Why West Bengal Government bans Import of Seed Potato?

The long shelf life of potatoes, its versatile texture and low cost has made it a long-term staple in human diet. By eating potatoes, you get an increased vitamin B-6, or pyridoxine, intake. Vitamin B-6 helps your body produce neurotransmitters, small molecules that facilitate communication between networks nerve cells, as well as between your nerves and muscles. Potatoes also provide a source of vitamin C, so adding more potatoes to your diet helps you reach the RDI for this vitamin.

But the West Bengal Government has issued a blanket ban on importing seed potatoes, particularly from Tamil Nadu, Uttarakhand, Himachal Pradesh and Jammu and Kashmir owing to presence of potato Cyst Nematode (globodera rostochinensis & G. Pallaid) in the produce. 

The notification from the Department of Agriculture was issued on November 2 following a warning from the Union Agriculture and Farmers department prohibiting movement of seed potatoes from the aforementioned Indian states to all other states. The notification directed all seed inspectors of the state to strictly adhere to the restriction of prohibiting movement of seed potato from the said four states into Bengal territory. 

Potato root nematodes or potato cyst nematodes  (PCN) are 1-mm long roundworms belonging to the genus Globodera, which comprises around 12 species. They live on the roots of plants of the Solanaceae family, such as potatoes and tomatoes.PCN cause growth retardation and, at very high population densities, damage to the roots and early senescence of plants. The nematode is not indigenous to Europe but originates from the Andes. Fields are free from PCN until an introduction occurs, after which the typical patches, or hotspots, occur on the farmland. These patches can become full field infestations when unchecked. Yield reductions can average up to 60 percent at high population densities. 

The eggs hatch in the presence of Solanoeclepine A, a substance secreted by the roots of host plants. The larvae then invade the tips of the root and establish a feeding site. Both susceptible and resistant potato varieties will suffer from growth retardation at low and medium population densities. At very high population densities mechanical damage of the root system will occur. The female individuals swell up and appear as cysts on the surface of the roots, each containing up to 400 eggs. In temperate zones only one generation per year will occur. In the Mediterranean countries sometimes a second generation is reported. Cysts can then also be found on the skin of the tubers. Each year without host a certain fraction of the eggs will hatch (spontaneous hatch). The eggs can survive for up to 20 years inside these cysts.