What diseases affect daylilies?

Wednesday, 09 September 2009 00:10 |

Daylilies, for several decades, have been the type of plant a gardener dreams of; low-maintenance, disease resistant and very easy to grow.

Environmental conditions and gardening practices can play a role in the development of diseases. Some cultivars may also be less adaptable to different conditions and climates, or less resistant to certain diseases than other cultivars.

Here is a list of diseases currently affecting daylilies for you to be aware of and how to identify each one:

Daylily Rust

Caused by a fungus (Puccinia hemerocallidis).
Doesn't survive over winter in the colder climates where prolonged freezes occur. May survive where the alternate host (Patrinia) is present.
Orange-yellow powdery spots on leaves and scapes. (not always rust)
Orange-yellow spores stain your fingers when wiped off. (not always rust)
Affects the outer leaves first. Rarely, if ever, will the plant die.
Hybridizers are breeding plants to be less susceptible than others to rust and will usually tell you about the susceptability when asked.
Over-head watering is reported to encourage the rapid spread of rust in a garden. Drip or soaker hoses will help to slow the spread of rust.
Fungicides are available such as Heritage, Cabrio, and several others. However, these are only controls and will not kill the rust.

Crown and Root Rot

The plant tends to yellow and dwindle away to nothing rapidly. Leaves seperate or pull away from the plant easily with a gentle tug. Affected tissue is mushy and the plant will die without intervention.
Foul smell is almost always present.
Excess standing water and extreme heat are main factors that trigger rot, as these are ideal conditions for bacterium and other pests.
Other factors may be nematodes, bulb mites or other pest damage, fungal and/or bacterial pathogens (disease causing agents).
Some cultivars are more susceptible than others. Luckily, very few are susceptible. Most hybridizers will let their stock of a particular cultivar die off and won't introduce it into commerce. However, some have slipped through the evaluation process and unfortunately, are in commerce today.
Mostly a particular concern in warmer climates, but can also occur elsewhere if given the right conditions.
Almost always uncontrolable unless anti-fungals are used.
Avoid over-watering during extreme heat.
Let wounds from division on daylilies dry in the shade before re-planting, apply anti-fungal, or the use of a mild bleach solution is helpful.

Leaf Streak

Spring Sickness

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