Snow mould
Microdochium nivalis
Description
Monographella nivalis is an ascomycetous fungus belonging to the order Xylariales. Oval to globose, papillate perithecia (100 - 260 x 300 µm) may develop in cereal leaf sheaths or the stem base. They have gold to dark-brown plectenchymatous walls (10 - 30 µm thick). Asci are clavate (60 - 70 x 6 - 9 µm), thin-walled, and contain 6 - 8 hyaline ascospores (10 - 17 x 3.5 - 4.5 µm).
Damage
M. nivalis can attack cereals during all stages causing various diseases:
Seedling blight: Infection of seedlings can cause pre- and post-emergence damage; death early after germination, discoloration of coleoptiles, superficial lesions on plants. Sometimes lens-shaped, pale-brown lesions appear on the first and second leaves.
Cause
M. nivalis is active over a wide range of temperature conditions favoring its wide geographical distribution on the Gramineae. With an optimum between 18 - 20 °C (64.4 - 68 °F) for most isolates, some isolates are able to grow at temperatures as low as -6 °C (21.2 °F) and as high as 32 °C (89.6 °F). Infections of roots, coleorhizas and coleoptiles generally occur under cold (0 - 5 °C; 32 - 41 °F)), dry soil conditions. The pathogen spreads to the ears via splash dispersal of conidia or wind dispersal of ascospores. Infection of ears occurs during anthesis at 12 - 18 °C (53.6 - 64.4 °F) and is promoted by prolonged periods of wetness.
![](https://static.catalog.farmis.lt/problems/3/39/39c/39c6f74b-edb9-444e-bebf-a32528f4b54a.jpg)
![](https://static.catalog.farmis.lt/problems/1/10/10f/10f03f00-208d-42bf-8aed-2d272e138cbb.jpg)
![](https://static.catalog.farmis.lt/problems/2/22/228/2281e058-36df-426d-8a51-7eab9e741284.jpg)
![](https://static.catalog.farmis.lt/problems/0/09/09c/09c24c31-fadc-4db6-8bfd-d63b187d612a.jpg)
![](https://static.catalog.farmis.lt/problems/9/9a/9a4/9a4e9d12-4e87-40bb-974d-fdedcdacdbfb.jpg)
![](https://static.catalog.farmis.lt/problems/4/4b/4bc/4bc86558-f9c5-4928-a887-0cfdf53f6a07.jpg)
![](https://static.catalog.farmis.lt/problems/1/19/196/1963820f-c02e-4a63-b893-35ee3bfdf48a.jpg)
![](https://static.catalog.farmis.lt/problems/7/7b/7be/7be51610-8c3c-4011-8f7f-3e51057bb050.jpg)
![](https://static.catalog.farmis.lt/problems/e/ee/ee6/ee6b06c4-0832-4829-bbcf-f7e1f244976c.jpg)
![](https://static.catalog.farmis.lt/problems/f/fd/fd2/fd2e42d8-c4b1-4f53-8599-dc7f8ac845e4.jpg)