A Lawn Retrospective on the Summer of 2023: Looking Ahead to the Fall Season

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Many lawns showed drought-stress symptoms in early summer. Photo: M. Talabac, University of Maryland Extension (UME)

It seems like ages ago, but during late spring and early summer we were in the midst of a long dry spell–and then things changed! Many areas in the region have seen more typical summer rainfall since late June. Since then, summer annual weeds and sedges were given new life with all of the wet conditions. For many homeowners, it has been a difficult summer keeping weeds like kyllinga, nutsedge, and crabgrass at bay during the wet, humid weather.  

Crabgrass and thin spots in a lawn. Photos: C. Carignan, UME

University of Maryland research (and others) has indicated that the best way to deter crabgrass is to mow higher. Experiment plots mowed in the 3.5-to-4-inch range have consistently had less crabgrass invasion than plots mowed at 2 or 3 inches. While this late summer weather has led to a lot of crabgrass and sedge invasion, homeowners can take solace in the fact that relief is in sight as far as the calendar is concerned. Late August/early September is the perfect time of year to re-seed with cool-season grasses like tall fescue to undertake a full-scale renovation or a lawn “rejuvenation.”

First, let’s define a few terms:

Complete renovation involves killing the existing sod to bare soil and re-seeding or installing sod.

Overseeding involves using an aerator or de-thatcher to open up the turfgrass canopy and then applying seed to increase density and sustain the stand. 

Repairing bare spots involves raking up old debris by hand or loosening it with a de-thatcher, then seeding.

More detailed information on these techniques can be found on the University of Maryland Extension Lawn Renovation and Overseeding resource page.

How do you decide what to undertake? If your lawn is thin, overrun with crabgrass, has a high percentage of broadleaf weeds, or is an otherwise “unsalvageable mess” you would probably consider a full renovation. If your lawn is a little weak in places, but otherwise dense and relatively healthy, overseeding would be more appropriate. Ensuring good “seed to soil” contact and maintaining adequate moisture in the seedbed is critical for successful germination.

Another key element in lawn renovation and overseeding is seed selection. There are a number of varieties (cultivars) of tall fescue available, however, some have performed better than others in the UMD evaluation trials and these are listed as “recommended varieties” in UMD Extension Bulletin TT-77-Recommended Turfgrass Cultivars (PDF). Although these varieties may be difficult to find at “big box” stores, many local garden retailers seek them out to stock them, and homeowners can often purchase them from local landscape professional suppliers or find them online at sites like seedsuperstore.com.

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

Vinegar Acidity for Home Canning: Preserve Your Garden Produce Safely

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The National Center for Home Food Preservation, which is out of the University of Georgia Extension, has been fielding questions about using 4% acidity white distilled vinegar that is available for home cooks on grocery store shelves. People will often use 4% acidic vinegar to help make salad dressings and sauces. However, it is recommended for safety when canning to use 5% acidic white distilled and cider kinds of vinegar. We ask home canners to read the label of the vinegar they intend to buy at the store closely to look for the acid percentage before purchasing and using it for canning purposes.

Vinegar-acidity-level-for-home-canning-1Download

Further questions? Email Shauna C. Henley, PhD at shenley@umd.edu.

Shauna is the Family & Consumer Sciences Senior Agent at the University of Maryland Extension, Baltimore County

Insects: Our Most Under-Appreciated Neighbors

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Why should I want bugs, insects, and creepy crawlies in my yard or green space?

Insects are an incredibly diverse group of organisms, with 91,000 described species in the United States and likely an equal number yet to be described by scientists. Only an exceedingly small fraction of these species ever have negative impacts on humans as “pests” (<1% of species). Often the overabundance of pest species is due to human agricultural and landscape practice choices. The vast majority of insects in shared spaces with humans like yards and parks are going about their own lives. In addition to being fascinating creatures deserving of habitat in their own right, they also often contribute to unnoticed but very important tasks that help humans, termed “ecosystem services.” The next time you see one of these critters in your yard, consider thanking them rather than smashing them.

What are ecosystem services?

Ecosystem services are benefits that humans gain from the environment. Examples of ecosystem services include water filtration, raw material production, erosion control, and pollination. Some ecosystem services, like the maintenance of atmospheric gasses (e.g. plants remove carbon dioxide and produce oxygen that humans breathe), are noticeable and directly impact our everyday lives. On the other hand, services like decomposition may go unnoticed because they indirectly affect us.  

Insects (and their arthropod relatives like spiders and earthworms) play vital roles in many ecosystem services. This is often due to insects interacting with plants in some way, though insects also provide food for many other animals. Below are some examples of the ecosystem services that insects contribute to.

Water filtration

Filter-feeding insects positively affect water quality because they remove particles of dead organic material. Insects retain many of the nutrients they filter out of the water, thus reducing the likelihood of algal blooms, their associated toxins, and dissolved oxygen “dead zones.” This is crucial because clean water provides habitat for other plants and animals like fish and amphibians. It also means less effort is required to purify water for human use. 

Types of insects that improve water quality:

  • Blackflies, mayflies, stoneflies, and caddisflies (Note: the underlined insect groups are not “true” flies in the taxonomic Order Diptera; they are part of other orders.) 

Other types of organisms that improve water quality:

  • Mussels, crayfish, snails

More information: Why Care About Aquatic Insects

an illustration of the diversity of insects in an aquatic environment
Source: https://www.nsf.gov/news/mmg/mmg_disp.jsp?med_id=66886&from=

Biocontrol

Biocontrol is when natural enemies are used to suppress pests and reduce the amount of damage they cause. Natural enemies are insects that are antagonistic to pest insects. There are three types of natural enemies: predators, parasitoids, and pathogens. Preserving natural enemy populations is crucial to reducing our reliance on pesticides because when natural enemies are active, pest outbreaks are less likely to occur in the first place. Predators need food all year, so they also need alternate prey available in order to prevent pest outbreaks. Pesticides eliminate beneficial insects in addition to pests, so they should be used only as a last resort.

Fun fact: Fireflies spend much of the year as larval predators belowground, feeding on pests like grubs in turfgrass yards. If no prey is available in yards, then there will be no display of adult fireflies in the summer.

Types of insects used for biocontrol:

Other types of organisms used for biocontrol:

  • Fungi, birds, amphibians, reptiles, and mammals

More information: Approaches to the Biological Control of Insect Pests.

a tiny black wasp next to insect eggs
Source: https://blog.pensoft.net/tag/parasitoid-wasp/

Seed dispersal

Seed dispersal is when seeds are moved away from the parent plant. Seeds are moved when insects knock them off while feeding or when insects collect and then move seeds to a new location. Seed dispersal is important because it reduces resource competition between the parent plant and offspring plants. It also makes germination and seedling survival more likely, especially in arid climates. 

Types of insect seed dispersers:

  • Ants (most effective), beetles, wasps, thrips, and some moths

Other types of seed dispersers:

  • Fruit-eating animals (frugivores), such as some monkeys, lizards, and bats
  • Unwitting animal dispersers of sticky seeds like this

More information:

Seed Dispersal – The Australian Museum

The Conservation Physiology of Seed Dispersal

Source: https://www.science.org/content/article/don-t-crush-ant-it-could-plant-wildflower

Decomposition & nutrient cycling

Nutrient cycling and decomposition are two important processes that rely on one another. Nutrient cycling is when soil nutrients are taken up by plants, insects eat plants, and then those nutrients are reintroduced into the soil when dead insects and droppings are broken back down into nutrients via decomposition. Decomposer insects help clear dead animals and plants off the ground which would otherwise accumulate everywhere. They also help create soil texture and circulate nutrients back into the soil, which plant populations and productivity depend on.

Types of insect decomposers:

  • Many beetles, springtails, termites, wood cockroaches, and some fly larvae (maggots)

Other types of decomposers:

More information: Decomposers

Source: https://www.atlasobscura.com/articles/flightless-dung-beetles-south-africa

Supporting food webs

Insects are a main source of protein and nutrition for many animals (and even some plants). They play a crucial role in transferring energy from plants to larger animals that eat insects like spiders, birds, frogs, fish, bats, foxes, opossums, and bears. This wide food base that they provide allows for functioning, stable ecosystems that are resilient to disruptions.

Fun fact: By weight, there are roughly 300 times more insects than humans on Earth.
There are so many animals that eat insects, but here are just a few examples:

  • Terrestrial bird species, in particular, feed their babies almost exclusively with insects, and if there are fewer insects, baby birds are less successful at fledging from nests.
  • Popular fish like salmon, bass, and trout eat insects, especially when they’re young.
  • Grizzly bears will eat tens of thousands of moths a day to prepare for hibernation.
chameleon eating an insect
Source: https://a-z-animals.com/blog/what-do-chameleons-eat-16-foods-in-their-diet/

Pollination

Pollination is the transfer of pollen between flowers, resulting in flower fertilization and seed/fruit production. It is an unintentional consequence of pollinators going from flower to flower to feed themselves. Pollination is crucial for human survival, as 80% of plant-based foods and products rely on animal pollination. According to the USDA, pollinated crops are worth $18 billion in the US alone. Foods requiring pollination include apples, blueberries, chocolate, coffee, grapefruit, peaches, peppermint, sugarcane, tequila, and vanilla. 

Fun fact: beetles were likely the first insect pollinators– starting 200 million years ago!
Types of insect pollinators:

  • Bees, wasps, beetles, flies, ants, butterflies, and moths

Other types of pollinators:

  • Birds and bats

More information:

Pollination Basics

What is Pollination?

Why is Pollination Important?

Pollinated Foods

two white and black butterflies on yellow flowers
Source: https://www.technologynetworks.com/applied-sciences/news/pollination-reduced-as-bees-and-butterflies-confused-by-air-pollution-357697

By Yasmine Helbling, Kelsey McGurrin, and Karin Twardosz Burghardt, from the University of Maryland Department of Entomology, Burghardt Lab

And the Pollinator Prize Goes to… Hoverflies!

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We hear a lot about pollinators these days, but most of the attention appears to always go to one group of them: bees. However, the diversity of pollinators expands way beyond this one group of insects, as we discussed in a previous post. In today’s post, I want to bring the spotlight to one of those non-bee pollinators, which I always feel stay in the background of our pollinator discussions and are massively underappreciated, despite their important role in our ecosystems. Come with me to give hoverflies the recognition they deserve.

What are hoverflies?

With over 100 species in Maryland, hoverflies (sometimes also called flower flies, or simply syrphids) are a group of flies that belong to a family of insects called Syrphidae. They are called hoverflies because they are very good fliers, able to quickly change directions or maintain their flying positions in very impressive ways. While their larval stages can have a huge variety of nutritional needs (some of which make them great biological control agents of pests), a very large number of the species are strongly associated with flowers as adults. In fact, the females require nectar and pollen consumption for their ovary development, making them depend strongly on floral resources for reproduction. For this reason, they act as important pollinators of many wild plants and crops, especially in temperate climates. Although not fully recognized by the general public, pollinating hoverflies have been shown to contribute globally to the pollination of over 70% of crops globally and about the same percentage of European wildflowers (few studies have evaluated the latter in North America)! You can learn more about this in this recent publication.

Hoverflies can be recognized by their large eyes, short antennae, and at rest their wings positioned perpendicularly to their body, as seen here in this (likely calligrapher or Toxomerus) hoverfly from Maryland. Photo: A. Espíndola

Ecology and biology of hoverflies

I hope that you’re now starting to get excited about these little creatures. Before you run outside to try to catch a glimpse of them, let me tell you some more about their lives, so you can continue to be amazed at what they do and why I am on a “pollinator recognition” mission for them.

As I was saying before, a vast majority of hoverflies are strongly associated with flowers. This makes them potentially important pollinators, and this is indeed true for many of them. However, there’s another reason why they are so important: their ecology. In fact, hoverflies have migratory or at least long dispersal behavior. This means that they have great potential for long-distance dispersal of pollen, and thus can contribute strongly to the pollination of plants that may be spatially far away from each other. Thinking about pollination and its role in plant reproduction, such long-distance pollen dispersal can be key in the reproduction of isolated plant populations, and even in increasing and maintaining genetic diversity in those populations. All of that tends to positively impact the ability of those plants to maintain their populations, making hoverflies key actors in sustaining the diversity of many wild plant species.

And also, because I really want to make an impression on you 😊, know that when I talk about hoverfly migration, I am talking about migration patterns that can in some cases be equivalent to those of more “famous” insects, such as monarchs. Some studies have shown some hoverfly species migrate thousands of miles, following the seasons. Although this is relatively well-studied in Europe, we know that similar migration patterns also occur in other parts of the globe, including North America. And as a fun fact, in our research group at UMD, we believe that we once observed and sampled a wave of migration of hoverflies right here, while studying pollination interactions in the endangered serpentine grasslands of Maryland.

a fly that looks like a bee with large black eyes

a syrphid fly that looks similar to a bumblebee

a syrphid fly has yellow and black stripes and two wings
Hoverflies often trick us into thinking that they are something they are not. Here we have some great examples of elaborate mimics of bees/bumblebees and wasps. Can you spot the traits that give them away? Top: Bare-eyed bee mimic (Mallota bautias); center: Hairy-eyed bee mimic (Mallota posticata); Bottom: Transverse-banded flower fly (Eristalis transversa). Photos T. Shahan, M. Wills, J. Gallagher. All CC.

How to recognize them?

Perhaps a reason why hoverflies are underrecognized is that many of their species display impressive body mimics of other species, many of which people tend to be afraid of because of their stingers. For example, some of the most common hoverflies in our area display yellow and black stripes, tricking us (and potential predators) into believing they are in fact wasps or bees. This is a strategy that protects them from predation but also requires us to be more attentive when we are trying to find them.

Despite this, there are some simple ways to recognize their trick. Because they are flies, hoverflies have characteristics that differentiate them clearly from other groups of insects, such as wasps. One of the main traits to look for when trying to figure out if we are facing a hoverfly (vs. a wasp, for example), is looking at their wings. Unlike bees and wasps, flies have only one pair of wings, which at rest they usually extend perpendicularly to their body, which makes them look like a plane or a “T”. Wasps and bees, on the other hand, typically don’t do this, and they fold their two pairs of wings flat over their abdomen while they are at rest.

Another way to tell them apart from most other wasps and bees is their heads (this may be also useful when the wing trait is not easy to see). In fact, flies generally have VERY large eyes (just think about any fly costume 😉). Hoverflies are no exception! They also have large eyes that cover a very large part of their heads, as well as very short antennae. On the other hand, bees and wasps, usually have much much longer antennae that extend way beyond their heads.

Ready to go out and find some of them? Remember that you can always check out iNaturalist to help you out with identifications! Good luck!

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!

Make and Plant a Bucket Garden

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If you don’t have space for an in-ground garden or access to a community garden, planting in 5-gallon containers can be a great option for making a “bucket garden” along a sunny walkway, balcony, or porch. In this video, Extension Specialist Jon Traunfeld demonstrates how to make a self-watering container garden using 5-gallon buckets and a few basic materials. You can get these buckets for free from restaurants, bakeries, and grocery stores. They are used for shipping food products and then they are usually thrown away afterward. This is a great way to give them a second use!

Tomatoes, peppers, and basil are some of the most popular plants to grow in a bucket garden. It is too late to start those plants this season, but in late summer, you can still plant kale and other leafy greens, carrots, beets, and perennial herbs. Use our Vegetable Planting Calendar as a guide.

Instructions for the self-watering bucket garden are also available on the University of Maryland Extension website, on the self-watering containers page.

By Christa K. Carignan, Coordinator, Digital Horticulture Education, University of Maryland Extension Home & Garden Information Center. Read more posts by Christa.

What to Know Before Applying Pesticides in Your Garden

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a man inside of a hardware store reading a pesticide label
Before using a pesticide, read the label. Photo: Oregon Department of Agriculture, CC.

You have a pest problem in your garden – maybe it is hungry insects feeding on your vegetables, or stubborn weeds taking over your flower patch, or fungal diseases killing your lawn. You might consider using pesticides (which include insecticides, herbicides, and fungicides), especially if the problem seems widespread or severe. How do you choose the right pesticides and apply them correctly to support a healthy and thriving garden? How do you ensure your food plants remain safe for consumption and adverse impacts on beneficial species and soil health remain minimal?

Choosing the right pesticide

Home gardeners can generally choose between two types of pesticides: general use pesticides and minimum risk pesticides. Both pesticide types come with labels that explain how to safely handle, use, and dispose of the products. The labels of general use pesticides are reviewed by the Environmental Protection Agency (EPA) and will have an EPA registration number (highlighted by the blue rectangle on Figure 1), typically on the back panel. The labels of minimum risk pesticides are less extensive and are not reviewed by the EPA as they pose minimal risks to humans and the environment. Since these labels lack an EPA registration number, you can verify the product’s authenticity by contacting the Maryland Department of Agriculture’s State Chemist Section (410-841-2721). Alternatively, you can check out this list of approved minimum risk pesticide substances (PDF).

an example of a pesticide label for Houseplant and Garden Insect Killer
Figure 1: First representative label (back panel)

Regardless of the pesticide type, it is important to select a pesticide that has a narrow activity range. If your pest is an insect, you would ideally want a pesticide that targets insects. It would be even better if you could narrow down your insect pest – is it a caterpillar, beetle, or aphid? Some pesticides are more effective against certain pest insects (for example, see the product in Figure 2) and are therefore less likely to harm non-target insects. If you are unable to identify your pest, you can submit questions and photos to the University of Maryland’s Ask Extension service. Ask Extension will help identify the pest and recommend a course of action. 

Another important criterion for pesticide selection is human safety, which can be determined from the signal words on the front panel of the label (see the purple rectangle highlighted in Figure 2). Danger signifies high toxicity, warning signifies moderate toxicity, and caution signifies low toxicity. A pesticide that is virtually non-toxic may have no signal word. Ease of use and application frequency can also help make your choice, as it may not always be feasible to measure and mix or frequently apply the product. This information is typically part of the section on directions for use, often found by peeling open the entire label (see the black rectangle highlighted in Figure 1).

a sample label from a biological insecticide called Monterey B.t. - the caution word on the label is highlighted
Figure 2: Second representative label (front panel)

What else to look for on the pesticide label

Labels also include the following information on the front panel (see Figure 2): product brand name, ingredients, and the statement “Keep out of reach of children”. Other information found typically on the back panel (see Figure 1, which includes the label peel) are precautionary and other hazard statements, first aid, and storage and disposal sections. It is important to read all these sections properly, including the entirety of the directions for use, prior to the use of the pesticide. 

  • The precautionary statement typically includes personal protective equipment that needs to be worn during pesticide applications (for example, full-length clothes, gloves, and eye protection) and informs the period of time during which one must not enter or come into contact with the treated area. The signal words are repeated in this section. 
  • Hazard statements warn of potential hazards to the environment, including soil, water, air, wildlife, and nontarget plants. An example warning statement is “This product is highly toxic to bees”. This section may also include possible fire, chemical, or explosion hazards posed by the product.
  • First aid section recommends steps to be taken in case of accidental exposure or poisoning. The instructions vary in accordance with the route of pesticide exposure (swallowing, inhaling, contact, and eye), and include statements like “sip a glass of water if able to swallow”, and “take off contaminated clothing and rinse skin with water for 15-20 minutes”. Often, there is information on who to contact in case of a medical emergency. If you need to visit an emergency health provider, remember to take the pesticide label with you. 
  • Storage and disposal section provides information on how to store the product (for example, “store in the original container in a cool and dry place” and “protect from freezing”) and dispose of it (for example, “triple rinse the empty container” or “place the empty container in the trash”). The Maryland Department of Agriculture has often had an annual program where one could recycle an empty pesticide container for free. If you would like to dispose of unused pesticides, follow the instructions in the disposal section. Never dispose of pesticides down any indoor or outdoor drain. Many Maryland counties offer options to safely recycle or dispose of household hazardous waste, including lawn and garden pesticides. Current or retired farmers and producers can also avail of a free pesticide disposal program offered by the Maryland Department of Agriculture.
  • Directions of use section instructs how to properly use the product. This section typically includes a description of intended uses, mixing and application methods, use rates, and sites where the product may be used. It can also include application restrictions – this consists of statements like “do not apply if rain is predicted within the next 48 hours” or “do not apply when bees are actively foraging”. In many labels, application restrictions are also found within the hazard statements section. 

Why is it important to follow the label?

A pesticide is any substance that prevents, destroys, repels, or mitigates pests. Thus, by nature, pesticides negatively impact living organisms. Federal law states that the EPA must ensure that pesticides entering the marketplace do not cause “unreasonable adverse effects to humans or the environment”. To carry out this mandate, the EPA assesses a variety of factors, including data on the pesticide’s chemistry, human health effects, environmental effects, etc. These data help inform the label language ̶ if the label is appropriately followed, the pesticide product should not cause unreasonable adverse effects to humans or the environment. For example, if a pesticide is highly toxic to fish, the hazard statement of the label would include a sentence like “Do not allow pesticide to enter or run off into storm drains, drainage ditches, gutters, or surface waters”. Applicators can be protected from unreasonable adverse effects by complying with precautionary statements like “Avoid contact with eyes” and “Wear chemical-resistant gloves”. Pesticide use/application rates are set to prevent hazardous quantities from entering the environment, including the infested plants you would like to consume. 

Given the label’s critical role in minimizing a pesticide’s negative impacts, it is little wonder that the label is the law. Remember, if you use pesticides improperly, you are legally responsible for any consequences that may occur!

References:

U.S. Environmental Protection Agency. Label Review Manual. https://www.epa.gov/pesticide-registration/label-review-manual

American Association of Pesticide Control Officials. FIFRA Minimum Risk Pesticides – 25(b) Product Label Guidance. https://aapco.files.wordpress.com/2018/03/fifra-minimum-risk-pesticides-label-guidance-3-12.pdf

By Niranjana Krishnan, Assistant Professor, Department of Entomology, and Maryland Pesticide Safety Education Program Coordinator

Golden summer: tomatoes and tomatillos

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A few times a year I like to take a moment to assess the vegetables I’m growing, their positives and negatives, and whether I’ll grow them again. This year I’m growing a few varieties new to me, so I’m going to look at those today: two tomatoes and one tomatillo.

Let’s start with the tomatillo. This is not a vegetable I always grow, because it takes up space–two plants are needed for cross-pollination, and they are not small plants–and because I always seem to have insect issues. Both those things are true this year as well, and yet I’m glad to have been tempted by catalog copy and fallen for Chupon de Malinalco tomatillo. It just isn’t like anything I’ve grown before.

The fruits are huge–over two inches long on average–and generally pear-shaped. They ripen quickly to a bright yellow, and the flavor is sweet-tart, great for salsas. The negatives: they’re hard to keep up with, and fall off the plant when fully ripe. Once on the ground, or even when hanging low on the plants, they get eaten. I don’t know by whom, though it could be rabbits, since they get into our community garden all the time. The fruits higher up are not safe either, since fruitworms and other pests get to them, and often I’ve removed the husk to find so much damage it’s not worth cutting away the bad parts. But with these larger fruits, often the damage is minimal and I can save some parts, which is an advantage over the smaller tomatillos I’ve grown before.

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