By: Nikki Tilley, Author of The Bulb-o-licious Garden
Hosta plants are popular perennials grown for their foliage. Generally, these carefree plants, which thrive in shady locations, suffer from few problems. However, occasional problems with hostas do occur, so knowing what to look for is important in order to treat or prevent further hosta problems.
What causes holes in hosta leaves? This is one of the most common questions associated with hosta plants. Essentially when bugs are eating hostas, slugs or snails are usually to blame. These nighttime foragers are probably considered the most common of hosta pests, eating small holes in the leaves. Silvery-colored slime or snail trail throughout the garden area is a good indication of their presence. Control of these slugs may include the use of beer traps, which they crawl into and die.
Another insect pest that chews hosta leaves is the adult black vine weevil. Signs of this insect are irregular notches along the outer edges of leaves. Their larvae also pose a problem by feeding on the crown and roots of hosta plants, resulting in yellow, wilted foliage.
Nematodes, which are microscopic roundworms, typically cause disease by infecting hosta plants much like fungi or bacteria. As with fungal infections, they thrive in moist conditions. Nematodes often feed within the leaves, producing brown areas between the veins, which result in an almost striped appearance. This generally occurs in late summer. Affected plants should be destroyed. You can prevent most nematode attacks by providing adequate spacing between plants, avoiding wet foliage through the use of soaker hoses, and removing and destroying all infected plants.
Think just bugs are eating hostas? Think again. Deer and rabbits will oftentimes feast on hosta plants. In fact, deer may leave only stalks where beautiful hosta foliage once was while rabbits usually prefer nibbling on the young shoots.
Anthracnose is one of the most common diseases affecting hosta plants. This fungal disease thrives in warm, wet weather. The most obvious sign of anthracnose includes large, irregular spots surrounded by a dark border. Once the centers of the spots fall out, the leaves may look torn and can sometimes be mistaken for pest damage. As with nematode prevention, try to keep a good distance between plants and avoid overhead watering which results in wet foliage. The use of fungicide spray in spring may be helpful as well. However, look for those that specifically target this disease.
Another fungus that affects hosta plants is Sclerotium blight. This disease first targets the lower leaves but then quickly spreads to the upper ones causing a path of wilted, brown leaves. In addition, there is usually a fluffy, white mass on the petioles. This particular fungus is difficult to control, as it lives in the soil and overwinters beneath mulch. Therefore, it often helps to pull back any mulch from the plant.
Crown rot also affects hostas and is often caused by overly wet situations. This disease usually results in yellow foliage, stunted growth, and root rot.
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If there was ever a popularity contest for perennials, the hosta would surely prevail.
Reliable and hardy with countless combinations of leaf color, shape, and texture, hostas are perennials that have won the hearts of northern gardeners with their fabulous foliage.
Hostas can survive in deep shade and can be planted in large masses for reliable color and texture in the garden. They are adaptable to many sites, and are generally easy to grow even for inexperienced gardeners.
Click on an image to see a larger view.
Hostas definitely make the list of easy-care perennials, and they make a great addition to almost any garden. But every once in a while, these stars of the shade can still run into a few problems — even with perfect growing conditions. Catch these hosta troubles early, though, and you won’t have as much damage to deal with.
The first step is to identify exactly what’s going on. Click through the slideshow below to see photos of and learn about three common hosta health issues, and, better yet, find out what to do to eliminate them!
These microscopic worms live in soil and devour the foliage between leaf veins. Look for brown spots, like the ones in the photo above, from late summer to early fall — but since control is difficult, prevention is your best bet.
Remove any infected leaves and throw them in the trash as soon as you can. And because this pest spreads as water splashes from plant to plant, keep leaf surfaces as dry as possible by watering at ground level.
Slugs are probably the most common pest you’ll find on hostas. If you notice irregular holes like these during the growing season, get out the Sluggo ® or other iron phosphate bait. It’s safe to use around kids and pets and works on snails, too.
If you prefer nonpoison options, here are 4 more easy ways to control slugs in your garden.
Scatter, don’t pile, the bait in thin strips around the base of the plant for the best results. To keep slug populations from really getting out of hand, put bait out in early spring as prevention. You can spread it as soon as new hosta leaves are peaking out of the ground.
It’s difficult to spot this relatively new disease because symptoms vary on different cultivars. Generally, look for leaf mottling, like in the photo here. Twisting, stunting or puckering of foliage and stems are also warning signs.
Once you find a hosta that has it, get the plant out of your garden. This virus spreads easily through the sap, so anytime you cut a leaf, divide a clump or remove flower stems you could be spreading the disease. Prevent this by dipping tools in a 10:1 water to bleach solution before moving onto another plant. (When you finish, be sure to dry tools thoroughly so they don’t rust.)
photo by: Jennifer Smith/Contributed Photo
Although Hosta plants have few pest problems, the plants are susceptible to a disease known as hosta virus X (HVX), and gardeners should be on the lookout for it.
Hostas are one of the most popular landscape plants in the U.S., known and loved for their shade tolerance, wide array of colors and sizes, and low maintenance requirements. Although they have few pest problems, the plants are susceptible to a disease known as Hosta Virus X (HVX) and gardeners should be on the lookout for it.
HVX is specific to hostas, so there is no concern about infecting other plants, animals, etc. But hostas infected with the virus may eventually die from the disease or die from other factors because they are weakened by the disease. Infected plants should be rogued from the landscape and removed from sale to avoid further spread of the disease.
HVX is identified by blotchy coloration on the leaves or color bleeding – when varying coloration bleeds across the leaf veins, mottling, puckering, twisting, brown spots, stunting and otherwise odd or unhealthy-looking plants. Many varieties of hostas have natural variegation, so it is important to know how the plant is supposed to look.
Plants in the landscape that are believed to be infected can be examined and/or tested by county extension agents and Master Gardeners through local county K-State Research and Extension offices. Samples can also be submitted to the Plant Diagnostic Laboratory that is operated by K-State Research and Extension.
Infected plants should be removed and destroyed. Clean digging tools and avoid handling healthy plants. The only ways the virus is known to spread is through propagation (division of plants) and from the movement of sap from an infected plant to a healthy one which can occur in handling or from tools.
HVX proliferated in the 1990s when many infected plants were sold that were believed to be new unique cultivars. Once the disease was defined in 1996, many growers have worked to change their practices to eliminate further spread of the disease. Difficulties in eradicating HVX include lack of recognition of symptoms by greenhouse and nursery workers, lack of symptoms in infected plants until plants are a few years old, and large-scale production of hostas worldwide.
Hostas are susceptible to a few other plant viruses, but they are less common in hostas than HVX. The Plant Diagnostic Lab through K-State Research and Extension can help identify the other viruses if plants exhibit odd growth symptoms but test negative for HVX. A few of the other viruses that can affect hostas are Tomato Ringspot Virus, Tobacco Rattle Virus, Impatiens Necrotic Spot Virus, and Cucumber Mosaic Virus. These viruses are widespread in the U.S., have a wide host range, and are most commonly moved through propagation of infected plants.
— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.
Rabbit damage appears with leaves missing from stems, dropped leaves and rabbit droppings in your flower bed. Deer also eat leaves from the tops of the hosta stems, leaving ragged bite marks on the stems. Voles tunnel under hostas to munch on roots, causing the leaves to wilt and the plant to die. Short of putting up wire fences or planting hostas in pots so voles can't get at the roots, try commercial repellents for all three pests. Apply the products heavily when the hostas begin to emerge in spring and are most tasty.
There's little you can do to prevent hail, frost or intense heat, but you can protect hostas from all three natural elements if you know when adverse weather is on its way. Drape sheets over the plants when heavy frost or hail is predicted and plant hostas out of direct sunlight if your climate is prone to hot summers. Hostas prefer partial or full shade and those with white or yellow in the leaves are most prone to sunburn.
Hostas don’t require pruning during the summer to be healthy.
For tidiness, you can remove the flower stalks at any time (even before blooming if you think they detract from the look of your Hostas).
The odd damaged leaf can be removed to make the plant look better.
But if all the leaves are damaged (from slugs or a hail storm for example), I usually leave them so the plant has the best chance of rejuvenating itself.
As I mentioned above, cut off the leaves to the ground (and clear them) after they have died in the fall to help prevent pests and diseases in the spring.