Hostas are low-maintenance, herbaceous perennials with beautiful foliage that can be grown in shady locations. They are wonderful addition to almost any garden.
Taking care of hostas is not difficult, but there are many animals and insects that may eat or disturb them as well as diseases that can infect them. Recognizing and dealing with these pests, or preventing them all together, is important to keep this perennial plant healthy.
Make sure you deal with these problems before all of your foliage is slowly munched away.
Blister beetles, leafhoppers, grasshoppers, and cutworms all eat holes in the leaves and chew on leaf edges. Cutworms can be discouraged by placing cardboard tubes around emerging hostas leaves which the cutworms cannot breach. Commercial insecticides can be used, but remember that insecticides don’t know the difference between beneficial insects and pests. You can encourage predatory insects and insect-eating birds instead.
Nematodes are microscopic roundworms that live in the soil and feed on plant structures. Nematodes travel from the soil to the leaves in spring and feed inside the leaves. The damage shows as yellow or brown streaks and wedges between the leaf veins. They overwinter in the soil, on dead leaves, and in dormant buds. A good garden clean-up can eliminate some of the population; chemical controls aren’t available to the home gardener.
Deer find the foliage to be incredibly tasty and will strip the leaves along the rib or all the way to the ground. They often leave the flower scape alone. Deer can be deterred with high fencing, your family dog, scare tactics such as motion sensing water sprayers, or a product such as Liquid Fence or Plantskydd. These products will need to be reapplied after a rain.
Rabbits eat the tender emerging shoots. Rabbit damage is very distinctive – the stems look as if they were cut with clippers on an angle. Some gardeners place chicken wire around their plants to discourage the rabbits. Liquid Fence and Plantskydd also work to deter rabbits.
Voles dig tunnels just under the soil surface and feed on roots and crowns of plants. They look a lot like mice, except they have a short tail. The best way to control voles is to make your garden less inviting to them. They like dense vegetation, which provides cover from predators, so clearing away weeds and debris, mulch, and woodpiles could help. Owls, hawks, snakes, coyotes, and domestic cats are all natural predators of voles. Commercial products to eliminate voles also exist.
Slugs and snails eat holes in the leaves. Their slime trails are easy to spot. They prefer to live in damp and cool places, so keeping the soil on the dry side might reduce the slug population. Slug and snail baits are commercially available and a small dish of beer set at soil level makes a good slug trap, but sometimes these methods attract more slugs! .There are slug-resistant cultivars of hosta.
Some diseases that affect hosta are related to cultural practices. These include sun scorch, mold, and some rots. Making sure your plant is shaded, that there is good air movement, and the soil drains well can prevent these problems.
Anthracnose is a soil-borne fungus that infects a wide variety of plants, trees, and shrubs. On hosta, it begins as small tan spots on the leaves that grow larger and darker until the spots eventually die, leaving the plant with a tattered appearance. Anthracnose spreads by water, so water early in the morning (if you need to water) so that the foliage can dry quickly. Anti-fungal sprays containing copper can be used as a last resort. Read the label carefully.
Southern blight (also known as crown rot) is another soil-borne fungus that causes plants to turn yellow, wilt, and die suddenly. This can happen in just a few days. Infected plants should be dug out and destroyed.
Hosta virus X starts as small dark spots on the leaves and the leaves will eventually become lumpy or puckered. This disease is sometimes mistaken for a naturally occurring mutation which is often seen as a desirable trait. Gardeners can unknowingly spread virus X by sharing infected plants because they look “interesting” or “pretty.” There is no cure; remove and destroy any plants with virus X.