chipping orchard prunings

This is question that arose recently while discussing with a friend...
He argues that the pruning clippings from his orchard should be brought and disposed outside of the orchard, as there is some dead wood there, possibly some branches with canker, and other microbes and fungus that we don't want to see around the trees.

However, when doing my ramial wood chips on my chipper, I use all my pruned branches from apple trees as well as branches from other trees that I have trimmed or cut during the year (I make my fire wood from trees that grow on the land, so this makes quite a bit of chips also).

Is there any evidence pro or con using apple tree pruning clips in the ramial wood chips?

Jolicoeur Orchard
Zone 4 in Quebec
Author, The New Cider Maker's Handbook



Edited 1 time(s). Last edit at 01/02/2013 12:26AM by Michael Phillips.

As far as I know, most conventional growers mow their prunings in the aisles. I remember reading something about this from a pathologist, saying that as long as chips were 1 inch or less (he didn't specify whether this was in all dimensions), they broke down quickly and didn't foster disease. I think what you are doing by adding chips from outside the orchard is great.

Hemlock Grove Farm
Zone 5 in New York

The key difference between "chipped prunings" and a pile of brush is that the woodsy material is now subject to the action of the soil food web. A coarse mulch (including lengthy twigs) is preferable from the fungal perspective, and unless you run brush through a combo chipper/shredder, that is what you will see. We want to take advantage of this organic matter resource as fruit growers!

Black rot fungi in dead apple wood will no longer maintain dominance in the face of saprohytic fungi. An oozing fire blight canker may discharge a final round of Erwinia in the immediate weeks following chipping (if its warm enough) but then the game is up, no longer having living cambium to infect anew. Any disease bacterium that might be released are not going to cause immediate infection but rather seek staging areas for when bloomtime comes round ... and this action will be strongly abated by virtue of the cankerous wood now being at ground level. Those mummified fruit in peach and cherry trees are sources of brown rot, and wisely removed when pruning, but even those become mere organic matter when dropped down to the ground and thus into the jaws of the soil biology. (Important nuance: This does not happen in an herbicide strip.) Take this one step further with old canes removed from the berry patch, which we're told are serious disease vectors ... pile e'm up, run a brush mower over the top and/or cover with rotting hay or compost ... and pathogens are going to be consumed. The fatty acids in holistic spring sprays seal the deal. Everything changes when we put the emphasis on the biology.

Lost Nation Orchard
Zone 4b in New Hampshire