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Nursery & Forest
Volume 56 Number 18 Date 08/25/2011 LACE BUG - Hawthorns and burr oaks in a Jefferson County nursery were severely damage by this pest. The lace bug family/group consists of at least 27 species that feed on deciduous trees and shrubs. Most exhibit specific host preferences. The hawthorn lace bug, for instance, feeds exclusively on hawthorn. Damage begins as whitish-yellow leaf stippling that progresses to bronzing and early leaf drop under heavy lace bug pressure. Other signs of infestation include dark, varnish-like excrement and cast skins that appear on the undersides of leaves. Injury is often most noticeable from mid- to late summer. Heavy lace bug feeding can reduce the aesthetic quality of trees, but does not normally harm the tree. POPLAR AND WILLOW BORER - Nursery inspectors report that new adults have begun emerging in Dane County nurseries, where extensive damage to quaking aspens was noted in the past week. Preventive treatments should be applied while the weevils are active, either now or in early spring. Damage from this pest is primarily caused by the wood-boring larvae, which excavate long galleries in alder, birch, poplar and willow trees, expelling sawdust from the tree as they feed Larval tunneling girdles trees and results in cracking and breakage. Attacks are most common in stems 2.5 to 10.0 cm in diameter. All nursery stock infested with this borer must be removed from sale and destroyed. OAK TATTERS - Oaks in the white oak group, including white, burr and swamp white, in a Dane County nursery were showing lacy, tattered leaves characteristic of this disorder. Some of the affected leaves were also smaller in size and lighter in color than normal foliage. Oak tatters appears at leaf emergence and many affect all sizes and ages of trees The specific cause is unknown, although environmental stress and herbicide drift have been implicated. Most oaks eventually produce a new flush of healthy replacement leaves. Adequate watering, mulching and fertilizing are all recommended to minimize tree stress and reduce the incidence of tatters. --Liz Meils, DATCP Nursery Inspector 
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