Issue link: http://read.dmtmag.com/i/366055
14 SEPTEMBER 2014 GOOD FRUIT GROWER www.goodfruit.com 509-662-1888 Wenatchee, WA 98801 509-452-7707 Union Gap, WA 98903 800-545-4206 www.cascadeanalytical.com ÝÛKj]]ÛJljm[lmj]Ûj]khgf\af_ Û lgÛghlaeYdÛgjÛklj]kk]\ Û [gf\alagfk ÝÛEmlja]flÛmhlYc]Ûj]dYlan]ÛlgÛ Û `]Ydl`q£\YeY_]\Û[YeZame ÝÛI]dYlagfk`ahÛlgÛ Û [YjZg`q\jYl]Ûkmhhdq Leaf Analysis shows ÝÛ=jmalÛeaf]jYdÛ Û Y[[memdYlagfÛd]n]dk ÝÛGgl]flaYdÛ^gjÛklgjY_] Û \akgj\]jk ÝÛ;YlYÛ^gjÛghlaemeÛklgjY_] Û k]_j]_Ylagf Fruit Analysis shows Now's The Time To Sample! Now's The Time To Sample! the specific pathogen and age of the vineyard, there can be slow or rapid decline of vines. Symptoms In mature vineyards, symptoms of trunk diseases include overall stunting of shoots, and in subsequent seasons, death or dieback of shoots, spurs, arms, and cordons. In young vines, symptoms include poor growth or poor vigor, chlorosis of leaves, and black streaking of tissue observed when vines are cut (primarily at the base of the rootstock). Eventually, the vine dies due to canker formation in the vascular tissue. Trunk diseases can be latent in grapevines for several years, often not showing up until the vineyard is seven to ten years old. Growers often follow paint or spray pruning wounds with fungicides, but such practices are usually started when symptoms are noticed, by which time the disease has already gained a foothold in the vineyard. Fungal spores can travel by winds and enter vineyards from nearby tree fruit and nut orchards infected with disease. Researchers in California and Australia found Eutypa ascospores were blown by wind, traveling up to 100 miles away from the source. Lack of spring growth from spur positions is the most prevalent symptom of Botryosphaeria dieback. PACIFIC AGRICULTURE RESEARCH CENTRE PHOTOS T he lack of effective chemicals to control grapevine trunk diseases makes preventive measures all the more important. Prevention can keep infection from entering pruning wounds, but once wood can- kers are in your vines, there's no eradicant to eliminate them. Preventive techniques espoused by University of California researchers include delayed pruning, double pruning (combining mechanical pruning with later hand pruning), and painting or spraying fungicide protectants on pruning wounds. Late pruning—delaying pruning as long as you can—is an effective strategy under California weather conditions because less rain is usually received after the late pruning work, said Dr. José Ramón Úrbez- Torres of Canada's Pacific Agri-Food Research Centre in Summerland, British Columbia. The concept behind delayed pruning is to shorten the vine's healing time and, in some locations, to avoid pruning during the rainy season. In California, the rainy season is typically January through March. Research has shown that spore release is associated with rain. Many California grape growers are practicing double pruning by mechanically pruning canes in late fall to early winter, leaving 10 to 15 buds. Final pruning cuts are made in late February to early March, leaving two buds. Double pruning works for vertical-shoot- positioned vines (cordon-trained, spur-pruned vines). He recommends small growers use delayed pruning, while larger growers follow the double pruning method. Pruning wounds made in December take much longer to heal than those made in early spring, Úrbez- Torres said. "The difference is weeks versus days. Big pruning cuts also take a long time to heal." But delayed or late pruning is not an effective technique in grape-growing regions where it rains in the spring. In British Columbia, most of the rain comes in May and June, so there would be a high risk of infection if delayed pruning were practiced. Some growers follow pruning with lime sulfur sprays. Other options are to use the fungicides Topsin M (thiophanate-methyl) and Rally (myclobutanil) as a dormant spray after pruning cuts are made—a practice that recently became available with dormant spray registration in California. In the past, Topsin was applied as a thick paste but the labor- intensive practice became cost prohibitive for most. Painting with latex has also been done, but again is expensive to implement. Lessons learned Dr. Kendra Baumgartner, researcher for the U.S. Department of Agriculture, said that California's grape industry learned several lessons from the late 1990s when young vine decline and other fungal pathogens caused major problems in the state's wine grape regions. She recommends grape growers adopt the following preventive management strategies: 1. Use certified plant material. This will help minimize introduction of the graft-transmissible agents in your vineyard. 2. Practice good soil sanitation when replanting. Fumigate the soil before replanting to eliminate nematodes and other soilborne pathogens. 3. Inspect nursery stock shipments. Use your eyes and hands to look over nursery material before planting. 4. Use preventive practices on a routine basis. The disease can be present for years without signs of visible symptoms. Assume that trunk diseases will eventually show up. —M. Hansen MANAGING trunk diseases Avoid the Orchard of No Return with Soil Fumigation orchardfumigation@tridentag.com Telone® II, Telone C-17, and Telone C-35 are registered trademarks of Dow AgroSciences LLC. Telone II, Telone C-17, Telone C-35, and Pic-Clor 60 are restricted-use pesticides. • Row and broadcast applications available • Specializing in tree fruit, hops, grape, berry, and nursery crops Soil Fumigation Specialists Serving the Northwest for 30 years Replant disease can take the profit out of any orchard. Soil fumigation services offered by Trident manage replant disease and other soil-borne pathogens. Trident offers custom applications of Telone® C17, Telone C35, and Pic-Clor 60. WASHINGTON NORTHWEST: Tim Purcell ........Mobile 360-630-4285 YAKIMA VALLEY: Robert Rauert ..Mobile 509-728-2004 COLUMBIA BASIN: Jason Rainer .....Mobile 509-731-5424 CENTRAL: Sage Shelton ....Mobile 509-314-1970 OREGON THE DALLES, HOOD RIVER: David Sbur.........Mobile 971-563-8848