Eye-shaped dark brown lesions appear on the leaves with tapering ends and light brownish center.
Irregular black areas encircle the nodes and affected nodes may break.
Infection at the junction of the leaf blade and sheath results in collar blast. The symptoms appear on the collar region as white to grey-green lesions or spots with dark green borders.
The fungus attacks the peduncle which is engirdled and the lesion turns to brownish black.
On the leaf sheath oval or elliptical or irregular greenish grey spots are formed. As the spots enlarge, the center becomes greyish white with an irregular blackish brown or purple brown border.
Symptoms observed 1 or 2 weeks after transplanting, when the infected leaves become greyish green and begin to fold up and roll along the mid rib. Rolling and withering of the entire leaf, including the leaf sheath follow.
On the leaf blades, the lesion usually begins at the margin from tip as water soaked stripes. The lesion enlarges both in length and width, have a wavy margin and turn grey/straw yellow within few days.
The flag leaf sheath shows oblong or irregular greyish brown spots. They enlarge and develop grey center and brown margins covering major portions of the leaf sheath.
Small black lesions are formed on the outer leaf sheath near the water line and they enlarge and reach the inner leaf sheath also.
The fungus transforms individual grains into yellow or greenish spore balls of velvety appearance which are small at first and 1 cm or longer at later stage.
Jorhat, PIN - 785013 Assam