SCEPTREplus: Tree fruit

Controlling plum rust

• Crop: Plum
• Target: Rust (Tranzschelia discolor)
• Period: Aug - Oct 2018, Mar-Dec 2019

Take home message

Plum rust management needs to combine knowledge about the disease with cultural control methods, and uses both conventional fungicides and biofungicides.

Further work is needed on all of these aspects before a robust integrated pest management strategy can be recommended.

New control treatments were identified and could be tested in screening trials on young plum trees.

Trial summary

The review looked at current and potential management techniques and plant protection products for plum rust.

The withdrawal of a number of plant protection control products means there are currently very limited options for growers.

The later trial in 2019 was a field-based trial located in Cambridgeshire was set up to identify chemical and biological treatments to effectively manage this disease.

Conclusions

Technical review

• Early season triazoles-based fungicide foliar sprays appear to be the most effective way of controlling plum rust.
• The use of resistant or tolerant plum rootstocks may play a role in reducing disease levels
• Removing leaf litter and pruning to create an open canopy may be worth exploring

Field trial results

Treatments AHDB 9851, AHDB 9852 and AHDB 9911 reduced rust disease incidence, with AHDB 9851 providing better control than the industry standard Amistar at trial end.

• Crops: Cherry
• Target: Bacterial canker
• Period: Mar-Sept 2018, Jul 2019- Jun 2020

Traditionally, bacterial canker of cherry has been kept below economically damaging levels by application of copper-based products. Regulatory restriction of the use of copper requires new approaches for control.  

The trial in 2018 looked at laboratory and glasshouse testing. A further trial in 2019/2020 evaluated control options in polytunnels. 

Conclusions

• Alternative control products with efficacy against bacterial canker were Serenade ASO, AHDB 9957 and Amylo-X
• Copper-based AHDB 9829 can offer very effective emergency protection, replacing previous standard Cuprokylt   

• Crops: A range of crops (Strawberry, cherry, raspberry, blackberry, apple, pear, blackcurrant, cucumber, celery, potato, tomato)
• Target: Capsid bugs
• Period: Sept 2018 – Jan 2019

Management of these pests currently relies on application of broad-spectrum insecticides. These can be effective at killing capsids, but also reduces numbers of the naturally-occurring and released natural enemies to control other pests.

This review aims to identify capsid control options that may form basis of further research including efficacy trials.

Conclusions

• Insecticides with more selective activity against sap-feeding pests, and lower impact on beneficial natural enemies (e.g. sulfoxaflor and flonicamid) have become preferred interventions for capsids in Australia and the USA
• Novel insecticides with alternative modes of action are available for testing against capsid pests
• Improved formulation of insecticides may be possible. This may be achieved by mixing with salt or enclosing them in attractant-coated microcapsules
• The entomopathogenic fungi Beauveria bassiana and Metarhizium brunneum are available as commercial formulations and should also be considered as candidates for inclusion in efficacy testing.
• Particular weeds (e.g. nettles) are assumed to be linked with capsids and control of these is recommended
• More information is needed on the role played by natural enemies
• Semiochemical-based approaches (including push-pull strategies and pheromone based monitoring traps) have been developed for capsids as part of previous AHDB-funded work and have potential for further refinement

Preventing spotted wing drosophila laying eggs

• Crops: Blueberry and blackberry, but relevant to soft fruit, stone fruit and grapes
• Target: Spotted wing drosophila (Drosophila suzukii)
• Period: January - March 2018

Take home message

AHDB9931 and Urtica showed greatest potential to reduce the emergence of spotted wing drosophila (SWD).

Further testing is required on different crops to validate the results

Trial summary

The aim of the project was to test whether products can act as egg laying deterrents for SWD or reduce their emergence.

Seven different chemical treatments were tested in a laboratory.

A further study on the most promising treatments proved inconclusive.