Learn what not to do in your garden this summer

Do you do to-do lists?  I do. They help keep me focused and organized.  And boy is it satisfying to check things off.  But this time of year, I have another list, a summer What Not To-Do List for my garden.  This keeps me from serious missteps which can harm plants or waste time and money.   

Don’t: Plant

First on my What Not To-Do List is planting.  It’s just too hot and dry for plants to establish well.  Spring and fall are your best planting times.  Be wise and wait.  I know there are plant bargains to be had now.  As a career tightwad I’m tempted, too.  Don’t succumb.  

Don’t: Dig or Divide

No digging and dividing either.  Most plants prefer to have this done in spring or fall so they can settle in and develop robust roots before extreme weather.  So step away from that shovel. If you do plant or divide plants in summer you will need to water, water and water again, a significant time drain.  And still, your plants will be stressed. Very stressed.  

Don’t: Prune

Third on my What Not To-Do List is pruning.  Trees hate to be pruned in summer.  They weep copious sap and those wounds attract the abundant insects and diseases afoot now.  Summer pruning courts disaster.  Instead, prune trees in the dormant season – January to mid-March – when they are less vulnerable.  

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Shade Gardening – The Garden Thyme Podcast

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Hello Listener,

The summer heat is here, and if you are like us, you are taking a break under the shade of a lovely tree. In this episode, we are talking all about shade — why we love it, some tips for gardening in your shady area ( 10:07 ), and a list of native plants ( 16:35 ) that enjoy the shade as much as Mikaela.

We also have our: 

  • Native Plant of the Month – Northern Maidenhair Fern- Adiantum pedatum  at 30:35
  • Bug of the Month – Eastern Beach tiger beetles at  33:50 
  • Garden Tips of the Month at  39:45

  1. If you have any garden-related questions please email us at UMEGardenPodcast@gmail.com
    or look us up on Facebook at https://www.facebook.com/GardenThymePodcast.
  2. For more information about the University of Maryland Extension and these topics, please check out the UME Home and Garden Information Center website at https://extension.umd.edu/hgic.

The Garden Thyme Podcast is a monthly podcast brought to you by the University of Maryland Extension. Hosts are Mikaela Boley- Senior Agent Associate (Talbot County) for Horticulture, Rachel Rhodes- Agent Associate for Horticulture (Queen Anne’s County), and Emily Zobel- Senior Agent Associate for Agriculture (Dorchester County). Theme Song:  By Jason Inc.

Spotted lanternfly: The latest invasive species spreading through the eastern U.S.

A man is holding an adult spotted lanternfly to show its wings
Adult Spotted Lanternfly. Photo: M Raupp, UMD

¿Hablas español? Aquí esta una traducción: Mosca linterna con manchas: la especie invasora más reciente que se está extendiendo por el este de los Estados Unidos.

Spotted lanternfly (SLF), Lycorma delicatula (Hemiptera: Fulgoridae), is an invasive planthopper moving its way through the eastern U.S. SLF was first detected in the U.S. in 2014 in southeastern Pennsylvania. It is native to parts of Asia and believed to arrive as egg masses laid on landscaping stones shipped to PA. Despite quarantines and eradication efforts, SLF infestations have been confirmed in 12 states and detected in several others.

A map shows that spotted lanternfly is confirmed in 12 states in the northeast USA
Since spotted lanternfly was first detected in Pennsylvania in 2014, confirmed infestations are in 12 states as indicated by this map (as of June 30, 2022). Image: https://nysipm.cornell.edu/environment/invasive-species-exotic-pests/spotted-lanternfly/spotted-lanternfly-range-us/

As we look at the SLF distribution map, we can see that counties with infestations are hundreds of miles away from any other infestation. This is related to the fact that SLF are excellent hitchhikers, taking advantage of human-assisted transportation. Many infestations occur along major interstates and train lines. In addition, the nymphs are active walkers and adults are able to hop and fly to new host plants and locations. Researchers at Penn State found that some SLF nymphs travel as much as 213 feet, and adult flights ranged from 30 to 150 feet in their search to find suitable hosts.

In response to SLF’s impressive ability to disperse, states have implemented regulatory quarantines and permitting programs implemented through State Departments of Agriculture, which requests actions be taken by businesses and the public who travel in and out of SLF-infested areas.

What do we know about the life cycle of SLF?

The life cycle of SLF consists of one generation per year, with eggs (the overwintering stage) laid in the fall (September – November). Egg masses are laid on smooth surfaces such as tree branches, landscape stones, rocks, wood from decks or fencing, outdoor furniture and equipment, etc. Egg masses are covered with a mud-like substance likely for protection. The protective covering is gray when freshly laid and becomes brownish with age. The eggs hatch in the spring between 240 (usually early to mid-May) and 1100 (late June to early July) degree days (DDs).

Spotted lanternfly egg mass ona tree trunk
Freshly laid egg masses of spotted lanternfly are gray in color and camouflage well on tree branches and other structures. Photo: M.J. Raupp, UMD

There are 4 nymphal instars (immature stages). Newly hatched nymphs are small (~1/8”) and at each molt they somewhat double in size. The first three nymphal instars are black with white spots and the last nymphal instar is red with white spots and black stripes.

early instar spotted lanternflies
Early instar spotted lanternfly nymphs are often found on new growth of plants. Photo: PA Dept. of Agriculture
late instar spotted lanternfly nymph
Late instar (4th) nymphs are about ½” long, bright red with white spots and black stripes. Photo: D. Ludwick, Penn State Extension
Spotted lanternfly adult
The adult spotted lanternfly has beautiful coloration and is ~ 1 inch in length. Photo: M.J. Raupp, UMD

In PA, adults begin to emerge in July (50% adult emergence at ~ 1,100 DDs) and they remain active (feeding, excreting honeydew, mating, and laying eggs) until the first hard freeze, which kills them. Adults of this planthopper are beautiful and relatively large (~1”). Adults have black bodies and legs; their front wings are gray with black spots and the ends are black with gray veins. Their hindwings are red, black and white. When the adult spreads its wings, the bright red color is quite impressive. Nymphs and adults are robust jumpers and adults can also fly.

Why is SLF problematic?

SLF is a voracious feeder on over 70 different plant species, which include numerous economically-important plants such as grapevines, some herbaceous ornamental plants, fruit trees, numerous ornamental trees, and tree of heaven. It uses its piercing sucking mouthparts to remove phloem sap from its host plants. Hundreds to thousands of SLF individuals can sometimes be found on a single tree. Surprisingly, even at these high numbers, death of hosts is only known to occur on grapes and a few sapling trees, although branch dieback on trees has occurred. Further research is needed to determine the longer-term impact of the stress of so many SLF feeding on trees has on secondary problems.

In addition to damage to hosts from feeding, SLF is also considered a nuisance pest. SLF excretes large quantities of honeydew which drops down onto leaves, branches, tree bark, driveways, cars, and anything else that might be underneath an infested host. The honeydew also has its associated black sooty mold, which makes it more unsightly. On sunny days the honeydew can be seen “raining” down from SLF infested trees.

Abundant honeydew-/sooty mold-covered foliage may reduce photosynthesis and further stress trees. In addition, many bees, wasps, and other insects that feed on sweets are attracted to the sugar rich honeydew. Because densities of SLF are so high, the honeydew/sooty mold can be quite significant and impactful to homeowners and growers.

An impressive breadth of hosts

An interesting aspect of SLF’s ecology is that it changes the plants it feeds on as nymphs and adults develop over the season.

table showing host plants preferred by spotted lanternfly nymphs and adults
This table is a (non-extensive) representation of common host plants that spotted lanternfly feed on during the season. The table allows knowing when to start monitoring for activity of nymphs and adults, and what host plants they are likely to be on. It is recommended to always monitor for SLF infestations, since densities change over time both within the season and between years even on the same host plant. Tree of heaven, Ailanthus altissima, is an invasive tree and a highly preferred host. Information in this table is based on observations in Eastern Pennsylvania and may vary based on local conditions. Image: https://extension.psu.edu/spotted-lanternfly-management-guide.

How can SLF be managed?

Managing SLF is challenging, as is the case for many emerging, invasive species. It is unlikely you can stop it from coming onto your landscape or farm, and unlikely you can get rid of all of them. Given this, the goal is to reduce SLF populations to acceptable levels. Using an Integrated Pest Management (IPM) approach will result in the greatest success.

At this time, natural enemies are not reducing SLF populations. However, many generalist predators (spiders, assassin bugs, birds, etc.) are feeding on SLF, a parasitoid brought into this country years ago for spongy (formerly gypsy) moth control has been found attacking SLF, and two fungal pathogens were also identified, one of which (Beauveria bassiana) is commercially available. Further research is underway to identify measures to enhance the impact of these biological controls for SLF.

Cultural controls can be implemented. This includes destroying the overwintering egg masses, putting traps (circle or sticky traps) on trees to catch the nymphs and adults as they move up trees, and removing tree of heaven. Numerous studies have examined the efficacy of contact and systemic insecticides against SLF (see websites below).

We need you!

Please assist in tracking SLF to help slow the spread of SLF and improve its management. If you find SLF, please report it to your State Department of Agriculture or University Extension Service. In Maryland, report SLF at the MDA website (click on “Report Spotted lanternfly here”).

For more information

By Dr. Paula Shrewsbury, Professor and Extension Specialist in Ornamental and Turf IPM in the Department of Entomology at the University of Maryland

Q&A: What is a good summer-blooming plant that’s deer resistant?

Yellow flowers of St. Johnswort plant
St. Johnswort flowers. Photo: M. Talabac

Q:  What can I use as a summer-blooming shrub, especially if this part of the garden is sunny and somewhat dry? I also sometimes have deer problems.

A:  I think St. Johnsworts (Hypericum) are underused, and several species are native here in Maryland, though those might be harder to source. Some of the commonly-grown forms are non-native hybrids, though well-behaved ecologically. (The only locally invasive species, Hypericum perforatum, is fortunately not likely to be sold at a nursery.)

St. Johnsworts bloom anywhere between June and September, prefer direct sun, generally tolerate drought well, and are distasteful to deer. Blooms are nearly always an intense yellow, and some species or cultivars have colorful summer or autumn foliage. A few cultivars have berry-like seeds that ripen by fall and make good bouquet accents. I love the bark on native Hypericum densiflorum – peeling with a smooth underlayer that’s a rich, warm-toned cinnamon-brown that’s especially showy during dormancy.

You’ll find St. Johnsworts sold as both perennials and shrubs, because some species stay low, sprawl like a groundcover, and have stems that aren’t very woody, occasionally dying back in winter as other perennials do. Other species have woody stems and grow to about three or four feet tall and wide. Flowers are loaded with pollen, but no nectar, so butterflies will probably detour while bees and flower flies (predators we like to keep in the garden) will visit. Don’t deadhead developing seed capsules if you want to support Gray Hairstreak butterfly caterpillars, which can use Hypericum as a host plant (among a huge variety of other plants).

For more plant ideas, visit the Home & Garden Information Center’s pages on Plant Selection and Deer-Resistant Native Plants.

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


Questions about home gardening? Send them to Ask Extension

How to soil test and actually utilize the results – a challenging task

As a newer gardener, I have not previously gotten around to using soil test information. I’ve been planning an ornamental overhaul in a small area of my yard and wanted to soil test to make sure the plants added to the area had the best chance of success. The HGIC website has a lot of soil test information, but I’ve never looked at it closely myself until now. Even though our content is well-written and organized, the subject is intimidating with many choices to make, multiple steps, math homework to figure out how much fertilizer to use in your space, and as I learned, many caveats or roadblocks. I can see plenty of people just giving up and not adding any soil amendments, or just going to the hardware store and buying a bag of fertilizer and applying without thinking too much about it.

Even after reading our material thoroughly, I still needed several questions answered from our experts. I’ve got a handle on it now, for the most part. With this post, I hope to detail how I figured out what fertilizers I needed, how to apply it, and then the most important things I learned that I didn’t feel are made clear.

The goal

I’ve got this space in my backyard that wasn’t being used for much. In the summer of 2020, mid-pandemic, pre-offspring, I decided to revisit a teenage hobby of mine – remote control cars. I took a shovel and cleared out an area and built ramps and hills out of dirt, for my very-own mini-dirt track. 2 years later, my wife asks me “are you going to keep the track? It’s ugly.” So, my task is to beautify it with improved landscaping and added vegetation. We also have a bunch of hostas in our front yard garden that keep getting eaten by deer. Our backyard is smaller and enclosed, so we hope the hostas will avoid attack in their new backyard, trackside location. We are also adding other plants good for shade conditions.

The location is on a bit of an incline, with the higher elevation area being more sandy and rocky, and the bottom softer and wetter. There is an “infield” of the track that is often stood on that is grass, but has been overtaken with weeds. I am planting nice plants and shrubs around the outside, and re-seeding the infield with grass. Since I know from a lot of digging to make the track that the soil is quite different in different areas, I wanted to soil test so that I could find out what exactly I might need to do to make sure the plants have the soil they need in their different locations.

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Manage bagworms now so they don’t harm trees

“Why are the pinecones on my tree moving?” a client asks.
“Because those aren’t pinecones, they’re bagworms,” I reply.  

Dangling from evergreens like teardrop-shaped Christmas tree ornaments, bagworms cause many a homeowner to scratch their head in wonder. Pinecones that dance?

Bagworms dangle from a juniper branch.
Credit: Erik Rebek, Bugwood

But the tell-tale thinning of trees that can follow is no laughing matter. Covered with bits of needles and leaves, the bags that give bagworms their name serve as protection for the caterpillars inside. Bagworm caterpillars are the juvenile form of a moth.  

That sounds innocent enough, but like all caterpillar-like insects, they are born hungry. Walking stomachs, they prowl among your trees, munching away to cause sometimes serious defoliation. They particularly enjoy evergreens such as arborvitae, cedars, junipers, and pines. But they will also dine on maples, locusts, lindens, and other deciduous trees.  

Eggs hatch out from bagworms’ bags in May. Tiny larvae spin an eighth-inch bag with bits of needles or leaves glued together with webbing. Like tiny backpackers, bagworms tote those bags around as they feed. As they grow, the bags get bigger and bigger and your tree foliage gets thinner and thinner.  

I don’t know if bagworms have an adventuresome streak, but they do a bit of hang-gliding. They spin a fine web and use the wind to glide to other trees in a stunt called “ballooning.” 

By August or September, the bags – and bagworms – are 1- to 2-inches long.  They stop wandering and feeding and tie up to a twig using tough silky threads. In late summer, they transform into moths. But get this, ladies, only the males have wings.  So the gals just hang out in their bags and wait for the boys to, um, visit. Post rendezvous, each female bagworm lays 200 to 1,000 eggs in its bag. Next spring, the eggs hatch to start the cycle over again.

Stopping that cycle is important and now is a crucial time. Mid-June to mid-July is the best time to treat trees with bagworms with a very effective organic control called Bt. A naturally occurring soil bacteria, Bt or Bacillus thuringiensis kills only small caterpillars. And guess what? Bagworms are just the right size right now.  Bt doesn’t harm humans or animals and is easy to find. It’s sold in hardware stores and garden centers under names like Dipel and Thuricide. Applying Bt is a do-it-yourself job if you can reach your trees with a sprayer. If not, call in a pro.

Even easier is picking off the bags if you have only a few bagworms. Snip them off with scissors or pruners, bag and trash them. Don’t leave them on the ground where the eggs can hatch. Since there can be as many as 1,000 eggs in each bag, removal is important. Get those bags gone. And gone before the eggs hatch in May.  

Tiny bagworms are hard to spot when they first appear in May on plants such as this Colorado blue spruce.
Credit:  Dave Lantz

Learn more about bagworms and see some great photos on the HGIC website.

You can beat bagworms and keep your trees safe. Fortunately, this is one insect for which there is an easy – and organic – fix.  So get out there and bag some bagworms.

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.

Abiotic Disorder – The Garden Thyme Podcast

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It has been a weird spring weather wise, and that weird weather may have stressed some of your plants out.  In this months episode we are talking all about abiotic disorder in the garden.  Abiotic disorder in plants are caused by non-living factors such as weather,  and the enviroment .   We will give some examples of what we have seen so far this year,  and what you should be looking for in your garden . 

We also have our: 

  •  Native Plant of the Month  (Bottlebrush grass)at 26:45
  • Bug of the Month (Green Lacewing) at 30:15
  • Garden Tips of the Month at 36:45

 If you have any garden-related questions, please email us at UMEGardenPodcast@gmail.com or look us up on Facebook.

The Garden Thyme Podcast is brought to you by the University of Maryland Extension. Hosts are Mikaela Boley- Senior Agent Associate (Talbot County) for Horticulture, Rachel Rhodes- Senior Agent Associate for Horticulture (Queen Anne’s County), and Emily Zobel-Senior Agent Associate for Agriculture (Dorchester County).

Theme Song: By Jason Inc