Issue link: https://read.dmtmag.com/i/506700
www.goodfruit.com GOOD FRUIT GROWER MAY 15, 2015 37 Shearer, entomologist with Oregon State University, have made is that the fly transforms into a different, tougher critter as temperatures drop and daylight diminishes. "It's actually a different kind of fly in the winter," Thistlewood said. "It's a different color, different size." Nourishment But as the days lengthen and temperatures rise, it emerges from its overwintering locations in search of the nourishment that allows it to reproduce and multiply. "In the coastal situation, that's going to be the berries. In our situation in the interior, that's going to be the cherries," Thistlewood said. The fly then moves onto currants in July and hon- eysuckle in August, as well as later-season cherries, elderberries, and chokecherries—a total of nine different plants in all. "It's continuously in all these other fruits as late as the middle of October, and when it's in all those plants, it's exponentially multiplying," Thistlewood said. When populations boom and non-crop hosts are insufficient to accommodate them, the flies will gladly move back into late-season cherries as well as grapes— anything that provides nourishment. This is why spraying is both helpful in controlling the pest, yet of little benefit in areas where there are several alternative hosts. Thistlewood notes that a trap adjacent to a research orchard that was regularly sprayed to control pests managed to rack up 1,600 flies one October. "During the season it's pretty well sprayed, yet the insects can build up in the non-crop plants around that block, in the bush, and then later in the year, they're back, blowing through in the hundreds or the thousands." The good news, however, is that growing conditions often allow early-season cultivars, such as Santina, to mature before the fly has gained a foothold in alternative hosts, reducing the need for early-season sprays. "You probably don't need to spray your early cultivars if you're in a certain location and you know that you can get them away in time," Thistlewood said. "If you're an organic grower, for example, it might be a good way to minimize spraying." However, later season cultivars such as Lapins, Sonata, and Staccato face greater risks because even if sprays are used, the pest might be taking refuge in non-crop hosts outside the spray area. "By the time you get to mid-August, you can start to see bigger issues," said Erin Carlson, manager at Carcajou Fruit Company Ltd. in Summerland. "You start to see them more, and they start to become a problem." This leaves growers without a simple solution. While area-wide control programs are effective against codling moth and cherry fruit fly (two pests with which Thistlewood has previous experience), spotted wing drosophila resists such an approach. "With this, there's no way," he said. "It has a wide range of crop hosts that it attacks, and so it's difficult to get that area-wide effect going." But if growers do their part by limiting hosts for the pest, maintaining regular spray schedules, and removing ripe fruit, they stand a chance of keeping ahead of pest populations. "We're going to have to live with it," Thistlewood said. "If growers do their job, it's not an impossible pest to manage." • PHIL BROWN WELDING CORP. PHIL BROWN WELDING CORP. PHIL BROWN WELDING CORP. +/64:22: 51(012 • 3:22: 51(5 • 125-5:%7)4:#:$:/6)76:%7,+76:1-10 888*+7) /8684)76*,/& the since '&'%"%'$ '&%%! '!& '$ $'#&' $'%& "# '#'&% '#%& '$ '#%&&% '# !'$ $!% "%! $"#&""#&$"!$ 9:339#::3!..:.'$9:3:3#!'"::99".9:9!'%9$" Contact Vine Tech Equipment your Northwest Phil Brown Dealer 0-( 55(0-00:::::888*7644,+4 7&46*,/& A properly planted tree produces like no other. • Adjustable tree depth. • Works on stony and tough ground. • Shoe swings for handling. • Electronic distance marker also available. • Two row tool bar available. TREE PLANTER Self-Propelled Work Platform Hydraulic Work Platform (sold separately) can be mounted on any available running gear.