Computer models have been used to investigate how potato late blight spreads in an agricultural landscape, and to analyse the effect of growing resistant varieties in a PhD project carried out at Wageningen University & Research in the Netherlands.
In the research, carried out by PhD student at the university, Francine Pacilly, these models show that an increase in the number of potato fields with resistant varieties increases the risk that aggressive strains of the pathogen will emerge and spread.
This risk falls if more than 50% of the acreage of potato fields consists of resistant varieties, according to the research report.
Various strategies are available to limit the consequences of a breakdown in resistance, for example, the spatial allocation of crops in combination with the use of small amounts of fungicides to limit the environmental impact, says Ms Pacilly.
In addition, growing resistant varieties with multiple resistance genes reduces the risk of susceptibility to the potato disease. It is expected that these type of varieties will enter the market soon, according to the research.
Last year, workshops with farmers were organised to increase awareness about the risk of resistance breakdown. After the workshop, farmers agreed that resistance management is important to increase the durability of resistant varieties and that collaborative action is needed. The workshops were useful to bring farmers together and to discuss strategies in the control of late blight to reduce the impact of the disease, according to Ms Pacilly.