Pest and Disease Resistance in Plants

[Eric Tyira]

A while back I had a great conversation with an organic cider maker in the US.  At one point he talked about how the old timers would check the sugar levels in the leaf tissue and spray sugar or molasses water.  As a non-orchardist I didn’t know why or how it affected the trees and fruit.  I’ve kinda been searching for the answer ever since. 

There’s a website and webinar in Canada called “Orchard People” and their latest spam email (sales pitch for something) had this link to a presentation from a guy who links sugar levels in leaf tissue to pest and disease resistance.  

https://m.youtube.com/watch?v=bnNOvA3diDU

The video is 1.5 hours long so I’ll summarize it for you in case you already know or don’t have the time:

1) the higher the sugar level, the higher the complexity of the pest that will attack your tree.  

2) once you hit 12% and preferably 14% brix, insects will leave it alone. 

3) how do you increase brix in your leaf tissue?  Sunlight, water, oxygen into the soil (for aerobic microbial life), proper soil nutrients.  

4) how do you decrease sugar in leaf tissue?  Pesticides, herbicides, fungicides (destroys microbial life), permanent no-till (no oxygen into the soil), standing water, improper balance of nutrients. 

5)  this one was eye opening for me.  Why do pests attack the young fruits?  It’s not because they are fruit.  It’s because they are weak points in the tree with the lower sugar levels.  Those fruits won’t build sugars until ripening.  

Back to spraying sugar or molasses water.  Perhaps they did this to boost the leaf tissue brix content in the tissue.  I can see this as a junk food high to the tree, so not a good practice in the long run.  I wonder if spraying any of this onto the fruitlets can make them seem undesirable to the pest?  Artificially boosting the surface sugar levels to trick the pest into thinking there’s too much sugar?

Now leaf tissue brix analysis isn’t the end all, be all, but it’s a start.  Actually it’s a result.  It will tell you that something subordinate is screwed up and needs to be remedied.  

All fascinating stuff and I thought it worthy of sharing. 

Eric

[Per T Buhre]

I have got the impression that the main purpose of foliar spray with sugar is that it will feed the microbes around the rootsystem and therefore in the long run make the tree healthier and more pest resistant. 

So you don’t really increase the brix in the leafs with the spray but rather give the tree a surplus of goodies to share with its allies in the soil. 

/ Per

Skickat från min iPhone

21 okt. 2021 kl. 03:02 skrev Eric Tyira <secretc...@lostruinswinery.com>:

A while back I had a great conversation with an organic cider maker in the US.  At one point he talked about how the old timers would check the sugar levels in the leaf tissue and spray sugar or molasses water.  As a non-orchardist I didn’t know why or how it affected the trees and fruit.  I’ve kinda been searching for the answer ever since. 

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[Eric Tyira]

Oh, so provide the carbohydrates to the root fungi through the leaves.  Interesting.  I wonder if it can be both: carbs to soil microbes and boosting brix in leaves making them unpalatable to insects?

I’d love to hear from others about their experience using leaf tissue sugar analysis as a tool to understanding tree health. 

To view this discussion on the web, visit https://groups.google.com/d/msgid/cider-workshop/64315FC4-0DB7-4B5F-ABCA-BC368809CB91%40gmail.com.