Anthracnose Disease of Ornamental Plants: A Pictorial

Transcription

1 Stephen H. Brown, Horticulture Agent Lee County Extension, Fort Myers, Florida (239) Aaron Palmateer, Plant Pathologist Tropical REC, Homestead, Florida 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). Click here for a publication on recommended fungicides for this disease. 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.

2 Table of Content Common Name Botanical Name Page Agapanthus Agapanthus africanus 3 Annato Bixa orellana 4 Awabuki Viburnum odoratissimum awabuki 4 Autograph Tree Clusia rosea 5 Begonia Begonia spp. 6 Blue Porterweed Stachytarpheta jamaicensis 7 Cardboard Palm Zamia furfuracea 7 Carissa Carissa macrocarpa 8 Cast Iron Plant Aspidistra elatior 8 Crinum Lily Crinum asiaticum 9 Desert Rose Adenium obesum 10 Dwarf Schefflera Schefflera arboricola 11 Elk-Horn Fern Campylonerium phyllitidis 12 Foxtail Palm Wodyetia bifurcata 13 Gold Mound Duranta erecta Gold Mound 14 Green Island Ficus Ficus microcarpa Green Island 14 Hibiscus Hibiscus rosa-sinensis 15 Indian Hawthorn Raphiolepis indica 16 Ixora Ixora coccinea 17 Jatropha Jatropha integerrima 17 King Sago Cycas revoluta 18 Mandevilla Mandevilla splendens 19 Mango Mangnifera indica Snake Plant Snaseviera trifasciata 21 Strangler Fig Ficus aurea 22 Sweet Viburnum Viburnum odaratissimum 23 Tree Philodendron Philodendron selloum 24 White Bird of Paradise Strelitzia nicolai 25 Xanadu Philodendron Xanadu 26

3 Agapanthus (Agapanthus africanus)

4 Annato (Bixa orellana) October Awabuki (Viburnum odoratissimum awabuki) August Front of leaves Back of leaves

5 Autograph Tree (Clusia rosea) June Front of leaves Back of leaves Autograph Tree as a hedge

6 Begonia (Begonia spp.) June November

7 Blue Porterweed (Stachytarpheta jamaicensis) September Cardboard Palm (Zamia furfuracea) August

8 Carissa (Carissa macrocarpa) November Front of leaves Back of leaves Cast Iron Plant (Aspidistra elatior) October

9 Crinum Lily (Crinum asiaticum) November More on crinum lily

10 Desert Rose (Adenium obesum) September Front of leaves Back of leaves

11 Dwarf Schefflera (Schefflera arboricola) July Dwarf Schefflera as a hedge

12 Elk-horn Fern (Campylonerum phyllitidis) October Front of leaves Back of leaves

13 Foxtail Palm (Wodyetia bifurcata) July January

14 Gold Mound (Duranta erecta Gold Mound ) October Green Island Ficus (Ficus microcarpa)

15 Hibiscus (Hibiscus rosa-sinensis) January Front of leaves Back of leaves Insect problems of Hibiscus Hibiscus as a hedge

16 Indian Hawthorn (Raphiolepis indica) August Left: Non-symptomatic leaves Right: Leaves with Anthracnose symptom Diseases of Indian Hawthorn

17 Ixora (Ixora coccinea) July Ixora as a hedge Jatropha (Jatropha integerrima) December

18 King Sago (Cycas revoluta)

19 Mandevilla (Mandevilla splendens) July Front of leaves Back of leaves Mango (Magnifera indica) July

20 Mango (Magnifera indica) July April November More on Mango

21 Snake Plant (Sansevieria trifasciata)

22 Strangler Fig (Ficus aurea) December Front of leaves More on the Strangler Fig Back of leaves

23 Sweet Viburnum (Viburnum odoratissimum)

24 Tree Philodendron (Philldendron selloum) October

25 White Bird of Paradise (Strelitzia nicolai) October

26 Xanadu (Philodendron Xanadu ) May

27 An Incomplete List of ornamental plants that are host to Anthracnose Common Name Botanical Name Anthurium Anthurium andraeanum Areca Palm Dypsis lutescens Azalea Rhododendron hybrids Bald Cypress Taxodium distichum Banana (ornamental) Nymphioides spp. Christmas Palm; Adonidia Palm Adonidia merrillii Daylily Hemerocallis spp. Eugenia Zyzgium paniculatum Fig Ficus carica Firecracker tree; peregrina Crinum asiaticum Heavenly Bamboo Nandina domestica Leatherleaf Fern Rumohra adiantriformis Lilyturf Liriope muscari Pomegranate Punica granatum Mondograss (dwarf lilyturf) Ophiopogon japonicus Pentas Pentas lanceolata Rubber Plant Ficus elastica Rose Rosa hybrids Sycamore Platanus occidentalis Weeping Fig Ficus benjamina Yucca (spineless) Yucca spp. All pictures taken by Stephen H. Brown, except where indicated. Useful Links Crinum Lily Fact Sheet Diseases of Indian Hawthorn Insect Problems of Hibiscus Strangler Fig Fact Sheet The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, religion, age, disability, sex, sexual orientation, martial status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M.. 1/2012.