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beneficial microbes vs disease pathogens

Posted by Dave Strnad 
beneficial microbes vs disease pathogens
August 01, 2013 04:58AM
I am trying to understand the dynamics of fungal and bacterial colonization and the effect of spraying neem or other foliar sprays. Why does it benefit only the good bacteria and fungi? Why wouldn't all bacteria and fungi benefit from these applications good and bad? Is it really as simple as, item A is good for all the good things and harmful to all the bad? Or am I missing the point, is it really beneficial to all good and bad, and simply a matter of supplying enough resources so that a diverse colony develops, good and bad but balanced.

Getting Started, 70 trees in the ground more to come.
Apples, Peaches, Plums, Cherries, Pears, etc.
Zone 4-5a depending on zone map.
Sandy Soil
Near Traverse City, MI
Growing for family and future income.

Edited 1 time(s). Last edit at 08/02/2013 04:18PM by Michael Phillips.
Re: beneficial microbes vs disease pathogens
August 02, 2013 05:17PM
This scene on the surface of the leaf and fruit isn't so much about "good" and "bad" but about diversity and nutrient resources. There are basically three pathogen groupings when dealing with fruit tree disease. These in turn have food preferences and specific launching points, all of which influence our choice of action as growers:

Fungi that tap directly into the plant for sustenance include scab, rust, leaf curl, and rots in the establishment phase ... all of which have a "primary infection window" that speaks to specific timing. These pathogens utilize certain enzymes to allow hyphal penetration into plant tissue in order to live. This grouping demands our attention from the first showing of green tissue to as much as a few weeks after petal fall, varying with the fungal invader in question. Here we need to be thinking about competitive colonization, plant immune function, and enzyme inhibition to keep disease at bay.

Fungi that feed on cuticle exudates include sooty blotch and flyspeck, and the fruit phase of rots which then quickly go on to consume it all. Footholds are gained in the immediate weeks after petal fall, coming round again from alternate plant hosts and/or launching sites at the base of blossoms and shoots (brown rot in particular). Here we need to be thinking about competitive colonization along with silica and calcium boosting of the cuticle to keep disease at bay.

Bacterial pathogens require an "opportunity" to get into the vascular system of the tree. Such discussion can be elsewhere but just know that competitive colonization is really key here.

Elaine Ingham has reported that maintaining a diverse colonization on the order of 70% on plant surfaces will thwart disease organisms. Biological reinforcement with compost tea and/or effective microbes is the means to do this. Deep nutrition from the fatty acids in fish and unadulterated neem along with a wide array of trace mineral availability from seaweed and ocean minerals has import here. What takes place after spraying a holistic brew is mostly beyond our ken. We don't know which benign/beneficial fungi and bacteria are going to dominate. We don't know the degree of nutrient uptake by trees -- through leaf stomata and bark surfaces -- that depends in part upon microbe consuming microbe in the arboreal sphere. We don't know how systemic resistance gets triggered by terpenoids and flavonoids in pure neem oil and other indigenous herbal remedies. What we do know are the results to be seen at harvest time in terms of great fruit.

Lost Nation Orchard
Zone 4b in New Hampshire
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