Be on alert for whitefly in poinsettias

26.10.2018

Growers are being urged to monitor protected poinsettia crops closely for whitefly as the pests seek refuge indoors due to the recent drop in outdoor temperatures, according to one large scale ornamental grower.

Alongside his brothers, Ian Paton of Hampshire based Pinetops Nursery, a family run business of 60 years, supplies a variety of protected ornamentals to major UK multiples.

Following relocation and expansion two years ago, he now produces 140,000 poinsettias, 700,000 lilies, 40,000 hydrangeas and 30,000 hellebores per year, across three hectares of newly built glasshouses.

Integrated pest management (IPM)

At this key time of the season, Ian says that crop monitoring for pressure is essential. With whitefly being an issue in susceptible poinsettia crops, he explains how he’s kept on top of the pest using a range of control methods. 

The first step is thorough cleaning before planting to remove weeds, which can attract whitefly. Weekly monitoring of yellow sticky traps throughout the glasshouse also helps to establish pressure.

Once potted, Ian covers the poinsettia crop with a fleece lining to retain humidity. This helps the single application of biorational fungus, Beauvaria bassiana, to thrive and achieve pest contact.

Beneficial insects, Encarsia formosa, a natural predator of whitefly, are then introduced once the fleece lining is lifted two weeks later.

Whitefly that are found are sent off for testing to identify any presence of notifiable pest, tobacco whitefly, and to differentiate it from glasshouse and honeysuckle whitefly, for targeted control.

Resistance management

Certis’ Technical Specialist, Alan Horgan, explains that because whitefly have a short lifecycle of three weeks, alternating actives helps to maintain efficacy and manage resistance.

Applaud 25 SC returned to the market following re-approval in 2016 due to its effectiveness against glasshouse and tobacco whitefly.

He recommends alternating applications of Applaud 25 SC with Botanigard WP and Majestik as part of an effective spray programme, when pest populations arise.

Best practice Applaud 25 SC application

• Use a maximum of 80ml per 100l of water

• No more than two applications per crop

• A minimum 22-day spray interval

• Avoid consecutive sprays

• Alternate with Botanigard WP and Majestik 

• Ensure good coverage

• Target whitefly eggs and scales