Title : Emerging nematode problems of crops in India
Phytonematodes are ubiquitous browsers of crop roots. About 3000(10 % of 30,000 parasites identified so far)plant parasitic nematodes attack different agricultural and horticultural crops and induce about US Dollars 524 billion annually monetary losses in crops globally. In general, 12-13% crop losses are exclusively due to phytonematodes. In India, It is about Rs .2108 crores only in 24 crops covered under AICRP on Nematodes estimated due to already known nematodes attacking crops in 2005.
But recently in last one decade, root – knot nematodes ( mostly Meloidogyne incognita) has been observed/recorded to attack new crops viz. Gherkin, Crossendra, Carrot, Coleus, Gerbera, Tuberose, Cabbage & Carnation in poly houses, Pomegranate, Mulberry, Olive, Castor, Groundnut, Cotton, Lac, Potato tubers, etc. Infection of M.graminicola on rice is a serious threat to farmers in almost all rice growing areas of the country. Now, M. incognita is reported to attack wheat crop which may perhaps create a big threat to Rice-Wheat Cropping system in Punjab, Haryana, Western UP, Bihar, etc. Similarly M. graminicola is observed to attack even Onion and Garlic in Shimoga area of Karnataka. Maize has been observed to be attacked by stubby, stunt& spiral nematodes in Shimoga area of Karnataka and even root- knot nematodes in Gujarat.
A new species , M. enterolobii is seriously attacking Guava fruit crop In TN, Karnataka, Gujarat, etc. Likewise, M. indica ,so called as Asian Citrus Root- Knot Nematodes is reported on citrus first time from Gujarat. It has been also observed on citrus in other states as well. Cowpea and Castor are also hosts of this nematodes. Potato Golden Nematodes( Globodera rostochiensis & G. pallid)are new threat to potato growing areas of J& K and HP, though it is only known to be restricted in Ooty & Koddaicanal hills in TN.Even few varieties of Marigold (Tagetes Spp.) well known as antagonistic crop, is attacked by root- knot nematodes. Field Tuberose is severely attacked by Leaf & Bud nematodes( Aphelenchoides bessyii )in West Bengal, Assaam and other N-E states. Weeds like Parthenium, Chenopodium, & Poi are also observed to be attacked by RKN.
Hence , it is suggested to initiate research programs on these new nematodes attacking different crops by the scientists.