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Curse of the Verticillium Wilt? Maples, and more. #861291

Asked March 13, 2024, 1:23 AM EDT

Hi OSU Extension Service, I'm a resident in N Portland who has planted everything in my garden (mostly focusing on natives) in the past 4 years. I've noticed stressed plants in this time, I thought maybe the harsh weather, but after this winter finding my three young vine maple trees dead/dying, and researching now I think it might be a certain fungus that's the cause. I also recall some selective branch die-off of my Red Elderberry at one point. I have several other plants listed as hosts: Red-flowering currant, golden currant, western redbud, a plum tree, a japanese maple (to name a few) that I haven't noticed dying off (yet). I have/had plans on planting several other plants also listed as hosts (sunflowers, salvia, clarkia, liatris, tomatoes, strawberry, melon, etc) - all that I have planted in prior years with mixed results. So I'm wondering: 1. Does this stand out as classic Verticillium Wilt? Could it be anything else? I've read other fungus (fusarium wilt) can show similar signs, but is that the case in our area? Is it worth mailing in plant samples to the lab (from several suspected plants?)? 2. Most sources state this is fatal and to replace plants with resistant varieties (I was really trying to avoid cultivars). And also this: The fungus is known to have at least two races that overcome single resistance genes, so planting a “resistant” variety is effective only if the race and the genetics of the resistant hybrid are known." Should I replace the vine maple, and wait to see evidence of die-off with other plants? And now avoid *all* listed host plants? Including taking out/avoiding crops like tomatoes/strawberries? Some annuals like clarkia have re-seeded and are already growing. And I have tomato/sunflower seedlings started in the garage. 3. If this is in the soil and will be for several years and it is likely to keep infecting/re-infecting host plants is it worth trying to manage/avoid? 4. I've kept a lot of the brush, leaves, compost from several of these plants (including sunflower stalks with compressed pith that looks similar to the kind in this article: https://www.sunflowernsa.com/growers/Diseases/Verticillium-Wilt/) for insects/critter habitat and I could see how this could enable the fungus to move around more easily to healthy plants. Does this all need to be discarded as well? 5. I am a fan of the ChipDrop service in the area and have received multiple drops, is this something that could be transferred from arborists trucks from cut/diseased trees? Is the only/best way to avoid this to purchase from a landscaping company? I would love your expertise on how to navigate this one! Thank you!

Multnomah County Oregon

Expert Response

Your question is a “big” one for this online forum, so I’ll offer a couple of resources and then share your question with our Extension Service professionals.
What risk do wood chips carry? Check out this WSU paper about research on pathogens in wood chips. This, from the PNW Handbook, gives fairly detailed information about Verticillium Wilt, and clear photos.
I hope you’ll hear from other Extension experts in a week or less.
I would not jump to Verticillium wilt just yet. True, maples are rather susceptible and many different plants can be infected. (See article referenced above.) But there are many different things that result in the symptoms you are finding. A diagnosis is a good place to start as you have indicated in question number 1. From there you can decide how to manage your garden. We do have a Plant Clinic that can help with diagnosis, see here: https://bpp.oregonstate.edu/plant-clinic

We could tongue in cheek think about what to do if you get a Verticillium diagnosis. If so, it has been there for some time and you would find the propagules of this fungus all over the place. I would not go on a re-planting binge all over the garden. Work with your plants and replace when it seems they are on the way out. Good attention to horticultural practices such as watering in the summer (not too much and not too little) can keep trees going for some time. Maybe try some of the vert wilt resistant plants that are annuals and see how they perform in your garden.
Being all over already, you might as well keep composting on site especially if you are finding it helpful in the garden. You might stop the ChipDrop service or use it only in certain areas of the garden.
Bottom line - lets get a good diagnosis first before slashing and burning the garden or doing a major makeover. Unless of course you really want to do something like that. 
Jay W. Pscheidt, PhD, Professor Replied March 15, 2024, 8:33 AM EDT
Hi Jay,

Thank you for your response! I agree the best path forward is to get a good diagnosis. In case it's helpful, I'm attaching additional photos of the sambucus and sunflower. I will work on getting samples packaged and shipped out to the lab for testing.

Thanks for the solid advice! 

My garden and I appreciate your help,
Audrey


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On Fri, Mar 15, 2024 at 5:33 AM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied March 15, 2024, 11:22 AM EDT
Dieback of the vine maple like this can be due to a lot of things including cold damage. I would do as you have already done and cut below the discolored tissue into healthy parts about 2 or 3 nodes down. Time will tell if you have Vert or not.

Not sure what you are seeing in the sunflower stalk. A fungal disease called Sclerotinia is common but I do not see signs of that fungus in your image.

Unless the elderberry is having dieback issues or if you are seeing insect tunneling in those stems, I would not worry too much about this hollow pith. Several plants can have what looks like a hollow pith.
Just for laughs I asked one of those artificial intelligence programs "What woody perennials have a hollow pith?" and got the following: ".....examples include: Elderberry (Sambucus spp.): Elderberry plants typically have a soft, spongy pith in their stems that may appear hollow when the stem is cut open; Raspberry (Rubus spp.):Blackberry (Rubus spp.): Bamboo (Bambusoideae spp.): Pokeberry (Phytolacca americana): Japanese Knotweed (Fallopia japonica): and Angelica (Angelica spp.). 


Jay W. Pscheidt, PhD, Professor Replied March 15, 2024, 11:39 AM EDT
Indeed, time will tell. The plants have endured many weather extremes in their short lives. I have two western redbuds, I noticed yellowing leaves and dead/dying tips last fall, I'll see how they do this year, and the Japanese Maple, another commonly affected species. 

This was the site that led me to think it might be verticillium wilt: https://pnwhandbooks.org/plantdisease/pathogen-articles/common/fungi/verticillium-wilt-pacific-northwest

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And I agree, I didn't include the best photo example of the sunflower, to me I've seen instances in the sunflower stalks that look similar to the "compressed blackened pith" example from this site: https://www.sunflowernsa.com/growers/Diseases/Verticillium-Wilt/

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And there were small white larvae (?) under the bark of the Red Elderberry but I didn't see them in the pith. Here's a photo of where the largest dying portion meets the soil.

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You bring up a good point that I hadn't considered, since the Vine Maple(s) had the worst effects simultaneously I assumed the problem was related, but this could be the work of several fungus sp. Or a myriad of other reasons, because as I'm learning even with native plants there's at least 10 things that want to kill them. Should be an interesting year!

Thanks for the feedback,
Audrey



On Fri, Mar 15, 2024 at 8:39 AM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied March 18, 2024, 8:06 AM EDT

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