Please see the latest edition of the Central States Forest Health Watch newsletter attached and at the link below. This is assembled by one of our Forest Pathologists, Linda Haugen, and although specifically targeted for Illinois, Indiana, Iowa, and Missouri, I believe there are topics of relevance to all Midwest states.
FACTSHEET: Commitments to strengthening America's natural resources and supporting green infrastructure. “A series of private and public sector commitments that will improve the management of our natural resources in the context of a changing climate and support investment in green infrastructure.”
Have you noticed the browning of the usually green Pine and Spruce trees? It frequently starts at the top of the tree and moves downward until there's no green left.
The most likely culprit is the Ips Pine Engraver, a bark beetle that lives predominantly in the inner bark, where they breed and feed on phloem tissue. Trees successfully colonized by Ips Engravers are killed by adult and larval feeding on the phloem (which can girdle the tree) and by colonization of the sapwood with blue-stain fungi that the beetles introduce. The blue-stain fungi spread into the xylem and block water flow, serving to hasten tree mortality (Connor & Wilkinson 1983, Kopper et al. 2004.
IPS beetles usually colonize only trees that are already stressed, declining, or fallen due to other environmental or biotic factors. They are attracted to fresh pine odors and readily colonize cut logs. Infestations may occur in response to drought, root injury or disease, timber management activities, lightning strikes, or other stresses. They sometimes occur in association with attacks by D. frontalis (Pine bark beetle), or D. terebrans (Black Turpentine beetle) (Anderson & Anderson, 1968, Lovelady et al. 1991, Miller 1983). When populations of Ips beetles are exceptionally high, they can overcome the defenses of apparently healthy trees by attacking them in large numbers.
Ips beetles can infest any Pine species within their range, and occasionally other conifers such as Spruce, and Fir, which has been verified in the Northwest Region of Missouri. Last year’s drought probably set them up for this.
It has been thought that once infected, a tree can’t be saved. However, in the NW Region, it has been found that, if treated soon enough, an infected tree can be saved. When an attack of Ips was identified on a White Pine in the area, it was treated instead of removed, and it survived the attack. Without treatment, it would be dead. In another instance, an egg-shaped section of the tree was dying, and the problem was identified as from an Ips beetle attack, but only after treatment stopped it.
Control of Ips can be obtained by treating infected trees with pointer injections, or imidicloprid as soil drench or soil injection. A basal treatment with Safari and a bark penatrent will also work. In case of concern, pre-treatment by a Certified Arborist is recommended.