Re: CULT:Fertilization (Was Iris Myths)
From: Gullo <tgf@frontiernet.net>
Hi Betty and everyone following this iris
myth/solarization/fertilization/compost/rot thread. I think that there are a
number of variables involved here that have been mentioned and need to be
considered.
Solarization- Does solarization in some way allow rot producing pathogens to
survive or have some advantage when the soil's microbial population is restored?
I am uncertain as to whether any microbes can survive if sufficiently high
temperatures are achieved. One has to look seriously at the possibility that
when a sterilized soil is planted in with plants carrying the rot producing
microbes ( whether showing active disease or not ) at the potential for said
microbes getting a strong foothold in the absence of other competing organisms.
Fertilization-I think it is commonly accepted that over fertilizing especially
with a high nitrogen fertilizer is almost a guarantee for rot related problems.
As compost is a natural nutrient source, using it in combination with additional
chemical fertilizer applications only increases the amount of overfeeding the
plants are receiving and increases the potential for rot.
Compost-My personal feeling is that compost is the natural way to provide your
plants with the nutrients they need and that if overfeeding is resulting then
supplemental chemical fertilization is problem that needs to be addressed. That
having been said I would acknowledge the possibility exists that there is a
qualitative difference in 'hot' and 'cold' composts. In a previous post I
mentioned that I use straight compost on occasion when I transplant young
seedlings into pots when I have not finished preparing a bed for them. I should
have also added that my compost is of the cold variety meaning that it does not
get hot enough to kill off microbes or weed seeds for that matter. I think that
this is relevant for at least 2 reasons. First , the natural microbial
populations are not killed off in a cold compost pile as they would be in a hot
pile where soil temperatures can reach high levels. Second , being a cold pile
the organic material takes significantly longer to break down fully giving
excessive nutrient amounts more time to leach out. I feel that both factors have
a bearing on whether compost is contributing to a rot problem. Rate of
application of any compost ( but especially hot compost ) could play a role in
making conditions more or less favorable for rot. Heavy applications of compost
(again I would think hot compost especially) could under conditions of high heat,
humidity or moisture result in in more problems.
Climate Conditions-sort of a general term to encompass temperature , humidity and
moisture. Again I think it is generally accepted that the combination of high
temperature coupled with either high humidity or high moisture from any source
(rainfall or artificial irrigation of some sort) is a recipe for rot related
problems. With it's capacity to hold moisture , compost could be contributing ,
in that manner , to make conditions favorable for rot producing organisms. In
climates that routinely see high daytime temperatures moisture management is I
think crucial to maintaining plant health. The amount , timing , retention and
drainage of moisture are all critical factors which need to be carefully
considered. Mismanage any of these variables and conditions can easily become
favorable for rot of various types.
Genetic factors-I mentioned earlier that rebloomers seemed to be more resistant
to rot in general. Could it be in their ability to resist dormancy and continue
growing as long as cultural requirements are being met? Is there something in
their genes? Other irises are labeled as tender or rot prone because they have
this or that iris species in their background. It seems reasonable to expect
that whenever an iris is grown under conditions, which are vastly different from
those in which the particular iris is genetically adapted to, that there exists
the possibility that the iris will suffer. Hybrids too closely related to such
an iris will suffer as well.
Probably other factors to consider also, but it is getting to late for me to keep
going. It would seem to make sense to consult with growers in one's local area
to see what cultural practices are successful in a particular climate.
Michael Gullo
West Walworth, NY
StorYlade@aol.com wrote:
> From: StorYlade@aol.com
>
> In a message dated 01/22/2000 5:06:20 AM Central Standard Time,
> Irisborer@aol.com writes:
>
> << I have never had more robust and glorious irises,
> nor have I suffered any rot whatsoever.
>
> I DO hasten to add that this bed is the only one in my entire garden that
> enjoys a southern exposure and it is also raised. >>
>
> Do people still raise irises in anything other than raised beds?!! No! No!
> Say it isn't so! (Except in sand, of course.) Two much fertilizer, organic
> or chemical, + prolonged dampness = rot. (Only my . 02 based on personal
> experience.) Dampness alone can do it, but the rate of rot increases with
> over-fertilization. My first round of rot met with this observation from
> more experienced growers in Region 7, "The prettiest iris beds have the most
> rot." Why? Fertilizer. I've seen new growers/show bench enthusiasts
> introduce so much rot in their beds that they were forced to abandon entire
> sections of their garden.
>
> I've been told this is the problem with many of the convention gardens. Too
> much TLC. In an effort to have a spectacular national showing, they
> over-fertilize.
>
> My most successful/prettiest/longest lasting iris bed was prepared slowly.
> The bed was on the west side of the house and several large trees were in the
> yard. Sun light varied from full to dappled depending on the time of day and
> season. Organic material, ashes, maple leaves (raw material), and compost,
> was on hand and was tilled into the bed area. Everything was watered well and
> left alone for 3 weeks or so. When the area was covered with new weed and
> grass growth it was tilled again, and watered again. Another 3 week wait and
> another tilling took place. Then, the bed was formed and the iris planted.
> The process took over six week, but the bed produced great irises for about 5
> years. No rot. Of course, the irises were thinned occasionally.
>
> Betty from Bowling Green, KY--What is this white stuff, falling from the sky?
>
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