Xanthomonas vasicola pv. vasculorum
Symptoms usually develop on lower canopy first and extend upwards under favorable conditions. Narrow, orange-brown or tan streaks of different lengths develop on leaves. They are translucent and have wavy margin and a yellowish hue, particularly conspicuous when leaves are backlit. In some cases, lesions may appear first in the mid or upper canopy. Symptoms varies widely between hybrids and can range from little lesions to as much as 50% or more leaf area covered. This may have an impact on grain filling and yields. The oozing of a viscous substance from excised leaf sections is another sign of this disease.
The symptoms are caused by Xanthomonas vasicola pv. vasculorum, a bacterium that may overwinter in infected crop residues. It is spread to healthy plants via rain splash and wind during the early stages of growth. Infected crop residue can also spread between fields with field equipment, harvesters or stalk feeding. It can enter the plant tissues directly, without any previous wound. Infection can develop in the same fields over several years if susceptible plants are grown and no measures are taken. Favorable environmental conditions for disease development are high relative humidity, heavy rainfalls and prolonged leaf wetness. Overhead irrigation and irrigation during hot weather also appear to increase the incidence of the disease.
To this day, there are no biological control options available for this disease. Preventive measures are essential to avoid its occurrence and reduce its incidence. Please notify us if you know of any.
Always consider an integrated approach with preventive measures and biological treatments if available. There are no chemical control options available to control the incidence and occurrence of this disease.