by Connie Oswald Stofko
Now is the time that certain troublesome insects and weeds can show up in your garden, and now is the time to take action.
Today we’ll talk about six insects and weeds to watch out for in spring: red lily leaf beetle, ticks, mosquitoes, lesser celandine, creeping Charlie and crabgrass.
Red lily leaf beetle
Calls have started coming in from gardeners who have spotted the red lily leaf beetle, so it’s time to look closely for it in your garden, said John Farfaglia, extension educator with Cornell Cooperative Extension in Niagara County.
“People are still seeing the red lily leaf beetle for the first time,” Farfaglia said. “If you have lilies, the likelihood is that you’re going to see it. By now, I’m a little surprised if people say they don’t have it.”
The red lily leaf beetle, which we first talked about in 2015, is a fairly new invasive species in Western New York. It can cause extensive damage to lilies and a spring bulb plant called fritillaria. The pests aren’t a problem for daylilies, which aren’t true lilies.
Updates on the red lily leaf beetle
Please report on cedar mulch
Last fall, Farfaglia told us that a gardener noticed that the red lily leaf beetle didn’t seem to bother the lilies in a bed covered with cedar mulch.
Did you try cedar mulch on your beds around your lilies? If so, Farfaglia wants to know if it worked for you. Just as important, he wants to know if it didn’t work. You can contact Farfaglia directly or leave a comment below. Thank you for being a citizen scientist!
Try coffee grounds
There have been some firsthand accounts that say placing coffee grounds around lilies could discourage the red lily leaf beetle. There isn’t any scientific evidence yet, Farfaglia said, but you could try it. Be prepared to let him know whether or not it worked.
Using wasps to battle red lily leaf beetle
A trial using certain wasps to reduce the numbers of red lily leaf beetles in Western New York is under way, but it may be a number of years before we hear whether it is having a significant effect, he said.
“I would like to think it will have a reduction in the population of red lily leaf beetles,” Farfaglia said. “My understanding is that it has at earlier sites” where the wasps have been released.
Watch to see which varieties of lily are least susceptible
While no lily is immune to damage from the red lily leaf beetle, Farfaglia said he thinks some varieties of lily will prove to be less attractive to the pest. In the future, we may be able to recommend certain varieties that are better than others.
Again, if you notice a difference among your varieties of lilies, please let Farfaglia know.
What to do now about the red lily leaf beetle
Now is the time to look for the red lily leaf beetle.
If you had a problem last year, you can start a preventive program applying a pesticide called neem oil now, at the beginning of May. Or you can monitor your plants and start treating them when you see the insects.
Farfaglia recommends neem oil for use by home gardeners because it is less toxic than other pesticides listed on the Cornell factsheet, and people have had reasonably good luck with it.
You can also try picking the adults off, but that’s difficult because they’re fast. The larvae are also difficult to handpick, and they’re gross because they cover themselves in their own feces to fend off predators. See the life cycles of the red lily leaf beetle here.
“As disgusting as it is, handpicking really does help,” Farfaglia said.
If you don’t want to handpick the pests or use insecticide, your final choice is to plant something other than lilies and fritillaria.
Ticks & mosquitoes
Ticks and mosquitoes are troublesome because they can cause disease in humans– and the number of diseases has increased.
The Centers for Disease Control (CDC) recently released a report that said nine new germs spread by mosquitoes and ticks were discovered or introduced into the United States from 2004 through 2016.
“Zika, West Nile, Lyme, and chikungunya—a growing list of diseases caused by the bite of an infected mosquito, tick, or flea—have confronted the U.S. in recent years, making a lot of people sick,” said CDC Director Robert R. Redfield, M.D. “And we don’t know what will threaten Americans next.
“Our nation’s first lines of defense are state and local health departments and vector control organizations, and we must continue to enhance our investment in their ability to fight against these diseases.”
Ticks are active now, Farfaglia said. Mosquitoes need warmer weather, but they will hatch around the end of May.
As gardeners, what should we be doing?
Learn how to protect your yard from ticks in this article we posted last year.
You can also take steps in your yard to control mosquitoes. Mosquitoes lay eggs near water, so once a week, look for items that hold water, such as tires, buckets, planters, toys, pools, birdbaths, flowerpots or trash containers. Turn them over so they don’t collect water, or empty them and scrub them, or get rid of them. See more tips for protecting yourself from mosquitoes here.
I see beautiful fields of lesser celandine when I stroll through my neighborhood. Unfortunately, those pretty little flowers will take over your lawn. Worse, they can end up in wild spaces and out-compete native plants.
“At this time of year, it’s so obvious that the plants are here,” Farfaglia said, “but they go dormant in the summer and people forget about them.”
Just because you don’t see them in the summer, that doesn’t mean that the lesser celandine has gone away. It has actually spread. Next spring you’ll have even more. One reader said it covered 7/8 of her yard.
Don’t let it get that far! If you have just a few patches, dig it up now. Lesser celandine is so troublesome because you have to kill the roots, and that is difficult, said Carol Ann Harlos, Master Gardener, garden writer and speaker. It has tiny tubers. If you try to dig it up and miss a tuber or even break a tuber, the piece left in the ground can generate a new plant, she explained.
The spread of lesser celandine seems to follow streams and creeks, Farfaglia added. The plant is also spread through compost and topsoil, so be careful not to get any of the tubers in your home compost. And don’t put any tubers you’ve dug up in with your weeds and brush that you put out for your town to compost, either.
To kill the tubers, you can also use the herbicide Roundup, Harlos told us last year.
“Spray Roundup on the leaves and it goes into the roots,” she said.
Another idea, which may or may not work, is solarization. The idea is to cook the roots by covering an area with black plastic. Keep the plastic there for several months. See the previous article for a few more details.
Please don’t just ignore lesser celandine. Remember, it’s not just a problem for your yard. It’s a problem that is spreading to your neighbors’ yards and to wild areas.
This is a weed that I struggle with. It gets everywhere!
The Master Gardeners of Erie County published a great article on creeping Charlie by Lyn Chimera. The key to success with this weed, she said, is to dig it up as soon as it appears.
If an herbicide is required, now is the time to apply it. During the heat of the summer, plants are not growing as fast and are not as susceptible to the effect of herbicides, she said. Studies have shown that spring and fall are the best times to apply.
Keeping your lawn healthy can also help keep creeping charlie at bay. And if you can live with creeping Charlie in your lawn, just let it be. It will remain green in the summer. Oh, and you can eat it!
See the Master Gardeners’ article for more information.
People have been calling with lawn questions, and one thing they ask about is crabgrass, said Farfaglia of Cornell Cooperative Extension in Niagara County.
If you need to apply preventive treatments for crabgrass, now is the time of year to do it, he said. Rule of thumb: Apply preventive crabgrass treatments when forsythia is in bloom.
But keep in mind that if you are reseeding or patching your lawn, crabgrass control could interfere with the sprouting of grass seed.
If your lawn is in good condition and fairly dense, crabgrass shouldn’t be a problem, Farfaglia noted. In that case, you don’t need to use a preventive treatment.
Get more information on caring for your lawn at this Cornell University site.