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The lupin is a stalwart of the cottage garden, available in a huge range of colour combinations. Unfortunately, it is susceptible to a fungal disease called lupin anthracnose, which in wet weather can cause severe dieback.
Common name Lupin anthracnoseScientific name Colletotrichum speciesPlants affected LupinMain symptoms Dead patches of brown tissue on leaves and stems, often covered in orange spores. ‘Corkscrewing’ of leaf stalksCaused by FungusTiming Spring and summer, particularly in wet conditions
Lupin anthracnose is a fungal disease of the leaves and stems. It is spread from plant to plant by rain-splashed spores, and is therefore particularly damaging in wet weather. Affected plants are not usually killed, but can become very unsightly as a result of severe leaf-spotting and dieback.
Anthracnose first became a problem on ornamental lupins in the 1980’s, and is now the most damaging disease affecting them. It is also a problem on commercial field crops of lupins, which are grown for their seeds, rich in protein and oil.
Lupins suffering from lupin anthracnose will look unsightly;
There are no fungicides available to gardeners with specific recommendations for use against lupin anthracnose. However, the fungicides tebuconazole (Bayer Fungus Fighter Concentrate), tebuconazole with trifloxystrobin (Bayer Fungus Fighter Plus), and triticonazole (Scotts Fungus Clear Ultra and Scotts Fungus Clear Ultra Gun) are labelled for the control of a number of other diseases on ornamental plants, and could therefore be used legally on lupins (at the owner’s risk) to try and control anthracnose.
There is no specific information available as to the efficacy of these products against lupin anthracnose, however. It is likely that repeated sprays will be required where the disease is present, particularly during unsettled weather. It would be prudent to apply a small amount of the chosen fungicide first, at a solution suggested on the packet for other problems, to ensure that the product will not cause plant damage.
Inclusion of a product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.
Fungicides for gardeners (Adobe Acrobat pdf document outlining fungicides available to gardeners)
Chemicals: using a sprayerChemicals: using safely and effectivelyChemicals: storing and disposing safely
Lupin anthracnose is caused by the fungus Colletotrichum. A number of species have been associated with the problem, including Colletotrichum lupini, C. acutatum and C. gloeosporioides. The disease is favoured by periods of warm, wet weather. The orange spore masses that develop on the surface of the lesions contain huge numbers of microscopic spores, and these are splashed around by rain droplets (or by overhead watering). They will germinate and infect the plant if the leaf or stem surface stays wet for a few hours, eventually producing new lesions.
The fungus can be found at the very base of affected stems, and sometimes on the roots, so the problem can develop again even if affected plants are cut back hard. Seed can also become contaminated by the anthracnose pathogen.
AphidsCornus anthracnoseDeadheading plantsDisposing of diseased materialLupin aphidLupinus: Plant SelectorPlane anthracnosePotentially harmful garden plantsWillow anthracnose
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