This post is one day late from my attempts to post something every Friday.
Things have been busy in the Plant Clinic with the 2nd week of classes at Texas A&M. We are trying to get our student workers started in the lab… but nothing always works on my own time schedule. Due to delays, I only have one of the 3 new student workers being prepped for the Clinic. In my frustrations and anger and disdain at the inefficiency, I was reminded that I am exhibiting an impatientness that (unfortunately) is characteristic of many humans. It is this characteristic of wanting and sometimes needing instant gratification that can lead us to wrong diagnosis or the inability to accept a diagnosis.
Trees are under tremendous amount of stress from this drought that we are experiencing in Texas. But all trees does not act similarly in response to this stress ( this is call species specific responses). Further, we find that trees of the same species may not even act similarly. this can be due to soil types, soil moisture, depth of roots, soil nutrient and so much more that can affect the health and persistence of the tree. One insidious situation that I have noticed is that some of the more sensitive plants: trees, woody ornamental and also shrubs, seems to show a slow to moderate decline. On analysis, majority of these specimens do not reveal any pathogens. Occasionally, we may find an associated pathogen which is usually a weak or opportunistic microbe. I have had some suspicions that this is a result of root damage from some environmental trauma. I remembered one year when there were lots of complaints of stunted and dying containerized trees. That was the year where there was a prolonged freeze incidence. In the absence of credible pathogens, I suspected that the roots of affected plants were damage from the freeze to a point that they were sufficiently damaged and  failed when the plants were trying to actively grow. Which brings us back to this year. It is possible for the roots to be damaged if they we ‘over’-dried. If you are seeing declining trees or woody ornamentals, think back if there was an extended period when the growing area of the plant was super dry. That may be a reason for your declining plants. On most established trees, the decline seems to start about 3-5 years after the start of a drought season.
In my impatience as a plant pathologist, I wish the cause and effect would be close to instantaneous. That would make diagnosing much easier. As a homeowner, I wish for the same thing so I can know what I did wrong and fix it immediately AND the plant would recover by 24 hours. Alas it is not so. The lesson for today is to be prepared to look back a good distance to find plausible answers to plant disease questions.
Have a great weekend!