Issue link: https://read.dmtmag.com/i/635697
www.goodfruit.com Good Fruit Grower FEBRUARY 15, 2016 7 rootstocks do not need visual strikes of fire blight in the scion to acquire the disease below ground. In the research block, trees from the 2010 planting on M9.337 rootstock were most likely to have died — in some cases, without a visual strike in the scion. A few planted in 2015 on Budavosky 9 experienced strikes but did not die. There were a few strikes in trees on Geneva rootstocks planted in 2004 and 2006 that have not spread into the tree as a whole. "I don't want to say a Geneva tree will never die from fire blight, but unlike M.9, the percentage that you'll lose will likely be insignificant," he said. Many of the 2015 replacement trees on Geneva and the M.9 trees planted as comparisons for the Geneva rootstocks were stubbed back to 4 inches at planting, removing nearly all the bloom that would have created significant risk of blight infection. Auvil said researchers will be working with the orchard operator at the Wapato block closely, advising to pull dead trees, prune strikes and manage cankers in the orchard. He advised growers with fire blight issues to do the same. "If you have a relatively young, vigorous orchard with M.9 rootstock, you have to be very aggressive at getting the inoculum load down," he said. That means pulling out trees with dead rootstock, monitoring the block from green tip through bloom looking at every rootstock union to check for a fire blight that may be oozing vast quantities of inoculum out of the union. "As diligent as one can be to get it out of the field, it won't cure the problem. It takes two, almost three years of seeing no strikes before you can breathe a sigh of relief on blight management," he said. "It's a relatively intense period of time." Tim Smith, regional WSU Extension educator, also noted that growers should take care when diagnosing their trees with disorders other than fire blight, such as collar rot, that can present similar symptoms. "People diagnose tree death as collar rot, but M.9 is actually pretty resistant to collar rot," he said. "I believe 99 percent is actually fire blight." Smith and Auvil also said the Wapato orchard will pres- ent an opportunity to learn more about the disease over time. Aaron Clark, field manager for Price Cold Storage and Packing Co. in Yakima, said Price's orchards located near the field plot didn't experience significant fire blight last year, but it's been an issue in the past — par- ticularly in a couple of older Bartlett blocks. "You just don't have Bartletts without having some blight once in a while. That's like put- ting your boots on in the morning," he said. But he said the com- pany has been diligent to stay on top of the disease, given that they have some young plant- ings, including 3-year-old Gala blocks that were planted from a sleeping eye. That includes examining the orchards regularly, aggressively cutting out cankers and treating for blight with a prophylactic approach whether they think they have an infection or not. Treatment methods include copper, the antibiotics streptomycin or terramycin and other products that help to retire blight. "We just try to take a forward approach to covering, so that we're applying some kind of blight protection every week. Otherwise, you get a weather system in that gives you a blight exposure, and invariably the weather is cruddy for a couple of days and you don't get in there to do it," he said. "And you're too late." • "It takes two, almost three years of seeing no strikes before you can breathe a sigh of relief on blight management." —Tom Auvil TJ MULLINAX/GOOD FRUIT GROWER 1-800-250-5024 • www.CertisUSA.com Recommendations: Cueva, Kocide Integrated copper solutions for season- long fire blight and summer disease control Double Nickel Broad spectrum foliar powdery mildew and fire blight disease control OSO FRAC 19 fungicide for summer diseases and post-harvest protection CYD-X HP, Madex HP Codling moth and Oriental fruit moth control PFR-97 Broad spectrum insecticide and miticide Neemix Insect growth regulator for psyllid control Deliver Bt for leafroller larvae control Screen Duo For sunburn protection and heat stress reduction Diseases and Pests: Fire blight Codling moth, Oriental fruit moth Powdery mildew Psyllids, aphids, mites, leafrollers Summer diseases and post-harvest rots Biopesticides. Short REIs and zero days to harvest. Resistance and residue management. Application flexibility. Better harvest management and timely shipping. Screen Duo is a registered trademark of Crop Microclimate Management Inc. Cueva is a registered trademark W. Neudorff GmbH KG. Kocide is a registered trademark of Kocide LLC. All others are registered trademarks of Certis USA LLC. ©2016 Certis USA De PFR CX Ma Nx DN O Cu K2 K3 SD