Unexplained crop yield reduction could be due to plant parasitic nematode infection.
Plant Parasitic Nematodes (PPN) are pests of economic importance that attack and infect a wide range of economically important crops in Ghana.
Plant parasitic nematodes can contribute to as much as a 60 per cent reduction in yield quality and quantity if unmanaged.
Globally, it is estimated that activities of plant-feeding nematodes alone cause about 12 per cent yield loss in crops annually, accounting for USD 157 billion loss to farmers.
This figure is projected to be far lower than the reality due to the lack of data from many countries with little or no nematological experience.
Losses
This huge loss has been attributed to both direct and indirect damage that plant parasitic nematodes cause. For example, damage to yam by root-knot nematodes (Meloidogyne spp.) and the yam nematode (Scutellonema bradys) causes tuber galling, crazy root, and dry rot in stored yam.
This reduces the storability and quality of tubers, impacting negatively on the household and national food security. Such infected yam tubers lose sprouting ability and need to be replaced at cost as seed yam in future planting.
This again leads to increased income loss, which negatively impacts farmers' and consumers' economic status.
Activities of parasitic nematodes
These pests are microscopic (can only be observed under a microscope), and unsegmented roundworms are mostly found in the soil. They attack roots, stems, and sometimes, the aerial parts of plants.
These pests attack and infect many economically important crops such as vegetables, root and tubers, and ornamental and tree crops in the country. Several reports indicate the widespread presence of plant parasitic nematodes in Ghanaian soils associated with all crops.
Sadly, the activities of PPN go unnoticed by several farmers. Usually, this is due to the inability of farmers and untrained eyes to tell the difference between PPN attacks and other conditions.
The PPN infection symptoms often look like those caused by other biotic and abiotic pressures; hence, attributing infections to other causes is justifiable. Infections usually are at the root beneath the soil surface.
This attack damages the plant's root systems, interfering with the plant's ability to absorb nutrients and water from the soil, even when they are in abundance or optimum quantities.
This situation leads to the expression of above-ground symptoms, including leaf yellowing, wilting, and stunting, just like those presented by conditions of water or nutrient stress.
In situations like this, farmers tend to apply more nutrients and water; yet, the plants do not respond because the parasitic nematodes have damaged the roots.
Another reason for PPN activities going unnoticed is that farmers refuse to seek professional advice during their farming operations.
Engagement
Engaging professionals from the Council for Scientific and Industrial Research (CSIR) and other research institutions can help farmers obtain information about the nematode pest status of their fields, and professional advice on various management practices to minimise the risks posed by these parasitic nematodes.
Professional nematologists at the CSIR-Crops Research Institute periodically offer customised practical training (in-house, community) for farmers, extension agents, agencies/organisations involved in crop production, farmer-based organisations, and interested persons on general nematology and integrated nematode management strategies to raise awareness of the menace that plant parasitic nematodes cause.
Soil and root/tuber analysis, interpretation and advice services could be secured at CSIR-Crops Research Institute, Kumasi.
The writer is a Senior Research Scientist, Nematologist (CSIR-Crops Research Institute)
Email: ydanso219@gmail.com
