Articles
DISEASES OF PROTEAS AND THEIR CONTROL IN THE SOUTH-WESTERN CAPE
Article number
185_20
Pages
189 – 200
Language
Abstract
Most local protea diseases are caused by fungi belonging to the Loculoascomycotina and Deuteromycotina.
There are no records of any rusts, smuts, powdery mildews, downy mildews, or bacterial or viral diseases.
Many leaf specks, leaf blotches and leaf spots reduce the value of cut flowers.
Important leaf spot diseases are those caused by Mycosphaerella proteae on Protea neriifolia and Protea grandiceps, by Leptosphaeria protearum on Protea magnifica and by Batcheloromyces proteae on certain Protea cynaroides ecotypes.
Canker, die-back, anthracnose and blighting of shoots and twigs are especially common in older plantations. Colletotrichum gloeosporioides is important on Protea compacta and other species, whereas a Drechslera sp. causes blighting of certain Leucospermum cordifolium cultivars.
The role of Botryosphaeria spp. is not clear, though they seem to be extremely successful opportunistic colonizers of protea shoots, flower parts and seeds.
Scab is caused by an Elsinoe sp.
Corky lesions develop on stems and leaves, particularly of L. cordifolium, and flowering is reduced.
Control of above-ground fungal diseases is largely by applying sanitation measures, by avoiding susceptible species and cultivars, and by strategic use of fungicides.
Witches’ broom is an important disease of P. cynaroides, P. neriifolia and P. compacta X P. neriifolia hybrids.
Control is by controlling the mite Aceria proteae and by strict sanitation.
Damping-off and seedling blight occur sporadically.
Some common pathogens are involved, but only C. gloeosporioides has been studied to any extent.
It is controlled by thiram seed treatment. Phytophthora cinnamomi root rot is particularly severe on Leucadendron argenteum, Leucospermum cordifolium, Leucadendron discolor and Leucadendron tinctum. Losses are reduced by avoiding soils with a history of root rot and by planting tolerant species or cultivars.
Cuttings sometimes die in mistbeds.
A preplant treatment with captafol has given promising control.
Postharvest diseases include rhizopus and botrytis decay of L. cordifolium blooms and blackening of Protea leaves.
Use of disease-resistant cultivars is an important general disease control measure.
But erosion of disease resistance in breeding programs means that shifts in importance of the different pathogens could occur.
There is also the danger that indigenous pathogens will be disseminated on breeding material distributed to growers.
There are no records of any rusts, smuts, powdery mildews, downy mildews, or bacterial or viral diseases.
Many leaf specks, leaf blotches and leaf spots reduce the value of cut flowers.
Important leaf spot diseases are those caused by Mycosphaerella proteae on Protea neriifolia and Protea grandiceps, by Leptosphaeria protearum on Protea magnifica and by Batcheloromyces proteae on certain Protea cynaroides ecotypes.
Canker, die-back, anthracnose and blighting of shoots and twigs are especially common in older plantations. Colletotrichum gloeosporioides is important on Protea compacta and other species, whereas a Drechslera sp. causes blighting of certain Leucospermum cordifolium cultivars.
The role of Botryosphaeria spp. is not clear, though they seem to be extremely successful opportunistic colonizers of protea shoots, flower parts and seeds.
Scab is caused by an Elsinoe sp.
Corky lesions develop on stems and leaves, particularly of L. cordifolium, and flowering is reduced.
Control of above-ground fungal diseases is largely by applying sanitation measures, by avoiding susceptible species and cultivars, and by strategic use of fungicides.
Witches’ broom is an important disease of P. cynaroides, P. neriifolia and P. compacta X P. neriifolia hybrids.
Control is by controlling the mite Aceria proteae and by strict sanitation.
Damping-off and seedling blight occur sporadically.
Some common pathogens are involved, but only C. gloeosporioides has been studied to any extent.
It is controlled by thiram seed treatment. Phytophthora cinnamomi root rot is particularly severe on Leucadendron argenteum, Leucospermum cordifolium, Leucadendron discolor and Leucadendron tinctum. Losses are reduced by avoiding soils with a history of root rot and by planting tolerant species or cultivars.
Cuttings sometimes die in mistbeds.
A preplant treatment with captafol has given promising control.
Postharvest diseases include rhizopus and botrytis decay of L. cordifolium blooms and blackening of Protea leaves.
Use of disease-resistant cultivars is an important general disease control measure.
But erosion of disease resistance in breeding programs means that shifts in importance of the different pathogens could occur.
There is also the danger that indigenous pathogens will be disseminated on breeding material distributed to growers.
Publication
Authors
P.S. Knox-Davies, P.S. van Wyk, W.F.O. Marasas
Keywords
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