Hort Notes 2021 Vol. 32:9

Jumping Worm Conference - January 26 & 27, 2022

When: Wednesday, January 26, 2022 - 9:00am to 11:45am

   Thursday, January 27, 2022 - 9:00am to 11:45am

Where: Live via GoToWebinar

Are you a land manager and have been receiving requests for more information about so-called "jumping/snake worms"? Are you a homeowner who is looking to learn more, ask questions, or perhaps you just found jumping worms on your property in 2021? No matter who you are, if you are curious or concerned about jumping/snake worms, this conference is for you!

Join UMass Extension as we welcome scientists who specialize in jumping/snake worm research to discuss the latest understanding of these earthworms. How to identify jumping/snake worms, what their potential impacts are, and the latest research into how we might manage them to be discussed. These LIVE virtual presentations will also give you the chance to get your questions answered following each speaker's presentation. So, bring your questions!

Click here for the full agenda and registration options.

Credits: Pesticide - 1/2 contact hour PER DAY for categories 29, 35, 36, 37, and Applicator’s (core) License. Association - 1 MCA, 1 MCLP, 1 MCH, and 1 CFE credit PER DAY. ISA and SAF credit requested.

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New InsectXaminer Video - Spotted Lanternfly

InsectXaminer ia a free short video series highlighting the incredible world of insects! Join UMass Extension as we observe these incredible organisms and look into a world that, while it happens all around us, sometimes goes unseen.

An established population of spotted lanternfly (SLF) was recently confirmed in Fitchburg, MA in 2021. Do you know what to look for right now and where to report it? Until your area experiences the first couple of hard frosts in Massachusetts, keep your eyes open for SLF adults. You can also search for egg masses, which is how these insects overwinter. Check out Episode 5 - Spotted Lanternfly (Lycorma delicatula). This episode highlights the identification of the adults and egg masses of this insect. An episode highlighting the immature (nymphal) stages of spotted lanternfly will be produced separately, once nymphs are again available for filming. 

Think you've seen the spotted lanternfly in Massachusetts? Please take a photo or collect a specimen and report it immediately here. 

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Show your clients you appreciate their business this year with a 2022 UMass Garden Calendar

Special pricing is available on orders of 10 copies or more to a single address (price per single copy is $14) - see our pricing chart.

UMass Extension works with the citizens of Massachusetts to help them make sound choices about growing, planting, and maintaining plants in our landscapes, including vegetables, backyard fruits, and ornamental plants. Our 2022 calendar continues UMass Extension’s tradition of providing gardeners with useful and practical information. Many people also love the daily tips and find the daily sunrise/sunset times highly useful!

Did you know planting the right trees can encourage more caterpillars that in turn support birds? The 2022 Garden Calendar's featured article is Keystone Plant Species for Caterpillars. While gardeners don’t always think of hungry caterpillars as desirable, robust caterpillar populations are important food resources that support bird populations. Learn about the top 5 most important plant genera that support caterpillar populations, which in turn helps feed the birds. As a gardener or land steward, choosing to plant one of these native tree species may have the largest impact on supporting caterpillar populations.

FOR IMAGES IN THE CALENDAR, details, and ordering info, go to umassgardencalendar.org.

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.

Persian ironwood (Parrotia persica)

Looking for a slow growing, small tree for the landscape? Parrotia persica might just be your answer. Plants can be a single trunked, small tree, or a multi-stem shrub growing 20-40’ tall and 15-30’ wide. As it is slow growing, Parrotia generally only reaches 10’ in 8 years. A member of the Hamamelidaceae family, features can resemble other members of the family such as witch hazel. 

Flowers emerge in later winter to early spring and although not impactful at a distance, the flowers are interesting up close. Red stamens are surrounded by brown bracts, with the flowers lacking petals. After flowering, leaves emerge reddish purple in the spring turning to a lustrous green in summer. Leaves are undulating, giving an appearance of wavy edges. In the fall, leaves are a mix of yellow, oranges, red, and purple, with a mixture of colors present on the tree at the same time. Fall color persists for an extended period, adding to the appeal. Winter reveals another ornamental attribute - exfoliating bark with patches of green, white, and tan.

Its small size makes Persian ironwood a good choice as a small lawn tree or can be incorporated into foundation plantings. Plants do well in full sun to part shade in an acidic, well-drained soil. They are tolerant of dry conditions and are hardy to USDA hardiness zones 4-8.

Newer cultivars on the market tend to have a more narrow form, making them a good choice for residential areas. Cultivars also offer interesting features such as variegated foliage (‘Lamplighter’), a weeping form (‘Pendula’) or specific fall color (ie ‘Golden Belltower’, which has golden yellow to apricot orange fall color). Although it can be difficult to find in the trade, Parrotia is a worthwhile addition to the landscape when you find it. 

Mandy Bayer, Extension Assistant Professor of Landscape Horticulture, UMass Amherst

Boxwood Blight

This year marks a decade since boxwood blight was first detected in Massachusetts. This highly destructive disease of ornamental boxwood (Buxus spp.), caused by the fungal pathogen Calonectria pseudonaviculata, is now widespread throughout the region. Despite aggressive scouting, diagnostic testing and sanitation by boxwood growers, the disease still occurs on nursery stock transplanted in the landscape each year. When it becomes introduced into landscapes with significant boxwood populations, the results can be devastating. The autumn season is a time when Calonectria is actively sporulating and new infections can establish, especially during periods of heavy rain that readily disperse the small, sticky spores. 

All species and cultivars of boxwood (Buxus) are susceptible to the disease. However, the popular and common edging boxwood (Buxus sempervirens ‘Suffruticosa’) is regarded as most susceptible to infection. The pathogen primarily occurs on stems and leaves, but root infections are possible at times. Calonectria is able to produce a resting structure within infected plant tissues that allows it to persist at sites where discarded leaves and stems become incorporated in the soil organic matter. Early detection of the pathogen is critical to limit its spread, making it necessary to understand the symptoms of boxwood blight. The most obvious symptom of the blight is rapid dieback and decline of the boxwood canopy. Upon close inspection of diseased stems and foliage, dark-colored and often circular-shaped stem and foliar lesions will be present.

Two additional diseases in our region that commonly harm ornamental boxwoods are Volutella blight and Macrophoma leaf spot. Of the two, Volutella leaf and stem blight is far more destructive. Volutella blight can be readily distinguished from boxwood blight in many (but not all) cases by closely examining the symptoms exhibited by a diseased plant. Plants suffering from Volutella blight often have scattered dead branches with tan-colored leaves that are held in the canopy. As mentioned above, boxwood blight causes rapid leaf shedding that often starts in the lower canopy and then spreads throughout. Signs of Volutella blight include cream to salmon-colored, oily masses on the underside of blighted foliage and on dead stems. These represent masses of infective spores produced by the fungus. Volutella blight is very common on ornamental boxwood and will often co-occur with the boxwood blight pathogen, which can create confusion.  

To make matters worse, the fungus responsible for boxwood blight has also been found infecting the common groundcover plant pachysandra. However, the pathogen does not cause widespread disease and mortality on pachysandra. Instead, it causes minor foliar lesions that may go undetected without careful scouting. While of minor concern to the health of pachysandra, infected plants can act as a reservoir of the disease, allowing the fungus to persist at a site or potentially spread and establish in a region. To date, infection of pachysandra has mostly occurred at sites where boxwood is also infected. 

Boxwood blight is primarily spread through plantings of infected nursery stock; therefore, new plantings are of particular concern. When purchasing new boxwoods, it is imperative that they be carefully inspected for any symptoms of the disease. After purchasing the plants, quarantine the shrubs in a safe area and do not apply any fungicides for several weeks to see if symptoms of the disease develop. The most effective way to manage boxwood blight is complete removal of the infected plants. Carefully bag and discard infected boxwood to limit the amount of leaves and stems that fall to the ground. Infected plants can also be buried or burned, yet they should not discarded in a compost pile near boxwood plantings. While not as common, there have been cases where boxwood blight establishes in landscapes where no new boxwood plants have been transplanted. This makes it more difficult to identify the point of entry for the pathogen. It also means that all landscapes with significant boxwood plantings should be diligently scouted for the disease. 

Because cultural management of ornamental boxwood is conducive to disease development, considerable care must be taken to ensure the health of these plants. To keep your boxwoods healthy and prevent disease, consider the following management strategies: 

1. Sanitize pruning tools between plants using rubbing alcohol or soap and warm water.
2. Hand prune shrubs during dry weather only. 
3. Applying mulch under boxwood canopies can physically cover fallen leaves and stems that harbor the pathogen. These diseased, discarded parts can harbor the pathogen, allowing it sporulate and infect nearby plants. 
4. Promote aeration and natural light around your shrubs, as fungal pathogens thrive in shaded conditions where air is stagnant. 
5. Provide a soaking irrigation of the roots during extended dry periods but avoid overhead watering, as this provides the splashing water needed to spread spores that initiate new infections. 
6. Manage other stresses that boxwoods experience, such as the boxwood spider mite, the boxwood leafminer, boxwood psyllid, soil compaction, and shearing wounds from mechanical trimmers, among others. 
7. Most importantly, if you regularly prune your boxwoods, consider reducing the amount of pruning cuts made to those that are absolutely necessary to maintain the desired form. Pruning wounds create an ideal infection site for fungal pathogens and removing the current year’s growth is stressful for any plant. 

Nick Brazee, UMass Extension Plant Pathologist

Q. A customer's property has a large number of poplar seedlings coming up in the lawn. What is the best way to control these?

A. While they could be seedlings, they are more likely to be root sprouts. The use of an herbicide such as a 3- or 4-way broadleaf turf herbicide product or the non-selective glyphosate can result in injury to the tree. Management options include physically digging up the roots that are producing the sprouts, repeat mowing, or removal of the poplar tree that is causing the problem.

Q. When I applied mesotrione, Tenacity^TM, the speed of weed control and the amount of bleaching symptoms to both turfgrass and weeds seemed to vary greatly. Is this a reasonable observation?

A. Yes, it is not only a reasonable observation but an excellent observation as well. Mesotrione inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD). In plants, HPPD is necessary for the biosynthesis of tocopherols and of plastoquinone, which is essential to carotenoid production. Carotenoids act as photoprotective agents by preventing the harmful photodynamic reaction and as accessory light-harvesting pigments, extending the spectral range over which light drives photosynthesis. The inhibition of HPPD by an herbicide affects pigment synthesis which results in rapid plant shoot wilting/browning, bleaching/whitening, growth reduction, and plant death. The biosynthesis of plastoquinone and the subsequent formation of carotenoids, directly impacts chlorophyll and photosynthesis. This entire process is light driven. So your observation is correct. Herbicide symptomology will be slower during periods of low light such as prolonged periods of cloudy, overcast weather.

Q. This season, our preemergence crabgrass herbicides performed fairly well with the exception of a few escapes in a couple of locations on a few properties. These escapes appeared to be large crabgrass. When we first noticed these, we treated with fenoxaprop-ethyl (Acclaim Extra^TM) or quinclorac (Drive XLR8^TM), but we were not able to control them with either herbicide application. Why would this be the case?

A. I suspect that the grass is not crabgrass but paspalum, Paspalum setaceum. A perennial grass, paspalum is not controlled by traditional preemergence crabgrass herbicides or postemergence applications of Acclaim Extra^TM or quinclorac, Drive XLR8^TM. Paspalum is commonly confused with large crabgrass as both species have long hairs on their leaves and leaf sheaths. Paspalum becomes obvious in turf in early July about the same time large crabgrass becomes apparent. Paspalum is a perennial with a short rhizome. The best management strategy of paspalum in turf is the use of the herbicide Pylex^TM (topramezone). Paspalum in landscape beds should be treated with a postemergence, directed-spray application of glyphosate.

Randy Prostak, UMass Weed Specialist

November is the month to . . . .

• Mulch berries and perennials. Organic mulch helps to moderate temperature fluctuations to protect plants from frost heaving caused by freezing and thawing of the soil. Fall mulch application can also help smother winter annual weeds, decrease runoff and increase water retention for the following summer. Mulches also protect the soil from compaction by rain and foot traffic.

• Service your lawn mower. Consider servicing your lawn mower at the end of the mowing season to have it ready to go next season and beat the spring rush.

• Remove spent plants. Spent vegetable plants and annuals should be removed to reduce the risk of disease carryover to the next season. Perennial plants that die to the ground can also be removed except for disease free ornamental grasses, Echinacea (coneflower), Eutrochium (Joe-Pye weed), and Rudbeckia (black-eyed Susan) that can provide birds with seeds, vertical accent during the winter, and necessary places for pollinators to overwinter. 

• Rake leaves and remove mummified fruit. Leaves and mummified fruit from fruit trees that were diseased should be raked, removed and destroyed to reduce the amount of disease pathogens carried over to the next season. The leaves and mummified fruits should not be thrown into the compost pile. Fungi that cause leaf and fruit spots can overwinter in infected debris in soil or under the plants. These pathogens stay in a dormant state until the following spring when rains and warmer weather induce the production of spores which are disseminated by wind and rain to infect plants during the growing season. Removal of infected plant material helps to reduce the amount of disease pathogens present in the area, thus reducing the amount of potential disease for the next season. 

• Protect tender evergreen shrubs from winter damage. Broadleaf evergreens such as rhododendrons, holly, boxwood and mountain laurel are susceptible to dry cold winds which can cause desiccation of leaves. During the winter when the soil is frozen, evergreen shrubs can lose water faster than they can take it up if they are exposed to cold dry winds. The leaves then get desiccated and appear brown and dead in late winter and spring. Protect plants from drying winter winds by erecting windbreaks made of burlap attached to frames on the side facing the prevailing winds. Stakes can be placed about 12-18 inches away from the plant to support the burlap barrier to buffer the wind. 

• Reduce watering and fertilizer application to houseplants. During the months of cold temperatures and shorter days, the growth of most houseplants slows down. During this period, new growth is minimal. Reduce fertilizer application and watering house plants until spring when new growth resumes. 

• Fall is an excellent time to get your soil tested. Since it takes several months for any applications of lime to change soil pH, testing and adding any needed amendments in the fall will prepare gardens for spring planting. A routine soil analysis from the UMass Soil and Plant Nutrient Testing Lab includes macro and micro nutrients, pH, and lead levels.

Geoffrey Njue, UMass Extension Sustainable Landscapes Specialist

A research group from France and Switzerland recently published a startling discovery in Science: when workers from a common European bumble bee species (Bombus terrestris) are pollen-deprived, they will damage plant leaves in order to induce early flowering. The study was inspired when the researchers casually observed bumble bees chewing holes in plants. They subsequently conducted a series of experiments and found that bumble bee colonies that were deprived of pollen were more likely to damage plant leaves, and that plants with bee-chewed leaves flowered significantly earlier (30 days on average!) than plants that were mechanically damaged or left undisturbed. This behavior was observed in two other bumble bee species, but not in honey bees. This is the first evidence that some bee species directly manipulate plants in order to accelerate flowering when forage is scarce. As climate change alters the phenology of both plants and their insect pollinators, this behavior could become increasingly important to help Bombus terrestris align flowering times with resource needs.

Read the full study here: https://science.sciencemag.org/content/368/6493/881/tab-article-info

For more info on new bee research, check out “The Research Buzz” – a quarterly column summarizing the latest in pollinator research. It is published in the Massachusetts Beekeeping Association newsletter, and also on the UMass Extension website. You can find past articles here.

Hannah Whitehead, UMass Extension Honey Bee Educator

For more details and registration options for any of these events, go to the UMass Extension Landscape, Nursery, and Urban Forestry Program Upcoming Events Page.

• Nov 17 - Fall Wrap-Up: Woody Ornamental Topics - live via GoToWebinar
  Three pesticide contact hours for categories 29, 36, Dealer, or Applicators License.
• Nov 18 - Fall Wrap-Up: Turf Topics - live via GoToWebinar
  Two pesticide contact hours for categories 37, Dealer, or Applicators License.
• Jan 26 & 27, 2022 - Jumping Worm Conference - live via GoToWebinar
  1/2 pesticide credit PER DAY for categories 29, 35, 36, 37, and Applicator’s (core) License.
• Invasive Plant Certification Program - live via Zoom
  • Mar 10, 2022 - State Regulations Pertaining to Invasive Plant Management (A2)
    Two pesticide contact hours in categories 29, 36, 37, 40, 48, and Applicator's License.
  • Mar 17, 2022 - Principles and Fundamentals of Weed Science (A1)
    Four pesticide contact hours in categories 29, 36, 37, 40, 48, and Applicator's License.
  • Mar 24, 2022 - The Invasive Plant Issue and Invasive Plant Identification (A3)
    Three pesticide contact hours in categories 29, 36, 37, 40, 48, and Applicator's License.
  • Apr 7, 2022 - Developing an Invasive Plant Management Program (B)
    Four pesticide contact hours in categories 29, 36, 37, 40, 48, and Applicator's License.

Pesticide Exam Preparation and Recertification Courses

These workshops are currently being offered online. Contact Natalia Clifton at nclifton@umass.edu or go to https://www.umass.edu/pested for more info.

InsectXaminer! 

Episodes so far featuring gypsy moth, lily leaf beetle, euonymus caterpillar, imported willow leaf beetle, and spotted lanternfly can be found at: https://ag.umass.edu/landscape/education-events/insectxaminer 

TickTalk with TickReport Webinars

To view recordings of past webinars in this series, go to: https://ag.umass.edu/landscape/education-events/ticktalk-with-tickreport-webinars