Plant Problems

Deer Damage Control

Do you hate walking out the door in the summer to find your impatiens nipped off at the ground or your hosta leaves cut back to the stem? Maybe you're plagued even earlier in the year, with mysteriously disappearing tulips or neatly cropped pansies. It’s almost time to start seeing deer damage, and if they're already sampling your garden your garden, now is the time to act. The longer deer have been allowed into your yard, the more you'll see, and the harder it will be to get rid of them. There are four main ways to deal with a deer problem: repellents, frightening them, fences, and deer resistant plants.

Taste and Scent Repellents for Deer

Repellents seem to be the most common solution, but they're generally not the most effective. They can manage mild to moderate deer problems if you start as soon as you see damage and rotate through different types. Both scent and taste repellents are available, and some commercial products combine the two. Scent repellents include rotten eggs, garlic, bars of soap, and deer fear pheromones. If you opt to used soap bars, pieces must be hung on wires for the smell to circulate, and you’ll need a ton to keep the deer away, so this option may not appeal to you if you're dealing with an ornamental garden. Deer pheromones repellents work by emitting a smell that deer release when frightened to warn other deer to stay away.

Taste repellents usually rely on capsaicin, the compound that makes peppers spicy. In store bought spray repellents, you'll often find capsaicin mixed in with the garlic and egg. You can find any of these at your local garden center, but be sure to read the packaging first. Some must be applied under certain conditions or reapplied frequently, and if you have a large property you may not want to deal with the time and expense required to keep the deer away by these means. Not all of these products are safe to use on plants you intend to eat, even if the active ingredients are things you recognize, like egg solids. Natural does not necessarily mean safe. Always be sure to read landscape product labels.

Scaring Deer Away

Deer can also be frightened away. Shooting them, while it may be an effective means of instilling fear, is not a recommended or legal way to deal with the problem in urban or suburban areas like Indianapolis (and it always requires licensed permission). An outdoor dog can be an excellent solution more appropriate for heavily populated regions. Sometimes people use noise-making devices to repel the animals, but they quickly adjust to the noise, and it can end up bothering you and your neighbors more than the deer.

Deer Fencing

Proper fencing is a reliable way to keep out deer. Deer fences should be at least 7 feet high and sturdy enough not to be easily knocked over. Mesh fencing designed specifically for this purpose is less expensive, but also less attractive. A solid wood fence will also keep them out, but at much greater expense, and you may not be interested in physically and visually cutting your property off from the world. If you have a smaller vegetable garden you want to protect, this may be a more fitting situation for using mesh fencing. Make sure your fence is solid down to the ground, because deer can just as easily climb under a fence as jump over it.

Plants Deer Avoid

The last way to keep the pests out is to use plants they don't want to eat. Deer will generally avoid plants with strong, pungent scents or tough, hairy, or thorny stems and leaves. I'll give you a list of some of the most common options, but if you check the plant tag at a nursery or garden center, if will often tell you if deer leave it alone since this is such a common problem. Here are some plants deer don't like. For a more comprehensive list, check out this resource from Rutgers University. I put a * next to any plants that are native to Indiana, and a + next to any that attract pollinators.

Perennials

Spring Bulbs

Annuals

  • Ageratum (Ageratum houstonianum)+

  • Annual Vinca (Catharanthus rosea)+

  • Marigold (Tagetes species)+

  • Cleome or Spider Plant (Cleome hassleriana)+

  • Sweet Alyssum (Lobularia maritima)+

  • Snapdragons (Antirrhinum majus)+

Groundcovers

  • Ajuga or Bugleweed (Ajuga reptans)

  • Lily-of-the-Valley (Convallaria majalis)

  • Pachysandra (Pachysandra terminalis)

  • Spotted Dead Nettle (Lamium maculatum)

Shrubs

If you mostly plant species deer don't like to eat, then you can selectively protect the plants you love that the deer also love and save yourself a lot of time and effort. The nice thing about these deer damage prevention strategies is that they are usually effective at keeping out rabbits as well, if you have problems with them. These are the most common solutions I'm aware of, but I know there are more deer repellent strategies out there, especially when it comes to home remedies. Do you have anything to add to the list? What has worked or not worked for you in the fight to keep deer from eating your favorite plants?

Coreopsis (photo by Maria Gulley)

Coreopsis (photo by Maria Gulley)

Siberian Squill (photo by Maria Gulley)

Siberian Squill (photo by Maria Gulley)

Snapdragon (photo by Maria Gulley)

Snapdragon (photo by Maria Gulley)

Lily-of-the-Valley (photo by Maria Gulley)

Lily-of-the-Valley (photo by Maria Gulley)

Bluebeard (photo by Maria Gulley)

Bluebeard (photo by Maria Gulley)

Bottlebrush Buckeye (photo by Maria Gulley)

Bottlebrush Buckeye (photo by Maria Gulley)

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Pest Alert: Spider Mites

Hot, dry summers stress plants out, and some pests take that as an opportunity to strike. One common pest in the height of the summer is the spider mite, a tiny, spider-like mite that sucks water and nutrients from the undersides of leaves.

Yellow stippling is a symptom of spider mite damage.  By Rasbak - Own work, CC BY-SA 3.0

Yellow stippling is a symptom of spider mite damage.
By Rasbak - Own work, CC BY-SA 3.0

How do I tell if I have spider mites?

There are a handful of different species of spider mites, some of which specialize on just a few plants while others attack a broad range, but the symptoms and treatments are all similar, so we’ll group them together. The first thing you’ll notice in a spider mite infestation is that the leaves of your plants will be covered in tiny yellow dots. If the infestation is bad enough, you may eventually have more yellow or bronze than green on the leaves. When spruces and other needle-bearing plants have a mite infestation, they look kind of dusty, like there’s a film of brown over the needles.

If you flip a leaf over, you’ll see the mites themselves as little orange specks. To see if they’re still alive and active, hold a white sheet of paper under the plant and shake it vigorously to knock some mites off. They will crawl around on the paper after being knocked off if they are still alive and eating your plants. In especially bad infestations, you’ll also see some webbing on the leaves.

What do they do to my plants?

Spider mites suck the moisture from your plants leaving an unattractive appearance and stressing the plants out. Since they tend to be a worse problem when plants are already experiencing drought stress, serious infestations can cause leaf loss, stunting, or even death in smaller plants, and they can leave larger plants more vulnerable to additional problems. In a healthy plant, a mild to moderate infestation is no serious problem, but if it spirals out of control in a stressed landscape you’ll need to start to worry.

What can I do to get rid of them?

In serious infestations, leaves become stunted and the mites start to create webs.  By Rasbak - Own work, CC BY-SA 3.0

In serious infestations, leaves become stunted and the mites start to create webs.
By Rasbak - Own work, CC BY-SA 3.0

The best treatment is prevention. Spider mites have a whole host of natural enemies, so the best thing you can do to control them is to avoid using pesticides on your plants unless your are actively controlling another harmful pest problem. Excessive or inappropriate pesticide use actually creates more problems than it solves. Mites aren’t killed by many common insecticides, so they will survive while their predators are killed off if you use chemicals without having an actual need for them.

Since drought increases the threat of spider mites, keeping your landscape watered during serious dry spells can help protect them, and it can help reduce problems if mites have already invaded. For tips on keeping your landscape happily watered, check out last week’s blog post.

But if you already have an infestation, there are some steps you can take. Mites don’t move very fast or very far, so spraying plants with a strong setting on your hose can knock them off as long as you’re targeting the undersides of the leaves. Start with lower pressure on more delicate leaves and check to see if the pests are knocked off so that you don’t damage the leaves with the water. Since there may be eggs left behind or some mites may hold on tighter, you might need to spray the plants down weekly or twice a week while hot, dry weather persists.

In widespread, intense cases, chemicals may be necessary. Insecticidal soaps and horticultural oils work on spider mites during the growing season. Dormant oils can be used in the winter to smother the adults that overwinter on the branches. Miticides designed specifically to kill mites do exist, but they must be applied by a state licensed professional. If you think chemical action may be warranted, it’s not a bad idea to contact a professional or submit a sample to the Purdue Plant and Pest Diagnostic Lab first to get customized instructions for your situation. We are happy to help! If you want more information or to see more pictures, Purdue and Ohio State have excellent resources that go into more detail.

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Pest Alert: Spotted Lanternfly

Spotted lanternfly (Lycorma delicatula) adult winged, in Pennsylvania, on July 20, 2018. USDA-ARS Photo by Stephen Ausmus.

Spotted lanternfly (Lycorma delicatula) adult winged, in Pennsylvania, on July 20, 2018. USDA-ARS Photo by Stephen Ausmus.

Another major tree pest has emerged: the spotted lanternfly. This striking planthopper was first identified in Pennsylvania in 2014, and while it has not yet become widespread, it has the potential to spread quickly. Tree-lovers everywhere need to be on high alert. Spotted lanternfly targets grapes, hops, and the invasive tree of heaven first, but it can also attack and kill maples, oaks, fruit trees, pines, sycamores, willows, walnuts, and poplars.

How did it get here?

Spotted lanternfly is native to eastern Asia and parts of India where it is a common agricultural and forestry pest. It was first spotted in Pennsylvania northwest of Philadelphia in 2014, and it is not known exactly how it made it here. The grey egg masses are easy to miss, so it could have arrived in any number of ways. So far it has spread to some areas of New Jersey, New York, and Virginia, and those states are on high alert to identify and contain the insect.

An adult spotted Lanternfly (Photo courtesy of Bugwood)

An adult spotted Lanternfly (Photo courtesy of Bugwood)

What does it do?

In late spring to early summer, typically around May, eggs hatch and young spotted lanternflies (called nymphs) emerge to begin feeding. During the early nymph stages, they like to feed on leaves and soft stems. As they develop into later stages (called instars), they start feeding on tougher tissues, even thick branches and trunks. The adults prefer to feed and mate on tree of heaven (Ailanthus altissima, also an invasive species), but they are not terribly picky, and they will still attack a wide range of plants. They use their straw-like mouths to pierce plant tissues and suck out water and nutrients. This saps the plants of valuable resources and creates weeping wounds that leave the stressed plants susceptible to other infections and infestations. Over time, even a tree can succumb to the prolonged stress and die. More tender plants like grapevines will die more quickly.

2nd and 3rd instar nymph (black), 4th instar nymph (red body) in Pennsylvania, on July 16, 2018. USDA-ARS Photo by Stephen Ausmus.

2nd and 3rd instar nymph (black), 4th instar nymph (red body) in Pennsylvania, on July 16, 2018. USDA-ARS Photo by Stephen Ausmus.

How do I spot it?

Partially covered egg mass, 11/15/15, photo by Emelie Swackhamer of Penn State University CC by 3.0

Partially covered egg mass, 11/15/15, photo by Emelie Swackhamer of Penn State University CC by 3.0

Fortunately, spotted lanternfly spends its entire life cycle on the outside of the plant where we can see it, and it is very distinctive. The egg masses are the most difficult stage to spot, but also the easiest to deal with. In October, adult females lay egg masses on just about any surface they find. The masses look like lumps of grey clay mud about 1” wide and 2” long. At first, they’re shiny, but over time they dry out to a dull, matte grey. They can be on trees, houses, cars, trailers, crates – just about anything. This is the species’ best way to spread quickly. When the eggs hatch, the first three instars are round, black, wingless little dudes covered in white spots. The final nymph instar is a brilliant red with black and white spots, and it doesn’t look like any other bug I’m used to seeing in the garden. The adults are about 1” long and ½” wide with brownish-grey outer wings with black spots and a netting-like pattern. When their wings are fully spread, the bright red inner wings are revealed.

What do I do if I find one?

If you think you find a spotted lanternfly, take pictures, collect it in a sealed container if you can, and contact the entomology department at the Indiana DNR immediately. You can reach them on the phone at 1-866-NO-EXOTIC (1-866-633-9684) or by email at DEPP@dnr.in.gov. You can also find your regional inspector and contact them directly. If you live outside of Indiana, you can go through this website from the USDA to find your state’s extension service, and they will put you in touch with the right people. Want to learn more about spotted lanternfly? The APHIS division of the USDA has all sorts of helpful information in their spotted lanternfly profile.


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