Onion rust treatment: rust disease will kill onions

What is Puccinia allii ? It is a fungal disease of plants in the Allium family, which includes leeks, garlic and onions, among others. The disease initially infects leaf tissue and can lead to the formation of stunted bulbs if the plants are heavily infested. Also known as garlic rust disease, preventing Puccinia allii rust can improve your Allium crop.

Will rust disease kill the onions?

First of all, the gardener must know which puccinia are and how to recognize them. The fungus overwinters on plant material and is most destructive in areas where there is heavy rain and fog. Over-watering can also promote the formation of spores that cause the fungal disease.

The fungus appears as white or yellowish spots on the foliage and enlarges as the disease progresses. The spots turn orange and eventually develop into black lesions.

So the rust disease will kill onions and other alliums? In some field crops, the fungus has caused dramatic losses and reduced yields. In most cases, garlic rust disease reduces plant vigour and bulb size. The disease is

is contagious and passes from plant to plant as spores are splashed onto nearby foliage or are born in the air through the crop.

Prevent oxidation of Puccinia Allii

There is a saying, «prevention is half the cure», which is appropriate for most crop disease situations. When a crop is affected by garlic rust disease, you have to turn to chemicals to cure it. It is much easier and less toxic to prevent spore formation in the first place.

Since the fungus overwinters on other plant materials, clean up dead plants at the end of the season.

Rotate your allium crops in areas that have not yet harboured plants of the family. Eliminate wild forms of allium, which may also harbour fungus spores.

Don’t water your head and don’t water in the morning. This gives the foliage time to dry out quickly before excess moisture forces the fungus spores to flower. There are no resistant varieties of Allium species.

Aluminum oxide treatment

Once you have the disease in your plants, there are several chemical treatments that can fight the fungus. Fungicides must be labelled for use on edible plants and specify their use against Puccinia yii rust. Always follow the instructions and use them carefully.

Fungicides must not be used within seven days of harvest. The best time to apply is before spores are visible. This may sound silly, but fungicide effectiveness is reduced when the plant is obviously infected and the spores are in full bloom. If you have had problems with orange onion leaves or spotted leaves, you can be sure you have the disease in your garden. Each season, apply a preventative fungicide to the leaves of the crop.

Cultural control of garlic rust

Plants that are not stressed seem to tolerate small infestations of the fungus. Apply bulb fertilizer in early spring and keep plants moderately moist. Plants with heavy layers of mulch can get the disease from soaked organic matter. Remove mulch around bulbs that form as the season progresses.