Champion Daylilies
Daylily Diseases and Insects
Daylily Diseases
Disease causing organisms (pathogens) and environmental conditions all play a role in crown and root rots of plants. Daylilies are susceptible to fungal rots caused by organisms such as Fusarium, Phytophthora, Sclerotium, Rhizoctonia and Pythium, as well as bacterial soft rot involving Erwinia. Very recently (2004) daylilies have been discovered susceptible to Armillaria, or shoestring root rot. Symptoms of rotting can include poor growth, wilting, yellowing of leaves, obviously mushy tissue and death of the plant. Bacterial soft rot is well known for its particularly foul smell.
Over-watering, over-fertilization and other poor soil conditions and plant stresses favor rot diseases. While fungal pathogens can invade intact plant tissue, bacteria can only infect through existing openings such as an injury from garden tools, pests, other diseases, frost damage etc.
In gardens where daylily rot is frequent, assistance in diagnosing the cause can be obtained by submitting a diseased plant to a diagnostic laboratory. Contact your local Master Gardeners or Extension Office for information on where to send a specimen.
While daylilies have a reputation as being disease free, there are some plant diseases that affect daylilies, most notably, Daylily Rust has been a cause for concern. Other diseases that affect daylilies include: Spring Sickness, Leaf Streak, Crown Rot and now, most recently (September 2004), Shoestring Root Rot also known as Armillaria.
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Daylily Insects
Plant pests include insects, mites, molluscs, millipedes and mammals. This section will concentrate on the "creepy crawlies" you may find from time to time around your daylilies and will provide you with a quick and easy means of pest identification. Many more pests are included here than you are likely to find causing problems in a single garden. Your daylilies may well have no significant pest problems; the intention here is merely to assist you to identify and develop a little understanding of any that you may possibly encounter.
All the pests mentioned have been seen at some time in daylily gardens, but not all are likely to cause significant problems. Finding one or two should not necessarily be cause for immediate control measures to be implemented; assess the damage level first to see if it can be tolerated. Control may not be necessary, as the problem could be limited in its extent; or natural pest enemies may take care of it for you. Make sure any suspect is actually the one causing the visible damage: look at the type of injury. Pests damage plants in different ways - some by chewing, some by piercing the tissue and sucking out the plant juices for example - so knowing the typical feeding damage can help with identification of the culprit. When in doubt as to the cause of your problem, consult your local Extension or Ministry of Agriculture specialists, who will be able to assist you with diagnosis.
Maintaining your plants in good condition with adequate water and sufficient nutrients will go a long way towards helping them overcome or avoid pest problems. But bear in mind that higher nitrogen levels are considered to make plants more attractive to certain pests.
If damage occurs, consider other options before using chemical pesticides; there may be less or non-toxic approaches to the problem. Even plain water sprayed from a hose can help minimize infestations by certain pests. Where possible, less toxic controls which can be tried are listed under the individual pests. If these fail to give adequate control and damage is significant enough that a chemical pesticide is considered necessary, local advice should be sought regarding its selection, since product availability varies regionally, as does the timing of application, etc. Remember that using a chemical pesticide inappropriately can actually increase pest problems by eliminating beneficial insects, and incorrect use may damage plants.
Tnanks to UC Davis for information and pictures in this section.
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