Destruction of crops by nematodes is one of the biggest problems facing farmers throughout the world. Crop yields can be significantly affected as well as the marketability of the crop. And potatoes, as a root crop, are one of the most common plants under threat from nematodes. Add to this the threat of plant pathogens, such as fungi and already the complexity of successfully growing a potato crop is apparent.
And yet, thanks to developments in agricultural research, studying all aspects of the problems and issues faced in agricultural production, farmers and agricultural producers are able to plan more effectively and manage their businesses using far more informed decisions than in the past.
In relation to the issues facing potato growers, research conducted by The Nematology and Entomology Research Group at the Crop and Environment Research Centre at the Harper Adams University College in the UK, into the relationship between the potato cyst nematode Globodera rostochiensis (G. rostochiensis) and the diseases caused by Rhizoctonia solani (R. solani) has indicated there are links between the two problems. Both problems can cause severe damage to a potato crop, with deformed or malformed plants that are not marketable as well as producing reduced yields or even potatoes with a lower nutrient value. It’s estimated that potato cyst nematodes could cause annual losses in the region of 300 million Euros to potato producers in the European Community alone; so a better understanding of the problem, which could lead to a way of controlling this threat, could mean huge cost savings and increased production.
The trial, undertaken by Dr. Matthew Back, Placement Manager (Agriculture) / Lecturer in Plant Pathology and the team at Harper Adams University College in 2000 and 2001, was the first to look at the issues under field conditions, rather than in a controlled environment. By looking at the nematodes and the fungus in natural conditions, researchers are able to determine far better how significant the interaction is between the two problems. Two sites were used, and planted with the cultivar Desiree and the plants were monitored for diseases related to the R. solani.
The results were analysed in GenStat. Regression analysis (again in GenStat) showed there were relationships between the density of the nematodes and the incidence and severity of disease caused by R. solani. Likewise simple linear regression analysis showed a significant linear relationship between the tuber yield and the infection of runners with R. solani. Multiple regression analysis showed that interactions between the nematode root invasion and the runner infection had a significant effect on the final tuber yield. The study has shown that there are clear interactions between this nematode and the fungus. There were positive relationships between the nematode densities and infection on all potato parts, but specifically between the invasion of potato roots by juvenile nematodes and the infection of runners with R. solani. It seems that the interaction is indirect given that each problem affects different parts of the potato. Interestingly it seems that the nematode plays an important role in the development of R.solani diseases, but these infections may reduce nematode development.
Studies such as these are vital in planning for future agricultural development. By understanding the relationship between different pests and pathogens, more precise and hopefully more productive growing strategies can be developed.
Full paper published in: European Journal of Plant Pathology, Issue Volume 114, 2 / February, 2006, pages 215-223.