Leaf rust is the most common rust disease of wheat. The symptoms depend on the susceptibility of the plant affected. It is characterized by numerous small reddish orange to brown pustules scattered on both surfaces of leaves, leaf sheaths and husks. They are up to 1.5 mm in diameter, slightly raised and round to oblong. In vulnerable plants, tiny secondary pimples and a pale green or yellow halo can appear around the primary pustules. Over time, the color turns to dark brown or black. In more resistant wheat varieties, the orange pustule are usually smaller and they might be surrounded by chlorotic or necrotic areas. The infection causes damage to plant tissues, water loss, and reduced productivity. These symptoms, added to reduced floral set and grain shriveling, compromise the yield.
The disease is caused by the fungus Puccinia triticina, an obligate parasite of plant tissues. It needs living wheat plants or alternative hosts to complete its life cycle. The spores are dispersed by air currents up to hundreds of kilometers from their source. The germination process requires high moisture or a long period of leaf wetness and temperatures between 10° and 30°C (16–22 °C are optimal). In these conditions, the germination of spores can take place within 30 minutes from their first contact with the leaf. High nitrogen fertilization rates are also favorable. The fungus enters the plant through natural openings on the leaves or sheaths. The fungi can complete their life cycle in 7 to 8 days, depending on field conditions. Puccinia triticina has a variety of alternative hosts in the cereal family.
Sorry, we don't know of any alternative treatment against Puccinia triticina . Please get in touch with us in case you know of something that might help to fight this disease. Looking forward to hearing from you.
Always consider an integrated approach with preventive measures together with biological treatments if available. Foliar sprays with fungicides containing propiconazole or triazole can be applied preventively to avoid the disease. Carefully read the instructions on how to use the product. Respect application times and doses to avoid the development of resistance.