We can share information about basic soil testing (see linked page), but it only screens for nutrient content (not all nutrients, just most of the major elements), acidity level (pH), organic matter content, and when certain labs offer it, heavy metal levels. Unfortunately, while that information would still have value (especially if the pH were to be wildly out of the normal range), it probably won't help diagnose a problem affecting so many different species. A standard soil test can't screen for pathogens, pests, or herbicide residues. An environmental testing lab could test for chemical residues, but they would need to know exactly what compounds to look for, as they cannot test for the large number of chemicals and additives used in various pesticides (even organic pesticides). If there hasn't been a chemical spill, suspected misapplied pesticides (mainly herbicides, given the dieback issues), then a toxin is not likely the cause.

Did anything flood the property (or areas of dieback) prior to the plant losses? As resilient and invasive as running bamboo can be, for example, it still has its limits, and too little soil oxygen from oversaturated conditions may kill it, and can definitely kill other, more sensitive species. Was there any digging in the root zones prior to dieback, such as from construction, regrading, or utility work?

Trees die for a variety of reasons, including root loss, stress and secondary pest/disease issues, physical damage, girding roots, and so forth. It's not uncommon for decline and dieback to begin weeks, months, or even years before symptoms become prominent, making it hard to trace back the original cause. Even if different species die around the same time, they won't necessarily share a common cause.

A certified arborist or licensed tree expert can help evaluate struggling trees to narrow-down a diagnosis and look for sources of tree stress that might be able to be alleviated, either for that specimen or, if it's unsalvageable, for a replacement tree. If it's too late for the current trees (little can be determined if they are already fully dead or decline is advanced), you can try that approach if this keeps occurring in the future.

If you'd like us to make some educated guesses as to contributing factors, we would need to know what plants have been lost, what seasons they declined in (or at least when it was noticed as being prominent), and what symptoms manifested. For example, we've seen numerous examples lately of dead or dying 'Green Giant' arborvitae around central Maryland landscapes that succumbed to this year's prolonged drought. (Which in most of the state, has still not abated; see linked map.) The drought of this year, combined with last year's drought, and even the excessive rains of 2018 (and to a lesser extent, 2019) have all been stressing even mature, well-established plants.

Some species have a greater tolerance for wet soil (such as Pin Oak) while others have a greater tolerance for dry soil (such as Bur Oak), so each will be stressed or suffer root loss under different circumstances. Unfortunately, in recent years, we've experienced both extremes of precipitation at different times, and while winters have been mild overall, summer heat waves are also taxing some species. Those who lost lots of roots to soil saturation one year might be more easily damaged by drought a few years later, since the root system may not have recovered fully yet and can't keep up with the moisture demands of the canopy. Some pathogens, like Volutella Blight in boxwoods and Botryosphaeria and Hypoxylon cankers in many shrubs and trees, can become infectious and damaging when their host plants are under stress, when before they lived harmlessly alongside the same plant. Similarly, some wood-boring insects preferentially attack plants stressed by either too much or too little soil moisture.

We're happy to help puzzle-out what might be going on, but unless it's one event that impacted such a wide area, each plant might have to be assessed on a species-by-species basis, since their vulnerabilities to different environmental stress factors or pests/diseases won't always overlap. We can also provide feedback on the results of a soil test if you opt to do one.

Miri

Miri, thanks for your prompt response. ( remain doubtful that these isolated were a result of an  which were source. There is a stand of 5 large philadelphus shrubs which were in full bloom and thriving in May of this year.. They have been in existence here since the mid-fifties, I was told. We bought our residence in 19 84 and they were quite large then . Now they are completely dead….dry thruout.   There is another stand of the mock orange some 12 feet away and they are completely fine. Both in the same environment : on a small slope under a large maple tree. There is no wash-out path near either of them that would be observed during harsh rainstorms.   There are 2 smoke trees….some 10 years old… ,located about 50 feet away which are dead.   There are winterberries in another part of the yard (irrigated) which appear to be close to death. We are most puzzled by the bamboo as that was planted in the early 50’s we were told and have been very aggressive during our time here. We just tried to control them by hacking away every year. Meanwhile, this year there is a section of bamboo (which pretty much is a virtual barricade around 3/4 of our property) measuring about 50 ft in width that is rainbrowned out and dead.  In my opinion, the damage we’ve seen cannot be attributed to heat, rain or any other natural cause..

I apologize in advance for some of typing which turned into gibberish….new computer which I have not mastered,

Do you see any pattern to the affected plants across the landscape? Have there been any chemicals applied to the turf grass areas? (There are weed killing chemicals that can kill trees/shrubs if applied over their underground roots, which can be found a good distance from the plants themselves in mature specimens.)
Any underground utilities like gas lines shared within those areas? 
It might be helpful for us to see some photos of the landscape to consider this further. If you are able, you can attach up to three photos at a time directly to this reply, and we will be happy to take a look.

Any other changes to these areas? Mulch? Any supplemental irrigation done at all? As mentioned, plants stressed over time can be more susceptible to becoming diseased or dying back. Did you notice any dead branches? Some plants, like the Mock Orange, may well bloom prolifically when under stress, sometimes as a last-ditch effort before death. Did the affected plants leaf out normally too? When did you notice the problems?

I would not underestimate the damage of the intense and prolonged periods of heat and drought for the last couple of years. Even mature trees and bamboo can be killed by prolonged droughts as we have had. Differences in soil and slope (where any water that they did get flows off more quickly) can make a difference. Large maples are thirsty, competitive trees with large root systems, and plants in the understory can definitely suffer when moisture is scarce.

If you'd like to do some sleuthing we'd also suggest that you look closely at the lower limbs and trunks of the shrubs to see if you see any signs of gnawing damage from rodents like voles, which can also feed underground. On dead ones, pull sharply on one or dig it up and look at the roots, which can sometimes be completely severed but still stand.

Do you have reason to believe some sort of chemical spill or unwarranted application was made by someone? Could there be herbicide drift from neighboring properties or farms?

Miri is correct that you can't test soil for generic chemicals. You'd need to have an idea of what the lab analysis was looking for.

 I know that is a lot of questions to think about, but let us know if anything rings a bell.
Lastly, are you seeing a variety of unexplained deaths of insects, birds or mammals within the landscape? 
If not, it would be extremely unlikely that your landscape would be dangerous to your pets or people.


Christine

Christine….   I appreciate your attention to addressing my concerns to the sudden collapse of a good portion of our property’s ;plantings. Perhaps I do need to get an arborist over here to better diagnose the problems.

You're welcome to send photos of the site when you are able. In the meantime, any arborist should do in that they all must pass a standard exam to become certified, plus take continuing education credits via symposiums or other training formats yearly to maintain that certification. Some will naturally have more diagnostic experience than others, as they as individuals will have a range of experiences with some plant species over others, and since their focus is on woody plants (trees, and by extension, shrubs), they might be less practiced in diagnosing a grass like bamboo.

A "consulting" arborist might be more independent of a tree-care company and thus less likely to recommend any unnecessary treatments (for still-living but stressed plants, that is), though you can always run any recommendations for intervention you may receive by us for a second opinion. That said, we are not certified arborists, so have a limited ability to provide feedback when it comes to particular nuances of tree care.

Still, an arborist can at least make an on-site visit and might notice something about the landscape features or conditions that we can't determine easily from descriptions or photos. You can also always seek a second or even third arborist's opinion to help determine what a likely diagnosis might be; they won't always agree with each other. It's entirely possible that each species in this puzzle will have a separate specific diagnosis, potentially stemming from the same original stressor (like soil moisture extremes that might not have been as noticeable while they happened, if they occurred during the bulk of the growing season in years while you were away). A few plant pathogens like root rot and certain canker fungi have the ability to affect a wide range of different plant species, so in that sense, several different plants examined might be deemed to have developed "root rot" (to pick an example).

An alternative (or addition) to hiring an arborist would be to seek an assessment by an IPM scout/consultant. (IPM = integrated pest management, an approach that uses multiple techniques to suppress or prevent pests and diseases that de-prioritizes pesticide use as a last resort.) IPM practitioners are trained to properly ID plants, pests, and diseases before determining if treatment is viable, and what treatment approach to try. They look for environmental contributors to plant stress, so can examine the surrounding conditions for the plants that have died off to try to find a common culprit. In general, arborists should ideally have IPM training or experience as well, but it's possible some have more experience in other areas.

As Christine noted, it's quite unlikely that a soil toxin is involved unless substantial volumes of contaminated soil was added to the yard in those particular areas. (Even then, we don't know what that toxin would have to be to cause that degree of damage, other than gross excesses of any typical soil minerals, which would still more likely cause noticeable nutrient toxicity symptoms in foliage before causing any actual plant deaths.) A drastic change in pH would do the same -- manifest as prominent leaf symptoms before causing plant loss -- and that would only happen if high quantities of something like sulfur or lime were applied to the soil in those areas. Even if a swimming pool's water, laden with chlorine (or salt, if it were a saltwater pool), had been pumped-out into those areas, we would expect all plants in that flooded zone to have succumbed (lawn, weeds, perennials, etc.) and not just some of the shrubs in isolated areas and a portion of the bamboo.

Miri