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Re: This is from the ASK US page- Re: [AZ] Phytophthora in your azaleas

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  • Barbara Bullock
    Thank you for your detailed response.   Barbara ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Be who you are and say what you
    Message 1 of 3 , Apr 20, 2013
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      Thank you for your detailed response.  

      Barbara
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      "Be who you are and say what you feel,
      because those who mind, don't matter -
      and those who matter, don't mind." -Dr. Seuss
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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      --- On Sat, 4/20/13, George Klump <mixturev@...> wrote:

      From: George Klump <mixturev@...>
      Subject: Re: This is from the ASK US page- Re: [AZ] Phytophthora in your azaleas
      To: azaleas@yahoogroups.com
      Cc: "Barbara Bullock" <barbazalea@...>
      Date: Saturday, April 20, 2013, 4:02 PM

      On 4/20/2013 8:45 AM, Barbara Bullock wrote:
      bject:
      Re: This is from the ASK US page- Re: [AZ] Phytophthora in your azaleas
      From:
      Barbara Bullock <barbazalea@...>
      Date:
      4/20/2013 8:44 AM
      To:
      azaleas@yahoogroups.com

       




      I do not ususally hear Perlite being recommended for improving drainage in landscape soils - only in containers.  Container mixes spoken of here in this forum are in fact "soiless".  These types of mixes do require regular feeding, careful monitoring for over feeding or overwatering; but usually in the landscape - the best "food" is decomposed organics and proper pH. Not too many people seem to realize the benefits of perlite, so your comment is no surprise.  I don't have any interest in perlite, but here is what it does.  It is a natural volcanic product which does not affect the pH of the soil at all.  However, it is marvelous in providing for soil aeration, since the individual pieces are very angular themselves and air pockets form often at the sharp corners.  This permits oxygen to get down into the root zone and promotes the proliferation of favorable soil bacteria.  It follows physically that, if oxygen can get down into the root zone, then, water can, too, and does.  I can only refer you to the AZALEAN, Summor 2008, pp.33-36, an article with which I assisted Greg Moore, himself a soil chemist who has had long experience in this area.  Perlite is not to be confused with vermiculite which is an industrial product and which you do NOT want spread into your soil for any reason. 

      SO, with clay soils, we all agree that adding gypsum can improve the drainage.  But shouldn't we also improve the soils by incorporating organics in the form of humus, decomposed wood chips, leaves, peat, etc.  Clay soils can always use organic material. 
      Re: [AZ] Phytophthora in your azaleas

      Thank you George.  

      I was just noticing some answers were perhaps geared towards mixing up soils for containers [ex: peat-perlite-bark] - but I think some of the "ask us" questions are from people who are growing azaleas in their landscape soils.  Each has its unique set of problems -the answer should be geared accordingly.  My real question is: could mixing a fine grade of peat into a landscape soil result in a collapsed-phytopthera-proned condition?  Peat is an organic - does it really matter the particle size in landscapes?  Won't it still improve the soil fertility? (in the landscape)?  You have more than one question mixed in here, Barbara, so I shall try to answer them from my experience.  The "peat-perlite-bark" mixture I was suggesting works anywhere, container or soil: there is no difference.  Containers can introduce other problems which I mentioned originally, specifically having to do with root growth and salt build-up in the container.  A "fine grade" of peat moss is NOT what you want, since the "fine grade" tends to pack up and causes several problems, one of them being the preventing of water moving through the soil.  This is why we recommend coarse peat moss, though many complain that it is a bit more difficult to acquire sometimes.  Nevertheless!  As for the particle size of the soil, it makes all the difference in the world.  Clay particles are so fine there is no effective space between them which means no oxygen penetration, no water penetration.  That's why gypsum is so effective with this type of soil, since it will break all of this up and permit water to flow freely down through it instead of running off of it. 

      One thing I have also noticed is alot of people mistakenly call their soils clay-like when they are simply low in organics.  These type soils are often hard, break up with difficulty; don't have alot of color in them, but are not clay.  Clay soils will be greyish or red in color and when dampened and squeezed into a ball in your hand, will remain shaped like a ball.  Low fertility soils can be improved by incorporating the organics into the soil at a depth of at least 8 inches.  If the soil crumbles, then what you have is probably something that can be improved with compost.  (peat, humus, decomposed leaves, woodchips, bark, etc.)  There are a myriad of soil types with variations on nearly any soil one wants to name.  Missouri "gumbo" is a good example, but it can grow corn beautifully, if properly handled.  But it takes some work, e.g. not tilling the soil and allowing the nitrogen to build up on the soil surface from year to year.  That will increase production right there, but many farmers insist on tilling the soil, breaking it with a plow, and that ruins the nitrogen insofar as the growth of the corn is concerned.  That also interferes with the drainage capability of the soil, makes it worse.  Not tilling the soil creates a condition for much better drainage and at the same time better water retention which directly benefits the plants.  Azaleas are plants, too.

      In earlier posts, folks mentioned the particle size peat comes in these days - can't this kind of soil be ammended with ANY kind of peat no matter the particle size?  Not in my book.  The finely milled peat moss will cause more trouble than its worth.  It tends to cake like cement and prevents water from even getting into the soil.  The water will run off the soil like off a duck's back.  That's no help to your azaleas.  Hence, the recommendation for the coarse peat moss which is chunky and does not do this.  The coarse peat moss, being chunky, often goes under the name of spaghnum peat moss or something like that. 
      East coast and west coast landscapes have their unique issues to overcome.  On the east coast, we recommend improving soils for azaleas by adding lots of decomposed organic matter - same on the west coast/ is that right?  I guess I'm just confused by the specification of using coarse versus whatever-you-can-find peat.  Nurseries sometimes will tell a customer anything, if they do not have what the customer is seeking or wants.  I was in Washington a few years ago.  The State flower is the rhododendron.  One is supposed to be able to drop a rhododendron [elepidote form] into the ground there anywhere and it will grow.  THIS IS NOT REALLY TRUE!  Most of the soil there has a very hard base just a few inches below the surface so that most rhododendron beds I saw were raised!  Drainage problems can be a real pain.  However, a prominent nursery in the area where we were claimed gypsum was a waste of time, not needed for their soil.  The real situation was that this nursery did not carry any gypsum and did not want any customers scouting around elsewhere for it, if anyone else happened to have it.  So they told their customers it was unnecessary.  That kept their customers and avoided the trouble of them having to order gypsum at all.  They were counting on the ignorance of their customers not to know the difference.  We have the same problem here with some nurseries.     

      We know that the opportunistic pathogen, phytopthera, is pretty much everywhere (ubiquitous) in landscapes -and so with of poor drainage, will attack our cherished plants in the Ericaceae. This problem can be minimized or avoided all together if one were to improve the drainage of the soil - [determine first if you do indeed have a clay soil or simply low-fertility]; move the plant into a location where it will get the drainage it needs; or raise it in place by propping it up higher over the soil grade - even plop it down on top of the soil surface and place a few select rocks over it's root hairs so it won't blow over - and voila - you're back in business!  Azaleas will thrive in wetter areas by doing this.  I tend to be a bit skeptical of some of this myself, especially setting rocks on the root hairs.  Those are the lifelines for all Ericaceae and many other plants as well.  The big roots serve mostly as anchors for the plant but don't necessarily serve any critical need in the food chain to the plant.  As I said initially, good drainage beats it all, at least in our experience here.  Phytophthora must have water around the roots for it to attach itself to the roots.  If the water table is down at a reasonable level, water will drain down and away from the root zone providing the soil will permit that.  If the water table is higher, i.e. closer to the soil surface, then, drainage may prove to be a problem, if the soil is heavy.  Phytophthora rarely bothers us out in the desert.  I will leave it at that. 

      George E. Klump

      Southern California Chapter, ARS/ASA




      Barbara
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      "Be who you are and say what you feel,
      because those who mind, don't matter -
      and those who matter, don't mind." -Dr. Seuss
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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