From steved@ncatark.uark.edu Tue Mar 28 22:23:10 2000
Date: Tue, 28 Mar 2000 17:08:56 -0600
From: Steve Diver <steved@ncatark.uark.edu>
To: sanet-mg@cals.ncsu.edu
Subject: Apple Trees and Mycorrhizae

Changing the Topic Heading: 

Douglas writes: 
> But we do want to look into making our own inoculants for the
> propagative material. The fungus I was looking at is Pitholithus
> tinctorius. It's been used in the US to aid apple root formation.

Here we learn that you are talking about mycorrhizae, which is used 
quite differently than field-applied microbial products.  

In the example of California strawberries that Sal posted, this work 
done by Elaine Ingham and Frank Sanses was based on the use of a 
microbially-inoculated compost, that additionally, had mycorrhizae 
inoculant added to the strawberry plug medium.  By shifting the soil 
foodweb to favor a fungal-dominated environment similar to a 
forest-based ecoystem where Fragaria are native, the yields from 
strawberry plug plots yielded similarly to methyl bromide treated 
plots.  In other words, by favoring a foodweb that provides 
natural protection and/or immunity against the dreaded disease 
complex that necessitates the use of a soil fumigant in the first 
place, this research shows that microbial inoculation is part of 
advanced organic agriculture rather than foo foo dust agriculture. 

Past sanet posts contain the web links to this information, archived 
at USDA's Methyl Bromide Alternatives website.   The data was 
also published in proceedings of international conference on methyl 
bromide alternatives.   

Mycorrhize incoulation for apple trees?  Might work, might not.  

For sure, mycorrhize can be an important inoculant to the nursery mix 
especially for trees intended for disturbed sites.  This is a regular 
feature of ecological restoration work.  

But on a rich, humusy soil -- presumably well-stocked 
and actively functioning biologically --  will mycorrhizal inoculants 
have extra benefit and under what circumstances?   

How many more dollars per bushel of apples per year would it take 
for a conventional grower to switch to organic production?  

This is a good question.  If you are a conventional grower, and we 
offered you $5 more per bushel, $10 more per bushel, $20 more per 
bushel, $40 more per bushel to go organic, what would it take?   
Would you find a way to make mycorrhizal inoculants useful in apple 
production, to use compost teas for foliar niche management and 
control apple scab, to use cover crops in the orchard instead of bare 
soil, to make compost instead of applying commercial fertilizer?  

Conversely, if $5 or $10 more per bushel ain't worth the trouble in a 
long shot, should we bemoan the lack of enthusiasm amongst farmers 
for a transition to organics?  Will the marketplace ensure this 
premium will be there in 3-4-5-6-7-8 years? 

I am curious to know how many more dollars per bushel of soybeans
a Mississippi Delta farmer would need before a transition to organics 
would occur.   Anybody got a spreadsheet with this survey data? 

The Mississippi-Louisiana-Arkansas Delta farmers have asked for 
the organic information, but what will we tell them about the costs 
and techniques of organic weed, bug, and disease control when the 
dollar returns for soybean and corn are at such low prices?

Steve Diver


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