Ufra Disease

Ufra Disease a disease of deepwater rice caused by feeding damage of the nematode Ditylenchus angustus. As early as in 1913, Butler first reported this disease from Noakhali. Normally, the disease is observed in deepwater rice growing areas such as Barisal, Dhaka, Sirajganj, Faridpur, Jessore, Khulna, Noakhali, Patuakhali and Sylhet districts. Susceptible varieties of rice suffer most.

The ufra nematode feeds ectoparasitically on the inner surface of unmerged leaves, sheaths, buds, and developing panicles. Typical symptoms are a mosaic or chlorotic discolouration of emerging or emerged leaves; yellowish or pale green splash-patterns on affected leaves and sheaths; and appearance of brown to dark brown spots on leaves. Margins of affected leaves become corrugated. The collective symptoms are known as ufra disease. In case of early infestation, panicles may fail to emerge. The symptoms of injury appear within one week in young plants and in 10-15 days in plants at, or prior to, flowering.

The causal nematode D. angustus is minute, about 1.25 mm in length, slender thread-like and tapering at both ends. It is an obligatory ectoparasite; survive and multiplies on living rice plants. It can swim actively. In dry situations it remains coiled in inactive condition. Coming in contact with water or rain, it becomes active again. In Bangladesh, irrigated or deepwater rice usually starts showing ufra symptoms from late July or August. The best way to control ufra is by completely drying fields when they are fallow, ploughing to destroy foci of infection in stubbles, and rotation of crops. Chemical control by using diazinon appears promising. [SM Humayum Kabir] [Kabir, SM Humayun Professor (retd) of Zoology, Dhaka University]