fungicides can be used to prevent future infestations and mitigate the effect of an established outbreak.