Anthracnose Disease of Ornamental Plants: A Pictorial
One of the most common diseases of plants is Colletotrichum leaf spot, or anthracnose. The Colletotrichum sp. that is most often present is C. gloeosportioides. Several other species have been identified in infections of various hosts. Frequently, the perfect stage of the pathogen, Glomerella spp., is also present in infected tissue.
Anthracnose disease may be confused with numerous other occurring plant diseases. Often laboratory analysis is the only way to confirm the presents of the disease. Infection often first become apparent at a portion of the leaf margin. The affected plant tissue frequently progresses from chlorotic to necrotic. Infected leaves develop tan to reddish brown lesions that are typically associated with leaf veins; leaves that have already expanded may become cupped and distorted with large areas of dead tissues. In severe cases leaf drop occurs.
This pathogen spreads by spores that are easy to splash with irrigation water or rainfall but since they are somewhat sticky they do not easily spread by simple air movement from the wind or fans. Wounding can increase disease severity but it is not necessary for pathogen entry.
To manage the disease, rake and destroy fallen leaves, prune out dead or infected branches, mulch and water during dry periods. Better control is more likely when fungicides are applied on a 7 to 10 day interval compared to a 14 day interval. This is especially apparent during the rainy season when spores of the pathogen are actively splashing. For this pathogen, spraying weekly in a preventative manner may be necessary to obtain the optimal results. Products recommended for managing Colletotrichum contain Chlorothalonil (Daconil Ultrex, etc.) pyraclostrobin + boscalid (Pageant, etc.) and Chlorothalonil + thiophanate methyl (Spectro 90WDG). The months associated with the pictures do not necessarily reflect the time of occurrence or expression of the disease. In some cases, the disease may be present on the plant year round.
To view pictures of the following, click to view the pdf below.
Common Name | Botanical Name
- Agapanthus | Agapanthus africanus
- Annato | Bixa orellana
- Awabuki | Viburnum odoratissimum awabuki
- Autograph Tree | Clusia rosea
- Begonia | Begonia spp.
- Blue Porterweed | Stachytarpheta jamaicensis
- Cardboard Palm | Zamia furfuracea
- Carissa | Carissa macrocarpa
- Cast Iron Plant | Aspidistra elatior
- Crinum Lily | Crinum asiaticum
- Desert Rose | Adenium obesum
- Dwarf Schefflera | Schefflera arboricola
- Elk-Horn Fern | Campylonerium phyllitidis
- Foxtail Palm | Wodyetia bifurcata
- Gold Mound | Duranta erecta ’Gold Mound’
- Green Island Ficus | Ficus microcarpa ‘Green Island’
- Hibiscus | Hibiscus rosa-sinensis
- Indian Hawthorn | Raphiolepis indica
- Ixora | Ixora coccinea
- Jatropha | Jatropha integerrima
- King Sago | Cycas revoluta
- Mandevilla | Mandevilla splendens
- Mango | Mangnifera indica
- Snake Plant | Snaseviera trifasciata
- Strangler Fig | Ficus aurea
- Sweet Viburnum | Viburnum odaratissimum
- Tree Philodendron | Philodendron selloum
- White Bird of Paradise | Strelitzia nicolai
- Xanadu | Philodendron ’Xanadu’
1
