Mohawk Viburnum died suddenly

I have a single Mohawk Viburnum, planted in 1996. This spring it bloomed normally, beautifully, and then leafed out normally. About the second week of July, it died suddenly.

Plant gets 6 or so hours of sunshine. It gets afternoon shade from a silver (ugh!) maple, and has competition from the maple's roots. Still, it gave 14 years of excellent service.

I will appreciate any insight.

Thanks,

Bill

I would love to hear the answer to this. I, too, have a viburnum carlesii (not sure if it's "Mohawk" or something else). The difference in my experience is it died before the buds opened up. The promising little plump, green/white buds just turned black and no leaves ever appeared. Mine was 6 years old.

I'm in Maine, and everything was a little late.

tia
las

While I've found viburnums to be generally trouble-free,
I also have experienced the sudden demise of several established viburnums.
Two were viburnum plicatum Newport and one was a carlesii.
They all looked fine, bloomed well, then abruptly toast.
Reminiscent of the famed Daphne Death...

VV, where are you?

While I grow more than 125 different kinds of viburnums, I don't work miracles - and my middle name isn't Karnak.

I, too, have had plants die - yes, even at the Valley - but I try to examine and document what is going on so that knowledge can be advanced. With only the anecdotes provided above, I could hazard wild guesses like aliens from another planet, sudden Weedeater syndrome, or other foolishness. But I don't really believe that is the answer.

Does anyone have any images of the aforementioned problems?

There are such things as the Viburnum Leaf Beetle (a scourge in the northeast US and Canada). There is a borer or two that can take a liking to this genus of shrubs and tunnel around in the bark of the stems. Crown gall and verticillium wilt happen occasionally. Botryosphaeria canker can cause sudden wilting and death of plants. Even those pesky rodents and rabbits gnawing on bark in winter (and summer) take their toll in generally unnoticed areas under the canopy of branches and foliage.

Inquiring eyes want to know: vhere in the vorld are the Viburnum visuals?

Sadly, the only visual would be a viburnum carcass.
I've always suspected my gardening woes were due to the work of aliens.
I think I'll just go with that one.
VV, I knew you'd have the answer!
Thanks.

And carcasses can undergo autopsies. Horticultural CSI, as it were.

There are a lot of clues left behind by the little devils that kill our plants - borer holes, cankers, teeth marks - along with the occasional otherworldly being bursting through cambial layers.

Hi, Viburnum Valley,

I could send a picture of the dead bush - no leaves, when I get back to Maine, but I don't think it would be any more informative than what I said: "The promising little plump, green/white buds just turned black and no leaves ever appeared. Mine was 6 years old." The buds literally turned black - not just a dried up brown. Ideas?

Do you have a recommendation for preventing borers? Maybe that was it? Didn't wilt. (No leaves had appeared - the buds were just very new.)

very interesting. I too had several vibrunums, mohawks too suffer an untimely demise.

i thought it was due to my neighbors nasty cat who insists on assisting my irrigation efforts!

had stopped buying them - maybe there is another reason.

ill be watching/luring/seeking answers too.

and Willheim - thank you for asking.

Again - with no images, all you'll get are wild guesses from me based on years of horticultural management for others and growing a lot of these plants here. None will be based on some idea of what your plant looks like, living or dead. I (and others) can tell a lot from living and dead plant parts - it's what diagnosticians do daily.

Everyone on this thread has access to Cooperative Extension Service facilities at their county government level. This service is paid for with your tax dollars, and its mission is assisting citizens with agricultural as well as other needs. It isn't necessarily fast turnaround, but they are well-equipped to provide diagnostic help when plants are sick or die. There is also a host of cultural information on growing all manner of plants. This is very useful for the home gardener, as well as for the professionals and scientists because they get a "snapshot" of pests and diseases that exist in your community. In addition to posting here and other websites, use this service when there are nemeses plaguing your plants.

Plants that have set buds but fail to leaf out in spring.
•Could be bark nibbled off around base of plant over winter, preventing movement of water/nutrients through plant when weather warms in spring. The plant is mostly functionally dead - no transport from roots to stems - but there is still "life" in buds and tissues. Turning black versus drying up brown? Could be fungi or bacteria colonizing those tissues before they dessicate.

•Could be bark damaged by mowing/weedeating equipment - same result.

•Could be bark damaged by B>cats exercising their claws, leading to borer infestation that damages the cambial layers - same result.

This very behavior ruined an allée of white ash on a farm near here. The scratching behavior was incessant for years on newly planted trees, and only stopped when the owner finally overcame her deference to the cats and put some hardware cloth (wire mesh) around the tree trunks long enough to allow the trees to recover and gain some age and woodiness to the bark. By then, borers were a severe annual occurrence and the trees are permanently stunted.

Plants have set buds, leaf out/bloom, then collapse and die.

•Could be milder version of all of the above, in that some of the vascular system is functioning enough to start spring growth processes but not enough to sustain it.

•Could be entirely different array of vascular damage, such as that caused by ice storms or snowfall. Just because plant parts don't break off when bent under the weight of precipitation, doesn't mean they haven't suffered injuries not readily noticeable. Cracks in stem tissues internally disrupt nutrient and water movement. Cracks in surfaces allow entry of insect and microbial pests that then do their deviance unobserved. Again, enough of the plant functions to start processes of growth but not enough to continue or overcome the internal disarray.

Sudden death of plant in summer months.

•A disease like the canker mentioned or borers acting in the main stems or branches of the shrub can present in this manner. Additionally, any of the damages mentioned above (at a less catastrophic level) can lead to the plant failing during the growing season, especially if summer is stressful due to heat, drought, etc.

•Drought stress can stunt a plant, preventing it from adequately storing the nutrients needed for the next year's growth.

•Wet feet (poor drainage) can cause weak root growth, root loss, and/or encourage soil diseases that rot roots.

•Inadequate root system can prevent a plant from colonizing enough soil volume to sustain growth. This happens very frequently with container grown plants.

•Underground disturbance, such as tunneling animals, trenching for utility work, chemical spills, etc. damage or truncate root systems and prevent/inhibit their proper function to support the above ground portions of the plants.

REMEMBER: the plant's time of death doesn't always coincide with when problems were initiated. Weedeater damage can occur randomly and well away from when the plant finally dies. Same with borer damage, weakness stemming from drought stress, ice/snow damage, etc. etc. etc.

Memories of pests and other things fade in our minds, but the plant goes on as long as it can.

With that litany of problems, it's a wonder any of them live.

OK, you got me rolling on that one. I am going to relate a few of anecdotes from past personal experiences to show how it isn't always a straight line between cause and effect (or at least not simply intuitive), and why close observation and some sleuthing is sometimes necessary to determine what went wrong. Not exactly like the NTSB or CSI, but horticultural equivalents.

CASE STUDY ONE:

Fine old beech trees were dying on the pastoral thoroughbred horse farm. This property had won national awards for the quality of architecture and landscape design, and the trees were well into a second decade of growth. There were no superficial signs of damage from man, animal, insect, or microbe. Yet, growth would be small and spindly, and the plants just seemed "peaked" somehow (a southern term - like pinched, or tired).

To save time and column inches, it turned out that shortly after the landscape was established and mulch rings came under the maintenance of the farm's staff, the practice of weed removal changed from hand weeding with some pre-emergent applications to an old tried-and-true method for deterring weed growth along fencelines.

Diesel.

The fine specimens were slowly but steadily being poisoned by the application of this hydrocarbon product, with no one the wiser. Observation of behaviors was the only thing that changed this practice, and many of these trees survived.

CASE STUDY TWO:

Irregular large patches of dead brown leaves were showing up on shrubs in the landscape, especially shaded situations. The dead spots were about three feet off the ground, towards the more open and sunny side of the plant, and were sometimes perfectly circular like they were drawn and sometimes more impressionistically oblong horizontal elliptical blobs. The damage wasn't restricted to any one species in particular, showing up on boxwood, viburnum, burning bush, forsythia, yews, and other varieties of plants.

It reminded landscape managers of urine damage from dogs, but was quite a bit removed from the normal target range of the average canine.

Turned out to be the result of your everyday rest stop for the guys on the riding lawn mowers. Intense heat due to the exhaust from the mower engine burned the foliage that was in line with the exhaust discharge as the operator sat and cooled off in a shady spot, with the engine running. Depending on whether the mower was completely still (or drifted a bit) left the tell-tale imprint on the plant's leaves. The really easy remedy? Park in the opposite direction, so that the exhaust discharged away from the shrubs. Problem solved, to the benefit of plant and human.

CASE STUDY THREE:

Plants were wilting and/or defoliating in midsummer, even when adequately watered by hose-mounted sprinklers or watered by hand. Landscape managers were paying attention to rainfall deficits and ground moisture, and making sure that employees were watering on an appropriate schedule but not saturating soils to the point of wet feet. It had been an excessively hot and dry summer, but the staff were resolute to keep up with the watering through that dusty season. Directives were precise as to length of watering time per plant, and to the rotation of sprinklers and personnel attending to them.

But they had black hoses, and when left laying in the hot summer sun, water in them was reaching exceeding high temperatures. Especially when timers turned off and water wasn't moving, or when the faucets were turned off during lunch or break times. Hot water on plant foliage can be devastating and doesn't match up with many of the normal things that horticulturists look for.

Burnt hands, on the other, raise all kinds of "red" flags, and ultimately clued everyone in to the problem. Running the hot water out of the hose till cool water was felt solved this dilemma, and plants recovered from the inadvertent scalding baths.

You just never know what will come around the corner next.

Thanks to VV and everyone else for your insights.

Sorry, I didn't think to take photos before I removed the viburnum. But when I had removed all the upper growth, and started on the root, I found that at least half the trunk at ground level was the consistency of dry rot.

While we've had unusual weather patterns in the past, the spring this year was particularly challenging. May was unusually warm, June was unusually cool. And throughout, there was rain, rain, rain. The poor thing must have had wet feet for at least two months. The shrub was well off the lawn, in the border; I use no chemicals in the garden except for beetle traps and their kin.

I found a photo from May 28, 2009, that shows the left half of the shrub. It's about 3 feet off the lawn, and 8 feet inside the wooden fence. As you can see, the growth looks promising at this point.

That sounds like a good part of the trunk had long been dead, but that there had still been some intact cambium layers that allowed some up/down transport (till this summer).

Without additional information, it could have been the activity of borer larvae tunneling around or gnawing animals having a meal at the 'Mohawk's expense. Observation of old plants around here reveals that both occur. I'm not sure that there is an absolute remedy.