Sunday, May 5, 2013

Tree myths, that's what's up.

This past week I saw an article from The Guardian about tree myths posted by The Garden Professors BLOG  I know what you're thinking, some one else spends spare time writing about plants.  But for-real, it was pretty interesting, and I'd encourage you to give it a read.  Below are my comments on the 9 myths they choose.

MYTH 1 Compost tea suppresses disease:
Compost tea can be a polarizing topic for arborists.  Compost teas are a way to introduce organic matter into the soil.  Over time this can improve soil nutrient availability, texture, and structure.  Compost tea pushers have made many claims, including that foliar application of compost teas can prevent leaf diseases.  That's just silly.  Wetting leaves with seeped organic matter may actually encourage the development of leaf diseases.  Most leaf spot fungus require a cool wet environment to proliferate, and spraying leaves with compost teas may provide the moisture.

MYTH 2 Lighten clay by adding sand:
I've seen arborists attempt to drill holes in clay soils and back fill the holes with sand, or a large aggregate like stalite.   The problem with this strategy is it ignores a basic principle of water.  Water does not move in between different textures well (i.e. course texture aggregate to a fine texture clay).  So when this management strategy is employed there is still poorly drained clay with sand filled holes full of water.

MYTH 3 Young trees should be staked:
Trees need to move naturally in the wind to put on reaction wood and build taper.

 MYTH 4 Sun through water burns leaves:
 This seems commonly reported on Japanese maples. In most cases it's actually fungal leaf spot, which really is just an aesthetic issue.

 MYTH 5 Tree wounds need dressing:
Most decay fungi need moisture to survive. Painting an open wound can allow moisture to build up behind the sealant, thus creating a perfect habitat for fungi. Now there have been some studies that show some wound sealants may discourage some insect pests from invading new tree wounds.

 MYTH 6 Biodynamic is best:
Using astrology to pick days to plant?  I suppose it would make sense to some early 20th century gardeners. 

MYTH 7 Gravel helps containers drain better:
Once again, water does not like to move between different textures. Putting gravel at the bottom of a pot has the exact opposite effect, keeping water in the finer texture soil longer.

 MYTH 8 Add bone meal and compost when planting trees:
Digging a tree, transporting it to a new area, and then planting it in a foreign soil is a big stress to a plant.  Throwing it in to a super nutrient rich media, believe it or not, can traumatize a new transplant.  Caution needs to be taken when choosing what type of amendments are being put in to the soil.  As the article states, adding to much of an element, like phosphorus, can inhibit plant growth.  More may often not be better, especially in the landscape.

MYTH 9 Natural is safer:
There is no such thing as a safe poison.  Be it found in nature or man made, poison is poison.  We use pesticides to kill pests and diseases.  Some are less toxic than others, and some have different modes of action.  When choosing a pesticide the mode of action, its persistence in the environment, etc. should be your deciding factors.  Not that it has an OMRI stamp and is made from dandelions.