Nursery seedlings of vegetable crops produced in Karnataka and various parts of India are infested by several plant parasitic nematodes. These nematodes attack the root system of seedlings in nursery beds. Galling of the roots and stunted growth of roots, as well as seedlings, are the manifestations of nematode damage in the nursery beds. Nematodes such as Meloidogyne incognita, M. javanica (root-knot nematodes), Rotylenchulus reniform is (reniform nematode), Heterodera sp., (cyst nematodes) are important among the nematodes attacking seedlings of horticultural crops in nursery beds.
Management of nematodes in the nursery beds Securing healthy seedlings of any crop from the nursery beds is essential to ensure optimum plant population stand, good growth of the crop and higher yields. If nursery beds harbor heavy populations of nematodes, it results in very weak seedlings with poor root growth. Seedlings with stunted root system cannot establish well after transplanting.
Nematode attack on the root system makes the seedlings weak and also vulnerable to the infection by secondary pathogens (soil borne fungi and bacteria). Nematodes damage also results in the breakdown of the resistance against pathogenic fungi and bacteria. Further, nematode infected nursery seedlings facilitate the spread of the nematodes in the main fields making the problem more difficult to manage in a larger area. Hence it is inevitable to manage the nematodes in the nursery beds. Almost all the horticultural crops are attacked by either one or more of the above-mentioned nematodes.
Methods for producing disease free seedlings under poly-house or shade net (protected) conditions
Methods of treatments
1. Seed treatment
Pseudomonas fluorescens and/ or Trichoderma harzianum can be used as a seed treatment or seed dressing agent.Dosage – 15 to 20 grams of talc formulation of P. ?luorescens and/ or T. harzianum /kg of seed.
2. Substrate treatment
Coco-peat or any substrate prepared by mixing Neem cake @ 50kg + carbofuran or phorate @ 5Kg + Trichoderma harzianum + Pseudomonas fluorescens each at the rate of 2 kg /ton, can be used for producing the seedlings of horticultural crops especially vegetable crops such as tomato, egg plant, capsicum, cauliflower, cabbage, chilies, onion.
Methods for producing the seedlings of vegetable crops in raised nursery beds in open field conditions.
- Apply Neem cake or Pongamia cake or Castor cake @ 500g/sq.m followed by solarization of the nursery beds and leave the raised nursery beds for a period of 20 days.
- Apply carbofuran or phorate @ 50g/sq.m in case where the nematode densities are higher
- Apply formulations of T. harzianum / Pseudomonas fluorescens and Paecilomyces lilacinus (each 50g/sq.m) to the nursery beds along with above-mentioned botanicals or chemicals
After addition of above nursery, beds have to be watered at 4 days interval for proper decomposition. At least 15 days are required for complete decomposition of these botanicals and hence a fortnight before sowing the seeds, nursery bed soil has to be incorporated with botanicals and bio-pesticides. IIHR, Bengaluru has developed mass production protocols of Pseudomonas fluorescens 1% W. P. (an effective bio-bactericide and also has nematicidal properties), Trichoderma harzianum 1% W. P. & Trichoderma viride 1.5 % W. P. (effective bio-fungicides and also have nematicidal properties) and Paecilomyces lilacinus 1% W. P. & Pochonia chlamydosporia 1 % W. P. (effective bionematicides). These bio-pesticide formulations that manage nematodes horticultural crops are also patented.
The method of seed the treatment with the IIHR patented organic formulation of bio-agents:
- This formulation can be used as a seed treatment or seed dressing agent.
- Dosage – 15 to 20g of formulation/kg of seed
The method of substrate treatment with IIHR patented formulation of bioagents:
- This formulation can be used for the treatment of coco-peat (substrate) in which seedlings are grown under shade net or protected conditions.
- Dosage – 5 to 10g of formulation/kg of coco-peat (substrate)
The method of soil treatment in raised nursery beds with IIHR patented formulation of bio-agents:
- This formulation can be used for treatment of soil (substrate) in raised beds in which seedlings are grown in open field conditions.
- Dosage – 50 to 100g formulation / m².
Management of Nematodes on vegetables in open fields Capsicum, tomato, brinjal, chillies, cabbage, cauliflower, cucumber, carrot, okra, beans when cultivated in open field conditions also are attacked by various nematodes (root-knot nematode – Meloidogyne incognita) and reniform nematode Rotylenchulus reniformis) and fungal or bacterial pathogens resulting in considerable losses.
Use of nematode infected seedlings of transplanted vegetables produces inferior quality vegetables as the nematodes carried along with the seedlings multiply rapidly in the main field conditions. Non-transplanted vegetables such as okra, carrot, cucumber and beans sown in nematode infested fields attack their root system and multiply rapidly in the main field conditions affecting the crop productivity adversely.
Nematodes feed on root-system and damage the root-system thoroughly. Nematodes make the plant weak and also vulnerable to the infection by secondary pathogens (soil borne pathogenic fungi and bacteria). Nematode
damage also results in the breakdown of the resistance against pathogenic fungi and bacteria. Nematodes along with these pathogens can cause loss to the tune of 40 – 70% in these crops.
Nematode management Solutions
Research conducted at ICAR- Indian Institute of Horticultural Research, Bengaluru for the last 15 years to come out with an alternative technology for chemical pesticides, which are costly and are also hazardous to human health and environment, resulted in developing the technology of management of nematodes using various bio-pesticides. Protocols for mass production of Pseudomonas fluorescens 1% W. P. (an effective bio-bactericide and also has nematicidal properties), Trichoderma harzianum 1% W. P. & Trichoderma viride 1.5 % W. P. (effective bio-fungicides and also have nematicidal properties), and Paecilomyces lilacinus 1% W. P. & Pochonia chlamydosporia 1 % W. P. (effective bio- nematicides) have also been developed by Dr. M. S. Rao. The technology of production of these effective and eco-friendly products have been patented.
- Indian Institute of Horticultural Research, Hessaraghatta Lake Post,Bengaluru