Clematis Diseases
| DISEASE | SYMPTOMS | PATHOGEN/CAUSE | MANAGEMENT |
|---|---|---|---|
| Leaf spot | Large spots form on the leaves, become tan or black in color and may have a zonate pattern within them. | Phoma (formerly, Ascochyta), Botrytis, Cercospora, Cylindrosporium, Phyllosticta, and Septoria | Ensure good air circulation around clematis stems. Remove infected leaves as they are detected. Irrigate plants in a manner that keeps water off the foliage. Apply copper sulfate or potassium bicarbonate to protect healthy leaves. |
| Clematis wilt | Plants with dark brown to black Ascochyta leaf spots develop a stem canker that leads to plant wilting and dieback. | Phoma (formerly, Ascochyta) clematidina | See leaf spot management above. Prune infected stems. |
| Powdery mildew | White fungal growth develops on the leaves. Leaves wither and die. | Erysiphe | Apply copper sulfate, potassium bicarbonate or sulfur as soon as mildew is observed. |
| Rusts | Slightly swollen areas on the vine have eruptions of yellowish spores. | Aecidium and Puccinia spp. | Ensure good air circulation around clematis stems. Remove infected leaves as they are detected. Irrigate plants in a manner that keeps water off the foliage. |
| Phymatotrichopsis and Phytophthora root rots | Wilting and dying plants have a rot at or slightly below the soil line | Phymatotrichopsis or Phytophthora | Ensure good air circulation around clematis stems. Remove infected leaves as they are detected. Irrigate plants in a manner that keeps water off the foliage. |
| Tomato ringspot virus (ToRSV) | Yellow mottling and spotting occurs on leaves. | Tomato ringspot virus (ToRSV) | This virus is moved from infected clematis and some weeds by nematodes. If plants are vegetatively propagated from infected stock plants, new plants will have the virus. Remove infected plants |
Active Ingredients and Trade Names of the Chemicals
Fungicides and Fungicide Resistance Management - Certain fungicides, usually systemic chemicals, are said to be ‘at risk’ to the development of resistance if they are used repeatedly. See the Risk Level in the table; 1 = low risk; 2 = moderate risk; 3 = high risk. Fungicide Resistance Action Committees (FRAC) have developed a numbering system in which chemicals with the same FRAC Group number have the same mode of action. That is, chemicals with the same FRAC number kill the fungus in the same way (See http://www.frac.info/frac/index.htm). If a fungus has resistance to a chemical with a particular FRAC number, it is most likely resistant to all the other chemicals with that same number. It is recommended that chemicals at high risk be used sparingly and in rotation or mixed with chemicals with different modes of actions (different FRAC number).
| FRAC Group | Risk | Class of fungicide | Active ingredient | REI Restricted Entry Interval (hrs) | Trade names (EPA reg. no.) |
|---|---|---|---|---|---|
| M | 1 | Copper, complex | copper sulfate | 24 | Phyton 27 (49538-3) |
| NC | 1 | potassium bicarbonate | 4 | Milstop (70870-1-68539) | |
| 1 | sulfur | 24 | Kumulus (51036-352) Sulfur 90W (19713-238-5470 |
NOTICE: THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING! PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF THE REACH OF CHILDREN, PETS, AND LIVESTOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS OR PONDS.
Issued in furtherance of Cooperative Extension work, Acts of Congress, May 8 and June 30, 1914, in cooperation with the U. S. Department of Penn State College of Agricultural Sciences research and extension programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.
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