Scald (barley disease)
Scald | |
---|---|
Causal agents | Rhynchosporium commune |
Hosts | barley |
EPPO Code | RHYNSE |
Distribution | temperate regions |
Scald is common disease of barley in temperate regions. It is caused by the fungus Rhynchosporium commune and can cause significant yield losses in cooler, wet seasons.[1][2]
Symptoms
Scald is a foliar disease of barley affecting the leaves and sheaths of the plant; however, lesions may also occur on
Disease cycle
The fungus can infect and survive in barley seed. It exists as mycelium in the pericarp and hull of infected seeds. Infection of the coleoptile occurs as it emerges from the embryo. Optimal infections occur at soil temperatures of 16C. At soil temperatures of 22C or higher, very little infection occurs.
In spring cropping systems, the fungus overwinters on the crop debris and stubble of previous diseased barley crops. The fungus produces abundant
Geographical distribution and economic importance
The disease is economically important in Europe, North America and Australia. It has been reported from South America, Africa, the Middle east, Japan and Korea. Yield losses as high as 35-40% have been reported, however, losses of 1-10% are more common. Yield loss is primarily due to reduced kernel weight, but both kernels per head and number of heads per plant may also been affected.
In the wetter areas of the United Kingdom, scald is the most damaging disease of barley, affecting both spring and winter crops.[3] In the
Management
Management of the disease involves the use of clean and/or treated seeds, resistant cultivars, crop rotation, residue management, and foliar fungicides.
Resistant cultivars
Fungicides
Foliar fungicides can be used to effectively control disease development. Product selection, application rates and timing, depend upon numerous factors.
The availability of fungicides as a management tool depends on whether the product has been evaluated and registered for use in a specific country or region.
Foliar fungicides: azoxystrobin1, bromuconazole1, cyproconazole1, epoxiconazole1, fluquinconazole1, flusilazole1, propiconazole1, 2, 3, prochloraz1, pyraclostrobin2, tebuconazole1
Seed treatment fungicides: triadimenol2
1. Registered for use in Europe.[6]
2. Registered for use in Canada.[5]
3. Registered for use in the US.[7]
Fungicide resistance
In the United Kingdom, there are issues concerning MBC fungicides and some of the triazole fungicides (e.g. flusilazole and epoxiconazole). To date there are no issues with strobilurin fungicides (QoI fungicides), but the situation is being monitored closely. There are currently no issues concerning chlorothalonil, cyprodinil or the morpholines.[3]
References
- ^
Mathre, D.E. (1997). Compendium of barley diseases. American Phytopathological Society. pp. 120 pp. ISBN 0-89054-180-9.
- ^
Martens, J.W.; W.L. Seaman; T.G. Atkinson (1984). Diseases of field crops in Canada. Canadian Phytopathological Society. pp. 160 pp. ISBN 0-9691627-0-7.
- ^ a b Rhynchosporium[permanent dead link], Scottish Agricultural College.
- ^ Scald of Barley, Department of Primary Industries, Victoria.
- ^ a b Agriculture and Rural Development - Scald Archived 2011-07-06 at the Wayback Machine, Government of Alberta.
- ^ Plant Protection Products, EPPO.
- ^ Plant Disease Control - Scald Archived 2012-07-15 at archive.today, Oregon State University Extension.