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New pheromone technology “messes” with moth’s head

Tender fruit producers had an
opportunity to view a new product in action that could play an
important future role in the control of Oriental fruit moth (OFM).

The tell-tale flagging of OFM on a peach tree.

OFM larva

Tender fruit producers had an opportunity to view a new product in action that could play an important future role in the control of Oriental fruit moth (OFM).

RAK 5 is a new mating disruption product from Europe and developed by BASF that is currently being demonstrated at three locations (Beamsville, Jordan and Niagara-on-the-Lake) in the Niagara growing region of Ontario. The idea behind the product is fairly straightforward – a white tag houses the product’s synthetic pheromone and that tag can be “clipped” onto tree branches. The pheromone then wafts throughout the treated orchard, causing male OFM to travel aimlessly in search of the female they appear to be “smelling.” Confused by the large volume of pheromone in the orchard, the males are less likely to connect with the females, thus no eggs are fertilized and no new generation of OFM develops.

“You’re not really killing them,” explained Neil Carter, tender fruit and grape integrated pest management (IPM) specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). “You’re just messing with their heads.”

David Wright

Neil Carter

The RAK 5 treatment could be used in place of the current conventional treatment for OFM, which involves an initial spray of Lorsban followed by repeated pyrethroid spray treatments all season long. It could also be used with just an initial Lorsban spray alone. There is no danger or damage to the emitter tag if spray is applied within a treated field.

Application of the tags is also quick with two people covering three acres in the amount of time it takes just to prepare the sprayer for action. Clip densities vary with the density of the orchard planting but work out to 100 clips per acre within the interior of the orchard (about every-other tree) and 200 clips per acre around the perimeter of the treated orchard (every tree).

Carter said the minimum size of orchard block required to have the product work is 10 acres. Anything less and the potential is high for a fertilized female OFM to migrate into an orchard and lay her eggs, despite the pheromone treatment.

“Potentially, you should be able to reduce the population over time,” he explained. “One grower doing it isn’t going to make a difference because of migration between orchards. But if everyone used it, you would see gradual population reduction.”

As part of the demonstration, Carter is assessing the orchards for OFM damage following the normal timings for conventional sprays. He is comparing the pheromone treated orchards against other orchards on the same farm that have been managed using conventional methods. So far, he is seeing very low levels of flagging (about zero to 0.4 per cent) within the treated fields with most damage occurring around the orchard perimeter. Using current threshold numbers, it would require two per cent or more flagging damage to trigger a spray treatment.

The RAKS pheromone clip.

But Carter added it will be the final fruit damage numbers that will really show if the pheromone treatments are a success.

“That’s the real test,” he said.

David Wright of Engage Agro, who will be marketing RAK 5 on behalf of BASF, said that registration of the product is about one growing season away. He added that pricing has not yet been established but will most likely be competitive with other registered pheromone treatments or the costs attached to a conventional OFM spray program.

Oriental fruit moth has been around North America since about 1915 and is a serious pest of stone fruit (peaches, plums, apricots and sometimes cherry) and pome fruit (apples and pears) in most areas of Ontario. It likes to overwinter in orchard waste, old fruit left in the bottom of bins and in host weeds near farm buildings. As an adult, it’s a rather small, grey mottled moth and can have a wingspan of about 0.5 inches. The female can lay up to 200 eggs in her lifetime. The eggs are flat, oval and white and are laid in singles on twigs or the underside of leaves. Newly hatched larvae, which can take up to three weeks to hatch in cool spring weather or only a few days during a hot summer, are a cream colour with a black head. After they hatch, first and second generation larvae will burrow into new shoot growth on the tree. Later generations of OFM will be laid directly on fruit where the larvae will hatch and feed. While shoot damage and flagging can lead to weakened scaffolding of the tree or provide a damage site for disease to enter the tree, it’s the fruit damage which is the most serious problem connected to OFM. Larvae usually enter the fruit from the stem end or where two fruit may touch one another on the branch, making it unmarketable.