The art of application to target Hylobius feeding activity
Accurate knapsack spray application techniques will give optimum performance from Lanzarta treatments to target Hylobius large pine weevil this summer, advocates Syngenta Technical Manager, Sean Loakes.
Speaking at the Hylobius Industry Research Programme (HIRP) Conference in Perth this week (24 April 2025), sponsored by Syngenta, Sean highlighted the company’s application research had focused attention on nozzle selection and spraying trees from the side.
“Historically forest trees have often been sprayed from directly overhead. However, trials have shown that crucial coverage of the lower stem and branch axials can be poor with this technique,” he warns.
“Making an application from the side of the sapling tree delivers far more effective coverage of the key target zone that needs to be protected.”
Sean pointed out that Lanzarta works by locking on to the bark of the tree, which is ingested when adult Hylobius weevils start to feed. The insecticide quickly takes effect to stop further feeding, after which the beetles perish.
“The more of the bark that is covered by Lanzarta the sooner the beetles rack up a lethal dose, and the less damage inflicted. Trials have shown a far higher proportion of treated saplings suffer only superficial damage and quickly recover, compared to untreated trees where more severe damage occurs.”
The trials have shown that in most situations application from just one side of the tree provides sufficient coverage to achieve good results and is the most practical approach for cost and convenience of application, he suggests.
“However, in high-risk situations - where there is a history of high levels of damage or insect activity has already been identified feeding on newly planted saplings – forest managers should consider investing time in application from both sides of the tree.”
Watch Sean's application advice video for Lanzarta knapsack application
The recommended application rate is 20ml of Lanzarta spray mix per tree, either as one sweep of the sapling from base to top, or to apply 10ml per side. Where trees are very small and spraying 20ml could risk over-wetting the surface resulting in run off, Sean indicates the application rate should be reduced accordingly.
The use of dosing devices on lances can be effective to deliver precisely the right dose, but in practice experience operators can be incredibly consistent when they get into a rhythm of application.
“But, as a quick check, we would suggest that operators regularly use a measuring jug and a set of digital scales to measure and calibrate that 10 doses is delivering 200ml, which assures consistent application.”
Sean acknowledges that where saplings are planted among dense brash it can be difficult to target the base of the stems, but since this is the area most affected by adult weevil feeding damage, it is important to try and achieve the best coverage possible.
The Syngenta application research has indicated that using a knapsack lance nozzle with a narrower pattern is currently the best practice to achieve the highest levels of deposition on Sitka spruce saplings, in the first two years after planting.
Further Syngenta application research is being undertaken in the UK and across Europe to identify new options and techniques to optimise coverage and retention of Lanzarta to protect tree saplings.
