Pine wilt, caused by the pinewood nematode, was discussed in issue No. 4 of this newsletter. I have seen several cases of pine wilt in the Champaign-Urbana area in the last two weeks, so review the symptoms of this disease and watch for it on your pines. Trees dying now were probably infected in spring or summer.
Watch for the appearance of entire dead branches or the sudden decline and death of an entire pine within a few weeks or months of initial symptoms. Be particularly suspicious of 15- to 20-year-old Scotch pines with these symptoms. If white pine is affected, consider the information on white pine decline in issue No. 2 of this newsletter. Although the Plant Clinic has certainly assayed many white pines for pinewood nematodes, we have confirmed this nematode in only two cases involving a white pine. In both cases, we suspect that the nematode invaded after the tree died. Also, keep in mind that Austrian pine is the only species that may show a tip dieback as the first symptom of pine wilt.
Sawyer beetles vector the nematode from pine to pine. Unfortunately, we still do not have an easy method of stopping the beetle, and we do not have a treatment for an infested tree. Early detection of infected trees is therefore critical to disease control. To break the disease cycle, remove infected trees quickly. Consult Report on Plant Disease No. 1104 for details about pine wilt.