Coimbatore: The symptoms caused by plant parasitic nematodes on crops include yellowing and marginal necrosis of leaves, stunting, patchiness and day-wilting, which are similar to that caused by micro-nutrient deficiency and lack of enough soil moisture.
Coimbatore: The symptoms caused by plant parasitic nematodes on crops include yellowing and marginal necrosis of leaves, stunting, patchiness and day-wilting, which are similar to that caused by micro-nutrient deficiency and lack of enough soil moisture.
Hence, it becomes mandatory to check the soil and roots once in a way for the presence of plant parasitic nematodes, so as to take necessary management steps at the appropriate time. In a field containing stunted chlorotic plants, apparently due to the presence of nematodes, approximately ten samples have to be collected from the rhizoshere of plants, from which a composite sample of 200 cc with 5g roots have to be collected.
The nematode population is usually more in the rhizosphere region and hence the 1-3 cm of top soil which is usually dry and hence nematode activity can be removed with the help of a spade or shovel. After removing the upper soil, a V-shaped pit of 15 cm depth has to be taken for most of the annual crops such as vegetable and flower crops. The fibrous feeder roots that are encountered in the pit and the soil scraped from the sides and base of the pit have to be collected either in a basin or a polythene bag.
Likewise, in the case of banana, onion, tuberose and turmeric, the partially rotten portions of the corm, bulbs and rhizome along with the adhering soil and fibrous roots have to be collected. For taking the sample from fruit crops such as citrus, guava, pomegranate and so on which has deeper roots, a 30 cm pit has to be dug out around the crop and soil, and root samples collected from within the pit. For taking samples from rice, collect tender fibrous roots and soil around the plants selected randomly without disturbing the plants. To test the presence of white tip nematode which causes the chaffy grain, a composite sample of 10-12 panicles have to be collected.
The collected soil, root and corms have to be packed in a recyclable polythene bag or cloth bag so as to avoid loss of moisture. The bag has to be properly labelled with information like the farmer’s name, location, crop, variety and collected date, preferably written using a pencil to avoid smudging caused by the soil moisture. The bag can be sent to the below address through 'Unregistered Post Parcel' on the day itself or on the next day of sample collection, to the below address for nematode analysis:
The Professor and Head,
Department of Nematology,
Centre for Plant Protection Studies,
Tamil Nadu Agricultural University,
Coimbatore- 641003.
Phone no: 0422 6611264.