Apple Moth Populations Spread

Cherry growers are waiting with bated breath to learn whether they will be allowed to use an insecticide to control a "new" pest that can devastate their crops if left to its own devices. It is the light brown apple moth, a native of Australia, now well established in England.

The trouble is that no caterpillar killers have label approval against the pest for post-bloom application to cherries. This problem was solved in 2007 when the Horticultural Development Company (HDC) obtained a SOLA for Steward (indoxacarb) but it only lasted until August 2008, leaving growers potentially defenceless this season.

"More data is needed on Steward to convince the Pesticides Safety Directorate (PSD) that the SOLA should be extended," said HDC communications manager Andrew Tinsley. "We've commissioned a research group to get the data and we are hopeful that it will satisfy the PSD in time for this season."

Just how devastating the pest can be is stressed by East Malling Research entomologist Dr Jerry Cross, who said that without the SOLA there is nothing that controls it well enough. The caterpillars feed on the shoot tips and fruit, making it unmarketable.

He said: "The light brown apple moth also feeds on apples (and a wide range of other plants) but because they're sprayed so often post-bloom against codling and tortrix moths it's not a problem. However, I would imagine that it damages organic apples."

During larval stages the moths could attack more than 250 types of fruit and vegetable, and numerous species of plants and trees. Fruit at risk in the UK included apples, grapes, cherries and plums. The pest has only become a problem on cherries in recent years.

When Cross carried out a pheremone trap survey to determine its presence in cherry orchards in Kent, Hereford, Somerset and Oxfordshire in 1994, he drew a blank. But when he repeated the exercise in 2005 he found the moth in every orchard surveyed.

"It first turned up in Cornwall in 1936 feeding on ornamental spindle and it stayed there for about 55 years. But it's got a sort of plastic biology ... it has been able to adapt to new plants and climates so it has spread much further afield." Recent results from New Zealand showed five to 20 per cent crop-yield loss in vines as a result of the moth, so it is definitely something that needs to be managed.

The light brown apple moth is from the family group Tortricidae, which contains other destructive pests like the codling moth. Though native to Australia, it has recently been found in the British Isles as well as New Caledonia, New Zealand and the US.

Article provided by Dynamic Pest Control