Dying Trees Investigated for Wastewater Link

There are many possibiliies, but one thing is clear.

The next report will be equally inconclusive and non-commital. The linked new report indicates "visits to the site on Feb 7-9 and then a final report to council at 4 pm on the 9th."

This timing allows no appropriate sampling, testing or investigation other than "kick the dust and smell the breeze."

Tree death is a process that takes up to 2 years (in some species) before being evident in the above ground performance of the tree.

Possible options for tree death would include such things as

• Wrong species for the specific location
• Leaves sprayed in HOT weather
• Nutrient condition of the soil
• Chemical imbalances (Especially phosphates)
• Copper accumulation (Assuming you use copper sulphate as part of the treatment) in the soil.
• Waterlogging
• old age
• pests and insects
• root compaction by vehicle access
• root disturbance from "heaving" winds, especially in water bearing soil
• Bacterial/Fungal process in the soil from not "rotating" the evaporation fields.

I'm not a tree doctor and could not necessarily diagnose any of the above DEFINITIVELY.

BTW, I am involved with our local water authority and we have significant plantations. They are "trickle" irrigated, not sprayed taking effluent and we have seen no unexplained deaths of mature trees. We also supply the same treated effluent to local farmers who irrigate pasture with it.

One question though. How big are your "wet weather detention basins"? We target 2 months of zero usage so that in prolonged wet weather we have capacity to allow the forrests to recover.

I'm interested in helping if at all possible. Stay in touch.

The article says it is Loblolly Pines that are dying, and that it started in a particularly dry year.

Pines are heavily dependent on mycorrhizae for water and nutrients. The fungal mycelium forms the "root hair" part of the tree's root system and provides both water and nutrients from the soil.

This is true of all trees to some extent, but in some cases there are exclusive or species-specific associations that are dominant, which means that fewer resources are shared with other tree species in the neighborhood, partly to cater to the tree species specific needs and tolerances. Some of the fungal symbiont species are more sensitive to extreme conditions such as drought or changes in soil pH.

For example, severe drought in my area started a die-off of the Larch (Larix laricina) that went on for several years and wiped out most of the mature trees. It seems the species-specific mycorrhizae were damaged/ died: this weakened the trees and further restricted their access to water, and bark beetles invaded as well. Luckily young trees were not affected, so they will eventually be restored.

In the case of these pines, the drought effects were probably worsened by the treated effluent. The chemicals used are not specified, but it's fairly certain that the concentration of salts in the material is high. This can create an additional physiological drought effect, as well as being prejudicial to the mycorrhizal symbiont which is intolerant. The salt concentration probably worsened the drought-related dieoff of mycelium, leaving the tree with no root hairs to absorb water or nutrients.

The picture of the dead trees also looks a lot like the work of bark beetles, although no closeup to check for sure. These die offs do happen in cycles for conifers, triggered by drought, and can't be entirely avoided. But it might be wise to avoid spraying around pines if it is worsening their chances of surviving the environmental stresses that can't be controlled.

GA to Artsmith and Justanengineer.

Both of these post have good information and may present an answer or portion of an answer. One thing I have noticed in landfill sites and in areas abutting the landfill are the premature deaths of trees. Sludge or waste water application on land may present some of the same issues that caused these tree kills on landfill sites.

Should the waste spread on the land exert a very high oxygen demand, the soils can go anaerobic and actually put the trees under severe stress. Methane migrating from landfill sites have been implicated in tree kills. A solution has been to set up some sort of aeration perimeter on landfill sites (hydrogen peroxide injection, blowing, trenching). In the case where you are spraying the waste and you are over applying it, you will create a similar condition. The site dosage levels should be monitored for nutrient metal ratios based on soils capacity. Also the waste will have a very high oxygen demand (chemical and biological). There are books on how to compute these values. Sorry I just can't think of the book I once used but I will try to get back to you or you can google for info (sludge application/metal ratios).Farmers must apply these rules to be accepted for sludge disposal but bear in mind they also till the fields several times a year and that adds aeration.

Good luck.