See:
Daffodil (Narcissus spp.) - Fire
Cause The fungus Botrytis narcissicola survives as sclerotia within bulb scales near the neck or in leaf debris. Emerging leaf tips are infected when they contact germinating sclerotia on the bulb or in the soil. Masses of spores produced in this tissue can infect injured or senescent leaves and flowers. The fungus also can enter the bulb by growing downward through infected leaves and flower stalks. The fungus can also colonize the cut end of stems after harvesting flowers. Plants showing symptoms the previous year will generally show symptoms the following year. Infection is favored by cool wet conditions, frost, hail, multiple-nosed bulbs, and leaving stocks in the ground more than 1 year. Pollen grains can also enhance infection at higher (64°F) temperatures. Bulb yields may be reduced. The cultivar Dutch Master was reported as least susceptible while Ice Follies was most susceptible.
Symptoms Newly emerging leaves become red-brown, distorted, and rotten. If partially infected, leaves show a shepherd's crook symptom. Neck rot also may develop. Lesions that develop on leaves later in the year are dark brown and bounded by yellowing areas. Often there are several lesions per leaf, which sometimes spread rapidly and coalesce to cause withering and death of the whole lamina. Flower stalks may be dwarfed with misshapen flower buds.
Cultural control
- Annual digging.
- Early digging.
- Avoiding planting in low, wet spots in the field.
- Use pathogen-free planting stocks.
- Rotate to a new planting site each year.
- Rogue out infected plants soon after primary symptoms occur.
- Remove and destroy plant debris at the end of the season in permanent beds.
Chemical control Best when used with cultural controls. Start applications before flowering when shoots are 4 to 6 inches tall. To minimize the development of resistant fungi, alternate or tank-mix fungicides from different groups that have different modes of action. Limit the use of any one group during the growing season.
- Astun at 10 to 17 fl oz/100 gal water. Group 7 fungicide. 12-hr reentry.
- Bonide Fung-onil Multi-purpose Fungicide at 2.25 teaspoons/gal water. Group M5 fungicide. H
- Chipco 26019 FLO at 1 to 2.5 quarts /100 gal water. Group 2 fungicide. 12-hr reentry.
- CuPRO 5000 at 1.5 to 2 lb/A. Group M1 fungicide. 48-hr reentry.
- Daconil Weather Stik at 1.38 pints/100 gal water. Group M5 fungicide. 12-hr reentry.
- Decree 50 WDG at 0.75 to 1.5 lb/100 gal water. Group 17 fungicide. 12-hr reentry.
- Fore 80WP at 1.5 lb/100 gal water. Group M3 fungicide. 24-hr reentry.
- Medallion WDG at 2 to 4 oz/100 gal water. Use with oils or adjuvants may cause plant damage. Can also be used at 8 oz/100 gal water as a preplant soak of sorted bulbs for 20 min, then dry. Group 12 fungicide. 12-hr reentry.
- Pageant at 12 to 18 oz/100 gal water. Do not use with organosilicone-based adjuvants. Group 7 + 11 fungicide. 12-hr reentry.
- Palladium at 4 to 6 oz/100 gal water. Avoid excessive runoff to small plants, which may result in stunting and/or chlorosis. Group 9 + 12 fungicide. 12-hr reentry.
- Spectro 90 WDG at 1 to 2 lb/100 gal water. Group 1 + M5 fungicide. 12-hr reentry.
- Spirato GHN at 2 to 4 fl oz/100 gal water. Use with oils or adjuvants may cause plant damage. Group 12 fungicide. 12-hr reentry.
- Thiophanate-methyl-based products. Tank-mix with another product. Group 1 fungicides. 12-hr reentry.
- Cleary's 3336 EG at 12 to 16 oz/100 gal water.
- OHP 6672 4.5 F at 10 to 14.5 fl oz/100 gal water.
Forecasting A spray timing model has been developed based on temperatures from 39°F to 61°F along with a wetness period of 24 hours or 6 hours of wetness at 54oF.
Reference O'Neill, T.M., Hanks, G.R., and Wilson, D.W. 2004. Control of smoulder (Botrytis narcissicola) in narcissus with fungicides. Annals of Applied Biology 145:129-137.