I have Copper Sulfate to add to the soil in the area that is infected...will that help? Is there any other fungicide that will help minimize damage to plants.

No, no. The spores will simply commute on the fog from the neighbor's yard.

Dan

Copper sulfate won't help. If you want something you can soil drench with, you need a product with one of the active ingredients mefanoxam, fosetyl aluminum, or a phosphorous acid derivative.

Another way to go is to apply gypsum and a 4 to 6 inch coarse organic mulch at the time of plant establishment, which has been shown in California avocado orchards to be about as successful as the above materials at suppressing phytophthora root rot. The mulch encourages beneficial organisms that are antagonistic to phytophthora and the gypsum provides calcium, which suppresses phytophthora spore formation. Just be sure to keep mulch at least 6 inches away from the base of the tree. Mulch up against the bark holds water against the trunk and opens it up to collar rot.

In any case, none of the stuff mentioned above will work unless soil moisture is properly managed. The soil should be allowed to dry slightly between irrigations to avoid creating an environment that favors the pathogen. However, avoid moisture extremes. If you can get a handle on soil moisture, the above methods can be very effective and you can grow pretty much whatever you want, including eastern and western red bud, although resistant plants are a good idea and "stack the deck" in your favor. Of the two, Eastern is more resistant to the disease.

Thanks, I'll forget about the Copper. There isn't anything planted in the area currently. My plan was to till the soil while adding gypsum. Then we are mixing new dirt along with compost before planting. The previous owner had a dough-boy pool near the area that leaked; which could have caused the excess moisture. Would I need to add mulch on top of that. I have been advised to use only decomposed mulch material, but I am already adding that to the soil prior to planting...any thoughts???

First, I wouldn't mix soil in with the soil. What kind of compost and how much are we talking? How much gypsum? How deep were you planning on tilling it in? (or were you going to mix it into the backfill?

One of the beds attached to the infected area is becoming a raised bed in front of our house. First, I was going to till the existing soil with some gypsum thrown in so that I can break down the clay soil. Then, I have some soil that we had trucked in from a basement construction project and mix that with 50% organic compost. I can add gypsum to that mixture as well. That is what we are adding to our current soil in order to establish raised beds. Our soil is very hard at this time of year, so we are using a powered shovel to begin with and then tilling - not sure how deep we can go...

Tilling gypsum into the soil would be fine at a rate of about 2.5 lbs. per 100 sq. ft. That can go into areas where existing soil will make up the surface and also in areas where existing soil will make up sub soil after the import is in place. If you're amending soil for a raised planter on a per cubic yard basis, uniformly blending about 1.5 lbs. of gypsum per cubic yard would be a good rate. (Although I don't want you to get the idea that gypsum breaks up clay soil. It only has an effect on tilth and water infiltration when reclaiming sodic soils, but that's a whole different topic. We're using gypsum to help with phytophthora control here).

I would not till organic material into any native soil that will eventually be 12 inches below the final grade or greater. Nor would I place an import soil amended with organic below 12 inches. Organic matter placed more deeply than 12 inches tends to A) hold excess water and provide a favorable environment for phytophthora and other root rot pathogens and B) decompose anaerobically.

50% by volume is pretty hefty for a raised planter. Let's say you placed that 12 inches deep. It wouldn't take too long for that material to settle 4 or 5 inches in the planters and then you'd be stuck trying to figure out how to get the grade back up. I would go 30% O.M. by volume maximum and only in the top 12 inches of the backfill or planter. Then I would place mulch and gypsum on top of that. Top mulch doesn't have to be decomposed or even nitrogen stable.

In regards to import soil for the raised bed, I wouldn't mix to different soil types together due to the fact that mineral soils are exceeding difficult to uniformly blend in the field and the fact that doing so can often lead to a soil with wide particle size distribution, which would compact readily, making your hard soil situation worse. I would just put it on top of the native.

Hopefully they're a good textural match, but if the import soil that you're using is significantly coarser in texture than the native (and amended with organic to boot), water movement through that import material will be pretty fast and then slow considerably when it hits the heavy textured native soil. This could result in the formation of a perched water table that remains saturated over extended periods, resulting in....you guessed it....anaerobic soil conditions and an environment that favors root diseases. In such cases, installing supplemental drainage is the best bet. If the import is significantly heavier in texture than the native, there's a whole different set of things to look out for.

You don't need gypsum to break down clay in CA. That is merely a marketing campaign and not an evidence-based practice.

Second, I respect garg's knowledge. AIUI the OP had a tree die of SOD and wants to ensure no more plants are infected.

And the Phytopthora ramorum that is the issue here I used to be fairly well up on until I moved away from CA in 2003. I suggest that clearing soil will be only a temporary expedient. Perhaps reading some COMTF literature to understand the disease and its life cycle before any money is spent on prevention is advised before any more energy, effort, and money is expended (but spend no money on gypsum regardless).

AISUI where the OP lives SOD is a fact of life and only individual high-value trees can be saved by Herculean effort via risky injections. Prevention? Fuhgeddaboudit. Not how the pathogen works - it can travel on fog and through runoff. And on wet coats of deer. And rain splash. And firewood moving. And car tires. And dog paws.

Dan

I respect garg's knowledge

You take that back! ;P

If an oak was lost to Phytophthora in the soil (and admittedly, I'm taking OP's word for it) we're talking Phytophthora cinnamomi. Completely different animal (uh...so to speak) and soil borne rather than aerial. It hangs out in the same neighborhoods though. It's a beast on oaks in California but in a different way from ramorum. Different biology and different control strategies.

(I still think you're the cat's knees or the bees pajams or however that goes, Dan)

...of course, not to give the impression that P. ramorum is strictly aerial. It too is soil borne. But, P. cinnamomi, isn't aerial.

My impression from previous threads is that the vague answers meant SOD. Perhaps we should not rest until we get a definitive, detailed answer.

Paso: what kind of oak, and what kind of Phyt. and where generally in CA are you?

Dan

We live on the Central Coast, inland a bit in Paso Robles, CA. We lost an 80 year old Blue Oak. My pathology report only indicates Phytophthora and Pythium and also Rhizoctonia. My understanding is that Rhizoctonia, although not good, is less serious than the others. The Oak was removed and the stump ground out. I was upset because they didn't remove the debris from the grinding as it was too fine and just became part of the dirt.

So at this point, we have a very large bed, clear of any plants. There is a 10" pony wall around the entire area, so we need to add soil to achieve the raised beds. I'm hearing that it isn't a good idea to mix soils so should we just add lots of compost or buy topsoil in order to raise the beds...just need about 6 inches or so...

To my understanding, there haven't been any confirmed isolates of P. ramorum that far south or on that side of the hills. Not say it's impossible, but pretty doubtful.

Also, if they tree suffered from sudden oak death, they would be plating canker margins rather than roots. I'm going to stick with my P. cinnamomi guess and management strategies.

The fact that they didn't remove the debris is no big deal. Even if they tried, you can't remove every list bit or root and it only takes 1 spore for the whole thing to start again. Management of the disease at this point is all about living with the pathogen at this point.

As far as how to raise the grade of the bed by 6 inches, see my post above regarding concerns about high amounts of organic, percent by volume mixes, imports, etc.

Also worth mentioning: When re-planting, don't put anything under the drip line of the new tree that has a higher water requirement than the tree itself.

Also, you're right about the Rhizoctonia being a minor problem and in the case of mature woody plants, you can put Pythium in the same basket. However, soil moisture management will help to discourage all three of the pathogens discussed in this thread.

By the way. OP never said that the lab plated roots instead of canker margins but considering the complex of pathogens that were isolated, trust me, they were plating roots.

Yes, on the dry side SOD just starting in Solano Co with the oaks there, but AIUI no blue oak yet with SOD as their environment and climate regime likely too dry (blue oak ecosystem abutting steppe: too little water).

You can try garg's strategy but all it takes is one spore and the ubiquitous fungus will come back to that spot - one spore from a nursery pot, for example.

But the real issue: the blue oak likely went down because its water regime was changed - even compaction from years of shading up from cows will do it - so the presence of ubiquitous fungus means very little because it was probably human land development that killed the blue oak, not the fungus. The fungus took advantage of humans weakening the tree by changing the land around it. Sorry, but well-studied in CA.

Dan

Dan -- thank you for that.

Thank you for all your help, but now I'm confused on how to raise the bed by the 6 inches as you have not recommended mixing the two soils. We will put the gypsum in the current soil using the formula above, but should I purchase topsoil or what?

Right, I wouldn't mix two soils. It sounds like you have an import soil from another project ready to go. I would just place that on top of the native to raise the grade. I don't know how good of a match those two soils are in regards to texture so drainage may or may not be an issue. Prior to placement in the planter, I would mix that import soil with organic amendment at a rate of 80% soil to 20% organic by volume. If you wanted to be a little more aggressive with the organic material, you could go up to 30% but I personally wouldn't go any higher.

so drainage may or may not be an issue.

IME drainage should be expected to be an issue, esp when changing texture by adding OM. I used to do tree failure reports in CA and on the checklist is a box for "mound planting". That is: mounds were installed incorrectly (eg import not incorporated into native, a perched water table resulted, the roots rotted, the tree failed).

You'll want to raise grade to close to top of pony wall - leaving space for mulch - as settling will take you down at least ~an inch, with 20% OM likely more than two+ inches of settling, perhaps more with time.

Again, gypsum is not needed in CA. If you are going to spend the money, spend it on something useful, not something that will do nothing. I used to own a landscape design and construction business in Sacto, and a % of my business was correcting mistakes such as spec'ing gypsum, and sundry cleaning up the mess made by landscape "designers" and LArchs.

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You're welcome Jean, altho I don't know what for... ;o)

Dan

Dan,
You're killin' me buddy.

If you break up compaction at the starting grade and the chosen import placed on top is a similar texture, the drainage shouldn't be an issue, even with the organic. Think of it this way, if you dig a planting pit and re-fill with the native plus organic, you haven't changed the texture of the backfill soil and water movement should be fine.

No need to incorporate the import and by not doing so, you take out the chance of bringing about a layer with wide particle size distribution that could become a compaction layer at the bottom of the planting pit.

However, if the import is significantly different
in texture (either coarser or finer), that perched water table you're talking about may form (hence the caveat in my post up there that supplemental drainage may be necessary).

Again, gypsum is not needed in CA.

We're not using the gypsum to correct a soil chemistry issue. We're providing a very slow release source of soluble calcium to help with the control of Phytophthora, (which you correctly pointed out will always be there) due to its ability to inhibit spore formation.

And yes, if the environment favored the tree more than the pathogen, it wouldn't have ended up with Phytophthora. But it's there now and there are cultural practices that can allow new plants to thrive in that area in the presence of the pathogen.

I would say that the soil we had trucked in is a bit finer and not as much clay, but I'm not sure how close they are in drainage...Is there some sort of a test I can do for that?

If you break up compaction at the starting grade and the chosen import placed on top is a similar texture, the drainage shouldn't be an issue, even with the organic.

IME textures rarely are close. We see that the OP had soil trucked in, I'd wager could be manufactured soil, with little clay. That will have to be incorporated in. And upthread it is unclear that the gypsum formula idea is ready to go into the soil.

Paso, there are hundreds of hits on The Internets describing how to do soil texture tests at home using a jar, dish powder, a soil sample, and a few hours then measuring and referring to a soil triangle after a little math.

Dan

IME textures rarely are close. We see that the OP had soil trucked in, I'd wager could be manufactured soil, with little clay.
I agree. There's a good chance that there's a significant textural difference. Best to check it out.

And upthread it is unclear that the gypsum formula idea is ready to go into the soil.
Not sure what you're saying here. Can you clarify a bit?

there are hundreds of hits on The Internets describing how to do soil texture tests at home using a jar, dish powder, a soil sample, and a few hours then measuring and referring to a soil triangle after a little math.
Yes, do that with the native and the proposed import soil.

That will have to be incorporated in.
*Pulls out hair. Flops to the floor in a dead faint.*

*Pulls out hair. Flops to the floor in a dead faint.*

I did that yesterday with the BH. Apparently we can have the bacterium E. coli in the house, but not B. thuringiensis. Odd, I know, that two highly educated people can have different approaches to the same problem!

Regards,

Dan

can have different approaches to the same problem!
True dat.

I think the only way to come to a satisfactory conclusion would be an arm wrestling competition.
*looks at Dan's profile -- he rides a bike? -- probably in shape*

I meant drinking competition.

hic!

As long as we don't have to ride home afterwards - I fell off my bike after the bar enough in college to know its a bad idearrrr (ever try to ride uphill drunk in Seattle? That'll harsh your buzz in a hurry...)

;o)

Dan

Thank you for all the info and you guys are having way too much fun! Been busy preparing the soil with gypsum and I have one last thought. We have 10 acres and about 200 Blue Oaks...can this pathogen spread and get them all...we are mindful of not moving the soil to other areas and we sterilize any garden equipment with a bit of Clorox AND we don't water anything near the oaks! We are trying to be good stewards of the land!!!