White rust caused by Albugo Candida, affects beet leaves and flowers and used to be considered a fungal disease. However, the organism has been reclassified and is no longer a fungus. It is a water mold – a relative of brown algae.
However, it looks and acts like a mushroom! And it still infects beets!
You will know if your beet plant is infected if the leaf bottoms have white pustules that look like bubbles and the top is faintly yellow with white spots.
Rusts don’t kill their hosts, but they don’t do them any favors either. This type of rust is found all over the world where beets are grown.
In the case of plant diseases, white rust on beets is usually not a serious disease. The leaves of infected plants look hideous, but the roots are usually fine.
Unfortunately, no fungicides to control white rust on beets are registered in the USA. You have to rely on preventive techniques.
We will guide you through the symptoms and life cycle of this disease, as well as cultural methods to combat it.
Symptoms of white rust on beets
White rust has both local and systemic symptoms.
The local ones are present as white pustules on the underside of the leaves, which look like chalk-white dust and faint yellow lesions on the top. Smaller stems and parts of flowers can also be infected.
This isn’t always the case, but if the infection is systemic (throughout the plant), you’ll see flowers that grow abnormally, distorted, and sterile.
These disturbed flowers are called Deer heads. These structures are typically formed on infected plants during periods of long rain and little sunlight.
How the infection spreads
Spores spread from the pustules, including those produced on cruciferous vegetables. Wind, insects or rain scatter them on other plants in the same fields or even on other fields.
The infection is more likely to spread from 60 to 77 ° F in wet weather.
Plants can also be infected by thick-walled spores, so-called oospores, which form in the deer heads and hibernate in plant remains in the soil.
Another disadvantage of this rust is that it can cause your plants to develop downy mildew (link to article on beet downy mildew), another disease caused by water mold.
The lack of fungicides registered to control white rust on beets limits your options for cultural controls. One of the most important is the purchase of high quality seeds that are produced in a dry climate!
Try to plant your seed in a well-drained bed, in which there are no plant residues, as the organism can overwinter in plant residues in the soil.
It is important to remove cruciferous vegetables, such as mustard or shepherd’s purse, from your plants as they can harbor the disease. If you can, turn your beets with a non-cruciferous crop for at least two years to clean the soil of infectious spores.
Try to keep overhead spraying as low as possible. This does not prevent the rust from causing disease, but it can minimize its severity.
After harvesting your beets, soak up any remaining crop residues in the soil as soon as possible to break down the spores and reduce the chances of survival.
Limiting damage is the key
While beet rust around the world causes hideous lesions on beet leaves and sometimes leads to distorted flower heads, this organism does not kill its host.
No fungicides to control beet rust are registered in the United States. You must therefore rely on cultural controls such as planting quality seeds, recklessly eradicating cruciferous vegetables and peeling off the vegetation after the season has ended.
With these techniques, you should be able to minimize the likelihood of an infected crop and produce beets that can be sold with their leaves.