Western Flower Thrips (Part 2)

July 3, 2023
4 mins
Sam Rivers

How to build Mainspring into IPM plan for WFT 

Having shone the spotlight on Western Flower Thrips (WFT) in part 1, Sam RiversICL technical manager for controls – explains how Mainspring, with its unique mode of action, has an important role to play managing resistance build-up. 

Based on the active ingredient cyantraniliprole, Mainspring has a unique mode of action and can therefore make a major contribution to managing WFT resistance on nurseries in the UK.  Thanks to its translaminar effect, it targets pests in hard-to-reach places – such as flowers and buds – making it a welcome addition to existing IPM programmes.  

Understanding the Sustainble Use Directive  

To build Mainspring into an IPM plan requires an understanding of the legislation on how we approach issues on the nursery, such as pest pressure.  

Part of the sustainable use regulations, the Sustainable Use Directive (SUD) is shaping the way we operate on the nursery – promoting a more sustainable approach to plant protection product usage. UK and EU growers are legally obliged to follow the legislation, which relates to promoting safer more sustainable means of crop production across the industry. 

Hierarchy of control  

The SUD outlines guidance on how to raise and protect crops, while also protecting the environment – this is known as the hierarchy of control.  

This begins with cultural control, followed by biological options, then physically acting products and lastly chemical controls – which is where Mainspring has an important role to play.  

Building IPM plan for WFT  

Using WFT as an example, we can go through how we would build an IPM plan to help control it on the nursery. 

  • Cultural control  

Under the SUD, we look at cultural control options first – this refers to measures such as nursery hygiene, monitoring, climate control, irrigation etc.  

For WFT, cultural control options include practices such as disposing of crop debris and older neglected stock, removing weeds (which can harbour the pest), use of clean equipment and avoiding taking cutting material from infested plants.  

  • Biological options  

The next level in the hierarchy of control is biological options; for WFT this includes predatory mites, beneficial nematodes and biopesticides.  

It is possible to achieve very high levels of control employing this approach, however timing of application must be accurate. Issues can also arise with compatibility, especially if employing other biocontrol agents on the nursery. To maximise efficacy, it is crucial to speak to your supplier.  

ICL’s Seeka range of beneficial nematode controls includes Steinernema feltiae which targets WFT adults and larvae on the plant and can control pupal stages in the growing media.  Like most biological controls, these beneficial nematodes should be used preventively and when pest pressure is low as they will have little impact on severe infestations.  

Physically acting products  

Next under the hierarchy of control is physically acting products. These immobilise pests in various different ways, for example by blocking breathing structures, creating ‘physcial’ barriers between the pest and plant etc.   For WFT these options are extremely limited.   

Chemical control  

The last line of control is chemical.  

As mentioned in part 1, the WFT lifecycle is very fast – so resistance can occur quickly through the misuse of chemicals.  These products should only be used when previous options have not delivered sufficient control of the pest, or if a WFT population has gone undetected and literally explodes overnight.  

Bear in mind that even a chemical cannot control the most severe outbreaks – sometimes it is best to discard the crop and start again.  This makes careful pest monitoring and early detection very important.  

Why Mainspring is so effective  

With a very quick mode of action, once Mainspring is ingested the WFT stop feeding.  Key when you consider the pest’s quick lifecycle, it can literally help prevent populations exploding. 

Mainspring has a different Insecticide Resistance Action Committee (IRAC) code to the other chemical options available. Why is this important? IRAC codes are given to insecticides to help develop rotations of chemicals to reduce the risk of resistance build up. The IRAC committee has developed a numerical coding system to help identify the different modes of action of chemicals.   

For example, it is bad practice to rely on two plant protection products with the same IRAC number, and therefore the same mode of action, as the pest is more likely to develop resistance. The greater the difference in IRAC numbers, the less likely resistance will build up. This is an important consideration when devising an IPM programme.   

Mainspring belongs to IRAC group 28, allowing it to be used in conjunction with the other chemical options available which have different IRAC codes – making it is a good fit in an IPM programme.  

So, with resistance build up a constant threat to workable IPM programmes to control WFT, Mainspring is an extremely welcome addition to the toolbox.  

For more information, please contact your local technical area sales manager.