Onion cervical rot is a disease of certain types of onions caused by the onion botritis ( Botritis allii ). It can cause significant damage on the farm, damaging the bulbs during storage, in the field causes underdevelopment of seeds. Most often, onions and shallots are affected.
Content
- 1 Infection
- 2 Development of the disease
- 3 Control measures
- 4 References
- 5 Literature
Infection
Infection occurs in the field and during storage: with mycelium and conidia from diseased planting material - bulbs or seeds, from diseased bulbs during storage or from sclerotia overwintered in soil and bulbs. Sowing on heavy loamy soils contributes to infection, since on other types of soil the mycelium of the fungus quickly dies, unable to withstand competition with microorganisms. Infection with peronosporosis (downy mildew) increases the likelihood of neck rot. Contributes to infection in the field, especially in the middle lane, and late harvesting in rainy weather. Prevents the penetration of the mycelium into the neck of the bulb rapid drying of the leaves. Early ripening varieties and varieties with dark colored bulbs are more resistant to the disease.
Disease Development
The disease develops after 1-1.5 months after the onset of storage of bulbs. The neck of the bulb softens and becomes mucous, then becomes covered with a gray or blackish fluffy coating - sporulation of the fungus. Later, black sclerotia appear in the upper part of the bulb, which can merge into a continuous crust, the tissue turns brown and becomes baked, sporulation also forms between the juicy leaves. For 1-2 months, the bulb rots and infects the healthy. Cervical rot develops most intensively at a temperature of 15–20 ° C.
When planting infected bulbs in wet weather, damage to peduncles and inflorescences develops, seeds are often underdeveloped.
Control Measures
- Compliance with a four-year crop rotation .
- Timely cleaning and drying of the bulbs until the leaves dry out before storage.
- Sorting during storage, rejection of damaged ones.
- Compliance with the optimal storage regime is a temperature of 0–3 ° C and a relative humidity of 70–80%.
- Heat treatment of seeds or dressing them with fungicides ( TMTD , fentyuram , etc.)
- With seed sowing - spraying from peronosporosis (drugs mancozeb , mefenoxam , chlorothalonil ).
- The correct mode of fertilizer application: nitrogen is applied in the initial period of the growing season, the dose of phosphorus and potash increases in the second half of growth.
Links
Literature
- Plant World / Ch. ed. A. L. Takhtadzhyan. - M .: "Enlightenment", 1991. - T. 2. Mushrooms / ed. M.V. Gorlenko . - S. 380-381 (genus Botritis (Botrytis). M.V. Gorlenko ). - ISBN 5-09-002841-9 .
- Cervical rot of onions - Big Encyclopedic Dictionary