Yes SIR, no SIR
British Columbia's sterile-insect release program has its fans and its foes.
SIR field supervisor Sherri Kimmie inspects codling moth traps in a Kelowna, B.C., orchard.
Fourteen years into the groundbreaking Sterile Insect Release program in British Columbia—the only one of its kind in Canada—accumulated expenditures have now surpassed $58 million, the cost to taxpayers and growers continues to rise, and the codling moth has still not been brought under control.
That's generating some grumbling from Okanagan orchardists, especially those in "hot spots" designated by the Okanagan-Kootenay Sterile Insect Release program where orchards continue to be heavily infested, though not all growers are dissatisfied.
"It's a divisive issue," says Sam DiMaria, whose Kelowna orchards include 54 acres of apples and 14 of pears. "More than 50 percent of the growers in the [Okanagan] valley feel they achieved high enough levels of control that they're happy to live with the program."
Since its inception in 1994, SIR has raised and released more than two billion male moths. The moths are fed a special diet so they can later be identified, and are sterilized with gamma rays before being released in orchards throughout the Okanagan, Similkameen, and Shuswap Valleys. Traps are set out throughout the control area, and the numbers of moths are closely monitored. Moth damage to apples and pears at harvest is also monitored.
In 1997, the program revised its objective from eradication to control to a point where no control interventions are required in commercial orchards and their surrounding areas. In 2006, the Regional District of Central Kootenay withdrew from the program.
But there has been progress. According to figures provided by the SIR, by the end of 2007, 93 percent of the 9,724 acres in the control area have less than 0.5 percent damage at harvest, compared to 86 percent in 2001. As well, at the end of last year, 14,431 wild moths were caught, compared to 29,029 in 2004.
The program's objective for 2008 is to maintain at least 90 percent of the acreage to 0.2 percent or less damage at harvest. It was at 85.9 percent in 2007.
However, while the southern part of the Okanagan and Similkameen Valleys (zone 1) has reached a steady state of control (98.5 percent at 0.2 percent or less damage), the central (zone 2) and northern (zone 3) partswere forced this year to extend the more costly maintenance phase for at least another year, at a cost to growers of $134 per acre, a 6 percent increase over last year.
That doesn't sit well with DiMaria, who has seen the codling moth problem increase dramatically on four acres of pears in recent years despite his efforts, in conjunction with SIR field staff, to combat the pest.
"In my case, prior to the SIR program, codling moth was basically under control," he said. "For whatever reason, since they started dispersing the sterile moths, in a couple of blocks of my orchard, we've had some serious codling moth problems."
DiMaria isn't happy having to pay a levy for SIR when he has to apply three or four chemical applications and still has large amounts of damaged fruit.
"I'll give it another year, but if I don't achieve better results in these two particular blocks, then something's got to happen," he said.
The SIR program might also have inadvertently contributed to an increase in leafrollers, which have supplanted the moth as the biggest threat to apple and pear crops in the area.
"You talk to anyone in the field service, and leafroller is probably the number-one cause of cullage in apples right now," said B.C. Fruit Growers' Association President Joe Sardinha. "There's no doubt that when we were spraying broad-spectrum pesticides such as Guthion [azinphos-methyl] for codling moth, leafroller was being controlled as a secondary pest."
Hugh Philip, former entomologist with the B.C. government and now a consultant with the BCFGA, pointed out that leafrollers breed on other types of backyard trees and that is likely contributing to orchard infestations.
"Unfortunately, homeowners haven't got the products anymore to control them satisfactorily," he said.
"A lot of the commonly used insecticides have been banned now, and that makes it more difficult for homeowners to do a good job trying to control their orchard pests."
Farlie Paynter, who grows five acres of apples and five of cherries on his Westbank acreage, says he hasn't sprayed his apples for codling moth in seven years, even though he lives in an area designated by SIR as a hot spot.
"I have one or two percent damage in my orchard," he said.
Paynter, who uses pheromone mating disruption, says he believes there are better methods of control than releasing millions of irradiated moths.
"We should be getting away from these dangerous radioactive waves. I think we should be building a healthier organism. The codling moth worm can only go a little tiny way into the apple, then it dies if the apple is strong and healthy and vigorous."
Paynter also takes issue with SIR's right to go onto people's property unannounced to inspect trees and release moths.
SIR, which employs 17 full-time staff, 5 consultants, and approximately 65 seasonal employees, monitors fruit trees in urban areas, and people who don't control codling moth by spraying or removing fruit are ordered to permanently remove the trees. That order can also be applied against commercial orchardists who don't comply with the program. This year, SIR's board of directors squashed the right of property owners to appeal the control orders. One Kelowna grower ended up cutting down his orchard, and another cut down almost four acres of apple trees.
Despite its problems, Philip said he would recommend the SIR program to other areas—under certain conditions.
"You'd have to have total cooperation from all growers in terms of dealing with the problem and the cooperation of all the tree owners in the city," he said. "Even if you want to use mating disruption or other tactics, you still need full cooperation. The idea of the SIR was to get it down to low numbers, and I think they're looking now at other tactics to assist in keeping the codling moth down to subeconomic numbers."
Sardinha also envisions changes to the program.
"Very soon, the SIR program is going to initiate a discussion, and it's going to have quite a few growers involved, looking at what the program has achieved to date, looking at establishing steady state for codling and what to do when steady state is achieved," he said. "You have a program that has a lot of fine areawide qualities to it, such as monitoring and putting up control methods for a pest. If we apply some of those same items to our model, why not apply them to other pests?"