Should we top these trees?

Should we top these trees?

Home Forums Cultivating Truffles Should we top these trees?

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    • #3896
      AvatarFabrice Caporal
      Keymaster

      A tree with 1.5 season in the ground.

      We are blessed with a very fertile soil, and most of the trees are growing very fast; too fast? The tree in the picture is a English White Oak (Q. robur) and at the time of the picture had been in the ground for less than 18 month (planted as a one year old about 12 inch tall). We have been receiving conflicting advice about these trees. I will outline them here in hope to start a conversation that will help us make an educated decision. Please share your educated opinion and suggestions.

      1. Enjoy them, they are growing well“. This school of thought proposed very little action and tend to come from professional arborists. Prunning should be reserved to guide the trees so they develop an optimum shape and healthy. Maintain the leading bud, help them grow straight and do not top them unless it becomes a problem with canopy control. The reasoning is that will allow the tree to be healthy and develop a strong root system, with lots of nutrients for the fungus.
      2. Slow them down“. This school of thoughts seems to be coming mostly from Spain. In Europe most truffles are produced on Q. ilex which grows much slower than Q. robur. Proponent of this school of thought is to “bonsaify”  the tree to slow down the root growth by starving their development. Their concern is that if the roots grow too fast the truffle fungus cannot keep up with it increasing the chance competing ectomycorrhizal fungi colonize the root. The rebuttal to this argument is that it might be a concern for Europe where truffle are endemic, but here in California, we modify the natural chemistry of the soil and thus limiting endemic competitive pressure on the truffle. Empiric observations seem to confirm that in the first year or two the root outgrow the fungus, but very quickly (a year or two later) the fungus catches up. This is pure hear say as I have not read any scientific paper about this observation. A concern about this approach is that it weakens the trees, make them more susceptible to diseases and reduce the amount of suggar made available to the development of the truffle.
      3. Top them up“. This school of thought came to me from Chile from a producing grower that uses Q. robur. The argument is that a tall tree will have tendency to send its root deep into the soil, instead of spreading them closer to the surface and truffle ideal roots are with 5 inch of the surface. My question to this argument is more of the level of “nature” vs “nurture”. I could see that a tree will have a root system shape mirroring its natural canopy. A tall tree with columnar growth habits will tend to have a pivoting root system going deep into the ground, and reversely a trees with wide growth patterns will tend to spread its root naturally. Now, does anyone have evidences that topping a tree that has a natural columnar growth patterns will result in the root changing there genetically programmed growth patterns?

      What do you think? Do you have any suggestions? What are your management practices and based on what did you choose to use them?

    • #4079

      Another consideration might be the type of truffle you are trying to cultivate. For example, melanosporum apparently prefers an open canopy with sunlight while aestivum/uncinatum apparently fruits best in shade. So topping the trees might lead to more lateral branching and more shade.

      I see your post is from April so….what did you decide?

      Hope all is well,

      Lisa

    • #4084
      AvatarElise Baker
      Participant

      I too am anxious to know what you decided. I am considering more of a Bonsai effect in my planned orchard. (Planting in April 2021). My thoughts on it were that it would be easier to manage the pruning if they were bonsaied. Could be true or not. Maybe I’ll experiment.

      • #4090
        AvatarFabrice Caporal
        Keymaster

        We have been studying the topic quite intensively lately. My understanding is that it boils down to what you want, what you are willing to do, and the tree species.

        I learn that pruning is not slowing down the tree growth, on the contrary invigorates it. Pruning results in the energy reserve of the tree to be redirected on the remaining buds promoting their growth. So the more you fight with the tree the more it will fight back until it will exhaust its resources.

        By reducing the canopy we reduce the amount of leaves, and thus amount of sugar the tree will produce, and thus reducing the sugar available to the truffle. Is this a problem?

        We have planted English White Oaks which have a fast growing habit, there is not much we can do about that, so what we will try to do is to redirect that growth in a way that is not closing the canopy. We will NOT top the trees but will reduce them striving in maintaining their good structure with a single leader branch. We will prune the tree following the guidelines as explained in this Master Guardner Class video.  Only the future will tell. We will make sure to keep you posted with our results.

    • #4097
      AvatarElise Baker
      Participant

      I’ll be very interested in what you decide. I have a few oak varieties arriving in the spring and the english white is one of them.

      • #4108
        AvatarFabrice Caporal
        Keymaster

        As mentioned in my post of the September 9th we will not top the trees yet but prune for shape and health of the trees. For the shape we will try to promote the upright growth pattern.

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