Soil-borne plant-parasitic nematodes are a key threat and a biosecurity risk to global food production. They cause estimated annual losses of €110 billion worldwide.
Root-knot nematodes (RKN) and potato cyst nematodes (PCN) rank 1 and 2 in the Top 10 of high-impact plant-parasitic nematodes.
Root-knot nematodes (RKN), a worm-like micro-fauna of the genus Meloidogyne, cause significant yield and economic losses in tomato production and other agricultural crops and vegetables. In their brief mobile stage as juvenile, they penetrate the root tips of plants, where they complete most of their life cycle. Inside these tissues, the nematodes move to the vascular cylinder and induce the formation of specialized feeding sites called “giant cells”, which act as the only nutrient source for the invading nematodes, leading to the disruption of the root system.
Potato cyst nematodes (PCN), different species of the Globodera genus, enter plant roots and establish a specialized feeding structure. Females develop eggs and die after forming a cyst containing hundreds of eggs. These cysts can persist for many years in soils. Therefore, this pest is particularly difficult to eradicate and can be dispersed over large spatial scales, either through natural means such as wind, water, and wildlife or through the transportation of soil and tubers due to human activities.
Both pathogens cause damage to plant roots, obstructing water and nutrient intake from the soil and making crops more sensitive to elevated temperatures and drought. However, RKN and PCN problems are often underestimated as these pathogens are small (barely visible to the naked eye) and the symptoms plants having been parasitised by them are non-specific above-ground. They can be mistaken for nutrient deficiency based on above-ground symptoms displayed by the plant. RKN damage can be confirmed with the presence of galls in the roots.
PCN and several RKN species are quarantine pests or emerging species listed on the Alert List of the European Plant Protection Organization (EPPO). This means that strict control measures must be applied upon nematode detection. These measures include restrictions on plant material movement and interruption of susceptible potato cultivation until nematode density is below the detection threshold. Recent studies report the emergence of new RKN and PCN problems in Europe and beyond due to two independent drivers: global warming and genetic selection.
Global warming has resulted in a northward migration of previously undetected ‘tropical’ RKN species. Furthermore, the increased incidence of heat waves in southern Europe jeopardizes the effectiveness of widely used host plant resistances, including the most important RKN resistance gene known in tomato, Mi-1, as they stop functioning at elevated ambient temperatures (above 28°C). Learn more about the NEM-EMERGE approach regarding global warming.
In parallel to the effects of global warming, strong genetic selection due to the prolonged (several decades) use of a small pool of plants containing inherent resistances against RKN and PCN has facilitated the emergence of virulent populations in tomato and potato fields in southern and northern regions of Europe. Current cultivars are unable to prevent the further expansion of such RKN and PCN.
For decades, large quantities of non-specific, environmentally harmful agrochemicals were used to manage plant-parasitic nematodes in high-input farming systems. Although these are banned by national and EU legislation nowadays, soils are often harmed and have their host resilience capacity disturbed.
Hence, there is an urgent demand to find inclusive, sustainable solutions to counter these RKN and PCN problems and prevent crop losses in the most affected major food crops: tomato and potato. This is where NEM-EMERGE comes in.
