Root stimulator applications encourage tree root development but specifically fine root hair development. A fall application should limit nitrogen as excessive nitrogen can upset the tree’s natural cycle into winter dormancy.
The main difference between root stimulator applications and deep root fertilization is that a root stimulator uses little to no iron and nitrogen. In certain situations, a root stimulator application will likely be more effective and over time our PHC programs have evolved to use use a spring deep root fertilization and a fall root stimulator. Why?
A root stimulation promotes the fine root density of the tree and it also adds a beneficial fungus, called mycorrhizae. It also helps the tree transition from fall to winter. Too much fertilization in fall can prolong the tree’s growth cycle leaving it more prone to vulnerability when the first freeze occurs. Keep in mind the context of your trees and lawn are important factors as well as the species of the tree.
This year, the overwhelming factor negatively affecting causing trees is higher temperatures and lower than average rainfall. For example, in another drought year (2012), hard soil and 70 days above 90 degrees created “abiotic agents” – a fancy way of saying non-living factors that cause trees to decline or even die off. Examples of abiotic factors are:
- Compact and hard soil
- Improper water application
The bottom line is, if you water your trees during a drought, you need to use a root feeder or have a tree service inject, with a 125 PSI pump, water into the soil zone. Any other way is ineffective in a sustained drought such as we’ve seen throughout 2018.
According to Colorado State University’s Yard and Garden Extension,
“One of the major causes of abiotic plant disorders is improper water application. Too much water can be just as damaging as not enough water, since both kill roots. Examples of abiotic disorders related to water are leaf scorch, winter desiccation, and oxygen starvation.”
Here is some of the damage that our PHC team sees as a result of these factors in parts of Denver.
- scorched leaves
- the top-down decline in a young or mature tree
- pine needles browning at the tips
We follow CSU’s guidelines for our tree services, and water management is their main recommendation, right now.
- Leaf Scorch On Aspens Source: CSU
Mycorrhizae are a beneficial fungus that forms a symbiotic relationship with the soil and promotes a healthy root-system growing medium. The end result is a treeless susceptible to heat and drought stress often observed during the growing season.