Issue link: http://read.dmtmag.com/i/61297
Soils & Nutrients FANTASTIC! WONDERFUL! AWESOME! VALUABLE! SUPER! Flowering weeds and legumes (left) attract bees and are hosts for damaging nematodes. Clean tillage (right) suppresses insect pests, but repeated tillage damages soil structure. Avoid weedy orchard floors A Weeds harbor fruit-feeding pests. by Richard Lehnert decade and more ago, it was thought that plant diversity in fruit orchards was a good thing, that clover and broadleaf weeds provide shelter and alternative food sources for beneficial insects and mites that feed on or parasitize insect and mite pests. But now, the thinking is, plant diversity is more beneficial to diseases and pests than it is to the beneficials that prey on them. Dr. Peter Shearer, an entomologist at Oregon State University's Mid-Columbia Agri- cultural Research and Extension Center in Hood River, Oregon, participated in much of the research after he began work at Rutgers University in New Jersey in 1996. He still uses that decade's worth of data and those conclusions in making recommendations to growers. "I was once a proponent of plant diversity," he said. "We know we can get reduced pest pressure by controlling weeds." —Peter Shearer "But it seems pests prefer these alternate hosts more than the beneficials do. "Our research at Rutgers and on growers' farms demonstrated the importance of removing broadleaf weeds to minimize damage from several key pests," he said. "Managed-sod drive rows and weed-free tree rows reduce catfacing insect abundance and damage in peaches." "Clean" orchards—whether clean tilled or with grass sod alleys—reduced damage by 60 percent, he said, and similar research in Oregon and Canada showed reduced damage in pears and apples as well. In peaches, at least eight arthropod pests are associ- ated with orchard ground cover, he said. These include tarnished plant, stinkbugs, green peach aphids, tufted apple budmoth, two-spotted spider mites, false chinch bugs, leafhoppers, and thrips. Tarnished plant bugs cause the most damage to New Jersey peaches, where they are season-long pests from prebloom to harvest. They, and stinkbugs, cause catfacing from feeding on the fruit. "We know we can get reduced pest pressure by controlling weeds," he said. In his studies, he found that keeping orchards totally free of vegetation—by use of herbicides or tillage—effectively reduced the level of tarnished plant bug to just above zero, even when no insecticides were used to control it. With no insecticides, orchards kept vegetation-free using herbicides had 3 percent damage from tarnished plant bugs. Grassed alleys containing fescues or Kentucky blue- grass did shelter more tarnished plant bugs, but less than half the number that were found in orchards with white clover or weeds, where damage levels in the study were about 10 percent. Weed-free sod ground cover also delayed the onset of tarnished plant bugs in the orchard by a month, he said, reducing the number of sprays growers needed to apply. Damage by thrips and Japanese beetle was also lower in clean-tilled orchards or those with sod alleys. Grasses are not good hosts for pests, but they need to be mowed to suppress flowering and the formation of seed heads, he said. Shearer also reminds growers that peaches have extrafloral nectar glands at the base of leaves, providing beneficial insects with an in-orchard food source even when there are no flowers. • www.goodfruit.com …those are just a few of the words we use to describe our customers. We love what we do, and you make it possible! A special THANK YOU to all of our loyal customers who come back to us year after year. ProTree Nurseries is dedicated to providing the best selection of apple and cherry trees, grafted on the heartiest rootstocks. If you're looking for a variety you can't find anywhere else, call ProTree Nurseries today. APPLES Banning Red Fuji (USPP 16,624 P2) Beni Shogun (USPP 7997) Brookfield® Buckeye® Blondee™ (USPP 19,007 McLaughlin cv) (USPP 10,016) (USPP 10,840) ® (USPP 21,300) Honeycrisp™ (USPP 7197) Gala Gala Crimson Gold Crab Dandee Red® (USPP 16,620) Frettingham Crab Golden Delicious CHERRIES ™ ® ™ ™ ® ™ ® ® ™ ™ ™ ™ Available on Colt, Gisela®, Krymsk®, Mahaleb, or Mazzard.* *Not all varieties are available on all rootstocks. Call for specific grafting information. Granny Smith Hilwell Braeburn (USPP 7526) Indian Summer Crab Joburn™ Braeburn (USPP 11,992) JonaStar JonaGold™ (USPP 20,590) LindaMac® (USPP 12,900) Pacific Gala® (USPP 9681) Manchurian Crab Midnight Red Spur™ (serial 74/458,730) Pearleaf Crab These apple varieties are available on B-10, B-118, EMLA-7, EMLA-26, EMLA-106, EMLA-111, G-11, G-16, G-30, M-9 337T, NIC®-29, or Supporter 4. Rising Sun Fuji® RubyJon® (USPP 10,115) RubyMac® Schlect Spur Delicious™ September Wonder™ Fuji (USPP 11,193) (USPP applied for) Simpson Crab Snowdrift Crab Torres Fuji™ (USPP applied for) Ultima™ Gala (USPP 13,753 P2) Zestar!™ (USPP 11,367) 741 Sunset Road, Brentwood, CA 94513 800.634.1671 (Alison Clegg or Richard Chavez) 877.457.6901 (Henry Sanguinetti) Fax 925.634.6040 www.protreenursery.com GOOD FRUIT GROWER APRIL 15, 2012 29 photos by bradley Majek