The Horticultural Development Company (HDC) has gained a specific off-label approval (SOLA) for Syngenta's insecticide Agrimec.
The flat scarlet mite has become a significant pest over the past few years - with independent fruit agronomist Roger Umpelby reporting pest attacks in more than 30 per cent of apple orchards in the West Midlands. The attacks have also hit east and south-east areas of the UK.
Umpelby said: "Mites feeding on foliage and developing fruits have a severe adverse effect on tree health and fruit quality. Leaves develop necrotic areas at the base, shrivel and can drop prematurely, while mites feeding around the eye of the fruit can cause russet damage."
East Malling Research (EMR) entomologist Jerry Cross has advised that Agrimec should be applied as soon as possible after the end of petal fall when the mite is identified as active in a crop.
"At this stage, the females that have overwintered in the bark invade the foliage and start feeding and egg-laying."
He continued: "Controlling these females is very important because it both prevents damage and population build-up. A second, later application will deal with any young mites hatching from eggs laid before the first treatment."
The Agrimec SOLA allows for up to two applications a year at a rate of 0.75 l/ha. The time scale of application from May to July should cover most crops.
Cross warned growers to be vigilant for the first signs of leaf speckling damage by paying close attention to outer rosette leaves of the blossom clusters and the lower surface of the rosette leaves, especially near the main vein.
Trials at EMR have shown virtual complete control of motile flat scarlet mite within five days of Agrimec application in mid or late May.
- For more information on protection products available, see the feature on page 33.
RESEARCH REVEALS BENEFITS OF EARWIGS
New studies in Holland have found that Agrimec application at the approved post-flowering time has virtually no effect on beneficial earwigs and predatory mites.
The trials at the Wageningen research institute showed earwigs remained just as active after being treated by Agrimec as those in trees treated with water.
Indoxacarb treatments, however, resulted in high numbers of moribund or dead insects and little or no normal activity even after 30 days post-treatment.
Syngenta's Michael Tait said that, historically, growers may have considered earwigs a pest for burrowing into apples, but in fact they only extend existing holes and cause virtually no damage to sound fruit.
"We now know that they have a beneficial effect as a predatory species and should be encouraged in fruit crops," he added.