There’s been a 95 per cent reduction in the amount of organo-phosphate pesticides used in the Okanagan Valley in the past 19 years due to the Sterile Insect Release program used to combat codling moth in apple orchards.
Entomologist Hugh Philip was reporting to the SIR board Thursday in Kelowna, which is made up of representatives from the four regional districts that are part of the area-wide program.
“The program has had a considerable impact on the prevalence of codling moth,” reported Philip, and that has translated into far fewer pesticides being applied in orchards.
In total, he said 74 per cent less pesticide is being used since the program began, from 5.4 kilograms or litres per hectare in 1991, to 1.4 kilograms or litres per hectare in 2010, in pome orchards such as apple and pear.
Philip’s figures take into account the reduction in apple orchard acreage in that time, which is a 53 per cent drop, from 8,900 acres in 1991 to 3,796 in 2010.
Even in zone two and three, from Peachland north, the use of chemicals to combat the devastating, introduced pest of apples, has now dropped to as low as in zone one, where the program began and where it has successfully replaced all chemical sprays for the codling moth for more than a decade, he reported.
With such low populations, an alternate, chemical-free option for control of the codling moth works very effectively, he said.
Mating disruption is now being used in this area instead of using sterilized moths that have been irradiated in the Osoyoos rearing facility.
Strips containing a synthesized sex pheromone that mimics a mating attractant are put out in the orchard and confuse the moths so they are unable to mate and reproduce.
Philip noted the area-wide program costs orchardists $139 an acre each season, while mating disruption costs $166 per acre per season, and chemical controls cost between $95 and $134 a spray, which must be applied three times a season.
It’s still necessary for people with backyard host trees such as apple, pear and crabapple to control codling moth or else strip all the fruit from their trees while it’s still immature.
Otherwise, commercial orchards could be re-infested with codling moth.
In areas around orchards, this year 240 residential property-owners have been ordered by the SIR program to strip the fruit from their trees, while eight commercial orchards have also been ordered to strip their fruit because of a high level of infestation of codling moth, which could re-infest their neighbours’ fruit.
Orchardist Fred King of Kelowna, who is also a member of the SIR board and of the B.C. Fruit Growers’ Association board, commented that there are still some orchardists who automatically put on three cover sprays a year for codling moth, whether it’s needed or not.
“We have to change that,” he commented.
Philip said few orchardists should need to spray even once this year for codling moth.
Organic orchardist Brian Mennell from Cawston noted that by reducing sprays, orchardists would find that they would be permitting the survival of beneficial insects, some of which would help to keep pests in check without chemicals.
Board member and orchardist Allan Patton said he stopped spraying 12 years ago and found a bit of a jump in damage from other pests for the first couple of years, but then those problems dropped right off and he hasn’t sprayed since.
The board also agreed to permit a Korean broadcasting company to film inside the SIR moth rearing facility for a farm to fork documentary on sustainability and green growth.
An international entomologists’ organization asked if Philip would come to a conference in Germany this fall to make a presentation about the program, but there is no funding for such a trip. Instead he will put together a profile poster about the program to send.