Enhancing orchard ecology for improved resilience to climate change and apple canker disease

This project aims to develop new approaches for increasing resilience of established and newly planted apple orchards. The two main threats to apple production currently are apple canker (_Neonectria ditissima_) and climate change induced severe weather events such as droughts and floods causing tree stress and devastating losses to growers. Apple canker is a perennial problem for the UK's apple production, more than half of which is based in the Kent and Medway region. It causes up to 30% tree mortality in newly planted trees and significantly reduces the yield and quality of mature orchards. The problem has recently increased in severity and impact due to high density planting of very susceptible commercial varieties and the absence of effective chemical control. The canker problem is compounded by the extreme weather events such high rainfall causing waterlogging and droughts that stress the trees, which stunts growth and further increases susceptibility of trees to apple canker. Another issue in young orchards is apple replant disease caused by a variety of microorganisms.

In this project we will develop new integrated pest management strategies to counter the effects of extreme weather and apple canker. Our approach will combine the use of sustainable above ground and below ground amendments based on beneficial microbes. A combination of biocontrol agents, plant growth promoting microorganisms, arbuscular mycorrhizal fungi (AMF), and biostimulation of plant defences will be used. Our previous research suggests that Trichoderma soil amendment can control oomycetes, such as Pythium, that are one of the main causal agents of in apple replant diseases. Arbuscular mycorrhizal fungi (AMF) are known to directly and indirectly combat the deleterious effects of waterlogging and drought and have been implicated in modulating plant defences.