Symptoms are seen as narrow, dark-greenish, water-soaked, interveinal streaks of various lengths, on the leaf blades.
The lesions enlarge and turn yellow-orange to brown. Amber colored bacterial exudates can be seen on the lesions. It is difficult to distinguish between leaf blight caused by X. oryzae pv. oryzae, the main difference in the later stages of infection being the shape of the edges of the lesions; straight in leaf streak and wavy in leaf blight. Bacteria frequently enter the damaged feeding sites associated with lepidopteran leaf rollers, leaf-folders and hispa beetles.
Bacterial leaf streak is caused by Xanthomonas oryzae pv. oryzicola.
Infected plants show browning and drying of leaves. Under severe conditions, this could lead to reduced grain weight due to loss of photosynthetic area.
Bacteria survive from season to season in crop debris. Transmission occurs byseed in summer crops, and in irrigation water. Rain and high humidity favors development of the disease. Bacteria enter leaves through stomata and surface damage, often caused by insects. Masses of bacteria develop in the parenchyma.
Young leaves are more susceptible to the disease. Two to three days of high humidity (RH 83-93%)or dew during morning are necessary for infection. If rain stops the spread of the disease also stops. Lesion enlargement is favored by temp. 260-30.50. Hairy varieties are more susceptible to this disease.
Bacterial Leaf Streak