SCEPTREplus: Ornamentals

EAMUs secured

Authorisations secured following SCEPTREplus trials for ornamental plant production: 

• Prolectus as a fungicide for ornamental plant production for the control of botrytis spp.
• FLiPPER as an insecticide for protected ornamentals for the control of aphids, whitefly and spider mite

Western flower thrips control in ornamentals

• Crop: Protected ornamentals (verbena)
• Target: western flower thrips (Frankliniella occidentalis)
• Period: June to December 2017

Take-home message

Two coded biopesticides and a tank mix of Botanigard WP with Majestik significantly reduced percentage flower damage when used in combination with N. cucumeris compared with using N. cucumeris in combination with water as a control.

Trial summary

Western flower thrips causes feeding damage to flowers and leaves that can make plants unmarketable. The pest is widely resistant to many chemical plant protection products. Biological control methods are widely used within Integrated Pest Management (IPM) programmes but sometimes these need supplementing with a compatible plant protection product therefore new effective actives need development. Control measures for Western Flower Thrips were investigated in CP 124 Managing Ornamental Plants Sustainably (MOPS) and the inclusion of Neoseiulus cucumeris in an IPM based approach warranted further investigation with other conventional and biopesticide products in SCEPTREplus.

Conclusions

The results indicate that the reduction in mean numbers of WFT adults and larvae per leaf and percentage leaf area damaged compared with the water controls are likely to have been mainly due to the use of N. cucumeris in combination with all treatments.

Neoseiulus cucumeris predates first instar WFT larvae and thus would reduce subsequent numbers of second instar larvae and adults. However, there were significant reductions in mean percentage flower area damaged compared with the N. cucumeris and water control by the standard treatment Actara and also by AHDB9970, Botanigard WP tank mixed with Majestik and AHDB9971, all used in combination with N. cucumeris. This result indicates that these treatments improved control of WFT flower damage when used as a supplement to N. cucumeris in an IPM programme. However, WFT pressure remained low in the controls during the first 14 days when treatments were applied. The final assessment 36 days after the first application was added as an ‘extra’ assessment when numbers of WFT were higher but no further treatments were applied after the 14-day period.

• Crops: Phalaenopsis (Orchid) 
• Target: Pot worm
• Period: July 2019 - April 2020

This report summarises research led by Wageningen University and Research in the Netherlands into the biology and control of pot worms.

Conclusions

Findings from the report include: 

• Using a substrate with a higher percentage of coir or fine bark to increase the pH and reduce the air filled porosity might inhibit web production by pot worm larvae
• Distracting pot worm larvae with alternative sources of carbohydrate, such as molasses, might help to reduce root damage
• The commercially available predator D. coriara did not provide sufficient control in laboratory tests but may perform better in different growing medium
• Releasing the predatory mite Macrocheles robustulus can reduce the availability of prey mites in the growing media, but might also increase the number of springtails.
• Nematodes can parasite pot worm laboratory and might be commercially effective when used on damp plugs

• Crops: Protected ornamentals and protected pot orchid
• Targets: Sciarid fly, shore fly and ‘pot worm’ 
• Period: April to July 2018

Growers are currently using cultural and biological control methods within IPM programmes for control of sciarid fly, shore fly and ‘pot worm’. IPM programmes for sciarid and shore flies are not always fully effective and there is no current effective biological or chemical control method for pot worms. Growers need additional IPMcompatible control methods to improve control and to reduce current losses.

Conclusions

New potential control methods for the three fly pests were identified. If further funding is available for efficacy trials next year, candidate IPM-compatible treatments will be selected as having a clear route to market if not already approved in the UK. Treatments may include both conventional chemical plant protection products and microbial and botanical biopesticides.

• Crops: Sweet William
• Target: General broadleaf weeds and grasses
• Period: Jun-Sept 2020

There are virtually no specific label approvals for the use of herbicides in cut-flower production. The range of species grown and their differing sensitivities to herbicides further complicates agronomy.

Sweet Williams have proved very sensitive to a wide range of herbicides. One possible way forward is band spraying at drilling. This is made possible by the use of GPS equipped sprayers to identify the location of the drill with precision. This enables a stronger herbicide mix to be applied between the rows and a weaker mix over the row. This approach has been successfully tested in vegetables in SCEPTREplus.

Conclusions

A tank-mix of Stomp Aqua + Defy with a reduced rate of Defy (either half-rate or quarter-rate) could be worth considering as a pre-emergence residual herbicide applied as a precision band in-between the crop row on Sweet Williams. It could also be worth looking at a tank mix of Stomp Aqua + Springbok with a quarter-rate of Springbok as an inter-row treatment. This mix was not tested in the trial and therefore would be at the growers own risk.

• Crops: Gladioli
• Target: General broadleaf weeds and grasses
• Period: Jun - Sept 2020

The loss of linuron for residual weed control is of industry concern. Linuron was used principally in bulb cut-flower crops such as Narcissus and Gladioli and herbaceous perennials of Peony. Gladioli are an important cut-flower crop but have not been subject to a herbicide screen for many years, hence why they have been tested in 2019. Outdoor crops of gladioli are usually treated with herbicides selected from the range used on bulb crops. However, products such as Wing-P and Sunfire have been tested on other cut-flower crops, and have an EAMU for use in outdoor ornamentals, so it is worth examining those for crop safety, along with some new potentially promising coded products.

Conclusions

Sencorex Flow, Wing-P and Springbok are all worth considering as pre-emergence residual herbicides on gladioli. Sunfire can also be considered but would need to be tank-mixed with another product to ensure both broad-leaved weed and grass control was achieved. Tank mixes were not tested in this trial, any tank mix would be at the growers own risk.

• Crops: Ornamental plants (seven species)
• Target: Downy mildew - crop safety  
• Period: Oct - Dec 2018

Downy mildew presents a challenge as it can be present but not always obvious, and is difficult to control with fungicides once established.

Previous work in SCEPTREplus in lettuce identified eight treatments for the control of downy mildew. Using a cross-sector approach, this work investigated the crop safety of the same treatments on seven commonly-grown ornamental species.

Conclusions

The trials tested treatments on species susceptible to Downy mildew: Buddleja, Aquilegia, Digitalis, Lamium, Veronica, Monarda and Potentilla.

Several promising downy mildew chemical fungicide and biofungicide products were tested. None had phytotoxic effects or left any visible residues on the plants