Develop strategies for sustainable management of apple replant disease
Lead Research Organisation:
National Institute of Agricultural Botany
Department Name: Centre for Research
Abstract
The symptoms of apple replant disease (ARD) can be poor growth within the first few years after replanting on previous orchard sites. Many affected trees survive, but overall fruit production and quality can be significantly reduced. A group of fungal, oomycete and nematode agents in addition to soil properties contribute to the disease. The relative importance of individual pathogens can vary greatly between orchards.
Broad-spectrum soil fumigants used against ARD in the past are now banned. Using more vigorous rootstocks in commercial production may reduce ARD; however, it may result in heterogeneity in tree establishment and thus in higher management inputs. ARD is an even more challenging problem for tree nurseries. A single disease control measure is unlikely to manage ARD consistently and effectively across regions; ARD management relies on implementation of multiple measures, especially at those sites where more than one replant pathogen is likely to be present.
The results of our two recently completed BBSRC-funded projects and an ongoing EU H2020 project show that:
Lack of beneficial microbes, abundance of specific pathogens and in some cases no clear candidate casual agents are associated with ARD.
Planting in alleyways and rotating genetically distinct rootstocks led to reduction in ARD.
Association of microbes in apple rhizosphere is rapid, within six months after replanting.
Amending soils at planting with biopesticides and arbuscular mycorrhizal fungi (AMF) improved tree establishment.
The objective of this proposal is to develop and evaluate an integrated strategy to minimise ARD. This holistic strategy is based on: (1) planting in the alleyways, (2) replanting with genetically distinct rootstocks, (3) amending soils with specific biopesticides; and (4) amending soils with beneficial microbes. The first two measures can be viewed as site-independent, whereas the exact implementation of the last two measures may depend on site-specific factors.
Proposed research consists of three workpackages (WPs). In WP1, we aim to assess the importance of soil physio-chemical properties and microbiological factors on ARD development from commercial orchards and nurseries. In WP2, we will isolate candidate causal pathogens from those WP1 samples in WP1 and conduct lab screening for potential biocontrol agents (including current commercial biopesticides) against these isolated candidate ARD pathogens. In the final WP, we will conduct a factorial field experiment to evaluate the effects of individual and combinational effects of the following treatments on ARD development: (1) planting in alleyways vs original tree stations, (2) two rootstocks (the one previously used vs. a genetically distinct one), (3) with or without biopesticides, and (4) with or without AMF.
The main aim is to integrate and expand our past ARD research into strategies compatible with integrated pest management and UK sustainability goals. For practical implementation of this ARD management strategy, growers will first collect site-specific information (WP1) to decide the need (and choice) for amending soils with (1) effective biopesticides and (2) beneficial microbes or other compost products if ARD is associated with other soil characteristics. The proposal is supported by leading a UK tree nursery who will help us running a field experiment and and promote outcomes to the industry. The proposed research will lead to improved soil quality and increased UK apple crop production. It can also benefit other crops prone to replant problems such as cherry, peach, plum, strawberry, rowan and rose.
Broad-spectrum soil fumigants used against ARD in the past are now banned. Using more vigorous rootstocks in commercial production may reduce ARD; however, it may result in heterogeneity in tree establishment and thus in higher management inputs. ARD is an even more challenging problem for tree nurseries. A single disease control measure is unlikely to manage ARD consistently and effectively across regions; ARD management relies on implementation of multiple measures, especially at those sites where more than one replant pathogen is likely to be present.
The results of our two recently completed BBSRC-funded projects and an ongoing EU H2020 project show that:
Lack of beneficial microbes, abundance of specific pathogens and in some cases no clear candidate casual agents are associated with ARD.
Planting in alleyways and rotating genetically distinct rootstocks led to reduction in ARD.
Association of microbes in apple rhizosphere is rapid, within six months after replanting.
Amending soils at planting with biopesticides and arbuscular mycorrhizal fungi (AMF) improved tree establishment.
The objective of this proposal is to develop and evaluate an integrated strategy to minimise ARD. This holistic strategy is based on: (1) planting in the alleyways, (2) replanting with genetically distinct rootstocks, (3) amending soils with specific biopesticides; and (4) amending soils with beneficial microbes. The first two measures can be viewed as site-independent, whereas the exact implementation of the last two measures may depend on site-specific factors.
Proposed research consists of three workpackages (WPs). In WP1, we aim to assess the importance of soil physio-chemical properties and microbiological factors on ARD development from commercial orchards and nurseries. In WP2, we will isolate candidate causal pathogens from those WP1 samples in WP1 and conduct lab screening for potential biocontrol agents (including current commercial biopesticides) against these isolated candidate ARD pathogens. In the final WP, we will conduct a factorial field experiment to evaluate the effects of individual and combinational effects of the following treatments on ARD development: (1) planting in alleyways vs original tree stations, (2) two rootstocks (the one previously used vs. a genetically distinct one), (3) with or without biopesticides, and (4) with or without AMF.
The main aim is to integrate and expand our past ARD research into strategies compatible with integrated pest management and UK sustainability goals. For practical implementation of this ARD management strategy, growers will first collect site-specific information (WP1) to decide the need (and choice) for amending soils with (1) effective biopesticides and (2) beneficial microbes or other compost products if ARD is associated with other soil characteristics. The proposal is supported by leading a UK tree nursery who will help us running a field experiment and and promote outcomes to the industry. The proposed research will lead to improved soil quality and increased UK apple crop production. It can also benefit other crops prone to replant problems such as cherry, peach, plum, strawberry, rowan and rose.
