Eastern Filbert Blight resistant trees to Lasqueti
As many are aware, we have been preparing a group order of blight-resistant varieties of filbert trees. These have been developed in Oregon, at Oregon State University, where they have had to deal with Eastern Filbert Blight (EFB) since the 1980s.
EFB is a disease caused by the fungus Anisogramma anomala. Spores are spread by wind and by rain. (Raindrops can be drawn up into the sky by updrafts that can travel hundreds of miles before they eventually fall to the ground.) Airborne spores can easily travel 30 or 40 miles. They also travel on other things, including people and plants.
I would like everyone to be aware of this disease, because filberts are so important to many of us, and we must take every precaution to avoid importing EFB to Lasqueti and infecting our many standard filbert trees. It is particularly important not to import Corylus avellana plants, especially EFB susceptible varieties, to Lasqueti. We should also be aware that it can travel here on other plants, on soil and other things, animals (including people) as well as by rain and the wind. EFB will likely arrive on Lasqueti some day, but we should be prepared for it, and careful to delay it as long as possible There are ways of reducing the risk to ordinary filbert trees. See the web site resources at the end of this posting
ESB infection is spread by spores landing on new growth in the spring, which can enter filbert trees and live there without showing any sign for 18 months or more. Then cankers form, usually with two rows of stromata, black circular bodies which produce more spores to spread the disease around further. The spores wait for new growth in the spring, and can infect susceptible plants,
The EFB strain that is present in the west is apparently only one (or a very few) of the strains of EFB that exist in the East. Importing filbert or hazelnut trees into BC has been prohibited, to try to stop EFB from spreading here, but it arrived in BC by 2002. It is now widespread in the Fraser Valley, and spreading further.
We want to be sure we are not importing EFB to Lasqueti, and have considered the issue carefully before proceeding with the order.
Oregon filbert growers have managed to keep their orchards productive by active management: scouting, removing and replacing the most susceptible varieties, using fungicidal sprays (including lime sulfur and copper (Bordeaux mix) which is acceptable in some organic orchards), pruning to remove and destroy infected wood, planting resistant cultivars, and destroying escaped seedlings and plants.
It seems like most Fraser Valley filbert growers have not managed to keep on top of EFB, and many have lost their entire orchards to the disease. There are virtually no uninfected orchards in the Fraser Valley, and infected trees produce cankers and spores, and less and less pollen and nuts, until they die.
Uninfected trees can be protected from infection by spraying fungicide every ten days to two weeks in the spring. Combined with vigilant inspection and aggressive pruning, orchardists and homeowners can prevent spore formation (and spread of the disease) and keep trees alive and producing.
Oregon State University has bred a number of EFB resistant varieties. These resistant varieties are now being grown, from tissue culture, by Nature Tech Nursery in Langley, and are offered for sale.
In researching the risk of importing EFB to Lasqueti with the trees, we contacted Thom O'Dell of Nature Tech Nursery, Neil Williams of Wilberry Orchards in the Cowichan Valley, and Peter Andres of Agassiz, former president of the BC Hazelnut Growers Association. Below are emails from Thom and Peter, and a brief report of a telephone conversation that Peter had with Neil.
Thom:
"It is possible that you could introduce the disease by importing infected trees. Trees can be infected for over a year (up to at least two years; http://oregonstate.edu/dept/botany/epp/EFB/lifecycle/lifecycle2.htm) without showing symptoms. This is true for any Corylus avellana and especially the highly susceptible varieties like the ornamental, Harry Lauder’s Walkingstick and seedlings which are still being grown and sold. It may also be true for plants sold as the native Corylus cornuta (Beaked Hazelnut).
"Let me explain our risk reduction strategy and the experience from orchards planted in 2011 and 2013.
“First I should mention that our nursery is about 2.5 km from an infected hazelnut orchard. We remove all 'volunteer' hazelnut plants on our property (virtually all become infected if left to grow). I apply copper sulfate-lime ('bordeaux' mix), copper oxychloride or other approved fungicide three times in spring from bud break at about ten day intervals. Bordeaux is typically allowed in organic production.
Before I began this program I saw EFB on one plant each of 'Red Lambert and 'Lewis' (affected branches were pruned and destroyed); we have never seen symptoms on any other cultivar in our nursery.
"In summer and fall 2011 trees of Jefferson, Eta and Theta were planted at 6 sites in the Fraser Valley and Hornby Island as a trial of new varieties in BC (see http://www.naturetechnursery.com/library-articles-and-other-info/ for a series of reports on the project), and funded by the BC Hazelnut.Growers Association and Investment Agriculture Fund (IAF). These sites were subsequently planted with Gamma, Sacajawea and Yamhill in 2013. By winter 2015-6 a couple trees of Jefferson had a branch or two with cankers at two sites and over half of the Sacajawea show extensive infection in all of the Fraser Valley sites (all are adjacent to severely infected orchards). The Hornby Island site (without an infected orchard nearby) has shown no EFB symptoms to date on any variety. The other difference between the Fraser Orchards and the Hornby one: regular fungicide application in spring at te Hornby site. All of these plants came from our nursery; so either the trees became infected after planting, or if we shipped infected plants then the disease was arrested with fungicide. We’ve heard from Oregon (where there are thousands of acres of hazelnuts and countless diseased older trees of susceptible varieties and seedlings) that new varieties can become infected at a lower rate and with less severe symptoms, but with management can overcome the disease. The recommendation there is to spray fungicide in spring on all new plantings for at least the first few years, longer for Sacajawea and Lewis which carry less genetic resistance than Jefferson, Yamhill, Eta, Theta and Gamma.
"I am not one to reach for a spray to solve every problem and someday we plan to have an organically managed hazelnut orchard. For now in our nursery (to reduce potential for shipping infected plants) we have to use fungicides, and in young plantings (particularly in areas with high disease pressure), I strongly recommend preventative use of active copper. Our understanding is that there are limited organic options available, but it may be challenging or impossible to alternate product use to reduce the chance for resistance developing; check with your certifying body about this. One way to reduce risk is to only plant the most resistant varieties and therefore not Sacajawea or Lewis. Since EFB spores are microscopic it is very likely that the disease will eventually reach you on Lasqueti – they typically travel by wind, but it may also be possible for them to arrive by opportunistic means like adhering to clothing or other plants. All trees old and new should be monitored for symptoms of EFB, which are not easily noticed on larger trees until you see branch die-back and the infection is advanced. If this is discovered, you can prevent spread by culling those trees, or, at least for the new varieties, the current thinking seems to be that timely and judicious pruning and burning (or burying) of the prunings can be an appropriate and effective control."
Conversation with Neil, who has 20+ acres with something like 6,000 ordinary filbert trees:
Neil told me that possibly 1 or 2 % of genetically EFB resistant trees might have EFB, and that up to 20% of Sacajawea (which is not genetically resistant, or at least not in the same way) might have EFB. I was already aware that Sacajawea was probably a good variety not to bring to Lasqueti, because it scores a 2 in resistance (scale 0 to 6, where 0 is most resistant and 6 is most susceptible). Yamhill, Jefferson and the three pollinators Eta, Theta & Gamma are all 0.
Neil more relevantly told me that the real reason they decide not to bring in the 200 to 300 resistant filbert varieties that they had ordered was that there was a clay patch in the centre of their planting where standard varieties of filbert trees had died, and if they replanted with resistant trees (or, presumably, any trees) they would require weekly watering by tractor-pulled tank for at least several years, and this was too much for an area that should grow grass, not trees. They sold the trees they had ordered to Charlotte Spencer of Hornby Island.
Neil also told me he didn't want to spray fungicide, even if it is acceptable in organic production, and doesn't.
I think that organic standards say you can use lime sulfur and copper to treat disease, but not ongoing on a preventative basis. I will try to check on this. Sue and I, and many others, don't want to spray, either.
Peter Andres:
"We have been very experienced by now in the new EFB resistant trees. I started the replant program in 2010 when Oregon released these varieties. We were fortunate that Nature Tech partnered with us in doing the leaf tissue work and growing the trial trees in several orchards in the Fraser Valley and then one orchard on Hornby. We wanted a Gulf Islands test site because we knew the interest would be there. Charlotte Spencer on Hornby is very knowledgeable by now in this as well.
"From my experience and seeing her orchard in Hornby, there has been absolutely NO evidence of EFB coming there in plants or pots on any of the 3 main varieties or their pollinators. I specifically looked for this evidence on the variety called Sacajewea which is prone to getting EFB when there is lots of spores around. We initially thought that maybe some of these trees could spread EFB, but, absolutely NONE of these trees in Hornby had any diseased twigs. Here in this valley about 25 percent of Sacajewea had some twigs diseased with maybe less than 3 percent being severely diseased.
"So, as to planting in Lasqueti, you should have no issues on it."
We should consider the option of keeping these new-to-Lasqueti trees isolated for at least a year, planted into the earth in their pots, so that we can monitor them for EFB, and possibly spray them with fungicides, as is recommended for the first two years. Someone would have to volunteer to keep and care for them.
https://catalog.extension.oregonstate.edu/topic/agriculture/hazelnut-pro...
catelogue of 22 OSU publications on hazelnut-production
https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pd...
Detecting and Controlling Eastern Filbert Blight 4p
https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pd...
Growing Hazelnuts in the Pacific Northwest – Hazelnut Varieties 7p This publication has tables and charts for both resistant and susceptible varieties, comparing nut and tree characteristics, relative susceptibiltiy or resistance to EFB, and compatibility of pollenizers
http://oregonstate.edu/dept/botany/epp/EFB/index.htm
http://oregonstate.edu/dept/botany/epp/EFB/risk.htm
http://oregonstate.edu/dept/botany/epp/EFB/lifecycle.htm
http://oregonstate.edu/dept/botany/epp/EFB/management/wheretofocus.htm
four of the EFB Help Pages from OSU
http://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/...
general information from BC Ministry of Agriculture 3p
BC Hazelnut Growers Association web site
http://www.naturetechnursery.com/
Nature Tech Nursery web site
