Thursday September 26th was the Planting for Beneficial Habitat Twilight meeting. Attendees learned how habitat for pollinators and other beneficial insects show good stewardship of the land. Dr. Dunn explained several methods of establishment, the benefits of hosting pollinators and other beneficial insects, and their impact as biological control.
Dr. Amara Dunn speaks with Cooperative Extension visitors.
Evergreen plantings on the NYSIPM plot, Cornell Agritech Fruit and Vegetable Research Farm
Does adding beneficial habitat reduce pest pressure on Christmas tree plots? We hope to find out.
Despite stormy skies, the Twilight Event was a success
Brian Eshenaur and Amara Dunn address attendees of the Twilight Meeting
Keuka College students in Dr. Bill Brown’s Animal Diversity class compare pairs of insect samples. Dr. Betsy Lamb invited them to hypothesize differences in collected insects at varying locations within the plots, and at different times of the year.
Thank you to all who helped make these teaching events possible!
March 28, 2019
by Joellen Lampman Comments Off on Happy National Weed Appreciation Day!
It really boils down to this: that all life is interrelated. We are all caught in an inescapable network of mutuality, tied into a single garment of destiny. Whatever affects one destiny, affects all indirectly. – Dr. Martin Luther King, Jr.
Ahhh, the weed. Despised by many, almost to the point of violence. Once, while waiting for my older child to get out of preschool, I sat in the lawn and blew dandelion heads to the delight of my infant. I’ve never forgotten the sudden manifestation of a red-faced man screaming at me about terrorizing the neighborhood. (I like to think my son was unaffected.)
The first step in IPM is determining if you have a problem. All those years ago, a large, angry man was a problem, but I contend to this day that the dandelions were not. An unknown author penned that weeds are people’s idea, not nature’s. And many through the years have found inspiration from weeds. While researching this post, I had the option of strictly sticking to quotes about weeds (don’t worry, I didn’t), but I will add a few. There are quotes about their survivability:
You can’t help but admire a plant that has adapted to lawn mowers.
A weed is a plant that has mastered every survival skill except for learning how to grow in rows. – Doug Larson
A fresh and vigorous weed, always renewed and renewing, it will cut its wondrous way through rubbish and rubble. – William Jay Smith
Quotes about weeding:
Plant and your spouse plants with you; weed and you weed alone. – Jean-Jacques Rousseau
And many waxed poetic about their hidden value:
What is a weed? A plant whose virtues have never been discovered. – Ralph Waldo Emerson
When life is not coming up roses, Look to the weeds and find the beauty hidden within them. – F. Young
But beyond their value as a philosophical aid, can weeds be beneficial?
In fact, what weeds you find can tell you something about the soil. Is it wet or dry? Lean or fertile? Compacted? Acidic, alkaline, or neutral? Check out the short overview from the University of Vermont, What Weeds Can Tell You. Then act accordingly.
Often, weeds we find troublesome are plants we once valued. Dandelions, garlic mustard, plantain, and burdock are examples of plants brought over and cultivated by settlers to North America for food and medicine. And there are efforts to regain that value. One doesn’t need to spend too much time on the internet to find many resources on edible weeds. Take a look at this short video, Edible Weeds | From the Ground Up, developed by the University of Wyoming Extension (which includes some precautions you should take if you want to try eating your problems away). The Northeast Sustainable Agriculture Research and Education recently funded a project looking at bringing edible weeds from the farm to the market.
These trichogramma wasp parasitized European corn borer eggs aren’t going to hatch.
There is research looking at the ecosystem services provided by weeds in agricultural settings. In their project, Integrating Insect, Resistance, and Floral Resource Management in Weed Control Decision-Making, Cornell researchers make the argument that while weeds can compete with crops, they can also benefit the entire system. They use milkweed along a field of corn as a case study. There are aphids that feed on the milkweed and produce honeydew, which benefits beneficial insects such as wasps that lay their eggs in the eggs of insect pests such as European corn borer. And that’s before they discuss the benefit to monarch butterflies.
Early flowering weeds, such as this purple deadnettle, provide an early spring food source for pollinators.
And speaking of butterflies… and bees… and other pollinators, in the write-up of a study looking at the capacity of untreated home lawns to provide pollination opportunities, they reclassified weeds as “spontaneous lawn flowers”. So much friendlier! By the way, they found 63 plant species in those lawns. In a parallel study looking at mowing and pollinators, they found that lazy lawn mowing led to more spontaneous lawn flowers leading to more pollinators. So now I have also given you an excuse to mow less. You’re welcome.
Some of our beneficial insect habitat plots looked really beautiful this fall! Others are still works in progress.
Today’s post is from our Biocontrol Specialist, Amara Dunn
Have seed and plant catalogs started arriving in your mailbox, yet? This is the time of year I start thinking wistfully about the arrival of spring. If your spring daydreams include planting habitat for pollinators and other beneficial insects, keep reading for the latest on NYS IPM’s beneficial insect habitat establishment project!
Back in October I described the purpose and design of this project. So what have we learned after the first year? First, here’s a reminder of the different treatments we were comparing. Each treatment involved either direct seeding or transplanting habitat plants, in the spring or the fall, utilizing a different method for weed control.
Replace dead plants
Till, transplant, mulch
Replace dead plants
Till, direct seed
Till, plant buckwheat
Mow 1x, till, plant buckwheat
Mow 1x, transplant
E – control
Till, lay plastic
Remove plastic, direct seed
Herbicide 2x, till 1x
Till 1x, direct seed
And here’s how much time and money we spent on each method during our first year. Each treatment was applied to a total area of 460 ft2 (0.01 A).
A – Spring transplant
B – Spring transplant and mulch
C – Spring seeding
D – Buckwheat & fall seeding
E – Control
F – Solarize & fall seeding
G – Herbicide/tillage & fall seeding
What did we get for the time and money we invested? Well, the only two treatments that looked anything like habitat for beneficial insects by October were the ones we transplanted in the spring (A and B). And of the two, treatment B looked a lot better because of the mulch we spread around the plants after transplanting to help suppress weeds. Even so, we still hand weeded this treatment (and treatment A) twice during the year. But we got much better weed control in treatment B.
Four and a half months after transplanting, the beneficial habitat plants in treatments A (left) and B (right) were mostly growing well. But there was a big difference in weed control, in spite of similar amounts of time spent weeding each treatment
Direct-seeding in the spring resulted in a few blackeyed Susans by October (and a few partridge peas slightly earlier in the year), but did not look very impressive and had a lot of weeds.
After direct-seeding in the spring and mowing four times during the summer and fall, there were a few blackeyed Susans blooming in treatment C plots.
Of the three methods we used to manage weeds during the season, alternating herbicide applications and tillage resulted in the cleanest-looking plot by October.
A few weeds were present a week after the last time the herbicide/tillage treatment (G) was rototilled. We broadcast, raked, and pressed beneficial habitat seed into these plots.
Solarizing the soil was low-maintenance once the plastic was laid in the spring. We did learn that solarization is not a good strategy if you’re trying to control purselane. It grew just fine under our clear plastic, while most other weeds didn’t. In some places, it probably reduced the efficacy of solarization because it pushed the plastic away from the soil and allowed other weeds to germinate and grow.
In some solarized plots, purslane grew happily under the plastic. Purslane was not a common weed anywhere else in the field during the season.
The two crops of buckwheat we grew in treatment D not only suppressed weeds, but also attracted lots of pollinators and natural enemies to its blossoms before we mowed the crop down to keep it from going to seed.
The buckwheat established quickly and crowded out many weeds. We mowed the first crop in July and re-planted. We had to mow the second crop about 3 weeks before we transplanted (not ideal).
In summary, if one of your 2019 resolutions is to plant habitat for beneficial insects, I have two pieces of advice:
Spend 2019 controlling weeds. Even where we transplanted, weed pressure was a challenge, and investing in weed control before you plant is worth it!
If you have sufficient funds and need or want to establish habitat quickly, transplants are the way to go. Mulch will help you with your battle against weeds.
In 2019, we’re planning to keep monitoring these plots. Check back to see how the fall-planted and direct-seeded treatments look in their second year. Most of these methods are expected to take several years to reach their full potential. We will also start counting the insects (and insect-like creatures, like spiders) we find in these plots. During 2018, we already started seeing some beneficial insects showing up in these plots, so I’m looking forward to counting them once spring finally gets here!
Here are just a few of the beneficial insects we spotted in these plots during 2018. Soldier beetles, many hover flies, and lacewing larvae are all natural enemies of pests. We also saw lots of lady beetles and several other types of bees.
Thanks to Betsy Lamb and Brian Eshenaur who are working on this project with me, and to Bryan Brown for doing a weed assessment for us. You can read more about this project and see more pictures from 2018 at Biocontrol Bytes. Subscribe to make sure you don’t miss future updates!
December’s wintery breath is already clouding the pond, frosting the pane, obscuring summer’s memory… ― John Geddes
Winter had an early showing in New York this year. So when the temperature hit 50oF yesterday, I took the opportunity to spend some time outside. And, as I had warned people that follow me and NYS IPM on social media with this great graphic by Matt Frye earlier today, the ticks were out and about. (Side note: follow us at www.facebook.com/NYSIPM and twitter.com/NYSIPM for up-to-date information you can use.)
Now, the ticks weren’t as active as the 70 oF day last February. I had to put in a little more effort to find them. But while tick dragging, I noticed where others regularly go off the beaten track (or, rather, create their own beaten track). We’re going to call this The Dog Zone.
There’s a perfectly good paved path, but the dog print laden path is inches from the woodline.
Let’s face it. Dogs want to stick their noses into interesting places, and there just aren’t that many interesting places on the pavement. So they will take advantage of the length of the leash to get off the pavement and follow the scent trails. And the smells of mice, chipmunks, squirrels, raccoons, deer, rabbits (you get the idea), are more likely to be wafting at the edge of the woods than in the short grass. I watched dog walkers leave the pavement themselves to indulge their furry friends. Unfortunately, ticks are more likely to be in those areas.
Talk to your vet about options to protect your pets from ticks and tick-borne diseases.
But the really important message here is that ticks are active during the winter. And even if the air temperature is less than 37oF, a protected, sun-exposed area next to a woodline can be significantly warmer. Last week a site we were monitoring had an air temperature of 40oF, but the ground temperature was 50.6oF. So I will end by emphasizing the need to protect yourself from ticks year-round and conduct a tick check EVERY DAY.
Today’s post is from Brian Eshenaur, Senior Extension Associate for Ornamental Crops Integrated Pest Management Program, working out of Monroe County.
As fall approaches with its chilly air and increased soil moisture, fungi often respond by producing mushrooms. Think of mushroom structures as the “flower” of the fungi. The gills under the umbrella cap produce tiny spores. Like seeds, they disperse on the breeze or foot traffic and may grow under suitable conditions.
The mushrooms we see indicate an extensive network of fungal hyphae below ground. They are not feeding on the lawn, rather it’s dead organic matter on which they decay and digest, and most often start on dead roots or stumps.
What should a homeowner do?
First, realize that they are not harming the lawn and will fade back into the ground in a matter of days. Enjoy the temporary display! However, if curious young children or pets will be around the mushrooms, it’s best to step on them to reduce their visibility and any temptation to take a nibble. Most mushrooms are harmless but, until you’re an expert at recognizing the poisonous ones, err on the side of caution.
Brian Eshenaur is a Sr. Extension Associate for Ornamental Crops Integrated Pest Management Program, 2449 St. Paul Blvd., Rochester, NY 14620
Brian works with producers of greenhouse and nursery crops as well as Christmas tree growers. He conducts applied research and delivers educational programs in these areas with the goal of improving pest management and the adoption of IPM techniques. For more about his work, visit our website.
May 16, 2017
by Mary M. Woodsen Comments Off on Keep Off the Grass? IPM for Anyone With a Lawnmower
Now that spring has arrived and you’ve dusted off the lawn mower …
PUBLISHED ON MAY 3RD, 2017, CANTON, N.Y. | Courtesy Paul Hetzler, CCE St. Lawrence County
As a kid of about five, I became suspicious of lawns. In a rare moment of TV viewing, I had seen a public-service ad wherein a bundle of green leafy stuff thudded into an eerily vacant playground while a baritone voice boomed out something like “Grass. We think it’s bad for kids. Stay away from it.” My mom insisted this was “bad grass” which did not grow in our yard. However, she declined to elaborate, which fueled my mistrust. So I kept off the lawn a while.
These days, “bread” is no longer money, “mint” is just a flavor, and the pernicious leafy stuff mostly goes by other names. There is only one grass, and it is almost time to cut it again. Jargon may change, but things like paying taxes and mowing lawns don’t seem to.
To help you, or so they say, a bewildering array of lawn-care products have sprouted at big-box stores and garden centers. It’s easy to spend a lot of dough — I mean money — on fertilizers, weed killers, and seed. But it’s hard to make sense of which products are right for you.
Before you shop, a couple of thoughts to help sort things out.
Grass is not for everyone. Or everywhere. If an area does not get 4 or more hours of full sun daily from March through September, trying to grow grass there is a waste of time.
Steep slopes and high-traffic zones probably need something other than grass, too.
Keep mower blades sharp — it can help reduce disease, plus it looks nicer and saves on mower gas. (Flickr Creative Commons Brian Boucheron)
Comparison spells trouble. Well not literally, but it’s mighty unfair. Fashion models have airbrush artists and makeup consultants. Golf courses have full-time turf experts and a massive budget. With good information and a little work, we and our lawns can both look good, but let’s not compare with deep-pocketed pros.
Dr. Frank Rossi, a leading Cornell Turfgrass Science researcher, puts it this way:
“Chances are you can grow a pretty good lawn without using insecticides, fungicides, or herbicides. You may even be able to do it using little or no chemical fertilizer… Will your lawn look like a putting green? No… But if you arm yourself with an understanding of what grasses need to thrive, and commit to a long-term plan to meet those needs, you can grow a perfectly acceptable lawn…”
Get the dirt on your soil. If your grass looks bedraggled, fertilizer may not be the answer; in fact, early-season nitrogen can weaken grass and make lawns worse in the long run.
At the very least, get a soil pH test—a pH more acidic (lower) than 6.0, or more alkaline (higher) than 7.0 will hinder plants’ ability to absorb nutrients. The majority of samples I get at the office have pH values too high for healthy lawns, sometimes 100 or even 1,000 times too alkaline due to annual lime treatments. Lime is only good if it’s needed.
If it’s been over three years since the soil was tested, you might want to invest in a lab analysis. For under twenty bucks you can get nutrient levels with specific recommendations, plus pH and salt content. This last item may seem odd, but fertilizers, herbicides, wood ash and deicing agents are all sources of salt — which can damage soil structure, harm microbes, and aggravate water stress.
Only fertilize based on soil test results, and only use nitrogen in the fall.
Nature abhors a vacuum, which is why I keep mine hidden away indoors — no sense offending nature if you can avoid it. This hatred of emptiness means that if you don’t re-seed bare or weak spots in the lawn, Nature will fill it with whatever is handy — probably weeds.
Edging along the sidewalk or driveway may produce the look you want, but it also produces a lot of bare earth, so if you have a weed issue, especially crabgrass, breaking this habit will give you an edge on weed control.
Another type of vacuum is a close-cropped lawn. Not only does close mowing cause weak, stunted grass roots (and thus plants), it allows the sun full access to the soil. This gives weeds a tremendous advantage.
Have trouble with ground ivy? Put away the vacuum. Stop shaving the earth and start mowing the grass.
The most important thing you can give your lawn is more of its hair. Studies show that changing to a grass height of 3.5 inches leads to a vast improvement in lawn health. Leaving grass longer will greatly reduce weed pressure, lawn diseases, and fertilizer requirements. Perhaps the most dramatic change with longer grass is a lasting drop in weed population.
If you need to use herbicides to reduce weeds, follow the label instructions closely. Some broadleaf (selective) herbicides contain chemicals that could stress or injure trees. Pre-emergent herbicides inhibit weed germination, and are used for crabgrass control. Apply pre-emergent products around the time forsythia flowers are starting to drop.
Another tip is not to mow more than a third of the grass at a time. For example, to maintain a 3.5-inch turf height, mow before the grass gets over five inches high. Try to keep the blades sharp — it can help reduce disease, plus it looks nicer and saves on mower gas. And it almost goes without saying that grass clippings belong to the lawn, not the landfill. Leave the clippings—that’s your fertilizer.
White grubs — we have five species in northern NY — can become a problem if there are more than ten per square foot of lawn. Several nontoxic and low-toxicity treatments have come on the market in the past few years, but timing varies for all of them. Milky spore treatment is safe, but is not effective up north due to cool soils. You can also use beneficial nematodes to kill grubs.
There are many solid lawn-care resources out there, but always check the source, which should be from .edu or .gov sites. Cornell Senior Extension Associate Lori Brewer has assembled the work of many experts, including Dr. Rossi, into a comprehensive 47-page book entitled “Lawn Care,” which is free at http://hort.cornell.edu/turf/lawn-care.pdf
I think it will contribute to a better world if we teach our kids to stay grounded and let the grass get high.
These nematodes Hetzler mentions — beneficial organisms — are key to good IPM. In fact, good IPM embraces every concept Hetzler stands by. With IPM, prevention is always the best cure. And remember: even herbicides are a type of pesticide, because weeds are pests too. If you’ve ever spent a whole day weeding a not-that-big garden, you know that sometimes weeds are the most difficult contenders we face. — ed. MW.
August 26, 2016
by Mary M. Woodsen Comments Off on World-class Golf Comes Home. Thank You, IPM
The Barclays PGA Tournament kicks off the FedEx Cup playoff in professional golf. This year it’s right here, right now — at Bethpage State Park on Long Island in downstate New York. The IPM (integrated pest management) piece of this story? Here’s where we tested, developed, and showcased preventive, threshold-based IPM protocols that can steeply reduce year-in, year-out pesticide use on any golf course, anywhere — all while protecting habitat for pollinators and many other creatures. In fact, we’ve scored environmental impact quotients up to 96 percent lower than conventional practices.
Happening as we speak — at Bethpage State Park, also home to IPM research that informs thoughtful, preventive tactics for golf-course care.
The IPM tactics we honed on Bethpage’s Green Course over 12 years are also used on its Black Course — among the most challenging courses you could find anywhere. Think of it. Putting greens buzz-cut to within an inch of their life. Talk about stress! (Technically, that’s an 1/8th inch of their life.) Fairways mowed to about ½ inch. Roughs to an inch or so — and even that’s a height we don’t recommend trying at home.
Which is why we can’t stress how important long-term, real-world research is. Whether it’s searing heat and no rain or relentless rain and chilly weather — or any combination thereof — well, you just don’t get truly useful results until you’ve tested your work in widely differing seasons and situations. And in dealing with pests on golf courses, it’s all about the season. It gets even more impressive when you consider that Bethpage (along with the other 24 public-park golf courses across New York) is open to all comers, facing heavy traffic and tight budgets.
92-plus: that’s an impressive number of pollinators to find in mid-April 2015 after a long, difficult winter.
We’ve always known how important beneficial insects and other organisms are to ecosystem health. In fact, many of our IPMprotocols are built around using beneficials and biocontrols to keep pests at bay. Equally as important: protecting nontarget organisms — frogs, for example — from exposure to pesticides. Which is why we were happy to find this fine fella hanging out at Bethpage in a marshy verge during an Earth Day trek around Bethpage. And a 2015 survey of pollinators in naturalized areas at Bethpage revealed at least 92 species of bees, wasps, and other pollinators as well as a diversity of plants that attract them.
Good stuff. Thank you, Integrated Pest Management.
A green frog? Bullfrog? From this angle, hard to tell.
August 2, 2016
by Mary M. Woodsen Comments Off on Climate, Weather, Data: Crops and Landscapes
With all the talk about climate change you might wonder how it will affect food production, pests, and even landscapes—and what you can do about it. From the Valentine’s Day massacre winter freeze to plant life gasping for water, changing weather patterns have affected our crops all over the Northeast. Learn how gathering information on weather and climate can help growers, gardeners and landscapers plan for changes. Find details on The Climate and Weather Conference webpage.
Remember the adage “knee high by the 4th of July”? This year it was ankle high. And dry.
Climate, Weather, Data: Protecting Our Crops and Landscapes. It’s all happening August 15, 2016 at the Albany County Cornell Cooperative Extension Office, 24 Martin Rd., Voorheesville, NY, 12186.
We’re honored that Richard Ball, the Commissioner of the New York State Department of Agriculture and Markets, will kick off the conference. Speakers from New York and across the Northeast will discuss the current state of knowledge on climate change and changes in weather patterns. We’ll also learn how collecting climate and weather data can help us predict and manage pests. Open discussion sessions are included so you can ask your own questions. Join us.
The New York State IPM Program seeks four new staff to amplify our IPM outreach and research for farms and communities around New York. Here are the positions (three of them new) we seek to fill:
Biocontrol Specialist (Extension Associate)
Alternative Weed Management Specialist (Extension Associate)
Coordinator for the Network for Environment and Weather Applications (Extension Associate)
Coordinator for Livestock and Field Crops IPM (Senior Extension Associate)
Our mission: to develop sustainable ways to manage disease, insect, weed, and wildlife pests; and to help people use methods that minimize environmental, health, and economic risks. Our agricultural and community programs have overlapping issues and settings. Agricultural IPM programming includes fruits, vegetables, ornamentals, and livestock and field crops. Community IPM promotes insect, weed, plant disease and wildlife management in schools, homes, and workplaces as well as on lawns, playfields, golf courses, parks and landscapes; it also includes invasive species and public health pests. NYSIPM is a national leader in developing and promoting IPM practices.
Hands-on workshops held on neighborhood farms are a tried and true way to get IPM practices to stick.
We foster a collegial and cooperative environment where teamwork is emphasized and appreciated. We also collaborate with Cornell University faculty, staff, and Cornell Cooperative Extension educators, as well as with specialists from other states and universities. These positions will be housed either in Geneva (NYSAES) or Ithaca (Cornell campus).
Education and Experience
All applicants must have an MS (required) or PhD (preferred) degree in entomology, plant pathology, horticulture or other suitable field. A minimum of two years professional experience in extension education and research or demonstration in required for extension associates and eight years for the senior extension associate. We will consider experience as a graduate student.
Additional Information AND HOW TO APPLY
For more information and application instructions, click here. Applications will be accepted until 8/31/2016 or until a suitable candidate is found.
June 9, 2016
by Joellen Lampman Comments Off on For Wasps, Prevention Is Key — and the Time Is Now
Most of the wasps we’re too familiar with (and afraid of) are sociable with their own kind, building large nests in trees or underground. The problem is when they build nests under your eaves, picnic tables, or even (if you’re a farmer) under the seat of that baler you’re about to rev up as part of your pre-harvest maintenance check.
At a distance these wasps make great neighbors. As predators of flies, caterpillars and other soft-bodied insects, they help keep their numbers in balance. And that balance, that ounce of prevention, is a core tenet of IPM. But wasps are trigger-happy, so to speak — grab that picnic table to move it out of the sun and you’ll wish you looked underneath it first.
We could talk about any wasp you want, but today we’re focusing on bald-faced hornets. Just know that you can also apply IPM’s preventive tactics — we’ll get to that later — to your standard-issue yellow jackets, paper wasps, mud daubers and honey bees.
Big nests for big bruisers: this carton nest is too close to home.
Bald-faced hornets house their colonies in large, enclosed carton nests. Like most wasps (and bees) these mostly mild-mannered critters turn nasty when their nest is threatened. They don’t know you had no intention of harm. But when bald-faced hornets live too close, yes, they represent a public health concern.
Bald-faced hornet, up close and personal. Courtesy Gary Alpert, Harvard U.
Did You Know…?
What’s in a name?: White-faced hornets can be easily identified by the large patch of white on their faces.
Family relations: This hornet is the largest yellow jacket species in North America.
By the numbers: A nest can contain hundreds of hornets, and most will attack to protect their queen.
Danger! White-faced hornets have unbarbed stingers, so they sting repeatedly. (Author’s note: Take it from me — disturb a nest and yes, you might get stung way more than you’d like.)
Beneficial insect: White-faced hornets are important predators of flies, caterpillars and other soft-bodied insects.
Only one way out of a carton home, but space enough for a battalion of angry moths to exit. Courtesy Wikimedia Commons.
Since technically it’s still spring and a chilly May slowed them down, you still have time. Inspect (in IPM lingo, “scout”) the aforementioned eaves, picnic tables, and outdoor equipment as well as the undersides of the railing on your porch or deck; that sort of thing. You’re looking for small carton nests that look like these, only way smaller. For other stinging wasps, keep and eye out for what looks like clots of mud (nifty inside, should you get a chance to dissect one) and the clusters of open cells, rather like honeycombs, that comprise a paper-wasp nest. Basically, you want to find a nest under construction, as it were — one with just a few workers ferrying back and forth to care for their queen.
Did You Know…?
Last year’s empties: See a scary-big nest? Most likely it’s from last year — and wasps don’t reuse them. On the other hand, a subtle scent left behind tells other wasps that this could be a good place to build a nest of their own. So get rid of empties.
Moving quietly on a warm-enough day, stake out a claim nearby and watch the nest for 15 minutes or so. See any wasps? You’ve got an active one. No wasps? Best to scrape the old nest off so they won’t worry you later.
How to get rid of them? At dusk or dawn (dawn is better — it’s usually cooler) get out there with a tall pole, a SuperSoaker, or a hose with a good nozzle on it (you want a focused, powerful stream of water) and knock them down one at a time. Then stomp on them. Need a light? Don’t shine it right on the nest; better yet, cover your light with red cellophane. (Wasps don’t register red.)
Looking ahead — for larger nests later in summer, ask yourself if the nest is close enough to where you live, work or play to pose a significant threat. If it’s at a distance, best to leave it be.
More prevention (core IPM!): cover outdoor garbage receptacles and pick up dropped fruit under fruit-bearing trees. Integrated pest management can help to determine if a bald-face hornet nest is a danger and what to do if it should be removed.