Red Spots & Dead Leaves on a Pear Tree

Disorder Identification

• Pear trees are likely to be infested with the pear-leaf blister mite. The insects cause damage to pears in all the pear growing zones throughout the United States and Canada. Other host trees of the pest include the European mountain ash and apple. The pear-leaf blister mite is a native of Europe and has been seen in the United State since 1902.

Pest Description

• The adult pear-leaf blister mite is 1 inch or less in length and white to light red in color. The long body tapers near the rear. The entire body is covered with long hair and there are two pairs of legs near the head. The tiny, oval eggs are dull white and the younger, immature mites are similar to the adults but smaller in size.

Symptoms

• The pests infest the undersides of the plant buds during winter. This causes the buds to dry and fall during spring. The insects then move to new foliage and start feeding. This leads to the presence of sunken, oval, red spots ranging between ¼ to ½ inch in diameter on foliage undersides. Infested leaves gradually die. The pests lay their eggs in these blisters. The young mites hatch and start to feed within the blisters. New blisters are green in color and eventually turn red. The spots are not as red on apple trees as on pear.

Control

• Use resistant pear varieties to reduce chances of infestation. Though the use of preventative pesticides during the dormant season is highly recommended, avoid using pyrethroids, as these can lead to an increase in pest populations. Sulfur based products are recommended as organic control strategies. Chemical control options include the use of narrow-range oils and abamectin.