Emerging Important Nematode Problems in Field Crops and Their Management

Abstract

Plant diseases are one of the major limiting factors in the production of food crops and in attaining food security and food safety. Around 40–50% of the crop produce is eaten away or destroyed by pests and pathogens, and its one fourth is attributed to plant diseases. Among various groups of plant pathogens, phytonematodes cause 5–20% yield decline in food crops, which may account to a net loss of 2–7% in crop-based food. Rice, wheat, and maize are most important food crops and are frequently attacked by plant nematodes. Generally, the crop damage caused by nematodes remains hidden to farmers because of nonappearance of discernable symptoms. In addition to direct damage, nematodes aggravate the infection of soilborne pathogens or act as vector leading to development of disease complexes. To prevent yield losses and to improve crop productivity and yield quality, it is essential to make growers realize the economic significance of plant nematodes. Adequate extension programs are needed to be implemented to demonstrate and advise appropriate nematode management methods to the crop growers. With regard to food crops, especially cereals, primary emphasis may be given to some of the most important nematode genera such as Meloidogyne, Pratylenchus, Ditylenchus, and Heterodera as these nematodes are widely distributed in agricultural fields and cause tremendous damage to food crops. Common cultural practices, viz., deep plowing, flooding, fallowing during summer, removal and burning of weeds and remnants of previous crops, use of certified and disinfested planting materials, and cultivation of non-host, resistant, or tolerant crops, may substantially prevent crop losses in cereals caused by nematodes. Further, seed priming with biopesticides of Trichoderma spp. or Pseudomonas fluorescens as a general treatment may prove quite effective in growing healthy crop with considerably higher yields.