Utah Plant Pest UTAH PESTS Diagnostic Laboratory USU Extension Summer 2021 QUARTERLY Vol. XV NEWSLETTER IN THIS ISSUE Research Efforts to Curb Cold Temperatures Injured Utah Trees Balsam Woolly Adelgid Box Tree Moth: A New Invasive Pest Feeding by this Abiotic Problems of non-native insect Tomato causes swellings (gouting) on fir twigs. Spittlebugs in Utah Health Management William M. Ciesla, Forest International, Bugwood.org No 17-year Cicada Guest authors Liz Rideout and Grayson Jordan are each pursuing a M.S. degree at “Plague” in Utah USU, and researching balsam woolly adelgid. Liz is in the Dept of Biology, under Diane Alston, and Grayson is the Dept of Wildland Resources, under Justin DeRose. – But We do Have Cicadas! True firs are important high-elevation trees Close-up of an that are threatened by numerous stressors. adult adelgid, Bee Assassin Bug Adding to the list of stressors is the balsam showing body Predating on BMSB woolly adelgid, a small plant-feeding shape (normally insect that was discovered in northern Utah covered in cottony IPM in the News in 2017. USU research is investigating the wax). Its length is a adelgid life cycle, host susceptibility, and little over 1 mm. site factors to predict outbreaks. NEW MEDIA primary host in Utah), with differing levels of Backyard Garden - Balsam woolly adelgid (BWA) has been a intensity. The ubiquity of fir in mountainous pest of eastern North American firs for over areas of the Intermountain West may allow Tomato Pests and Leafy a century, initially found attacking balsam Greens Pests for continued spread of BWA. True firs are fir in eastern Canada and Maine. Native to important sources of food and shelter for southern and central Europe, it is believed high-elevation wildlife, and in mixed stands, High Tunnel Pest to have been introduced on nursery stock. they provide diversity in the event of pine or Management - Aphids By 1960, populations were established spruce beetle outbreaks. along the east and west coast regions of the Powdery Mildews on U.S. and Canada, likely from independent Identification and Symptoms Vegetables introductions from Europe. During the adelgid’s initial spread in the 1960s and In its native European range, BWA has a Quagga Mussel and 70s in the Appalachian Mountains, Fraser complex life cycle alternating between Zebra Mussel fir populations declined by 80%. spruce and fir host trees, causing very little damage to these trees due to their BWA are found on bark, feeding on plant long evolutionary relationship. In North cells (parenchyma) of all members of the America, only asexual reproduction occurs, Abies genus including balsam fir, Fraser and tree damage has been severe. fir, grand fir, white fir, and subalpine fir (its continued on next page Balsam Woolly Adelgid, continued UTAH PESTS TEAM In the heaviest of infestations, matrices of white, woolly masses of adelgids occur along the Diane Alston tree bark, branches, and twigs. Toxins in the adelgids’ saliva cause swellings (also known Entomologist as gouting) along the nodes of young branches. Extended feeding leads to dieback and Head, Dept. of Biology flagging of branches, and tree death may occur within five years of initial infestation. Asexual [email protected] reproduction creates BWA offspring that are nearly genetic clones of the parent, increasing the 435-797-2516 likelihood of pesticide or environmental resistance that can be passed on to the next generation. Marion (Mair) Murray Evidence suggests that fir species have differing levels of resistance, and a better understanding IPM Project Leader Utah Pests News Editor of this is needed as BWA continues to colonize white and subalpine fir in Utah. In addition, [email protected] BWA is difficult to detect during early establishment, and rates of establishment can vary. 435-797-0776 Learning its adaptability to gradients of climatic conditions is essential. Claudia Nischwitz Research at Utah State University Plant Pathologist [email protected] With funding from USDA Forest Research and Development, 435-797-7569 researchers at Utah State University and the US Forest Service-Rocky Mountain Research Station are conducting Ricardo Ramirez several studies in the Intermountain West, including: Entomologist [email protected] • Improving understanding of BWA’s seasonal 435-797-8088 phenology (development) on subalpine fir: We Zach Schumm are sampling stands in northern Utah with a range of Arthropod Diagnostician elevation and site characteristics for BWA presence [email protected] and intensity. We will collect bark samples to count 435-797-2435 and identify adelgid life stages. • Providing predictions for risk of spread and Lori Spears establishment: We will lab-rear BWA at USU Prof. Practice Associate Prof. to identify the minimum temperature at which USU CAPS Coordinator development begins. From this, we will generate a [email protected] model to use in combination with local climate data 435-797-0354 to provide insights to timely management of BWA in Utah’s subalpine fir forests. Nick Volesky Vegetable IPM Associate • Developing a rating system that can be used by Bark samples are removed from [email protected] stakeholders to assess the risk of BWA in their 435-797-0319 stands: Through an interagency effort, we have the tree and a photo is taken identified sites across northern and central Utah weekly of the tacked square to and southern Idaho where BWA and associated track "woollies" (woolly masses Utah Plant Pest damage are present. For each stand, we will produced by the adelgids) over Diagnostic Lab collect assessment data such as composition of tree time. BNR Room 203 species, sizes, ages, and health, elevation, and soil Utah State University type. On individual fir trees within each stand, we will also record BWA symptoms such 5305 Old Main Hill as crown flagging, extent of dieback and gouting, and level of bole infestation. Stand Logan, UT 84322 characteristics that appear to contribute to susceptibility, spread, and damage will be identified and quantified. Individual variables included in the rating system may be used to identify areas of concern within stands (such as structure or average size) and guide To subscribe, click here. preventive or responsive treatments to balsam woolly adelgid. All images © UTAH PESTS and USU Extension unless Die-off in fir stands contributes to ecosystem decline including increased erosion, loss of forage otherwise credited. and habitat for wildlife, and declines in watershed quality and forest resilience. Losses may also affect tourism, in particular, in Utah’s ski industry where subalpine fir is common along ski slopes. Stakeholders in various organizations such as the USDA, the US Forest Service, and USU are coordinating efforts to monitor and study BWA’s potential spread and impact in Utah. Our study results will help support forest management agencies and landowners in timely and specific extension.usu.edu/pests management practices based on site characteristics. Utah Pests Quarterly Newsletter / Summer 2021 / page 2 GENERAL IPM INFORMATION Cold Fall Temperatures Injured Many Northern Utah Trees On the morning of October 26, 2020 in northern Utah, Average temperatures (F) for weather stations in after temperatures during the day averaged 70 to 80°F northern Utah counties, and the drop in temperature and at night from 40 to 50°F, the temperature dropped to from the daytime high on October 25 to the low well below freezing. At that time, trees were still fully leafed temperature on October 26. out and were not fully dormant. The cold snap resulted in tree damage that was not visible until spring, in the form of dead flowers on fruit trees, and injured vascular tissue on Oct. 25 Oct. 26 other trees, causing dieback of the outermost branches, or high temp low temp Temp drop complete death of the above-ground portion of the tree. County (4 pm) (6 am) in 14 hr Box Elder 48 15 33 Tree Acclimation to Cold Temperatures Cache 49 10 39 Davis 47 17 30 The process of trees becoming dormant is a gradual one that starts in late summer and concludes in late fall. Over Juab 49 8 41 this time period, trees become the most cold-hardy when Utah 47 11 36 they experience temperatures that cool slowly but steadily Weber 47 17 30 with few swings from warm to cold. This prolonged slow- cooling is required to promote starch degradation into cold-protectant proteins and sugars which protect against of acclimation, resulting in maximum cold tolerance, is ice formation in cells. initiated by exposure to temperatures approaching 0°F. Shorter day-length triggers the first step to acclimation, Daytime temperatures during early fall 2020 were warm, called a pre-conditioning period, where above-ground and were followed by mild evening temperatures, creating growth ceases, chlorophyll is lost, and leaves change a prolonged pre-conditioning period, leaving trees colors. Warm daytime temperatures (60 to 70°F) and non- susceptible to injury during a cold snap. The table above freezing evening temperatures (ideally, 40°F) accelerate shows the drop in temperature for several northern Utah acclimation during this phase. The second stage of counties, with many locations having a shift of 30 to 40 acclimation further increases cold-hardiness and occurs at degrees from the daytime high on October 25 to the low colder evening temperatures (23 to 27°F). The final stage temperature that occurred around 6 am on October 26. continued on next page extension.usu.edu/pests Utah Pests Quarterly Newsletter / Summer 2021 / page 3 Cold Injury and Trees, continued This fast-cooling swing contributed to the severe damage • Fertilized trees are more vulnerable to frost damage by interfering with starch degradation, freezing cell-water because application of nitrogen fertilizer in late contents, and leaving trees susceptible to cold injury.