Written by: Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665.
White pine trees in many counties in northeast and northcentral Wisconsin have developed rusty-colored wilting needles on outer branch tips scattered throughout the tree’s crown. These dead branch tips are associated with the feeding by white pine bast scale. The scale is a tiny insect that inserts its straw-like mouthpart into the twig to suck sap from the outer layers of phloem called bast. Damage has been observed on trees over 20 feet tall this year.
Branch tips on this white pine indicate a problem with bast scale and the disease Caliciopsis. Photo Credit: Wisconsin DNR
Continue reading “White Pine Branch Tips Red And Wilting”
Written by: Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665.
Pear slug sawflies (Caliroa cerasi) feed by scraping off the upper layer of the leaf, leaving the veins and the lower leaf surface. Severe defoliation has been observed and reported recently on crabapple, apple, mountain ash and serviceberry in Oneida, Forest and Oconto counties. The first generation occurs earlier in the summer, so the larvae and defoliation seen now are due to the second generation of the insect, which is larger than the first generation.
Pear slug sawfly larvae feed by scraping off the upper layers of the leaf. Photo Credit: Wisconsin DNR
Continue reading “Pear Slug Sawfly Defoliation: Treatment Tips”
Written By: Todd Lanigan, DNR Forest Health Specialist, Eau Claire, Todd.Lanigan@wisconsin.gov or 715-210-0150
As we head into September, fall webworm is starting to make its presence known. This native insect feeds on deciduous trees and shrubs and appears every year in yards and forests. Fall webworm forms loose webbing over branch tips and can completely cover a small tree with webbing. You will find both live and dead caterpillars, partially eaten leaves and frass (caterpillar poop) inside the webbing.
Fall webworm larvae inside webbing. Photo Credit: Wisconsin DNR
Continue reading “Fall Webworm Is Active”
Written by: Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665
Oak wilt symptoms are active right now, but so are several other oak issues that may be mistaken for oak wilt symptoms. Issues including Tubakia leaf spot, Botryosphaeria canker, kermes scale damage and mite damage are all causing problems and may be mistaken for oak wilt.
Oak Wilt Leaf Symptoms
Trees in the red oak group (those with points on their leaves) that became infected with oak wilt in the spring will suddenly start to drop their leaves in July and August. Trees that were infected later in the high-risk period (April 15 – July 15 in northern Wisconsin) may start to drop their leaves later, in September or even into October.
Leaves dropping from oak wilt trees can be fully green, tan or a water-soaked, greenish color away from the petiole (leaf stem). There will often be an area that is still green near the petiole, even though the leaf has fallen to the ground. Wilting leaves typically start near the top of the tree and progresses downwards.
Recommended control measures depend on if you have just one tree actively wilting (and no others have died in past years) or if you are dealing with established pockets that have been present for more than a year. Contact your regional forest health specialist to discuss these control options if you think you have oak wilt.
Leaves dropping from trees dying from oak wilt often are brown or water-soaked on the outer portions of the leaf with green still found near the base of the leaf. Photo Credit: Wisconsin DNR
Continue reading “Oak Leaves Turning Brown? There Are Several Reasons This Year.”