Back to top

Hort Notes 2022 Vol. 33:7

September 1

A monthly e-newsletter from UMass Extension for landscapers, arborists, and other Green Industry professionals, including monthly tips for home gardeners.

To read individual sections of the message, click on the section headings below to expand the content.

To print this issue, either press CTRL/CMD + P or right click on the page and choose Print from the pop-up menu.

Deadlines Approaching for Financial Assistance for UMass Extension's 2022 Green School

UMass Extension’s Green School starts October 25th! This comprehensive 60+ hour certificate short course offers fundamental horticultural training in a compact time frame. The curriculum emphasizes a systems-based approach to plant and land care based on current research and is built on a framework of Best Management Practices (BMPs) and Integrated Pest Management (IPM). There are several options for possible financial assistance. For more details, go to http://ag.umass.edu/greenschool and scroll down to Program Fees & Options for Tuition Assistance. 

  • Massachusetts Workforce Training Fund Express Grant Program - deadline to apply is Sept. 27!

For eligible Massachusetts employers, the Green School registration fee may be partially to fully reimbursed through the Massachusetts Workforce Training Fund Express Grant Program. Employers should submit an online application to the Express Grant program at least 4 weeks in advance of Green School's starting date. 

  • Career Access Scholarships - deadline to apply is Sept. 15!

The goal of this scholarship program is to enable students from diverse backgrounds to successfully prepare for and join the horticulture industry in the areas of General Landscape, Turf, or Arboriculture. We are seeking applicants who have a minimum of a high school diploma or GED/HiSET, are motivated to receive training in the care and maintenance of plants and soils, and have an interest in entering the horticultural services industry workforce in a professional capacity.

Who Should Attend? The program is designed for professional practitioners such as landscapers, lawn care providers, nursery operators, public and private grounds managers, arborists, professional gardeners, landscape and garden designers, industry sales and support professionals, and others in the green industries. Both experienced individuals as well as those aspiring to be will benefit from this course.

Where? Green School in 2022 will be an entirely virtual course taught by UMass Extension Specialists, UMass faculty, and distinguished guest instructors. 

When? Tuesday, Wednesday and Thursday afternoons from 10/25/2022 thru 12/15/2022.  

Choose from three specialty tracks: 

  • Landscape Management
  • Turf Management 
  • Arboriculture

For complete information, detailed schedules and registration options, go to http://ag.umass.edu/greenschool

Hot Topics

Caring for Perennials in Hot Weather 

The Northeast has experienced several stretches of exceptionally hot weather this summer. These heat waves can cause significant stress for landscape plantings, including perennial gardens and flower beds. Symptoms of heat stress in perennials include leaf rolling, dry brown leaf margins, leaf drop, diminished leaf size, wilting, sunscald, and blossom drop.

Temperatures above 90°F impair growth in most plants. At 104°F, sunscald may be observed on leaves and fruits. A quick rise in temperature will cause more harm than a gradual one as plants have no time to acclimate. The duration of the heat wave is also important; the longer it goes on, the greater the potential for damage. Heat waves are frequently accompanied by drought, which compounds the heat stress.

Some extra care will help your perennials survive a heat wave: 

  • Unless there are watering restrictions in your area, provide irrigation. Plants need at least one inch of water per week in the absence of rainfall, but more water is required in times of heat stress. Water twice weekly instead of once. Be sure to water deeply, allowing moisture to penetrate several inches into the soil profile. Water early in the morning and avoid overhead irrigation if possible. 
  • Weeds will compete with perennials for precious moisture and nutrients, so keep the garden clear of them. 
  • Add an inch or two of mulch, which will help retain moisture and cool the soil in the root zone.
  • Don’t use fertilizer or any pest control products until the heat subsides. 
  • Structures that provide shade can reduce the temperature and prevent sunscald. 
  • In the fall, consider replacing any heat sensitive perennials that are not doing well with more heat tolerant ones such as daylilies, Echinacea, Rudbeckia, Penstemon, Gaillardia, Sedum, Phlox, or Coreopsis

Heat and drought stress on hosta. Heat and drought stress on Shasta daisy.

 

 

 

 

 

Angela Madeiras UMass Extension Plant Pathologist

Trouble Maker of the Month

A Challenging Summer for Turf Areas: What Now?

The set up: Experienced managers know that the turfgrasses best adapted to this region are in the category of cool-season grasses. These species experience their best growth when air temperatures are in the range of approximately 60-75 degrees F, and when soil temperatures are proportionally lower, 50-65 degrees F.

The key cool-season grasses also vary genetically at both the species and variety levels in their ability to perform under moisture deficits. At the species level, grasses like tall fescue or fine fescue are more drought resistant, widely-utilized species like Kentucky bluegrass and perennial ryegrass are in the moderate range, and more thirsty, shallow-rooted grasses like creeping bentgrass and annual bluegrass have generally poor drought resistance. Management plays a role as well; for example, lower mowing heights result in proportional reductions in root mass, which translates to lower overall drought resistance. Weather, of course, also factors in very heavily; for example, grasses will use more water more rapidly under elevated temperatures, breezy conditions, and low relative humidity.

Summer weary turf on the UMass Amherst campus 9/2/2022 Thus, the typically high temperatures and below-average precipitation of the “meteorological summer” months of June, July and August create the most stressful period for our otherwise well-adapted cool-season grasses. The summer of 2022 has certainly been no exception, with predominantly above-average temperatures, including a 4-day heat wave to close out July that was quickly followed by a 6-day heat wave during the first days of August. These excessive temperatures have co-occurred with muted precipitation inputs that may rival our most recent notable drought season (2016) when things are said and done. This has left approximately 38% of Massachusetts classified as D3 (“Extreme” drought) as of this writing, with an additional 56% classified as D2 (“Severe” drought) according to the U.S. Drought Monitor (https://droughtmonitor.unl.edu). The entirety of Massachusetts is currently under official drought status.

Cool-season grasses have evolved the capacity for dormancy in response to these seasonal extremes. Dormancy is another way of saying “survival mode”, and substantial reductions in both appearance and function of turf come with the territory. As dormancy progresses, the turfgrass plant essentially retreats to the crown (the principal plant growing point at the soil interface) and, under extended dormancy, virtually the entire shoot and root system can die back. As long as the crown remains viable, however, re-growth is possible when more favorable conditions return.

What determines whether the crown remains viable? Most of it comes down to water and carbohydrates… these are the main currencies of the plant. The crown must maintain some minimal level of moisture to stay alive as well as a store of carbohydrates sufficient to support recovery when conditions moderate. The precise elements that influence how long a plant may survive under dormancy are many and include length of dormancy, degree of dormancy, plant genetics, prevailing weather both prior to and during dormancy, management practices, and turf use.  

A rough rule of thumb is the longer that dormancy continues and the more severe the summer weather, the smaller the percentage of plants that will recover adequately. Pests, traffic, and other abiotic factors can also kill fragile crown tissues when plants are in a dormant state, and dormant turf is far less competitive against encroaching weeds.

Where do we go from here? The saving grace is that the ideal period for planting occurs immediately after summer stress, from late August through September. In the case of existing turf areas damaged by drought, there two basic approaches to re-establishing the turf on a site:

  • Renovation (less disruptive) – Process of replacing the turf plants on a site without making changes to the soil or grade. Does not normally include total removal of existing turf, but usually includes eradication of the existing stand with non-selective herbicides, extended covering, or mechanical defoliation. May include light cultivation in the interest of promoting seed-to-soil contact.
  • Reconstruction (more disruptive) – Involves wholesale removal of existing turf on a site in conjunction with tilling or other soil cultivation, at least to the depth of the root zone or deeper. Frequently also includes addition of soil amendments, addition of topsoil, and/or changes to grade. 

If renovation compares to remodeling an out-of-date kitchen, reconstruction is like rebuilding the whole house. Renovation is most appropriate when turf has deteriorated but the soil and overall growing environment remain generally suitable. A general guideline is to renovate when 50% or more of the turf is composed of undesirable grasses or weeds. Renovation is also a great opportunity to match grasses more closely to site conditions and future management objectives.

When there are ongoing problems that go beyond just the plants present, a full-scale reconstruction may be warranted, but any decision to take on a reconstruction project should be carefully considered. In modern medicine, for example, there is an effort to better tailor patient treatments to precisely fit the severity of the condition. When health problems are dire or life threatening, there is more opportunity to gain from major intervention. When issues are less severe, however, major intervention may be less appropriate because there is smaller opportunity for benefit. In other words, the risk of net harm is increased when the degree of intervention is greater than what the problem truly requires.

Decisions to ‘open’ the soil in a turf system, as is the case with reconstruction projects, should always be approached cautiously. Cultivating soil can damage soil structure, introduce the possibility of soil erosion, and stir the ‘seed bank’. At the same time, cultivating the soil provides opportunities not typically available in a perennial turf system including ability to incorporate fertilizer and soil amendments, improve drainage, and alter the grade. In other instances, opening the soil may be required to remove boulders or buried debris, or to install physical infrastructure such as irrigation system components. Therefore, in most circumstances, complete reconstruction should be based on identifiable need or, from a strictly agronomic perspective, treated as a last resort.  

Compared with renovation, reconstruction is more expensive, time-consuming, labor intensive, and functionally and aesthetically disruptive. When circumstances or budget do not permit a justifiable reconstruction, a renovation approach will most often yield measurable improvement. Even in situations where the means and need for reconstruction exist, opting for renovation first may at best have satisfactory results and at least buy some time (perhaps multiple seasons) before the larger investment of funds and energy in a wholesale reconstruction project.

Door number three for post-summer tune-ups is seeding into an existing, living (or partially living) stand. Overseeding involves seeding into established turf in the interest of repairs or maintaining adequate density. Late summer is also a great time for interseeding, as part of a plan to gradually introduce different grass species or cultivars and alter the stand composition over time. A fantastic way to accomplish this is with power slice-seeding equipment; a less sophisticated method is broadcasting seed after cultivation practices such as core aeration.

For more details on planting and selecting the best establishment approach, refer to UMass Extension’s Best Management Practices for Lawn & Landscape Turf, Section 5, Establishment, Renovation & Repair.

How can I improve a situation for next time? In non-irrigated scenarios, planting heat and drought resistant grasses will mean better performance and lower tendency for dormancy for under summer stress. On irrigated sites, heat and drought resistant grasses will save water. Heat and drought resistance among species was already detailed above, but there is also much variation within species. Poring over producer or University data to identify grasses with positive water use traits can be tedious; thankfully there are a few notable University and industry groups that do this work for you. Look for these seals of approval on seed products: A-LIST, which is the Alliance for Low Input and Sustainable Turf (http://a-listturf.org/), the Turfgrass Water Conservation Alliance (https://www.tgwca.org/), and even the EPA Water Sense program (https://www.epa.gov/watersense/turfgrass-and-water-efficiency)... yes, the same criteria that are applied to all kinds of products like appliances and toilets, are used to qualify turfgrass seed.

The wild card: Remember that adequate and consistent moisture is necessary for successful establishment, renovation, or repairs. This is true for even the most water-efficient grasses that will ultimately be very drought resistant and have low water demands. Because of the adversely dry year to date in 2022, many Massachusetts communities have water restrictions in place that could affect the ability to irrigate and therefore should be reviewed prior to jumping into any planting activities. For complete information on current restrictions, see: https://www.mass.gov/info-details/outdoor-water-use-restrictions-for-cities-towns-and-golf-courses

Jason Lanier, UMass Extension Turf Specialist

Q&A

Q. Several drought tolerant trees and shrubs planted in late summer of 2021 died this summer. The plants received supplemental watering through the fall. I have been told the plants likely died because of a lack of supplemental watering and were not established. I am looking for some guidance on how long plants require supplemental watering and how to know when they have become established.

A. An important disclaimer for plants is that drought tolerant plants are not drought tolerant until established. A plant is considered established when the roots have grown into surrounding soils, have consistent growth and can support the plant through periods of dryness. Observing root growth is not practical, therefore above ground growth is often used as the indicator of establishment. During the establishment period, shoot growth is reduced. Once shoot growth resumes to pre-transplanting levels or is consistent with the species or cultivar, the plant is considered established. 

The establishment period for plants can vary greatly and is impacted by the size and age of the plant, growing conditions and the species. In general, smaller and younger plants will establish faster. Establishment of trees and shrubs can take many years and will require supplemental watering during periods of low soil moisture. A common misconception is that transplants only require supplemental water during the planting year; this often results in failures when drought or low soil moisture occurs in the following seasons. If supplemental water is unlikely to occur for the entire establishment period, the choice to plant smaller nursery stock is wise.

Q. I hear that coffee grounds are particularly good for my rhododendron and azaleas. Are they also good to use around plants like tomatoes?

A. Coffee grounds are the result of processing the fruit from Coffea arabica and Coffea robusta. The fruit of these plants are drupes, a fleshy fruit with thin skin surrounding a central stone containing a seed, like a peach or cherry. The drupes are processed by removing the outer layers of the fruit, leaving just the seed (bean) which is further processed by roasting, grinding, and brewing. The result is a fine dark organic material, coffee grounds. The plant benefitting attributes of coffee grounds are often widely touted but may be more myth than truth.

The value of coffee grounds as a fertilizer source is relatively low because of the relatively small amounts of nutrients and their C:N (carbon to nitrogen) ratio. Coffee grounds have about 2% Nitrogen and a C:N ratio of about 20:1 (ie. 20 parts carbon to 1 part nitrogen).  C:N ratios determine whether nitrogen will be immobilized or mineralized as the organic matter is decomposed. Mineralization results in nitrogen being released and made available to plants and occurs with C:N ratios are below 15:1.  Immobilization results in reduced nitrogen availability to plants, at least initially, as soil microbes compete for nitrogen to break down carbon molecules and occurs with C:N ratios above 30:1.  C:N ratios between 15-30:1 are considered nitrogen net neutral. Though the fertility value may be low, it is still a valuable organic matter source and ideal as a compost feedstock or incorporated into soil where it would be decomposed by soil microbes and help increase soil organic matter. The benefits of compost and soil organic matter are well known and can improve soil properties, including water holding capacity, water infiltration, nutrient holding capacity, microbial activity, and soil aggregation.

Coffee grounds have also occasionally been promoted as a soil acidifier. However, this is a common gardening inaccuracy that has also been applied to oak leaves, pine needles and compost. Whether a material is acidic or not does not correlate directly to the effect on soil pH. As organic matter is decomposed, some weak acids are produced but these have little impact on overall soil pH. More often, the end result of decomposition of organic material is a pH near neutral.

Coffee grounds are unlikely to make a great mulch. Mulches conserve soil moisture, reduce weeds, and protect soils from extreme temperature fluctuations. Organic materials used as mulches typically have a high C:N ratio, resulting in a long-lasting residual mulch. Coffee grounds are likely to decompose quickly and the fine texture increases potential for compaction and poor moisture infiltration. Coffee grounds in small amounts applied to the soil surface or mulch will not harm anything but do not make an ideal mulch.

Coffee grounds have been promoted as being a deterrent or pest remedy; these are primarily anecdotal and have not been substantiated with research.

The take home message is that coffee grounds are a valuable source of soil organic matter whether directly applied or composted and should not be discarded with household waste. However, coffee grounds are by no means a panacea for plant health or fertility. 

Russ Norton, Agriculture & Horticulture Extension Educator, Cape Cod Cooperative Extension

Garden Clippings Tips of the Month

September is the month to . . . .

  • Plant cool weather vegetables. Leafy vegetables such as spinach, lettuce, arugula, kale, bok choy and mustard greens grow well in cool weather and can be directly seeded into the soil. Root vegetables like radishes, turnips, carrots and beets have short crop times and so can be planted by seed in early September. Broccoli, cauliflower and cabbage should be planted as transplants and can be bought from garden centers.

  • Plant a cover crop. Cover crops can be very beneficial in managing garden weeds and building up organic matter in the soil. A legume cover crop such as hairy vetch can fix nitrogen; small grain cover crops such as winter rye can help to scavenge leftover nutrients from the vegetable garden. Cover crops are tilled into the soil before planting your main crops in the spring. When incorporated into the soil, a cover crop is called a green manure and helps improve soil organic matter and fertility. 

  • Plant garlic. Late-September through October is a good time to plant separated garlic bulbs for harvest of garlic next summer. The fall weather helps garlic form roots and start sprouting before the cold treatment of winter that is required for proper development. Garlic needs a cold period for proper shoot and bulb formation, and should to be planted at least six weeks before the soil freezes to allow enough time for good root growth but not enough time for leaves to emerge from the soil. Cloves are planted 3 to 4 inches deep, oriented with the root end down. In fall, when it is cool and day length is short, garlic forms roots and begins sprouting. In spring, leaf growth resumes. Bulb formation is initiated in response to the longer days and warm temperatures of late spring in May and June. Bulb growth continues until the leaves turn yellow in July and the bulbs are ready for harvest.

  • Renovate the lawn. Lawns sometimes deteriorate over a period of years due to thatch accumulation, disease and/or insect damage, drought stress, or a heavy infestation of difficult-to-control weeds and may require renovation. Renovation may consist of simply reseeding bare spots or as involved as killing all vegetation, followed by reseeding the entire lawn. Cooler temperatures and ample rainfall in mid-September provide favorable growing conditions for new seedlings and for grass to become established. Amend the soil and alter site conditions as needed before seeding, being sure to correct pH and nutrient deficiencies according to soil test results. For info on how to take and send a sample to the UMass Soil and Plant Nutrient Testing Laboratory, go to  https://ag.umass.edu/services/soil-plant-nutrient-testing-laboratory.

  • Divide spring and summer blooming perennials. Early September is a good time to divide summer and spring flowering perennials because fall weather is typically cool and wet, reducing plant water loss and stress after being transplanted. Dividing these plants when they are not in bloom allows all the plants’ energy to go to root and leaf growth, and dividing in early September will allow time for plants to become established before the ground freezes. Plants that are to be divided should be well watered a day or two before dividing. Dividing plants into smaller segments helps alleviate competition between roots and shoots and often results in new growth and more flowers. 

  • Plant daffodils, tulips and crocus for spring bloom. Plant bulbs two to three times deeper than their diameter. On heavier clay soils, set the bulbs an inch or two shallower. Follow the instructions provided on the bulb package. Remember when purchasing bulbs, the size of the bulb is directly correlated to the size of the flower to come in spring.

  • Add organic matter to soil. Adding organic matter to the soil improves soil structure, increases the nutrient holding capacity of the soil, improves soil drainage and water holding capacity, provides plant nutrients, and increases biological activity in the soil. Organic amendments can be added in the soil as manure or compost which should be thoroughly incorporated into the soil when dry to prevent layering. This can be done by thoroughly tilling in the compost or manure after applying on the soil surface. Fall manure or compost application gives it time to break down to provide plant nutrients and other soil benefits in the spring.

  • Start fall clean-up. Fall clean-up will help with the success of the garden next spring. Remove all diseased materials to reduce overwintering of pathogens in the garden, although leaving the stems of perennials, etc provides a place for beneficial insects like pollilnators to overwinter. Harvest all useable vegetables and annual flowers. Left-over disease-free debris can be composted or tilled into the soil, where they will decay and enrich the soil with organic matter. 

  • Start a compost pile. You can start a compost pile using disease and insect free plant material. Do not include weed plants laden with seeds since even though some seeds will be killed during the composting process, those that survive will create a weed problem next year. Grass clippings and fallen tree leaves can be included in the compost pile. Locate the pile on a level area with good drainage, partial shade and protected from strong winds which can dry and cool the pile.

  • Plant or transplant woody ornamentals. September is a good time to plant trees and shrubs when air temperatures are cool and soils are still warm and moist. Planting in September allows enough time for the plant to establish a root system during cooler weather. Fall conditions provide the greatest chance for successful establishment and for surviving the following year’s hot summer temperatures. Make sure to select healthy trees and shrubs, and keep the newly planted trees and shrubs watered well until the ground freezes. If there are water restrictions in your town, do not plant or transplant woody ornamentals as this time.

  • Do a soil test. A soil test will determine if an application of lime is needed to adjust soil pH. Fall is the ideal time to get a soil test as the turn-around time at the lab is quicker and fall is the best time to apply lime, since this provides enough time to change the soil pH by next spring. A soil test will also provide recommendations of plant nutrients that need to be applied, how much to apply and when to apply. For more information on soil testing, go to the UMass Soil and Nutrient Testing Laboratory at: https://ag.umass.edu/services/soil-plant-nutrient-testing-laboratory

Geoffrey Njue, UMass Extension Sustainable Landscapes Specialist

Be Tick Aware in the Fall!

Adult deer tick (Photo: L. Dapsis) September marks the time when we are entering the next phase of tick season; this is when adult stage deer ticks emerge. This typically begins in mid-September but is well underway by mid-October. In our surveillance research on Cape Cod, we found that about 50% of them pack the bacteria that causes Lyme disease.

And it’s not just about Lyme disease anymore. Other significant diseases deer ticks can carry are babesiosis, anaplasmosis, relapsing fever and Powassan virus.  We also see a certain level of co-infection where ticks are carying more than one pathogen.

A personal protection plan is very straightforward. When you are in tick habitat, which could be in the woods or at the edge of your backyard, wearing light colored long pants, which make ticks easier to spot, and shoes vs. sandals is a start. When you come back indoors, be sure to do a tick check of your body and throw the clothes in the dryer for 20 minutes to kill any ticks you may have missed.

Repellents are also important…skin repellents like DEET or picaridin are effective. Avoid “all natural” products, as there is no testing that shows they are safe or effective. From my standpoint, the most effective tool in the box is permethrin treated clothing and footwear. It not only repels but actually kills the ticks. You can find this product at garden centers and sporting good stores. Use the link below for a video on the ins and outs of using permethrin.

For additional resources from Cape Cod Cooprative Extension, including their ten-part recorded video series on ticks and tick safety, go to: https://www.capecod.gov/departments/cooperative-extension/programs/ticks...

Enjoy the fall weather, be tick aware and stay tick safe.

Larry Dapsis, Cape Cod Cooperative Extension Entomologist and Deer Tick Project Coordinator

Upcoming Events

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

  • 9/15/22 - End of early-bird rate for Green School registrations and deadline to apply for a scholarship. For complete details and registration options, go to http://ag.umass.edu/greenschool
  • 10/18/22 - Deadline for registering for Green School

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


Additional Resources

For detailed reports on growing conditions and pest activity – Check out the Landscape Message

For professional turf managers - Check out our Turf Management Updates

For commercial growers of greenhouse crops and flowers - Check out the New England Greenhouse Update website

For home gardeners and garden retailers - Check out our home lawn and garden resources


Diagnostic Services

Landscape and Turf Problem Diagnostics - The UMass Plant Diagnostic Lab is accepting plant disease, insect pest and invasive plant/weed samples. By mail is preferred, but clients who would like to hand-deliver samples may do so by leaving them in the bin marked "Diagnostic Lab Samples" near the back door of French Hall. The lab serves 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. See our website for instructions on sample submission and for a sample submission form at http://ag.umass.edu/diagnostics

Soil and Plant Nutrient Testing - The lab is accepting orders for Routine Soil Analysis (including optional Organic Matter, Soluble Salts, and Nitrate testing), Particle Size Analysis, Pre-Sidedress Nitrate (PSNT), and Soilless Media (no other types of soil analyses available at this time). Testing services are available to all. The lab provides test results and recommendations that lead to the wise and economical use of soils and soil amendments. For updates and order forms, visit the UMass Soil and Plant Nutrient Testing Laboratory web site. 

Tick Testing - The UMass Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing options at: https://ag.umass.edu/resources/tick-testing-resources.