December 1A monthly e-newsletter from UMass Extension for landscapers, arborists, and other Green Industry professionals. To read individual sections of the message, click on the section headings below to expand the content: Hot Topics Looking for something for the gardener in your life? Send them a 2020 UMass Extension Garden Calendar! For many years, UMass Extension has worked with the citizens of Massachusetts to help them make sound choices about growing and maintaining plants in their landscapes, including ornamental plants, backyard fruits and vegetables. Our 2020 calendar continues UMass Extension's tradition of providing gardeners with practical information. Featured this year is info on the care and cultural needs of rhododendrons and azaleas, some of the most popular choices for landscape plantings. Go to umassgardencalendar.org to see images from this year's calendar, online ordering, the chart for bulk discounts, and a printable order form. As always, each month features: * An inspiring garden image. * Daily gardening tips for Northeast growing conditions. * Daily sunrise and sunset times. * Phases of the moon. * Plenty of room for notes. * Low gloss paper for easy writing. Questions & Answers Selected few insect pest questions and answers from the 2019 growing season Q: Could the aerial applications for mosquito control due to the incidence of EEE in Massachusetts negatively impact the population of Cyzenis albicans released as a biological control of winter moth (Operophtera brumata)? (September 17, 2019) A:. Cyzenis albicans is the parasitic fly that was released by Dr. Joseph Elkinton of UMass Amherst and his laboratory to manage winter moth caterpillars (defoliators of trees and shrubs in eastern Massachusetts). Aerial mosquito control applications that were made in August and September of 2019 in parts of eastern Massachusetts likely had little to no direct impact on C. albicans populations in these areas. First, given the life cycle and behavior of the parasitic fly, it was well protected during this time of year. Cyzenis albicans remains in its puparia inside the pupa of the winter moth, which is located in the upper layer of the soil or leaf litter once winter moth pupation occurs beginning in late-May/early-June. Parasitized winter moth pupae, containing the developing flies, will remain in this protected location until the following spring, when adult flies emerge to lay their eggs on foliage being fed upon by winter moth larvae. Dr. Elkinton agrees – the mosquito control applications and Cyzenis albicans missed each other not only in timing, but also in space. Additionally, the active ingredient used by the MA Department of Agricultural Resources for these applications, sumithrin, has a very short half-life (less than one day), which reduces the chance of unintended consequences for non-target insects. Half-life is the amount of time it takes for a certain amount of a pesticide to be reduced (broken down) by half. For more information about half-lives, visit: http://npic.orst.edu/factsheets/half-life.html. For more information about aerial applications for mosquitoes in Massachusetts, visit: https://www.mass.gov/service-details/mosquito-control-and-spraying. Q: I hope you can help me ID this caterpillar (?) found on my client's Eastern red cedar in Bristol County, MA. Photos are attached. (August 12, 2019) A: The species of insect included in your photos is likely Thyridopteryx ephemeraeformis or the common bagworm (also called the evergreen bagworm, eastern bagworm, or North American bagworm). These caterpillars develop into moths as adults. Their behaviors, life history, and appearance are interesting. The larvae (caterpillars) form “bags” or cases over themselves as they feed using assorted bits of plant foliage and debris tied together with silk. As the caterpillars feed and grow in size, so does their “bag”. Young, early instar caterpillars may feed with their bag oriented skyward, skeletonizing host plant leaves. As these caterpillars grow in size, they may dangle downward from their host plant, and if feeding on a deciduous host, they can consume the leaves down to the leaf veins. Pupation can occur in southern New England in late September or into October and this occurs within the “bag”. Typically, this means that the caterpillars could encounter a killing frost and die before mating could occur. However, in warmer areas of Massachusetts or if we experience a prolonged, warm autumn, it is possible for this insect to overwinter and again become a problem the following season. If the larvae survive to pupation, adult male moths emerge and are winged, able to fly to their flightless female mates. The adult male is blackish in color with transparent wings. The female is worm-like; she lacks eyes, wings, functional legs, or mouthparts. The female never gets the chance to leave the bag she constructs as a larva. The male finds her, mates, and the female moth develops eggs inside her abdomen. These eggs (500-1000) overwinter inside the deceased female, inside her bag, and can hatch roughly around mid-June in southern New England. Like other insects with flightless females, the young larvae can disperse by ballooning (spinning a silken thread and catching the wind to blow them onto a new host). While arborvitae and junipers can be some of the most commonly known host plants for this insect, the bagworm has a broad host range including both deciduous and coniferous hosts numbering over 130 different species. Bagworm has been observed on spruce, Canaan fir, honeylocust, oak, European hornbeam, rose, and London planetree among many others. This insect can be managed through physical removal, if they can be safely reached. Squeezing them within their bags or gathering them in a bucket full of soapy water (or to crush by some other means) can be effective ways to manage this insect on ornamental plants. Early instar bagworm caterpillars can be managed with Bacillus thuringiensis var. kurstaki (Btk) but this is most effective on young bagworms that are no larger than ¾ inch in length. As bagworms grow in size, they may also have behavioral mechanisms for avoiding chemical management. Management should seek to preserve any natural enemies that would be found attacking this insect, such as certain parasitic wasps. It is also important to note that the bags from dead bagworms will remain on the host plant, so check the viability of the bagworms by dissecting their bags to avoid unnecessary chemical applications. Historically in Massachusetts, bagworms have been mostly a problem coming in on infested nursery stock. With females laying 500-1000 eggs, if those eggs overwinter the population can grow quite large in a single season on an infested host. Typically, this insect becomes a problem on hedgerows or plantings nearby an infested host plant. Thyridopteryx ephemeraeformis is found from Massachusetts to Florida, and is typically a more significant pest in southern climates; however, this insect was problematic in many communities across Massachusetts during the 2019 season. Q: Any tips for managing the viburnum leaf beetle (Pyrrhalta viburni; VLB)? I am noticing differences in feeding damage depending upon the species of viburnum involved. V. opulus is just decimated by the beetle. However, the V. acerifolium, not so much. V. carlesii, V. plicatum, and V. burkwoodii are fine. (June 14, 2019) A: Viburnum opulus is known to be highly susceptible to VLB (viburnum leaf beetle) feeding. So your report about them being decimated unfortunately makes sense. V. acerifolium is thought to be “susceptible” (but perhaps not as favored as the aforementioned species). V. carlesii and V. plicatum are actually considered resistant to VLB. And finally, V. burkwoodii is only “moderately susceptible”, and in this ranking is just a step above those considered resistant. The following provides a good outline of susceptibility: http://www.hort.cornell.edu/vlb/suscept.html For management, some options include, but are not limited to: Use resistant varieties. Viburnums in locations where they are constantly defoliated by this insect, and thus dieback occurs, should probably be removed and replaced with resistant varieties. Otherwise, management will be a constant battle. If you have plants that are not being completely stripped season to season, and are known to be perhaps only moderately susceptible, there are some things you can do: Mechanical management options: after the first frost or over the winter, in small plantings the terminal ends of twigs can be pruned off and destroyed if overwintering viburnum leaf beetle eggs are found. Look for the eggs (in capped pits created by the female beetle) and be sure to remove enough of the twig so that every egg site is removed. This will help reduce the overwintering population. Chemical management options: When larvae are still present and feeding on foliage, the reduced risk active ingredient (AI) spinosad can be sprayed on the foliage; but do so when the plant is not in bloom, as this AI is toxic to pollinators until it dries. Other active ingredient options include but are not limited to: acephate, acetamiprid, carbaryl, dinotefuran, horticultural oil, and imidacloprid. Read and follow all label instructions for safe and proper use. Each active ingredient can have different risks toward applicator health and the environment. The following fact sheet summarizes some of these risks, but should not be used as a replacement for reading the label: https://ag.umass.edu/landscape/fact-sheets/tree-shrub-insecticide-active-ingredients-risks-to-pollinators-other-non Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program Trouble Maker of the Month Black knot of Prunus Black knot of Prunus, caused by the fungal pathogen Apiosporina morbosa, is a common and destructive disease in our region. The winter months present a good opportunity to scout for and prune infected stems from the canopy, when they are more readily visible. As the name indicates, the disease affects species in genus Prunus. In landscape settings, the most common hosts are plum, cherry and chokecherry. Infections develop on young and succulent shoots during the spring, but the symptoms are often not visible until the following year. The initial symptoms appear as irregular swellings on the stems, but these are easily missed without careful inspection. After one year, these infected areas develop into black, gall-like cankers, which are a mixture of fungal and host tissue. Cankers can girdle small stems outright or become perennial on larger branches. In some cases, basketball-sized galls develop over the course of many years. When advanced infections develop in the canopy, serious dieback occurs and trees can die. If detected early, cankered stems can be pruned and destroyed, but regular scouting is essential. Prune several inches away from the visible canker to ensure the pathogen is eradicated. With regular scouting and pruning, the disease can be controlled in many cases. Prunus should be planted in full sun to avoid the disease, as deeply shaded settings are conducive to fungal infections. For more images and further information about black knot of Prunus, see the following fact sheet at http://ag.umass.edu/landscape/fact-sheets/black-knot-of-prunus Nicholas Brazee, UMass Extension Plant Pathologist Plant of the Month Picea pungens, Blue Spruce Blue spruce, also known as Colorado spruce, is an evergreen tree with a conical shape. It has stiff horizontal layered branches that skirt the ground and decrease in length as they ascend the height of the tree trunk, giving the tree a symmetrical form. The needles are prickly, 4 sided, ¼ to 1¼ inches long and range in color from green to gray-green, blue-green, or silver blue. Needles point outward from the branches in all directions. Trees with blue or silver-blue foliage are generally more popular than trees with green foliage. Cones are light brown and cylindrical, and 2 to 4 inches long. Trees grow 30 to 60 feet high and 10 to 20 feet wide. Blue spruce is native to the mountain states of the west and is hardy to USDA zones 2 – 7. Blue spruce performs best on moist well drained soils and 6.0 to 7.5 soil pH. However, it can tolerate virtually any soil, but does not tolerate flooding or poor drainage. It is very tolerant of drought, but benefits from irrigation in dry summers. Blue spruce does best in full sun; dense shade results in bare branches. Blue spruce can be used singly as a specimen landscape plant or in group plantings as a screen or windbreak. Cultivars with blue or silver-blue needles are popular as specimen landscape plants. It is also often used for Christmas trees. Numerous cultivars have been developed, based on needle color and crown form. Available cultivars include: Fall Albert – has a wide pyramidal habit and excellent rich blue needle color Hoopsii – has a dense, pyramidal form and extremely glaucous blue needles Thompsenii – has glaucous silver-blue needles and symmetrical pyramidal habit. This is considered as one the best cultivars. Moerheimii – has rich blue needles, but tends to be more open in habit than other varieties Glauca Globosa – an excellent blue needled dwarf tree Potential Problems This tree has no serious insect or disease problems. Common diseases include Rhizosphaera needle cast, Cytospora canker, and Lirula needle blight. Common insect pests include spider mites, spruce needle miner, pine needle scale, yellow-headed spruce sawfly, and aphids. Geoffrey Njue, UMass Extension Sustainable Landscapes Specialist Upcoming Events Pollinators in Our Landscapes Conference February 26 - Bringing together stakeholders with shared concerns about pollinator health, habitat, and their future success and prosperity in Massachusetts and New England. Location: Doubletree Hotel, Milford, MA UMass Extension's Landscape, Nursery, and Urban Forestry Program seeks to encourage communication between Green Industry professionals including landscapers, land managers, arborists, licensed pesticide applicators, and other landscape practitioners with professional beekeepers, researchers, and state officials who share the common goal of maintaining and encouraging pollinator health in Massachusetts. The goal of this shared day of education is not only to hear about the latest research, but also to encourage further networking between diverse groups of stakeholders who share at least one common interest: pollinator protection. Topics to include native bees and pollinators, a review of steps applicators can take to reduce unintended negative impacts on these insects, management of residential yards and other urban green spaces for native bee habitat, recent research looking at the impact of sunflower pollen on diseases of pollinators, and the top 10 most practical actions you can take to protect our pollinators. CREDITS - Pesticide and Association credits pending. Registration and Additional Information Other Upcoming Events: 1/6-2/14 - Winter School for Turf Managers 2/19, 3/18, 4/1 & 4/15 - Invasive Plant Management Certification Program 3/10 - Community Tree Conference: Challenges and Opportunities for 2020 - What’s New in Arboriculture & Urban Forestry? 3/26 - Spring Kickoff for Landscapers: UMas Extension Landscape Education Day 10/26-12/10 - Green School For more information and registration for any of these events, go to the UMass Extension Landscape, Nursery, and Urban Forestry Program Upcoming Events Page. Additional Resources For detailed reports on growing conditions and pest activity – Check out the Landscape Message For commercial growers of greenhouse crops and flowers - Check out the New England Greenhouse Update website For professional turf managers - Check out Turf Management Updates For home gardeners and garden retailers - Check out home lawn and garden resources. UMass Extension also has a Twitter feed that provides timely, daily gardening tips, sunrise and sunset times to home gardeners, see https://twitter.com/UMassGardenClip Diagnostic Services A UMass Laboratory Diagnoses Landscape and Turf Problems - The UMass Extension Plant Diagnostic Lab is available to serve commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. For sampling procedures, detailed submission instructions and a list of fees, see Plant Diagnostics Laboratory Soil and Plant Nutrient Testing - The University of Massachusetts Soil and Plant Nutrient Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The function of the Soil and Plant Nutrient Testing Laboratory is to provide test results and recommendations that lead to the wise and economical use of soils and soil amendments. For complete information, visit the UMass Soil and Plant Nutrient Testing Laboratory web site. Alternatively, call the lab at (413) 545-2311.