Climate change induced drought impacts on plant diseases in New Zealand

Abstract

Climate change is expected to increase the frequency and duration of drought in many parts of New Zealand. This may affect the natural lifecycles of plant pathogens, influence host predisposition to infection or disease expression, shift the natural ranges of the pathogens, and alter the rate of genetic change in pathogen populations. Collectively, these influences are likely to affect a range of pathosystems of significant economic importance to New Zealand’s productive sectors. We undertook analyses of potential drought impacts on several diseases of plants important to New Zealand: pea root rot (caused by Aphanomyces euteiches), onion white rot (Sclerotium cepivorum), wheat take-all (Gaeumannomyces graminis var. tritici), wheat crown rot (Fusarium spp.), brassica black leg (Leptosphaeria maculans), grapevine black foot (Ilyonectria/Dactylonectria spp.), kiwifruit sclerotinia rot (Sclerotinia sclerotiorum), and radiata pine red needle cast (Phytophthora pluvialis). For most pathosystems, increased drought is expected to increase disease expression. However, drought may reduce the severity of some diseases, such as Scelerotina rot of kiwifruit and red needle cast of radiata pine. To exemplify how drought can affect different components of the host-pathogen-environment interaction, a case study on red needle cast of radiata pine is presented. We recommend that land-based productive sectors need to better prepare for the deleterious impacts or beneficial opportunities of increased drought for plant diseases in New Zealand.