SCEPTREplus: Tomato

Control of two-spotted spider mite on tomato

• Crop: Tomato, with trial data expected to apply to other Solanaceae 
• Target: Two-spotted spider mite (Tetranychus urticae)
• Period: July - October 2017

Take home message

This trial has identified a number of safe and effective products for controlling two-spotted spider mite. The conventional products tested performed at least as well as Borneo over the duration of the trial.

Trial summary

Two-spotted spider mite (TSSM), is a significant economic pest of glasshouse tomatoes and other protected crops, causing visible damage to leaves and reducing yield. Control options are currently limited. The aim of this trial was to confirm products for inclusion in the trial, and evaluate the efficacy of selected products for control in glasshouse tomatoes. A mix of conventional and ‘low risk’ products were selected for testing, with likelihood of compatibility of products within an IPM approach for TSSM considered as a selection factor. Though not tested in the current trial, such compatibility is likely to be optimised with use of the ‘low risk’ products tested.

Conclusions

All treatments, including the standard and ‘low risk’ products, gave statistically significant reductions in numbers of TSSM adults, juveniles and eggs during the trial. All treatments mixed and sprayed well. There were no phytotoxic effects.

TSSM established well, and all products (Borneo, AHDB9946, AHDB9945, AHDB9944, Met52 OD and AHDB9967) gave statistically significant reductions in pest numbers, relative to the control treatment. No treatments caused phytotoxic effects

• Crops: Tomato
• Target: Phytopthora infestans EU39_A1 strain
• Period: Jun-Sept 2019

In January 2018 a new strain of P. infestans (EU39_A1 genotype) was identified by the James Hutton Institute (JHI), occurring on multiple UK production sites.

Few products are currently registered against late blight in tomato and these have a limited number of applications authorised. New products are therefore needed to provide UK growers with effective treatments against P. infestans for the entire growing season.

Conclusions

Although the four applications of seven of the nine test products reduced P. infestans lesion size on at least one assessment date, only AHDB9841 successfully, and consistently, reduced both disease incidence and severity compared with the untreated control.

• Crops: Tomato
• Target: Tomato Russet Mite (TRM)
• Period: Aug 2018- Aug 2019

The aim of this review was to highlight methods to control TRM which are compatible with tomato production IPM programmes, and could be used in the UK.

Conclusions

• Interplanting may increase the risk of TRM outbreaks
• The mite does not survive below 8 °C, so break periods during the winter combined with removal of all plant material and sterilising the glasshouse should eliminate TRM
• Effective and thorough monitoring by trained personnel using a 20x hand lens and/or microscope is the key to controlling TRM
• Marking plants and the height of the TRM symptoms can assist with long term monitoring and TRM activity
• After spraying plants should be assessed for surviving TRM, and follow-on sprays should be applied as required
• Targeted spraying with good coverage will improve the effectiveness of the products used.

• Crops: Tomato
• Target: Tuta absoluta 
• Period: July 2018-2019, Aug-Dec 2019

Currently most UK-grown tomatoes are protected from damage due to caterpillars of Tuta absoluta by the use of a mating disruption pheromone. However, if ineffective, a ‘knock down’ insecticide treatment may be required. With increasing resistance, novel insecticide or bio-insecticide treatments are needed.

The trial in 2019 built on results from the first trial to evaluate further novel bio-insecticides.  

Conclusions

In the initial trial, Conserve did not provide effective control of T. absoluta, provably due to insecticide resistance in the population of T. absoluta tested. 2019 trial:

AHDB 9971 could provide sufficient control of T. absoluta larvae if applied immediately upon sight of fresh mines. Control of embedded larvae may be limited but higher levels of control of larvae hatching from freshly-laid eggs is likely. A number of spray or drip applications may be necessary to reduce T. absoluta numbers to acceptable levels.

• Crop: Protected edibles
• Target: Glasshouse mealybug (pseudococcus viburni)
• Period: Apr-Dec 2019

Glasshouse mealybug is a pest of many protected edible crops and control in commercial production is extremely difficult. This review set out to look at control options compatible with integrated pest management strategies. 

Conclusions

Remedial control is particularly challenging due to the concealed nature of the pest, the protection given by the waxy coating that develops as they move through their lifecycle and high reproductive rates that allow rapid resurgence of populations

Monitoring and cultural management remain important. Thorough hygiene and quarantine protocols that are strictly adhered to remain an effective way of limiting spread to un-infested areas. Careful cleaning down between crops remains important in limiting the survival between crops. Though challenges arise in hydroponic and layered systems

Natural enemies which are commercially available remain the most effective means of biocontrol, but should be used as part of a control strategy

A range of on- and off-label products are available, though these often have limited or variable efficacy. There is potential to develop IPM programmes further based on relatively new biopesticidal and chemical options, but efficacy under commercial glasshouse conditions still needs to be validated

Immature stages of the lifecycle are often the most strongly affected by product applications. Monitoring of the crop to ensure targeting of the motile crawlers may help improve efficacy. Adjuvants or dewaxing agents can also help improve control, though results can be varied.  

Southern green shieldbug (Nezara viridula)

• Crop Group: Protected edibles – Solanaceous and cucurbit crops
• Target: Southern green shieldbug
• Period: October 2018 – March 2019

Take home message

Begin monitoring for southern green shield bugs early in the season

Consider using light traps and trap plants, as well as use of certain biological control organisms to develop a novel integrated pest management approach. However, no firm recommendations can be made on the effectiveness of these techniques against the pest.

Trial summary

The southern green shieldbug can be a significant pest of protected crops, particularly peppers. It occurs in south-east England. It has a broad host range and is able to spread quickly.

It’s important to be familiar with the pest so it can be easily recognised.

Key conclusions

At present, control options are limited. However, there is the potential to develop integrated pest management programmes based on improved monitoring, chemical, biopesticides and biological control options.

• 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