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Appropriate organic and low input management of fruit pests, diseases and weeds - OF0376

Description
This research will assess alternative methods of pest and disease management in organic and low input apple orchards. An ecological approach to orchard floor vegetation management will determine if this can lead to reductions in pest populations. Research to identify the components of the apple blossom weevil sex pheromone should lead to new methods of monitoring and controlling this important pest. New insights into scab biology and epidemiology should increase the potential for successful management of this disease. Finally a review of the effects of calcium on fruit rotting in store will identify areas for future research.
Generalist predators will attack a range of prey species. Many species of predators/parasitoids occur naturally in crops and surrounding vegetation, but they may colonise and remain in crops only as a response to high pest numbers. Manipulation and management of the ground cover plants within the crop to provide attractive vegetation both in terms of refuges and alternative food sources is likely to increase the abundance of beneficials in the cropping area, leading to reduced pest numbers. Apple is susceptible to a range of pest species that have different life cycle strategies. Some species have a ground inhabiting stage (e.g. codling moth, apple leaf midge), where they may be accessible to ground dwelling predators such as carabids and earwigs. Other pest species occur only on the plants (e.g. aphids) and these are accessible to predators that colonise by flying (e.g. anthocorids, syrphids) or to predators such as earwigs that can climb into the trees. This research will produce information on the types of vegetation that have positive value as refuges and provide alternative food sources for a range of generalist predators. When incorporated into the ground cover of orchards, and managed appropriately, this vegetation should increase functional biodiversity in the area of the crop and increase biocontrol of pests.
Apple blossom weevil was identified as the most important pest in organic apple production in the recent organic apple LINK project (HLO150LOF) where it reduced yield and fruit quality by up to 40%. Identification of the sex/aggregation pheromone of apple blossom weevil will be completed. Once pheromone components have been identified and synthesised, they will be tested for attractiveness to apple blossom weevil in the field Identification of the pheromone components will provide the opportunity for further work in a subsequent project to exploit the pheromone for control of the pest by mating disruption, mass trapping or attract and kill approaches.
Project HLO150LOF recommended that using scab resistant varieties is the only viable option for sustainable organic apple production under UK conditions. Despite its potential importance for scab management, there is limited knowledge of the infection and colonisation of Venturia inaequalis within old leaves; symptomless infections may be present on old leaves in autumn. Lesions of a 'diffuse' type are frequently observed in late autumn on some resistant apple varieties. It is necessary to understand whether such diffuse scab lesions on resistant cultivars can produce ascospores. If they can, then selection for more virulent scab isolates that can attack resistant varieties in the early season may become a real possibility. If selection for virulence is occurring, growers will need to carry out stringent control measures during autumn or winter.
Rotting in store in UK apples is caused by a number of different pathogens, the incidence and importance of which is dependent on orchard and season. New approaches to disease control are needed for rots such as Colletotrichum spp., Gloeosporium spp. and Nectria that infect early in the season, remain latent and develop in store. Currently control for these latent rots is dependent on fungicide applications, usually near harvest, leading to residues (usually below the Maximum Residue Limit permitted) in the fruit or vegetable. Calcium is regularly applied to apples such as Cox and Bramley from June to harvest to improve fruit quality, reduce the risk of physiological disorders and prolong storage life. Calcium applied to fruit crops in this way improves fruit quality and indirectly increases resistance to fungal rots. More recent research in tropical fruits, and to a lesser extent apples, has shown that certain calcium compounds have direct effects on pathogens, reducing spore germination, mycelial growth and sporulation and possibly also on the host, inducing resistance to the pathogen. Thus calcium, if effective, could be used as part of an integrated approach to control of rotting in fruit crops. Much work has been published on the effects of calcium on rotting in fruit. In this project all published work on calcium, fruit and vegetable quality and rotting will be reviewed, and any gaps in knowledge will be identified. Further experimentation required to develop the research into practical applications that can be integrated into strategies for sustainable management and control of rotting in fruit crops will be outlined.
Objective
The overall objectives of this research are to develop sustainable pest and disease management strategies for organic and low input fruit production and to review the use of calcium to reduce fungal rotting of fruit in store.
Objective 1: To determine the impact of orchard floor management practises on the abundance of naturally occurring predators
Objective 2: To determine the biocontrol potential of the major ground dwelling predators (carabid beetles and earwigs) against a target apple pest
Objective 3: To complete the identification of the male sex/aggregation pheromone of apple blossom weevil and demonstrate attraction in the field.
Objective 4: To determine if late season diffuse scab lesions can produce ascospores
Objective 5: To define the practical implications of the findings for optimising the management of pests and diseases in organic and low input orchards
Objective 6: To determine the effects of calcium on fruit quality and susceptibility to fungal rotting
Objective 7: To determine the effects of calcium on growth and development of fungi responsible for rotting
Objective 8: Identify gaps in knowledge of the use of calcium in fruit production and suggest areas for further research
Project Documents
• Final Report : Organic and low input management of fruit pests and diseases   (756k)
• Final Report : Organic and low input management of fruit pests and diseases   (578k)
• Final Report : Organic and low input management of fruit pests and diseases   (381k)
Time-Scale and Cost
From: 2007

To: 2010

Cost: £277,505
Contractor / Funded Organisations
East Malling Research
Keywords
Allocated - EMR              
Disease Prevention              
Farming              
Organic Farming              
Pest Control              
Vegetables              
Fields of Study
Organic Farming