Cornell Cooperative Extension | Yates County

From time to time pest alerts are made known to the extension offices and others specializing in given varieties of plants, trees and shrubs. We take these alerts very seriously. Many originate within the United States Dept of Agriculture or State Agriculture Departments. Usually the alerts are about foreign insects being accidentally introduced into the United States. One of the most recent pest alerts received was for the Asian Longhorned Beetle. This is a bad guy for trees. So far there have been no known reports in our area of sightings of this insect. However, in New York City, several trees have been taken down that were infested with the insect. Tree removal in urban areas is a noticeable loss. Master Gardeners are on the lookout for this insect as a direct result of the issued pest alert.

Pest alerts are not limited to insects. The most recent one received has to do with an imported rust fungus that attacks one of our hardiest of perennials- daylilies. Not much is known about this fungus except it is suspected of originating in Asia and was identified in 2000 as being here in the U.S. How it arrived in the United States is not known. So far, this daylily rust fungus, (suspected as being Puccinia hemerocallidis, research is continuing on identification) has been observed in southern states of Alabama, Florida, Georgia, Louisiana, South Carolina and in California. It will destroy the host plant and rapidly spread to surrounding plants. A few southern commercial gardens have been quarantined as result of discovery of the fungus in them.

There was one unconfirmed report of the fungus being spotted on daylilies offered for sale at a mid-west discount store. Like most perennials, daylilies cris cross the country in large quantities every spring. In New York, as in most other states, all commercial nurseries are state inspected and licensed. There are some small backyard plant sale operations that do not pay the semi-annual $80 license fee from the NYS Ag Dept and therefore are uninspected. This is a problem and should be considered before purchasing any kind of plants. Once pests, either insects or fungus sneak into a garden, they can be very difficult to remove.

It is not known if the daylily fungus will survive in northern gardens. It is suspected, however, that since some evergreen daylily varieties do not go completely dormant in our northern winters, their foliage might survive and especially so if enough snow cover is available for winter protection. In this case, the fungus may also survive.
As to add fuel to the fungus fire, it has been reported that another host plant for this fungus is hosta. Hosta isn't a southern loving plant and therefore research with the fungus on hosta is inconclusive. The University of Georgia has been working on hosta and the fungus. The tests are in the early stages and results should be known before this growing season is over.

The daylily fungus is characterized by small roundish orangish dots on the foliage. This observation should be carefully made since several other things can happen to daylily foliage to lead to mis-identification such as aphid damage or leaf streaking. The key is the round orange dots. The cure is to cut off the infected foliage and either burn or bury it. Then spray the plant and surrounding plants with an approved fungicide following labelled directions and precautions. Most broad spectrum contact and systemic fungicides are expected to be effective. However, at this time we do not have an approved list of funicides specific for daylily rust and cannot recommend any one chemical. Should the daylily fungus reach the Finger Lakes, you can be sure we master gardeners will have the best advice available for assistance in resolving the problem. More information about daylily rust including photographs can be found at the web address of www.ncf.ca/~ah748/rust.html

Last updated: 6/7/01

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