Pest Activity -- March 16, 2007

Pest Activity > March 16

Welcome to the Woody Ornamental Pest Scouting Report for Western Pennsylvania brought to you by Penn State Cooperative Extension. This report is updated weekly with growing degree day counts and insect activity through the end of June. If you would like an email copy of this report, send your request to mcm2@psu.edu.

As of March 14, the following growing degree days with a base temperature of 50 degrees have accumulated.

Uniontown	17
Pittsburgh	14
Wexford	11
Butler	7

Pest Activity

Winter Injury

I have noticed several hemlocks in the City of Pittsburgh exhibiting winter injury symptoms. The injury is also called winter drying, winter desiccation, or winter burn. This injury usually occurs during midwinter or early spring when water is lost from the needles and cannot be replaced in sufficient amounts. As a result, needles turn brown and often fall from the tree as temperatures start to warm in the spring. Those needles that do stay on the tree are likely not to recover their green color. Rapid fluctuations in temperature, extremely low temperatures, and very windy conditions may increase winter injury on conifers. Injury is most severe on the south side of the tree where exposure to the warm sun is greatest and on the side that receives most of the prevailing, drying wind. Browning of the foliage is usually restricted to areas above the snowline. Some needles and branches will be lost, but most buds on the affected branches will develop normally. In many cases, needle discoloration and loss due to winter injury cannot be prevented. However, there are few methods to help reduce the extent of injury in conifers. Mulching around the base of the tree will help hold in heat and prevent deep freezing around the tree. Well-drained, aerated, and fertile soils will help to improve tree vigor and thus a greater likelihood of keeping winter injury to a minimum. source: Michigan State University

 

The next scouting report will be on March 23, 2007 .