Common Disease Problems
Leaf Streak: This fungus causes yellow streaks along the mid vein in the leaf followed by browning or spots with yellow borders. The streaks begin on the leaf tips. Leaves may wither and die. Burpee Recommends: Avoid overhead watering. Remove affected foliage and destroy. Some varieties are resistant.
Leaf Scorch: Semicircular brown areas develop along leaf margins. It is most severe in high acid soils with low nutrients. Burpee Recommends: Daylilies prefer a soil pH of 6.5 – 7.0, raise your pH if it is not lower than 6.0. Provide adequate fertilization, especially nitrogen and calcium.
Root Knot Nematodes: Microscopic worm-like pests that cause swellings (galls) to form on roots. Plants may wilt or appear stunted. Burpee Recommends: Do not plant into infested soil. Some varieties are resistant. Remove infected plants and destroy them.
Rust: This fungus causes yellow to brown streaks on the leaves with small yellow spots. Orange colored pustules develop on the undersurface of the leaf. This disease can spread quickly by the wind or gardeners handling the plants. Burpee Recommends: Avoid overhead watering and remove infected foliage. Contact your Cooperative Extension Service for recommendations.
Soft Rot: A bacterial disease that causes rot at the base of flowers and rhizomes. The disease is favored by high temperatures and poor drainage. Burpee Recommends: Make sure your soil is well-drained. Avoid overcrowding. Avoid over watering and over fertilizing. Discard infected plant parts.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.
Tarnished Plant Bug: These insects cause distorted leaves and flower buds. The adults are about ¼ inch long, oval shaped and flat. They are greenish brown with reddish brown markings on their wings. There is a small but distinct yellow tipped triangle in the center of the back behind the head. Burpee Recommends: Introduce beneficial insects to your garden. Traps are available. Try insecticidal soap.
Thrips: Thrips are tiny needle-thin insects that are black or straw colored. They suck the juices of plants and attack flower petals, leaves and stems. The plant will have a stippling, discolored flecking or silvering of the leaf surface. Thrips can spread many diseases from plant to plant. Burpee Recommends: Many thrips may be repelled by sheets of aluminum foil spread between rows of plants. Remove weeds from the bed and remove debris from the bed after frost. Check with your Cooperative Extension Service for pest controls.
Are daylilies good pollinator plants? Yes, daylilies attract hummingbirds and also beneficial insects.
Can I grow daylilies in containers? Yes, smaller varieties are great for containers.
Why are they called daylilies? Daylilies produce flowers that only bloom for one day. Each flower stalk produces many flowers, however, so they appear to be blooming for a number of weeks. Some varieties have been developed to repeat bloom later in the season.
Are these the same plant that I see growing along the roadside? Yes, the orange varieties we see along the roadside have “escaped” from garden varieties. The home gardener has a very wide range of varieties available to him or her, in a broad range of colors and color combinations, flower types, different sizes and different bloom times.
Are daylilies deer resistant? Unfortunately, no they are not.