Sugar beet rust
Causal agent : This disease is caused by the fungus Uromyces betae, an Oomycete of the Pucciniaceae family.
Description :
- Sugar beet rust is manifested by the presence of small pustules with a diameter of 1 mm and a yellow-orange color on both sides of the leaves and on the flower stalks.
- This species exhibits a structure called uredospores which are summer spores contained in rusty-red pustules on host plants. It also shows another structure called teliospores, which are darker in color, which are winter spores that keep the fungus from year to year.
Biology :
- The development of the disease is favored by cool (15 ° C to 21 ° C) and humid weather.
- The Uromyces betae fungus does not require an alternate host to complete its life cycle.
- It overwinters on volunteer beets and in infected plant debris.
- The evolutionary cycle of rust has 5 kinds of fruiting bodies.
- It is especially the uredo-teliospore stages that are harmful.
- The disease is spread by wind, people and machines.
Symptoms :
- Small reddish-brown spots (uredospores) are found on the surface of leaves, petioles and stems.
- A dark brown spore stage (teliospores) is sometimes found on the leaves towards the end of the growing season.
- Sometimes the disease destroys the foliage, making it difficult to pull beets.
- Sugar yield losses of up to 11% have been observed in field trials, researchers say, but the economic importance of beet rust is still debated.
Control :
- The choice of sugar beet cultivars with tolerance to beet rust should be considered in an integrated disease management strategy.
- The choice of fungicides with different modes of action.
- Balanced plant nutrition.
- Chemical control: ACANTO PLUS at a dose of 0.5l / ha.
