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tant to armillaria, at least under labora- tory conditions. “From my findings, there were two rootstocks that showed greater resis- tance that were already available to growers,” Tweedy said. “OHxF 87 and OHxF 97 are the two commercial root- stocks that had great resistance to armil- laria and also fire blight.” There is adifference, however, between rating the development of the disease
over six weeks in a laboratory and seeing how those rootstocks would hold up in infested soil over years or even decades. “My findings were only in the in vitro form, so I do not knowhow theywill hold up in the field setting,” Tweedy said. The process of breeding new root- stocks is painstaking, and it takes years to produce reliably resistant rootstocks. The in vitro lab test should give re- searchers clues as to the genetic mate-
rial that could be used to add armillaria resistance to rootstocks that already have other valued characteristics. But it takes years of field trialsunder dif- ferent conditions to confirm that OHxF 87 andOHxF 97, or other rootstocks, have genetic resistance to the disease that will holdupover the long lifeof apearorchard. ( Bo b J o hn s o n i s a r e p o r t e r i n Sacramento. He may be contacted at bjohn11135@gmail.com.)
UC Cooperat ive Extens ion Lake County farm advisor Rachel Elkins has conducted pear rootstock field trials of armillaria resistance but has yet to find the silver bullet. It can take years to eval- uate rootstock resistance to armillaria in greenhouse trials with plants grown in soil. And the results may not always be consistent and reliable. But Tweedy developed an in vitro screen to identify pear armillaria resis- tance in six weeks, adapting a technique used first for grape rootstocks and later for walnuts andalmonds byU.S. Department of Agriculture plant pathologist Kendra Baumgartner, who runs a research pro- gramon sustainable viticulture. The plants aremicro-propagated, root- ed in vitro and inoculated with the dis- ease pathogen on a tissue culture rather than in soil. Using this technique, Tweedywas able to distinguish two pear rootstocks that are already in production as more resis- DWR plans aerial surveys to watch aquifer status Cal i fornia Depar tment of Water Resources announced that it is using he- licopter-based technology to gather infor- mationabout thestate’sgroundwateraqui- fer structure to support drought response andthe implementationof theSustainable GroundwaterManagementAct, or SGMA. “The data collected during these sur- veys will provide a better understanding of California’s groundwater systems, and in turn support more informed and sus- tainable groundwater management and drought preparedness and response ap- proaches,” saidStevenSpringhorn,DWR’s SGMA technical assistancemanager. Beginning this month, DWR will use airborne electromagnetic technology to survey groundwater basins in the Salinas Valley, Paso Robles and Cuyama Valley. During the surveys, a low-flyinghelicopter towsalargehoopwithscientificequipment approximately 100 feet above the ground surface. The helicopter, flown by experi- encedandlicensedpilots,willmakeseveral passes over the survey areas and may be visible to residents. Surveys will be conducted during the next several years in high- and medi- um-priority groundwater basins around the state, where data collection is feasi- ble, DWR reported. The agency explained that survey data creates an image of the subsurface down to a depth of about 1,000 feet be- lowground and provides information about large-scale aquifer structures and geology. DWR added that this informa- tion will support implementation of local groundwater sustainability plans, which help local agencies sustainably manage groundwater. For more information, visit https:// water.ca.gov/programs/SGMA/AEM.
2021 California Farm Bureau
PHOTO CONTEST
2020 Grand Prize winner
$2,500 in prizes!
Any amateur photographer who is a member of a county Farm Bureau in California can participate. Not a member? Join today at cfbf.com/join. AGRICULTURE THROUGH YOUR LENS What does California’s agricultural bounty mean to you? Show us with photos such as: Fresh food—plated or in the field Rural scenery Animals, crops and harvests Life, work and family on the farm or ranch
PRIZES All ages $1,000 Grand Prize $500 First Place $250 Second Place $100 Third Place $50 Honorable Mention (six winners) Budding Artists (ages 13 and younger) $250 First Place $100 Second Place
It’s easy to enter: Submit up to five print or high-resolution digital photos. Enter online or postmark by Sept. 30. Go to cfbf.com/photocontest to find rules and forms, enter or see past winners. Or email photocontest@cfbf.com for rules and entry forms.
August 11, 2021 Ag Alert 13
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