Controlling Moth Pests in Apples

Dr Jim Walker from Plant and Food, and colleagues; together with Apollo Apples Ltd have developed and successfully trialled a “twist-tie” impregnated with appropriate pheromones that is tied to apple trees and disrupts the mating behaviour of codling moth and three leaf roller moths.  The result is a 70% reduction in insecticide spraying, little or no fruit damage and no residue problems.  The combination is now available commercially and is marketed as “4Play”.

Dr Walker has been involved in working with pheromones to control midges on apples and mealy bugs on apples and grapes since 2005.  This area of work has continued with different apple pests and recently, he and his colleagues won a NZ Innovators Award in the ‘Innovation in Environment & Agriculture’ category for their recent work in combining four pheromones into one dispenser to control four apple pests.

Sex pheromones, the natural chemicals released by the females of many insect species to attract mates, can be used to disrupt communication between insects, reducing their ability to identify mates and subsequently leading to a reduction in the population and less need for insecticides.

A team at Plant & Food Research has been working in this area for many years.  Dr Jim Walker based in the Hawkes Bay, along with his colleague Dr Max Suckling at Lincoln, has developed a pheromone combination and delivery mechanism to disrupt the mating of four key apple insect pests:

• Codling moth
• Lightbrown apple moth
• Green-headed leafroller
• Brown-headed leafroller

The team identified and isolated pheromones from these four species and developed synthetic pheromones.  Initially they were used in individual dispensers but they are now able to be blended for use in a combination dispenser to disrupt the mating of all four species. This dispenser, a little like a “twist-tie” that is attached to apple tree branches, is now a key part of the Apple Futures programme that aims to produce apples for export with ultra-low residues to meet market regulations and supermarket customer assurance programmes.

Dr Walker says that what is particularly novel is coming up with a system that uses a single dispenser to control four species of insect.

“There’s no baiting, no bugs and we have got to a point where putting these out at the beginning of each season disrupts the communications and mating behaviour of all four species simultaneously.  The products mimic the natural compounds that the female moth produces to attract the males, so it’s male confusion on a grand scale. Since there is no mating there is no egg laying and no larvae to damage fruit or leaves,” he says.

“We did development work over three seasons as a Sustainable Farming Fund project with Apollo Apples, one of the major growers here.  A year ago the product went on sale for the first time and somewhere around 2000 ha were under that form of control last season.”

Dispensers are put out at 800 per hectare, which generally means one per tree, and they are applied at the top of trees by workers on a hydraulic platform.  No special precautions are needed and operators need only wear latex gloves when handling the dispensers.

Trials have shown that the system is very effective, says Dr Walker.

“It involves less spraying, so whereas previously six or seven insecticide applications would have been normal, today under the combined control strategy, you are looking at about two applications,” he says.

“In terms of costs it depends on what insecticide you use but the overall costs are probably about the same as for normal spraying.  The big advantage is you have a lower residue profile and your overall ability to manage codling moth and leaf roller in successive seasons is enhanced because you reduce the population each year and you lower the risk.”

The product is now readily available and whether or not it is used is a question of economics and how significant the pests are to growers.

“In the Hawke’s Bay they are very significant and here about 50% of commercial production is covered by this treatment, which is pretty good for the second year it has been available,” says Dr Walker.

“It has taken quite some time to get to this point.  We started in 2004 with single species and progressively we have been able to get to a four-in-one blend because obviously you don’t want to be putting out 800 items per hectare for each species,” he says.

“The project has involved the team at Plant & Food Research here and at Lincoln with support from the Sustainable Farming Fund and Pipfruit New Zealand, and the co-operation from Apollo Apples.”

Lachlan McKay, orchard technical manager for Apollo Apples Ltd, says that for three years the company has trialled dispensers in orchards that are susceptible to the pests, and as a result they haven’t had to spray the trees nearly as much and they have been able to use low residue sprays so that there are no residue problems with their fruit.

“As time has gone on, spraying has been less and less necessary, and on average it has reduced the number of applications from about six to two. That means less labour input and safer conditions for staff,” he says.

“We find very, very few codling moth and leaf roller moths in our orchards now, and residues are at a very low level.  Also, it doesn’t affect any of the other natural moth predators in the orchard, whereas some of the sprays we used to use killed the predators too.”

“The cost is about $700/ha so the cost savings are not great but the marketing access advantages are huge because our fruit is residue and pest free.  So the system works very well for us and we will continue using it – if anything we may expand its use.”

The combination ISOMATE®4Play dispenser is now manufactured by Shin-Etsu Fine Chemicals (Japan) for Etec Crop Solutions.