SCEPTREplus: Alliums

EAMUs secured

Authorisations secured following SCEPTREplus trials for alliums

• Emerger as a herbicide for garlic, onion and shallot

Control of onion thrips on leek

• Crop Group: Field vegetables - alliums (Leek)
• Target: Onion thrips – Thrips tabaci - THRITB
• Period: May 2017 – October 2017

There are currently a limited number of control options and an overreliance on a single active, which could lead to resistance in the pest population.

Two coded insecticide treatments reduced thrips damage to leek significantly compared with the untreated control. Six treatments, four of which were bio-insecticides, reduced significantly the numbers of plants damaged by leek moth compared with the untreated control. Further work would be advisable to ensure the most effective treatments identified in this trial are robust under higher pest (thrips) pressure

Weed control in leeks

• Crop Group: Alliums – leeks
• Target: Weeds
• Period: March - December 2018

Controlling broad leaf weeds in leeks has become more and more difficult, mainly due to the loss of contact herbicides in recent years.

This trial screened potential new contact herbicides, both on their own and mixed with existing actives, to test their effectiveness on leeks ion a peat soil site.

The herbicide active aclonifen is very promising and approval will be sought.

AHDB9889 could be useful if we can get an approval.

• Aclonifen gave the best weed control, either when applied alone at 1.0l/ha or in mixtures.
• AHDB9890 gave the poorest weed control, although all treatments improved weed control when compared with the untreated control.
• AHDB9889 caused most damage to the crop, but that grew out within 3-4 weeks.
• Crop damage from all treatments grew out four weeks after treatment

• Crop group: Alliums (leeks)
• Target: Rust (Puccinia allii)
• Period: May 2019 to October 2019

All products tested provided significant levels of leek rust control by the end of the trial. 

AHDB9862 and AHDB9851 were the two best performing products, providing important new product options which, if taken forward for registration could help with fungicide resistance
management strategies in the future.

The biopesticide AHDB9852 also performed well and has the potential to provide an additional disease management tool to growers of both conventional and organic leeks.

A replicated field trial carried out in the West Midlands identified potential new products to effectively manage downy mildew in salad onions.

AHDB9841, AHDB9862 and AHDB9827 all performed well in the trial and were effective in reducing downy mildew in salad onions. These products could provide additional modes of action to current control programmes and will prove useful in informing future fungicide resistance management strategies.