Wheat diseases

From Wikipedia, the free encyclopedia

1 In Europe
2 In the USA

[edit] In Europe

Cereals are at risk from numerous diseases due to the level of intensification necessary for profitable production since the 1970s. More recently varietal diversification, good plant breeding and the availability of effective fungicides have played a prominent part in cereal disease control. Use of break crops and good rotations are also good cultural control measures. The demise of UK straw burning in the 1980s also increased the importance of good disease control.

Active control measures include use of chemical seed treatments for seed-borne diseases and chemical spray applications for leaf and ear diseases. Development of resistance by diseases to established chemicals has been a problem during the previous 30 years.

[edit] Fungicides

Some cereal fungicide groups and examples of active ingredients:

Benzimidazoles
- carbendazim

Ergosterol biosynthesis inhibitors
- prochloraz
- flutriafol
- tetrachonazole

Morpholines
- fenpropimorph

Strobylurines
- kresoxim-methyl

Phthalonitriles
- chlorothalonil

[edit] Principal diseases

Barley yellow dwarf virus, BYDV
Brown rust Puccinia recondita
Bunt (see covered smut) Tilletia caries
Ergot Claviceps purpurea
Eyespot (see cereal eyespot) Pseudocercosporella herpitrichoides
Leaf spot, glume blotch, see wheat septoria, septoria nodorum, septoria tritici
Mildew (see cereal mildew) Erysiphe graminis
Seedling blight Fusarium spp., Septoria nodorum
Sharp eyespot Rhizoctonia cerealis
Take-all Gaeumannomyces graminis
Yellow rust Puccinia striiformis

[edit] References

Cereal Pests and Diseases (Gair, Jenkins, Lester) 1987 Farming Press ISBN 0-85236-164-5

[edit] In the USA

Wheat is subject to more diseases than other grains, and, in some seasons, especially in wet ones, heavier losses are sustained from those diseases than are in other cereal crops. Wheat may suffer from the attack of insects at the root; from blight, which primarily affects the leaf or straw, and ultimately deprives the grain of sufficient nourishment; from mildew on the ear; and from gum of different shades, which lodges on the chaff or cups in which the grain is deposited.

[edit] Examples of wheat diseases:

[edit] Bacterial diseases

Bacterial leaf blight Pseudomonas syringae subsp. syringae
Bacterial sheath rot Pseudomonas fuscovaginae
Basal glume rot Pseudomonas syringae pv. atrofaciens
Black chaff = bacterial streak Xanthomonas campestris pv. translucens
Pink seed Erwinia rhapontici

[edit] Fungal diseases

Alternaria leaf blight Alternaria triticina
Anthracnose Colletotrichum graminicola
Ascochyta leaf spot Ascochyta tritici
Black head molds = sooty molds Alternaria spp., Cladosporium spp.
Common bunt = stinking smut T. tritici, T. laevis
Downy mildew = crazy top Sclerophthora macrospora
Dwarf bunt Tilletia controversa
Ergot Claviceps purpurea
Foot rot = dryland foot rot Fusarium spp.
Leaf rust = brown rust Puccinia triticina
Leaf and glume blotch, Stagonospora nodorum or Phaeosphaeria nodorum
Pink snow mold = Fusarium patch Microdochium nivale
Powdery mildew = Blumeria graminis
Scab = head blight Fusarium spp., Gibberella zeae,
Septoria blotch Septoria tritici = Mycospharella graminicola,
Smut = Ustilaginomycotina clade of the class Teliomycetae, subphylum Basidiomycota
Storage moulds Aspergillus spp., Penicillium spp.
Wheat mildew

[edit] Nematodes, parasitic

Grass cyst nematode Punctodera punctata
Root gall nematode Subanguina spp.

[edit] Viral diseases and viruslike agents

Agropyron mosaic genus Rymovirus, Agropyron mosaic virus (AgMV)
Barley stripe mosaic genus Hordeivirus, Barley stripe mosaic virus (BSMV)
Oat sterile dwarf genus Fijivirus, Oat sterile dwarf virus (OSDV)
Tobacco mosaic genus Tobamovirus, Tobacco mosaic virus (TMV)
Wheat dwarf genus Monogeminivirus, Wheat dwarf virus (WDV)
Wheat yellow mosaic Wheat yellow mosaic bymovirus

[edit] Phytoplasmal diseases

Aster yellows phytoplasma

[edit] Link between air pollution and septoria blotch

A team of researchers examined a library of British wheat samples dating back to 1843. For each year, they determined the levels of Phaeosphaeria nodorum and Mycospharella graminicola DNA in the samples. After accounting for influences such as growing and harvesting methods and weather conditions, they compared the DNA data with estimates of emissions of air pollutants. The effect of sulfur dioxide correlated with the abundance of the two fungi. P. nodrum grew more successful with the dawn of the Industrial Revolution. M. graminicola was more abundant before 1870 and since the 1970s. The success since the 1970s may be linked to reductions in sulfur dioxide emissions due to environmental regulations. (Bearchell, et al., 2005)

[edit] References

Sarah J. Bearchell, Bart A. Fraaije, Michael W. Shaw and Bruce D. L. Fitt (2005). "Wheat archive links long-term fungal pathogen population dynamics to air pollution". Proceedings of the National Academy of Sciences 102 (April 12): 5438-5442 Abstract.