Tomato farmers in Maharashtra and other South Indian states are witnessing a substantial decrease in their crop yield. The primary cause of this decline is identified to be infestation from two viruses, namely Cucumber Mosaic Virus (CMV) and Tomato Mosaic Virus (ToMV). Growers have noted an increase in these infestations over the past three years, declaring partial to complete losses due to these viruses.
Understanding ToMV
Tomato Mosaic Virus commonly referred to as ToMV, belongs to the Virgaviridae family. It shares close similarities with the Tobacco Mosaic Virus (TMV). This virus was first identified in tomatoes back in 1935.
How ToMV Spreads
Transmission of the ToMV primarily occurs through infected seeds, saplings, agricultural tools, and human contact. Some insect vectors such as thrips and whiteflies can also transmit this virus.
Impact of ToMV on Crops
Infected plants exhibit distinct symptoms like green mottling and yellowing of leaves, often appearing as blisters or fern-like patterns. Leaves may curl downwards or upwards and present distorted shapes. Other indicators include dwarfed younger plants and affected fruit setting.
Control Measures for ToMV
Enforcing biosafety standards in nurseries and implementing compulsory seed treatment can help control the spread of this virus. Farmers are encouraged to inspect saplings before planting and discard any infected material.
About CMV
Cucumber Mosaic Virus, commonly known as CMV, is part of the Bromoviridae family. Recognized as one of the most widespread plant viruses, it has a wider host range. It affects cucumber, melon, eggplant, tomato, carrot, lettuce, celery, cucurbits, and some ornamental plants. This virus was first identified in cucumber in 1934.
Transmission of CMV
CMV mainly spreads through aphids, sap-sucking insects that can acquire and transmit the virus within minutes. The virus can also be transmitted by seeds, mechanical inoculation, and grafting.
Effects of CMV on Crops
Manifestations of a CMV infection primarily distort leaves at the top and bottom, leaving the middle parts relatively unaffected. In cucumbers, it causes mosaic-like patterns of yellow and green spots. The virus affects fruit formation and leads to stunting and reduced production.
Control Measures for CMV
Preventing aphids using quick-acting insecticides or mineral oils plays a crucial role in controlling CMV spread. It is important to prevent aphid migration and the subsequent spread of the virus to other fields.
Similarities Between ToMV and CMV
Both ToMV and CMV are single-stranded RNA viruses encapsulated in rod-shaped protein coats. They enter the plant cells through wounds or natural openings and replicate within the cytoplasm. They then move systemically throughout the plant via the phloem. Both viruses can lead to almost 100% crop loss if not properly treated in time.
Understanding Key Terms
Phloem is a complex tissue in vascular plants responsible for nutrient transport, primarily sugars, throughout the plant. Cytoplasm, the gel-like substance filling the cell’s interior, consists of water, salts, proteins, and other molecules. RNA or ribonucleic acid carries genetic information in the form of single-stranded nucleotide sequences.
Source: IE
