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We still have no idea what is causing AYLS! Lab tests thus far have all been negative for the presence of Bacterial, Fungal, and 11 Viral Pathogens. Tests of leaves showed no probable Plant Nutrient Deficiencies or Toxicity causes.
AYLS symptoms were first visible at my place in Seattle this year on a potted seedling arguta on June 16, 2018. As noted last year, there appears to be a correlation between about 1,500 Degree Days (using the uspest.org model for my Neighborhood) and the annual emergence of AYLS. We reached 1,525 Degree Days on June 18. Thus far symptoms are visible on potted arguta, hypoleuca, kolomikta, macrosperma, melanandra, polygama, tetramera, arguta x deliciosa, & melanandra x arguta plants as well as in-ground argutas & argutas grafted to in-ground deliciosa vines.
Those of you living in North America can use the Map function at the following link to locate the weather station nearest your location, then run the calculations to see when you reached 1,500 Degree Days: http://uspest.org/cgi-bin/ddmodel.us?sta=C6259&mdt=all&spp=aaa&cal=A&stm=1&std=1&styr=18&enm=12&end=31&cel=0&fcast=1&spyr=0&shd=1&mkt=0&mkg=1&ipc=1&evnts=3
Why AYLS is PRESENT in nearly all Western Washington locations that have Reported, but ABSENT in all Oregon locations that have Reported is of particular interest to me. I hope to visit Corvallis Oregon this growing season to see the U.S. germplasm collection of smooth skinned Actinidia species to see if they have any answers.
The extent of AYLS Distribution Worldwide is only documented for a few locations in the Northern Hemisphere, with only one report in 2014 from the Southern Hemisphere. If you are growing Actinidia species, particularly the hairless fruiting species (such as arguta, kolomikta, melanandra, & polygama), please take the time to file a report after your location has reached 1,700 Degree Days using the form on either the Home page or the Map of AYLS locations Worldwide page. The Report form has fields for both AYLS is PRESENT and AYLS is ABSENT at your location. Knowing where AYLS is ABSENT is just as important as knowing where it is PRESENT! If AYLS is PRESENT on your vines and you know the date symptoms first appeared, please report that date in the comments field.
Seattle, WA. USA