Pheromones are becoming a mainstream method of controlling important Lepidoptera pests in dessert apple orchards across the country
This season, Agrovista’s fruit agronomy team has been supporting the use of the novel pheromone system called RAK 3+4
across dessert apple orchards at risk of codling and tortrix moth attack.
After a successful run of trials and commercial use over the past few years, many growers were keen to use the system again in their
orchards or to try it for the first time, says Agrovista fruit technical manager Alex Radu.
“RAK 3+4 provides control by disrupting mating behaviour, blanketing the orchard with artificial female pheromone released by ampules
that hang in the trees.
“This masks natural pheromones given off by female moths so males can no longer find them and mate, preventing females from laying viable eggs.”
Trials have shown the system has consistently saved three or four rounds of insecticide for first generation codling control
and has prevented potentially difficult-to-control and highly damaging second generation flights from occurring.
“This has potential economic and environmental benefits, and helps growers meet tightening retailer protocols,” says Mr Radu.
Each RAK ampule has two compartments, one containing artificial codling moth pheromone and the other summer fruit and
fruit tree tortrix moth pheromone.
Ampules are placed in the top third of trees in late April or early May before the first flights begin, at a rate of 500/ha in a
grid formation that provides season-long coverage.
Jim Burston, farm manager at Herefordshire-based Tillington Top Fruit has been trialling RAK 3+4 for the past three years.
Mr Burston manages 350ha of apples and cherries from his base at Upper House Farm, Tillington. Key varieties include Red Prince, Junami, Gala, Red Windsor and Spartan destined for Morrisons and other major retailers. Overall dessert apple output is around 2500t of fruit a year from 75ha.
Codling moth pressure is very high and summer tortrix moth can also be troublesome, partly due to climate and topography
but also because a lot of the farm is planted with cider orchards.
“It is not economic to control codling in established classic cider orchards. They are basically high-rise flats for moths, but we can’t always keep cider and dessert orchards well apart as we plant the later-flowering cider trees in frost pockets spread across the farms,” says Mr Burston.
Codling moth counts in dessert apple orchards regularly exceed threshold, with 30-40 males per week being caught in pheromone
traps at some sites season after season. The chemical treatment threshold is just 5 males per week.
Second-generation thresholds are also breached, typically in three years out of five.
Until two years ago, three or four insecticide treatments for first generation control was the norm. In 2017 he tried RAK 3+4 on 10ha of dessert apples. No chemical applications were used to control codling or tortrix moths in these orchards and fruit yields and quality were maintained,
with no grade-out due to damage.
In 2018, he raised the RAK area to 15ha. The same results was achieved, despite some test orchards being closer to cider orchards,
which can reduce the efficacy of RAK 3+4.
This is because they harbour high populations of moths and mating readily occurs.
Female moths are not affected by the artificial female pheromone, so they can fly into adjacent RAK-treated orchards and lay eggs.
“As well as helping us in terms of marketing, reducing pesticide use also has obvious environmental benefits and is good for
beneficials that help keep moths and other pests at bay,” says Mr Burston.
“The RAK system is also very reliable, offering as good control of the first generation as we were achieving with chemicals,
but with a lot less management. We don’t have to worry about getting our timings just right,
and it takes the worry out of second-generation control, which can be difficult due to harvest interval limitations.
“It also reduces the amount of paperwork and removes any concerns over harvest intervals and residues on fruit.”
Purchase costs are similar to first-generation chemical control, and the system costs about £65/ha to install each season.
“Given the advantages and the level of control, that’s a cost I’m willing to bear,” Mr Burston adds.
“In seasons when a second generation occurs, we’d clearly be better off.”
Increasing pressure
This season RAK 3+4 will be used in some dessert orchards adjacent to cider orchards at Tillington to provide an even tougher test.Mr Radu hopes the results will reflect those at a Cambridgeshire high-risk site in 2015, where only one or two fruits per 1000 suffered
codling moth damage in RAK 3+4 treated areas, compared with 60-70 in untreated areas.
As before, manufacturer BASF is supplying product for part of the work. “They are as keen as Agrovista is to see how well the system
copes under increasing pressure,” says Mr Radu.
“We as a company strongly support integrated pest management to help growers reduce pesticide use and its effect on non-target species.
“We believe that through effective monitoring, the use of RAK 3+4 and our GCI pest and disease warning service we can help growers
meet these aims while greatly simplifying control programmes for no extra cost.”
RAK 3+4 – key benefits
• Reduces/eliminates need for pesticides• Matches or exceeds chemical control
• Helps address tightening supermarket protocols
• No impact on non-target species or wider environment
• No residue risk on picked fruit
• Simplifies management
• Helps reduce over-wintering populations
• Comparable cost to first-generation codling spray programme.