Onion Rust

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

Onion rust affects onion, shallots and leeks. Leaves heavily affected by this fungal disease begin to dry out and die off, the yield is noticeably reduced, as well as the commercial quality of the harvested bulbs. Sometimes, of course, new onion leaves can grow, but their primary fall often provokes the development of much smaller bulbs. But onions are one of the most popular crops in our plots, so you should definitely take care of growing a good onion crop

A few words about the disease

On the leaves of the onion affected by rust, small swellings (the so-called ecias) of a brown-reddish or yellowish-orange color begin to appear, which contain spores of the pathogen fungus. Such swellings are usually located in rings. Spherical eciospores reach a diameter of 21 to 24 microns and are covered with finely warty membranes.

Subsequently, the development of reddish-yellow oblong or rounded uredinia with brownish ellipsoidal spores begins on the leaves. And at the end of the growing season, teliopustules containing teliospores can also be seen in the affected areas, which serve to protect pathogens in winter. These ellipsoidal or clavate teliospores can be either unicellular or bicellular, and they are located on short, colorless legs.

Harmful spores are characterized by very high winter hardiness and winter mainly on plant debris. Also, the causative fungus can persist on perennial varieties of onions. Fallen and dried leaves with teliospores are considered to be the source of primary infection.

To a large extent, the development of rust is facilitated by cool and rather damp weather in the spring, as well as at the beginning of summer, the introduction of nitrogen fertilizers in substantial doses, as well as excessive overcrowding of plants.

How to fight

Before planting, you should try to warm up the sevok. This is done at a temperature of thirty to forty degrees for ten to twelve hours. It is also recommended to use hybrids and varieties resistant to this ailment. It is equally important to try to grow onions without excessive thickening, as well as to follow the rules of crop rotation (in this case, the crop rotation should be two or three years old, maximum four years). And good drainage of the soil will do a good job. But it is definitely not worth getting carried away with nitrogen-containing fertilizers in the spring. The development of weeds related to onion-related species should also be suppressed. And after harvesting, it is necessary to eliminate all plant residues.

A good preventive measure to prevent the development of rust is to observe the spatial isolation of onion plantings from poplar plantations. Onion plantings of different ages should also be isolated from each other.

Every one and a half weeks, it is necessary to inspect the beds for rust and systematically remove infected vegetation and then destroy it.

When watering onions, it is important to try to prevent water from getting on its leaves. At the same time, the best water for irrigation is considered to be slightly settled water, slightly warmed up in the sun.

To prevent the spread of onion rust, during the period of mass growth, it is recommended to spray this culture with a solution of the notorious copper oxychloride (it will take only one tablespoon for ten liters of water, you should also add a tablespoon of liquid soap - this will help the solution to attach to the leaves). A week later, this spraying must be repeated. In this case, one liter of solution is consumed for every ten square meters. Can be used for spraying and Bordeaux mixture.

Among the fungicides that have proven themselves in the fight against rust are Falcon, Folikur, Ordan and Topaz.

Before removing the collected bulbs for storage, they are kept for ten hours at a temperature of 40 degrees. Dusting the bulbs with chalk is also allowed.