PATH 372 Diseases of Horticultural Crops
PATH 372 Diseases of Horticultural Crops
PATH 372 Diseases of Horticultural Crops
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7) Root knot nematode – Meloidogyne sp.<br />
Root knot is the most important group <strong>of</strong> phytonematodes and was first recorded in<br />
green house vegetables in England in the year 1855. Of the four predominant species<br />
<strong>of</strong> Meloidogyne, M. incognita and M. javanica are commonly found in the tropics,<br />
whereas M. arenaria is more common in the sub-tropics. M. hapla is common in the<br />
temperate region and can occasionally found in the cooler uplands <strong>of</strong> tropics.<br />
Symptoms<br />
Formation <strong>of</strong> galls on host root system is the primary symptom<br />
Roots branch pr<strong>of</strong>usely starting from the gall tissue causing a ‘beard root’<br />
symptom<br />
In severely infected plants the root system is reduced and the rootlets are almost<br />
completely absent. The roots are seriously hampered in their function <strong>of</strong> uptake<br />
and transport <strong>of</strong> water and nutrients<br />
Plants wilt during the hot part <strong>of</strong> day, especially under dry conditions and are <strong>of</strong>ten<br />
stunted.<br />
Seedlings infected in nursery do not normally survive transplanting and those<br />
surviving have reduced flowering and fruit production<br />
Mode <strong>of</strong> spread and Survival<br />
Juveniles and eggs survive periods <strong>of</strong> moisture stress in a state <strong>of</strong> anhydrobiosis<br />
Irrigation water and soil adhering to animal feet and implements help in<br />
dissemination <strong>of</strong> juveniles and eggs <strong>of</strong> nematodes<br />
Management<br />
Crop rotation with graminaceous hosts<br />
Inclusion <strong>of</strong> non-preferred hosts like mustard, sesame, maize, wheat, etc., in the<br />
cropping system<br />
Intercropping <strong>of</strong> marigold with tomato reduces nematode population<br />
Nursery should be raised in nematode free sites or fumigated beds<br />
Deep ploughing <strong>of</strong> infested fields during summer. Three summer ploughings at 10<br />
days interval reduces juvenile population<br />
Flooding the field for prolonged periods<br />
Use <strong>of</strong> biocontrol agents like Paecilomyces lilacinus (egg parasite)<br />
Nursery bed treatment with metham sodium (Vapam)@25ml/m 2 or<br />
Carb<strong>of</strong>uran@0.39g a.i/m 2<br />
Bare root dip treatment in EC formulation <strong>of</strong> systemic pesticides like Dimethoate<br />
or Phenemiphos for 6-8 hours before transplantation<br />
Grow resistant varieties like Hissar Lalit and PNR-7<br />
Integration <strong>of</strong> three summer ploughings or use <strong>of</strong> treated nursery with spot<br />
application <strong>of</strong> carb<strong>of</strong>uran @1 kg a.i/ha at transplanting stage have been found<br />
successful to manage nematode population in tomato.<br />
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