Smoulder in daffodils

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Smoulder is a disease of daffodils that I had not seen in northern Michigan until recently. Last year following a snow fall during full bloom of early varieties followed by wet weather, I noted infected daffodils in my mass plantings of some varieties. The disease caused by the fungus Botrytis narcissicola (Sclerotinia narcissicola) was especially severe in the ‘Unsurpassable’ variety. The disease is characterized by curling and shortening of leaves as they push out of the bulb and brown streaking on these leaves. These infected leaves may turn yellow along the outer edges.

Typical Botrytis (gray mold) spores (think of gray fuzzy rotten strawberries) will form on the base of the necrotic tissue. Later, over-wintering fungal structures, sclerotia, can be found in the diseased bulb tissue and base of the infected leaf. These sclerotia, black bodies with white interior, are about 3 to 4 mm long in my daffodils. The disease is favored by cool, wet weather.

Smoulder is again a problem this year. Prior to making the mass plantings of bulbs from one company, I had never seen this disease in the hundreds of daffodils that had been grown at my site. I assume the disease was imported with the bulbs. The literature indicates that it is a problem in the United Kingdom and is well known in the variety ‘Unsurpassable.’ Fungicidal control appears difficult. Field tests are reported in the Ann. Applied Biology 145: 129.

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