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Mycologia, ASCOMYCOTINA, ERYSIPHALES, ERYSIPHACEAE .

Crops attacked: wheat, .

Powdery mildew

Identification, Description, Biology, Epidemiology, Treatement, Possible misleading, Images

[R]Description
The leaves, stems and ears are affected, especially in densly populated crops.
In winter, powder mildew colonies cover the plant from the first leaf to the tiller mainly in barley and winter wheat.
From the beginning of the "boot" stage to the swelling stage this surface white mildew turns grey and is spotted with little black marks (perithecia). At this stage loss is more frequent in wheat than in barley.
From the heading stage to the harvest, the disease becomes devastating if it affects the ears. White greyish crusts occur on the glumes.
A 1000 grains-loss in weight is reported in wheat when the ears are affected.
In barley, the early attacks are most damaging as they reduce the roots and imppede ear development (reduced tillering).

[R]Biology
The fungus overwinters as perithecia (cleistothecia) on grasses and wild Gramineae.
Winter cereals are the living hosts on which the fungus survives and through which it is passed on from one season to the next.
The dissemination of the disease is conidial.
Perithecia occur at the end of the vegetative cycle.

[R]Epidemiology
Conidial sporulation occurs in a wide range of RH but is inhibited by free water.
Conidia are transported by the wind, in dry sunny weather.
They germinate in most RH conditions in the absence of free water and contaminate the crop at temperatures ranging from 2 °C. to 30 °C.
Successive wet and dry days increase the epidemic.

[R]Treatement
Fungicidal treatment is recommended :.
- in wheat : at heading when the last leaf is heavily contaminated.
- in winter barley : in the first stage (two nodes) if the attack is severe on the tiller.
- in spring barley : at the beginning of the boot stage.
Treat according to regional knowledge and counselling with diversified chemicals to avoid resistance.
Use cultivars with low susceptibility.

[R]Possible misleading
.

[R] Images

1. Erysiphe graminis , Powdery mildew (VIDAL L.,INRA)
   Cereal powdery mildew Sporulation on a hard wheat ear.
   
2. Erysiphe graminis , Powdery mildew (BASF)
   Cereal powdery mildew Cleistothecia (= perithecia) of powdery mildew on a wheat leaf.
   
3. Erysiphe graminis , Powdery mildew (VEGH I., INRA)
   Cereal powdery mildew Detail of cleistothecia (= perithecia) on wheat leaf (teleomorph of powdery mildew on wheat leaf).
   

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