Hint: The simultaneous planting of multiple crop types, Intercropping, has been used throughout history and remains widespread among small landholding farmers in the tropics. Regulation of pathogens may be one advantage of this practice.
A. Leafhoppers is the most effective vector, transmitting Tungro virus disease. It induces leaf discoloration, stunted growth, reduced tiller numbers, and sterile or partially filled grains. Tungro affects cultivated rice, some wild rice relatives and other grassy weeds typically found in rice paddies.
B. Spotted bollworm and dried disease - which causes dryness and shedding of terminal shoots before flowering. Harm is caused by the larvae of the spotted bollworm, Earias vittella, a common insect.
C. Mosaic viruses are plant viruses that provide the leaves with a speckled appearance.
So, the correct option is 'Tungro virus disease'.
The rice plants damaged by Tungro are stunted and have a limited number of tillers. The young developing leaves experience interveinal chlorosis, beginning from the tips downward, leading to discoloration of the leaves. The entire leaf is also decolorized. Generally, plants poisoned at an early stage die prematurely. Because of delayed flowering, infected plants take longer time to mature. The panicles are also poorly formed, and dark brown blotches often cover the grains and are lighter in weight than those of healthy plants.
Hence, the correct answer is option (A)
Note: Tungro Virus viruses, with icosahedral and bacilliform geometries and T=3 symmetry, are non-enveloped. The genomes are spherical. For 10 minutes, the virus can survive temperatures below 63 degrees Celsius. At least two strains - S and M - are known to have the tungro virus. In these types, the 'S' strain develops prominent interveinal chlorosis, giving a yellow stripe appearance on younger leaves and often unusual chlorotic specks. The 'M' strain, on the other hand, causes just mottling.