Climate Change and Potato Production in Contrasting South African Agro-Ecosystems 3. Effects on Relative Development Rates of Selected Pathogens and Pests

J E Van Der Waals,K Krüger,J M Steyn,A J Haverkort,A C Franke

doi:10.1007/s11540-013-9231-3

J E Van Der Waals, K Krüger + Show 3 more

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https://doi.org/10.1007/s11540-013-9231-3

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Abstract

A set of daily weather data simulations for 1961 to 2050 were used to calculate past and future trends in pest and disease pressure in potato cropping systems at three agro-ecologically distinct sites in South Africa: the Sandveld, the Eastern Free State and Limpopo. The diseases and pests modelled were late blight, early blight and brown spot, blackleg and soft rot, root-knot nematodes and the peach-potato aphid Myzus persicae (as indicator of Potato virus Y and Potato leaf roll virus). The effects of climate on trends in relative development rates of these pathogens and pests were modelled for each pathogen and pest using a set of quantitative parameters, which included specific temperature and moisture requirements for population growth, compiled from literature. Results showed that the cumulative relative development rate (cRDR) of soft rot and blackleg, root-knot nematodes and M. persicae will increase over the 90-year period in the areas under consideration. The cRDR of early blight and brown spot is likely to increase in the wet winter and wet summer crops of the Sandveld and Eastern Free State, respectively, but remains unchanged in the dry summer and dry winter crops of the Sandveld and Limpopo, respectively. Climate change will decrease the cRDR of late blight in all of the cropping systems modelled, except in the wet winter crop of the Sandveld. These results help to set priorities in research and breeding, specifically in relation to management strategies for diseases and pests.

Highlights

Climate change will directly affect crops, as well as the fecundity, dispersal and distribution of plant diseases and pests
This study focussed on Phytophthora infestans, Alternaria solani and Alternaria alternata, Pectobacterium carotovorum subsp. brasiliensis, the root-knot nematodes Meloidogyne javanica and Meloidogyne incognita and the peach-potato aphid Myzus persicae (vector of Potato virus Y (PVY) and Potato leaf roll virus (PLRV))
The impacts of changes in weather parameters on trends in cumulative relative development rate (cRDR) of these pathogens and pests were modelled, indicating whether the intensity of the respective diseases is likely to change in future

Summary

Introduction

Climate change will directly affect crops, as well as the fecundity, dispersal and distribution of plant diseases and pests. The effect of environmental conditions on disease intensity is clearly illustrated in the classical disease triangle of pathogen, plant host and environment, which is a reminder that changes in disease incidence due to climate change will vary depending on the individual host responses and the pathogen or pest under consideration. With potato being the most important tuber crop globally, a number of studies have been conducted on the effect of climate change on potato production (Kaukoranta 1996; Boland et al 2004; Secor and Rivera-Varas 2004; Salazar 2006; Hannukkala et al 2007; Haverkort and Verhagen 2008; Kapsa 2008), relatively few of these have focussed on pathogens and pests of the crop. The majority of research carried out on potato diseases has been on late blight, which is considered one of the most important pathogens of potato. All chosen pests and pathogens cause serious economic losses in South Africa

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