Thursday, August 24, 2017

Growing Daylilies - Part 4 Pests and Disease

Pests and Disease of Daylilies

Daylilies are relatively pest and disease free, but there are some notable examples of problems you may encounter while growing them.

Commonly Seen Pests:
Click here for AHS Pest and Disease Page
Click pest name below for AHS Page for the individual pest


Spider Mites


Slugs and Snails

Larger Insects such as cutworms, beetles or grasshoppers


Commonly Seen Diseases:
Click disease name below for AHS Page for the individual disease

Daylily Rust

Crown and Root Rots

Leaf Streak

Spring Sickness

Some Advice from Personal Experience

In my own garden, I have not encountered all of these pests and diseases. I have encountered Daylily Rust, Leaf Streak, Crown Rot, Aphids, Thrips, Spider Mites and Deer. 

Of the diseases, I have the most experience with Daylily Rust and insect predators such as thrips, aphids and spider mites. I have rarely seen leaf streak, typically only after late spring freezes that damage the leaves. 

The most important thing to know about rust is that in most locations it will not kill your plants, though it is unsightly. If you can't ever have rust in your garden, only buy from garden that are rust free. If you buy from those where rust is endemic, you may well get rust. You can spray with fungicides to suppress the rust spores. If you are in a cold-winter area, the cold will generally kill the rust and if you don't bring in rust the next year, you won't have it. Some people have rust every year and aren't bothered, some go to great lengths to not have rust and some spray to suppress it. A few even use rust to screen plants for genetic resistance and to make selection of cultivars and seedlings that show resistance for gardens and breeding use. You have to decide how to deal with rust if you get it, but the most important advice I can give you is to not freak-out. Things may look bad, but you most likely aren't going to loose your plants. The AHS links give good general information on rust. For more information on selecting and breeding for rust resistance, go to my rust resistance articles page.

The most important thing to understand with thrips is that if they are present, they are going to feed on those plants they are most attracted to, but they are not attracted to all plants equally. Some seem to have resistance. If you have thrips and daylilies that are heavily fed upon by thrips (or aphids, etc.), you will need to spray with a product such as spinosad. Preying Mantis can also help. The only other solution would be to go over to those plants that are resistant to thrips, but it is nearly impossible to find good information on this point at present.

On deer, there is only one point to know. They will eat any of your flowers that they want to eat if they can get to them and are hungry. The only real foil to deer is a fence of about 8' tall and/or outdoor dogs to scare them off. There are a lot of sprays and various scare-techniques that work for some people in some situations. My experience suggests that a fence is the only sure barrier to deer. All else has only worked sporadically or temporarily for me.

Luckily, most daylilies will be healthy and hardy, but to be forewarned is to be forearmed!