Good Fruit Grower

March 1

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Page 32 of 47 Good Fruit Grower MARCH 1, 2016 33 split oranges are now recognized as the primary reservoirs for SWD before they move into cherries, he said. "In our area, spotted wing drosophila is active all win- ter long, so it's really in the citrus from November until about March, and then it moves over into the cherries in March and April as they start to get ripe." Other parts of the country will have different SWD reservoirs, Haviland noted. "It might be a riparian area with various host plants, or it might be a forest that's around your orchard." Reviewing reservoirs That's exactly what researchers are finding, according to extension spe- cialist Nikki Rothwell, coordinator of the Northwest Michigan Horticulture Research Center. She presented infor- mation about SWD reservoirs during a talk at the December Great Lakes Fruit, Vegetable and Farm Market EXPO in Grand Rapids, Michigan. She men- tioned Cornell University research that described numerous noncrop hosts for adult SWD, including barberry, buck- thorn, choke cherry, honeysuckle, laurel, mulberry, pokeweed and many others. With that in mind, she and other Mich- igan extension personnel put together a trapping effort in northwestern Lower Michigan to determine the prevalence of adult and larval SWD in noncrop hosts adjacent to both tart and sweet cherry orchards. This included mulberry and honeysuckle, which are common wild plants in the area. They conducted weekly checks of 21 traps, harvested the fruit of those host plants as soon as it started to ripen, gathered any larvae in the fruit, and then reared the larvae so they could verify whether they were SWD. The project confirmed that adult and larval SWD were indeed present in good numbers. "And we were getting a lot of larvae out of very few fruits," she said, noting that they found their first 48 SWD larvae in just 60 fruits collected from a mulberry tree right next to a sweet cherry orchard. These results indicate that SWD does build up in noncrop hosts and therefore can migrate to nearby commercial blocks and attack salable fruit, so growers should definitely be trapping for SWD in these potential reservoirs, she said. "What's your threshold for taking action? Here's my threshold: one." She added, "If you're trapping and you catch one fly, I think that is the signal that you need to start protecting your fruit if it has lost that green color." Trapping in nonhost plants is a good strategy, Haviland agreed. "We've had growers make the mistake of thinking that they don't have any spotted wing drosophila because they don't see them in their traps in the orchard. By the time they do find something in a trap, they've already got damage. That's because they didn't understand what was coming their way." Growers everywhere can learn from that lesson, he added. "Every orchard is going to be different, and each pest-con- trol advisor needs to think where flies might be coming from. If they trap those areas, that will give them a better indica- tion of the threat that spotted wing dro- sophila poses to their cherries than if they only trap in their orchards." • For over 40 years, growers have been enjoying the fruits of our labor. At ProTree Nursery, experience has taught us to select the best varieties, graft only the highest quality rootstocks and grow hearty trees. As one of the leading suppliers of apple and cherry varieties to orchard growers, our customers have come to depend on our trees and our service. You can too, call us today. 10500 Brentwood Blvd., Brentwood, CA 94513 800.634.1671 or 925.634.2191 (Alison Clegg or Richard Chavez) 877.457.6901 (Henry Sanguinetti) M E M B E R O F w w w . p r o t r e e n u r s e r y. c o m Apples Aztec Fuji ® (DT-2 cv) Banning Red Fuji (USPP 16,624 P2) Buckeye ® Gala (USPP 10,840) Cosmic Crisp™ (USPP 24,210) Firestorm™ Honeycrisp Honeycrisp™ (USPP 7197) Lady in Red * (USPP 18,787) Royal Red Honeycrisp ® (USPP 22,244) September Wonder™ Fuji (USPP 11,193) Ultima™ Gala (USPP 13,753 P2) Available on B10 ® , B-118, EMLA, Geneva ® , M-9 T337, NIC -29™, or Pajam #2. ** * Trademark license for Pink Lady ® brand available upon request. Cherries Benton™ Bing Black Tart BlackPearl ® Brooks™ BurgundyPearl ® Chelan™ Coral Champagne Cristalina™ EbonyPearl ® Available on Colt, Gisela ® , Krymsk ® , Mahaleb, or Mazzard. * * ** Not all varieties are available on all rootstocks. Call for specific grafting information. Lapins RadiancePearl ® Rainier Selah™ Skeena™ Sweetheart™ Tamora Tulare™ Vans NEW! NEW!

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