Horticulture - Reducing the risk of oomycete pathogens, thrips and weevils for sustainable, coconut coir based soft fruit production

Lead Research Organisation: National Institute of Agricultural Botany
Department Name: Centre for Research

Abstract

Coconut coir is the most widely used substrates strawberry and raspberry production. Its biological, chemical and physical properties enable high yield and consistent crop production with low pest and disease pressure. Root rot causing oomycete pathogens, thrips and weevils however can threaten coir based production causing over 30% decline in yields. Root rot pathogens can spread to coir based production with infected plant material and irrigation water, while incest pest colonise coir from the neighbouring fields. The bans of effective chemical control products and consumer pressure for reduction of pesticide use are driving the need for more sustainable pest and pathogen control such as the use of biocontrol fungi and bacteria.
Oomycete pathogens can persist as spores in the coir across several seasons and can cause large yield loss if coir is reused over several cropping seasons. Pest such as western flower thrip and vine weevils can also infest spent media and build up populations with if substrate is reused over several seasons. The risk of pests and diseases devastating production is the reason why coir substrate is used for a single cropping season. This results in over 600,000 m3 of spent coir substrate discarded every year in UK strawberry production alone. The single use of coir substrate is expensive, labour intense, and environmentally unsustainable.
In this project, researchers from NIAB East Malling will collaborate with coir recycling company Overland Ltd. with the aim 1) to unlock the potential of coir recycling to produce sustainable recycled alternative to virgin coir material and 2) to investigate if biocontrol organisms can help to further reduce oomycete root rot pathogens in virgin and recycled media.
We will assess to what extent the recycling and sterilising methodology developed by Overland can reduce pest and disease risk. We will use a wide range of methods, from field scale experimental strawberry bioassays and biocontrol amendments to state-of-the-art microbiome analysis to ascertain the risk of known and new pathogen complexes and efficacy of biocontrol.
The outcomes will enable growers to better understand and more sustainably manage the risk of pests and disease in soft fruit production.

Technical Summary

Coconut coir is the most widely used substrates soft fruit production. Its biological, chemical and physical properties enable high yield and consistency. Root rot causing oomycete pathogens, thrips and weevils to threaten soft fruit production even in coir based systems causing up to 30% decline in yields. The bans of chemical control products and the pressure to reduce the use of pesticides are driving the need for the use biocontrol fungi and bacteria. The survival and efficacy of biocontrol organisms in coir based systems however has not been properly studied.
Oomycete pathogens and pests such as western flower thrip and vine weevil can persist the coir across several seasons and can cause total yield loss if coir is reused over several cropping seasons. The risk of pests and diseases reducing yields is the reason why over 600,000 m3 of spent coir substrate is discarded every year in UK strawberry production alone.
In this project, researchers from NIAB East Malling will collaborate with coir recycling company Overland Ltd. with the aim 1) to unlock the potential of coir recycling to produce sustainable alternative to virgin coir and 2) to investigate if biocontrol organisms can help to reduce oomycete root rot pathogens in virgin and recycled media.
Our hypotheses are: 1) Recycled coir will have higher residual pest/disease risk but more diverse microbiome than virgin material. 2) Recycled coir, high in accessible nutrients, will facilitate the establishment of biocontrol organisms better than virgin coir.
In WP1 we will use strawberry bioassay, microbiological/molecular identification and shotgun metagenome analysis to compare the pest and pathogen risk in virgin and recycled material. We will highlight coir microbiome functions and potential new pathogen complexes.
Establishment and efficacy of biocontrol agents against crow rot pathogen Phytophthora cactorum will be assessed in virgin and recycled coir in WP2.

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