Arctic air won’t kill ash borer

Q. I have heard that there is a bright spot in this cold, arctic weather pattern. The below-zero temperatures will kill off the emerald ash borer that has been destroying our neighborhood ash trees. Is that possible?

James from Poland

A. I am afraid that our period of arctic weather will not be enough to wipe out the invading emerald ash borer. A period of extended subzero temperatures might slow the spread of EAB, but only a regular, prolonged winter of subzero temperature such as that found in extreme northern Minnesota would be expected to significantly affect the advancement of EAB.

The EAB larvae found under the bark of infected ash trees enter a pre-pupal stage to over-winter. As winter approaches, the larvae excavate a deeper chamber at the end of their tunnel. They take on a compact appearance, with body segments somewhat telescoped together. At this point they are called pre-pupae and remain as such until spring.

This pre-pupal stage has been shown to be quite immune from damage by temporary periods of sub-zero temperatures. For example, in recent studies, logs containing pre-pupae were held at -18 F. Only about 40 percent were affected by the extremely cold conditions.

So, cold temperatures may limit the potential for spread or damage from EAB in northern Minnesota where stands of ash are extensive. The likelihood of an especially cold winter in northeastern Ohio having a noticeable effect on the advance of EAB is unlikely.

To take a look at the “cool” research on the survival of this invasive pest and a map of where it will be killed most years, check out this factsheet: http://go.osu.edu/eabcold.

This week’s answer is provided by Bill Snyder, program assistant for agriculture and natural resources in Mahoning County. Call the OSU Extension hotline at 330-533-5538 from 9 a.m. to noon Mondays and Thursdays to submit your questions.