Yard & Garden

Q&A: What can I do about rust fungus on my juniper?

March 17, 2023March 16, 2023Maryland GrowsLeave a comment

A rust gall on juniper with spore “horns” just starting to emerge. As soon as it rains after this point, the “horns” turn gelatinous and bright orange. Photo: M. Talabac

Q: I heard rust fungus can infect junipers but they aren’t worth spraying to treat. Is there anything else I can do to reduce the fungal spread from them to my other trees?

A: If you see and can reach fungal galls on the branches, clip them off. Some rust fungi (though not all) create a gall on their juniper hosts. Plant galls are tumor-like in that they’re clusters of malformed tissue, often in response to a pest or (in this case) an infection. When the weather starts to be consistently mild in spring and we receive enough rainfall, the galls where the fungus is spending the winter will begin to exude their spores.

These rust spores blow on the wind or wind-driven rain to vulnerable host plants like various members of the rose family. In our gardens, this includes apples and pears, hawthorn, serviceberry, quince, and crabapple. Fungus spores are extremely tiny, so how will you know what to look for? If the gall is producing orange goo, you’re missing the window since spores are already being dispersed. Ideally, remove all visible galls before this point, while they’re still hard and dry. Now is an excellent time to inspect junipers on your property for galls. Trim them off with hand pruners and toss them in the trash (don’t compost).

This is not a foolproof method for eliminating the risk of rust infection on other plants this year, but it certainly could help reduce the disease pressure. Fortunately, infections like cedar-apple rust, while an aesthetic nuisance from time to time, generally don’t cause serious damage to all hosts, though they can be more serious for some, like apple.

Find photos and more information about Rust Diseases of Trees on the Home and Garden Information Center website.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.

Early Spring Lawn Tips for Fertilizer and Pre-emergent Timing

March 13, 2023March 10, 2023Maryland Grows3 Comments

Speedwell is a winter annual weed. It will end its life cycle and die naturally once we have consistently warm temperatures. Photo: G. Rinehart

The warmer-than-normal weather during February had many people thinking about an early start to lawn and garden season. However, as temperatures have dropped and been below normal for much of March, it looks like we may have a couple more weeks before lawns really start growing. Lawn growth and crabgrass emergence are related to soil temperature, which is slower to change than the air temperature. While I have heard reports of soil temperatures topping out in the mid-50s for a day or two, it’s important to remember that in order to germinate crabgrass needs soil temperatures around 53-55⁰ F sustained for 5 days. These two things lead to a few questions, particularly pertinent this year when February felt like March and now March feels like late February.

Should I fertilize my lawn now?

While the legal window for applying fertilizer to lawns in Maryland began on March 1, that doesn’t necessarily mean you should fertilize your lawn just yet. Unless the grass is actively growing (which is dependent on warmer soil temperatures) it likely won’t take up and use the fertilizer—so you are better off waiting until the lawn is actively growing. Temperatures consistently around 60 and enough growth to warrant a second mowing are pretty good indicators of this. Keep in mind that if you fertilized your lawn in the fall you can probably wait until after the “flush of growth” in the spring (usually April/early May) and then schedule your spring fertilizer application for after that “flush” and leading into summer—usually around mid-late May. If you didn’t fertilize last fall it is tempting to try to “jump-start” the lawn in early spring with a fertilizer application, but hold off until the soil temperatures are consistently warmer and highs are around 58-60⁰ F on a regular basis.

Should I apply crabgrass pre-emergent now?

I would wait until soil temperatures are 53-55⁰ F sustained for 5 days. Keep in mind that your best defense against crabgrass is a dense turf that crowds out crabgrass seedlings. So, if you have good turf density and mow at 3” or higher, your overall crabgrass pressure should be lower anyway. The typical recommendation is to wait until the forsythia is “half green-half gold” (or even a little earlier), but with the warm February we had, that indicator may or may not be as accurate this year. You can check soil temperatures for your location at the following website: https://www.greencastonline.com/tools/soil-temperature.

Is there harm in applying crabgrass pre-emergent too early?

Probably not, unless it’s applied several weeks early and the product starts to break down before crabgrass even starts germinating. If you want to maximize the period of time your crabgrass application is effective, wait until when conditions are conducive to crabgrass germination and then apply it.

grassy lawn weed called roughstalk bluegrass — Roughstalk bluegrass *(Poa trivialis)* is a cool-season weed that shows up in early spring. If you only have a few patches, you can dig them out by hand (including the roots) and overseed to fill in the bare spots. Photo: G. Rinehart

On another note, this is now the time of year when many winter weeds become more noticeable as they are likely producing flowers and setting seeds. While you can apply selective products to control these weeds, remember that these winter annuals like chickweed, purple deadnettle, speedwell, henbit, etc. are almost at the end of their lives and will die naturally once we have consistently warm temperatures. Another weed often noticed this time of year is the grassy weed called roughstalk bluegrass (Poa trivialis). Seeds of this grass are often a contaminant in turfgrass seed mixes (the cheaper the seed, the more likely you will have weed seeds) and this grass starts growing much earlier than tall fescue. As the temperatures warm, it is not as aggressive and noticeable. There are few selective control products that are labeled for roughstalk bluegrass and they tend to be restricted to professional sites and/or are expensive. If you only have a few patches in your lawn, digging these out (including the roots) and then re-seeding the spot with a soil-tall fescue mix is the best control approach for most homeowners.

By Geoffrey Rinehart, Lecturer, Turfgrass Management, Institute of Applied Agriculture, University of Maryland. Read more articles by Geoff.

The value of a pile of sticks in your yard or garden

March 10, 2023March 13, 2023Maryland Grows11 Comments

With spring coming up, many of us are already starting to get our yards and gardens ready for the growing season. Among the activities we may take on, there can be the managing of branches, sticks, and wood that may have been trimmed from trees and shrubs in the fall, over the winter, or just recently. In today’s post, I want to talk about how to integrate these resources into our green spaces, to support wildlife and the natural services they provide.

a pile of stick in a yard — Wood and stick piles can provide welcoming habitat to beneficial organisms. Photo: A. Espíndola

Increasing the diversity of our green spaces

In several of the posts that we publish on this blog, we recommend different actions that can be taken to increase biodiversity in our green spaces (see local ecotype plants, helping pollinators in small green spaces, and conserving parasitoids for some ideas). We know that increasing biodiversity improves the ability to control and restrain pests, increases wild and crop plant pollination, and in many cases leads to better soil quality. Among these practices, there is one that increases the physical complexity of our green spaces, providing nesting, shelter, and food resources to beneficial organisms. The practice I’m talking about consists of building wood and stick piles that can be established in our green spaces. The idea behind this practice is to create a space where birds, small mammals, insects, and even pest predators can find their preferred resources, and thus be attracted and present in our environments (learn more about the landscaping rationale for using dead wood).

What organisms are attracted by these piles?

Depending on the size of the pile and its composition (e.g., large logs, smaller sticks, a mix of them), different organisms will be attracted and may establish themselves in our green spaces. The presence of a mix of logs and sticks usually attracts birds, which may nest within the pile or may just spend time within the pile searching for food or finding shelter at different points during the day. These birds will certainly contribute to increasing the diversity of animals present in our green spaces and can also in some cases participate in the control of insect pests that we may not want in our gardens and yards.

Carolina wren bird with a caterpillar in its mouth — Carolina wrens are very attracted to shrubby habitats, meaning that piles of wood and brush represent a great way to provide resources to these little cute birds who in turn can help us keep herbivore populations in line. Photo: Shenandoah NP.

Other animals we can observe in these piles are a variety of insects then may be associated with the decomposition of wood or that may use wood as a nesting or overwintering resource (e.g., bees, solitary wasps). While the former can help recycle the wood material and reintegrate it into the habitat, the latter may participate in the pollination of plants and crops that we may grow in that area or predate on unwanted pests.

Similarly, ground-dwelling invertebrates like millipedes and ground beetles can also find shelter under these piles, while the brush can also contribute to the nesting of pollinators such as (ground-nesting) bees, the overwintering of some butterflies and moths, and help improve the quality of the soil in that part of our yard.

Larger organisms may also be attracted to these piles, such as small mammals, amphibians, and even reptiles. Although we may tend to dislike these groups of animals, many of them feed on unwanted soil organisms and may help with soil quality, while others can actually control vermin through their predatory abilities. This is particularly the case of snakes that may find shelter in these spaces, which, while harmless to humans (the vast majority of snakes in Maryland are non-venomous, readily feed on rats and mice that may be present around the house.

a pile of wood branches and sticks in a yard makes a habitat for beneficial organisms — A mix of thick and thin pieces of wood can provide a diverse habitat to many different organisms. Photo: A. Espíndola.

How to build these piles?

These piles can take many different shapes and sizes, which depend in part on the materials and space available. When very large spaces are available (e.g., in the woods), it is recommended for these piles to be relatively large – at least 10 to 20 feet in length, and up to 8 feet in height (read more about these larger brush piles). In smaller spaces such as in urban or suburban gardens, these piles can be much smaller, occupying areas that may not be regularly used for other purposes. In all cases, it is ideal to build these piles using a combination of different types of materials, such as twigs and branches of different thicknesses, some logs, and even some branches that may still have dead leaves attached to them…always using healthy materials.

An important consideration when putting together these piles is that they should not be built leaning on or very close to wood-based structures or the foundations of our buildings. This is because of the potential risk of termite infestations of buildings if the piles are not physically separated from them. However, it is important to stress that establishing these piles has not been shown to be associated with higher termite infestations if the pile is not in contact or very close to the built structure. (You can read a very good discussion about mulch and termites from Iowa State Extension).

So, as you work on your spring garden, I encourage you to think about plant stems, logs, and branches not as waste that needs to be cleaned up, but as beneficial resources that you can incorporate into your available space.

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

Anahí also writes an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish-speaking friends and colleagues in Maryland. ¡Bienvenidos a Extensión en Español!

Plant shopping soon? Avoid buying invasive plants

February 28, 2023March 7, 2023Maryland Grows2 Comments

It’s a sunny day in late February and that means I’m looking at seed catalogs and dreaming of new plants! Have you been plant shopping yet this year? Adding new plants and seeds to your garden creates new scents, textures, colors, and shapes and is the easiest way to increase biodiversity in your landscape!

As you begin revitalizing your garden space this spring, I want to bring some attention to invasive plants, a category of plants that should strike fear and dread in your heart! Okay, maybe that’s a bit dramatic, but truly this is a topic that everyone needs to learn more about.

Q. What is an invasive plant?

A. An invasive plant is a non-native, “alien” species that was introduced intentionally or by accident into the landscape and causes ecological and/or economic harm. These plants tend to be free from predators, parasites, and diseases that could help keep them in check. These plants reproduce rapidly with multiple methods (i.e. seeds, stolons, root cuttings, runners, etc.) and spread aggressively. They tend to be deer resistant or deer tolerant, a big reason why they are purchased and planted in landscapes. Below is a photo of purple loosestrife. Notice how it is creating a monoculture, a visual key that might mean the plant is “invasive.”

purple loosestrife flowers crowding a field — Invasive purple loosestrife (*Lythrum salicaria*).
Photo: Richard Gardner, Bugwood.org

Did you know that some invasives are still for sale at nurseries, greenhouses, and in mail-order catalogs?

It’s true. Many of the plants on “watch lists” are still readily available to purchase. Japanese barberry is an invasive plant that is a very popular landscape plant still being widely planted today; however, research shows that black legged ticks have been found in areas with invasive barberry thickets because these non-native, invasive forest shrub thickets create ideal microclimates.

Continue reading →

Look out for wintercreeper

February 22, 2023February 22, 2023Maryland Grows3 Comments

wintercreeper vines climbing up trees in a forested area — Wintercreeper euonymus (*Euonymus fortunei*) overrunning a woodland floor and climbing tree trunks. Photo: Ryan Armbrust, Kansas Forest Service, Bugwood.org.

Q: I realize English ivy is widespread in Maryland, but there are some evergreen vines clinging to trunks that look a bit different than typical ivy leaves. Are they native, or should they too be removed?

A: An evergreen climber I see covering tree trunks in parks which might be confused for English ivy at a distance is wintercreeper (sometimes written winter creeper; Euonymus fortunei). This non-native invasive acts like English ivy in that it’s a groundcover when no support to climb is present, and a clinging vine when trunks or walls are available.

wintercreeper vine — Wintercreeper vine. Photo: Chris Evans, University of Illinois, Bugwood.org

wintercreeper flowers — Wintercreeper vine. Photo: Chris Evans, University of Illinois, Bugwood.org

This species also has negative impacts on the trees and our ecosystem and should be removed if growing on your own property. Parks manage invasives as best they can, but with limited resources, we can do our part by not cultivating the species likely to spread into them, even if we don’t live immediately next to parklands. Weed Warrior volunteer programs exist, such as in Montgomery County, if you wish to be trained in invasive plant ID and to help with their removal on public lands. While wintercreeper has been banned for sale by the Maryland Department of Agriculture since 2018 as a Tier 1 invasive plant, established plants in the region can still mature enough to produce fruit (berries) that wildlife then inadvertently spreads into natural areas. Long a popular landscaping groundcover due to those vibrantly green leaves (and the variegated forms for their color), I always recommend removal and replacement with alternatives, preferably a medley of native species instead.

As with English ivy, it’s safest for the tree to simply sever the climbing wintercreeper stems’ connection with the roots in the ground and let them slough off the trunk on their own as they dry out and disintegrate. Even though they attach via root-like structures, those aren’t functional roots and no moisture or nutrients are absorbed by them. Pull up, smother (deny them light), or spray any running stems covering the ground. As with any tenacious weed, eradicating an established patch of this species may take time and repeated efforts at removal before finally being successful. Be vigilant, because birds could always re-introduce it in a future year. (Invasive plants…the gift that keeps on giving.)

Invite spring indoors with forced flowering branches

February 15, 2023February 14, 2023Maryland GrowsLeave a comment

Cherry branches are ideal for forcing into bloom indoors.

If the muted greys and browns of winter have you down, beat the blues by forcing some cut branches into flower.

It’s easy, gets you outside, decorates your home, and gives you the pleasure of watching buds open and flowers unfurl.

All you need is a sharp pair of hand pruners and some spring-flowering tree and shrub branches to cut and bring indoors.

Fortunately, this is a great time to prune most deciduous trees and shrubs, so this is a twofer. You’re pruning your plants and gathering branches to force into bloom.

Branches are ripe for harvest in February. Plants have had the six weeks of dormancy they need and are starting to plump their buds in anticipation of spring.

And no, you’re not harming these trees and shrubs by cutting them. You’re just nudging their branches into flower a few weeks earlier.

Cut branches on a milder day when the buds are softer and better able to make the transition to warmer indoor temperatures.

Snip branches one- to two-feet long for forcing. Branches pencil-thick or thinner are best.

Look for branches loaded with flower buds. These are the fat, round ones. Leaf buds are smaller and pointed. When in doubt, slice a bud open. Do you see tiny leaves or flower parts?

Sorry, I couldn’t resist sneaking in a botany lesson.

As you’re cutting, remember your pruning basics. Make sharp cuts at an angle so water runs away from the cut. Prune out crossed branches or ones that grow inward.

Thin dense areas for air circulation. And step back often to make sure you’re creating a good shape and not cutting away more than a third of the plant.

Gather the branches you’ve cut and bring them inside. Recut the stems and put them in a bucket of warm water in a cooler room. Let them drink overnight, then arrange them in vases.

Some experts cut stems underwater, add floral preservative, or put stems directly into vases. Regardless of your technique, change the water at least weekly to keep bacteria at bay.

Place your finished design away from fireplaces and other heat sources. To mimic spring’s temperatures, display your branches in a cooler room out of direct sunlight.

But certainly, put some of your branches somewhere where you can have the pleasure of watching the buds pop open to reveal their spirit-lifting blooms.

Did I say blooms? You need not limit yourself to bold flowers. Pussy willows and other plants that form catkins – fuzzy or thin, dangling clusters of tiny flowers – look wonderful indoors.

Cut branches of pussy willow. Photo: C. Carignan

Is it possible to walk by a vase of furry pussy willow catkins and not pet them? I think not.

Some spring-blooming trees and shrubs that force well are cherry, forsythia, redbud, quince, serviceberry, red maple, witch hazel, magnolia, crabapple, pear, and plum.

For catkins, take cuttings from beech, birch, filbert, and willow. If you want a longer show, cut branches every few weeks.

Make spring come early. Gather branches for forcing and enjoy the show.

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.

This article was previously published by Herald-Mail Media.

Lawn alternatives for shady yards

February 9, 2023Maryland Grows3 Comments

Although a non-native example, this New Zealand Hair Sedge (*Carex comans*) illustrates the soft, flowing look multiple sedge species provide. Photo: M. Talabac

Q: I’m happy to try a lawn alternative for my shadier areas but I’d like it to look more like a lawn than a groundcover or mix of flowering plants. What kind of grasses work for that?

A: Not many true grasses will grow well if you have less than full sun, but several perennials that look like grasses can work nicely. My primary recommendation would be to try one or more species of sedge (Carex). I was excited to see the study results for sedges from Mt. Cuba released recently: “Carex for the Mid-Atlantic Region” that may be a useful reference.

Mt. Cuba Center is a public garden and research facility in Delaware which displays and studies native plants, and they perform periodic plant trials to evaluate species and cultivars for garden performance. Lately they have been including an assessment of pollinator appeal as well, though in this particular case that wouldn’t apply since sedges are not grown for pollinator draw. (Even though the caterpillars of several of our less-often-seen butterflies feed on sedges.)

Sedges are a species-diverse group and make for an excellent grass-like aesthetic in partial shade to full shade. Many form low soft-looking tuffets, though with time or dense planting can form a more-or-less uniform “lawn.” Still, don’t expose them to much foot traffic since nothing is quite as tolerant to that as turfgrass. Well over one hundred sedges are native in Maryland, and the Mt. Cuba study results include lists of those well-suited to more sun than shade, more shade than sun, and a tolerance to mowing (not that they require it by any means).

A few true native grass species tolerate some shade, but won’t give you a comparable look to a lawn since they grow much taller or have a different leaf color or texture (often wider, coarser leaves). Examples include river oats (Chasmanthium latifolium) and Eastern bottlebrush grass (Elymus hystrix), which still could make nice accents if you wanted spots with showier seed heads.

The non-native asparagus relative mondo grass (Ophiopogon), which has dark green grassy evergreen leaves and a slowly-spreading growth habit, has been successfully grown as a lawn look-alike under mature trees. I would not recommend using its cousin Liriope, the spreading form of which (Liriope spicata) can be too aggressive and is considered invasive. (Plus, it’s way over-planted.) Mondo grass thus far does not appear to be colonizing natural areas in or near Maryland.

Maryland Grows

UMD Extension Home and Garden Information Center Blog