Narcissus Diseases
Gary W. Moorman, Professor of Plant Pathology
| Disease | Symptoms | Pathogen/Cause | Management |
|---|---|---|---|
| BASAL ROT | Plants are stunted and foliage dies prematurely. The few roots present are brown and the basal plate is decayed. White or pink fungal growth develops between the bulb scales. | Fusarium oxysporum f. sp. narcissii | Do not plant bulbs that have white or pink fungus on them. Purchase and plant hot water treated bulbs. |
| FIRE | Flowers are spotted, turn brown, and die. Small, tan, oval spots form near leaf tips. Leaves have bright yellow streaking near tips. | Botryotinia polyblastis | Discard infected plants. Apply thiophanate methyl, or chlorothalonil to protect healthy plants. |
| LESION NEMATODE | Plants are stunted and the foliage dies prematurely. | Pratylenchus penetrans | Purchase and plant bulbs that were treated with hot water. Discard infected plants. |
| SCORCH | Reddish-brown spots with yellow halos develop on leaf tips as they emerge. The spots enlarge, merge together, and the leaves die. Spots have small brown dots (fruiting structures) within them. | Stagnospora curtisii | Purchase and plant bulbs that have been hot water treated. Apply thiophanate methyl as new leaves emerge. |
| STEM AND BULB NEMATODE | Leaves from infected bulbs are small, distorted, and sometimes swollen. Infected bulbs are rotted and feel lighter than normal at planting. | Ditylenchus dipsaci | Purchase and plant hot water-treated bulbs. Discard infected bulbs. |
| VIRUSES | Leaves may have a mosaic, have yellow to white stripes or have dead tips, and die prematurely. | Many viruses are known including white streak, narcissus tip necrosis, cucumber mosaic, yellow stripe, tobacco ringspot, and tomato ringspot. | Discard infected plants. Maintain good insect control. |
Rhizoctonia and nematodes affecting bulbs.
Active Ingredients and Trade Names of the Chemicals
| FRAC Group No. | Risk Level | Class | Active ingredient | REI Restricted Entry Interval | Trade Names (EPA Reg. no.) |
|---|---|---|---|---|---|
| 1 | 3 | Benzimidazole | thiophanate methyl | 12 | 3336 (1001-69), OHP 6672 (51036-329-59807), Fungo Flo (51036-329-59807), Systec 1998 (48234-12) |
| M | 1 | Chloronitrile | chlorothalonil | 48 | Daconil (50534-9), Exotherm Termil (70-223) |
| 12 | Echo (60063-7), PathGuard (60063-7-499), Concorde (72167-24-1812), Pegasus (72167-24-1812) |
Fungicides and Fungicide Resistance Management - Certain fungicides, usually systemic fungicides, are said to be 'at risk' to the development of resistance if they are used repeatedly. See the Risk Level in the above table (1 = low risk; 3 = high risk). The Fungicide Resistance Action Committee has developed a numbering system in which chemicals with the same FRAC Group number have the same mode of action (See http://www.frac.info/frac/index.htm ). 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).
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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.
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