The drought of 2011 was responsible for the loss of 500 million trees in Texas per the estimates of the Texas Forestry Service. This one factor will contribute an additional degree to temperatures in the State. This will increase the evaporation of water on the ground making the forecast drought of 2012 even worse for our beautiful trees. If climatological history repeats its 125 year records we can expect another drought in 2013.
In the urban environment conditions are worse. Poor irrigation practices, high pH of the water, soil compaction, insect pressures and other plant competition for water and nutrients aggravate the health of our landscape trees.
We have a simple and inexpensive solution called vertical mulching, not to be confused with over mulching on top of the ground. Vertical mulching is inserting beneficial materials into 2” x 12” holes around the canopy of the tree to allow air to enter the substrate of soil.
The holes are filled with an inert product: we prefer Lassenite. This porous material allows water to percolate past the turf and shrub roots and go directly to the tree absorption roots which are about 4 to 6 inches deep. What is not immediately consumed by the plant is stored in the honeycombs of the Lassenite and is offered to the plant on demand, reducing time between watering.
As we fill the hole we introduce a fertilizer with an appropriate ratio for drought stress trees, and a number of beneficial fungi and bacteria to the mix. One is Mycorrhizae Fungi. See the benefits of this fungi as show in the photograph as the white spider web like strands populating a Pine seedling planting. This is a common, naturally occurring element in the forest, but the compacted urban landscape is void of these organisms. Mycor grows spider web type mycelia underground and attaches itself to tree roots. Mycor is able to extract nutrients and water from the soil but the fungi does not use it for sustenance and consequently offers what it captures to trees in exchange for some sugars. This is commonly known as a symbiotic relationship. In essence we are bringing the forest to our urban trees.
Because of our high pH soils the essential minerals needed for photosynthesis in a tree are unavailable because this condition will not release the minerals from the soil to be absorbed by the tree roots. To resolve this problem we introduce millions of rhizobacteria in the fill mix. These beneficial bacteria solubilize the minerals from the soil making them available to tree roots and Mycorrhizae. These subterranean bugs also protect the trees roots from soil borne pathogens. And if that is not enough they decompose organic matter, improving physical properties of the soil.
I only hope you are as interested as we are in giving our landscape trees everything we can to improve their chances for survival. Insects typically only attacks stressed trees. This is a subject in itself. Please follow our irrigation schedule that is on the right border of our blog post.