March 15, 2012
Control of Pests
Agrii senior fruit consultant Colin Bird affirms he is not aware that there are any pest and disease problems that growers cannot control in some way.
“The problem may be that we are on the brink of losing numerous products because many are coming up for re-registration with the CRD [chemicals Regulation Directorate] and some may come back with a restricted label,” he says. “This will impact on the control of certain pests and diseases that affect a number of crops with gaps starting to appear in growers’ ability to effectively combat them.”
Arguably tortrix and weed control in cherries and plums present the biggest challenge to growers. The options for their control may not be perfect but if product application and timing are right the result should be satisfactory, he reckons.
“The arsenal for moth control in cherries is very limited but we’ve got a SOLA for Steward which can be used up the end of blossom,” adds Bird. “The trouble is that it needs to be applied later to get the best control.
“For weed control in stone fruit there are no hormone herbicides approved which restricts the control options for weeds like nettles and docks,” he explains. “If the application window [for alternative herbicides] is missed you may not be able to fully recover.”
Another problem faced by growers is that pests can develop resistance to insecticides resulting in control failures. Possibly the main current example of this is the increased sensitivity of fruit tree red spider mite and rust mite to the METI (mitochondrial electron transport inhibitor) products Masai and Sequel.
“This has happened largely because we have imported increasing numbers of fruit trees from the continent where there is known resistance [to these miticides],” claims Bird. “There is a strong link between the time we first saw increased sensitivity five or six years ago and when we began importing the bulk of our trees.”
Not all red spider and rust mite populations are affected, though, and growers have a very good alternative in Envidor that also has good activity against mussel scale. It has the added advantage of being relatively kind to typhs, a good predator of these pests.
Bird believes that biopesticides will play an increasing role in combating fruit pests and diseases. They will not necessarily replace conventional products but work alongside them to enhance the results and provide a background of prevention . Biopesticides account for an estimated 11% of the global pesticide market although the figure is much lower in the UK.