Dirr calls the little leaf linden 'small-leaved limes'.
Yes much more common in europe; see below for text since no pdf's here.. Typical for these to hollow out; tap tap!
“Let’s head out while it’s still light,” I changed the subject as I shouldered my diagnostic kit. “We’ve been asked to inspect a grove of young trees. On the way, we can look at local landscapes and learn about Czech arboriculture.”
“That’s our idea of a vacation.” Ashley shook her head as she paid the bill.
As we strolled down the avenue toward the capitol building, Codit played tour guide. “The Czech national tree is the linden and, as a historical symbol of freedom and independence, it has been overplanted. Unfortunately, lindens are susceptible to damage in areas with salting and temperature extremes and heavy air pollution.”
“This bigleaf linden, Tilia platyphyllos, has red twigs, so the cultivar is called ‘Rubra’. The species can hybridize with littleleaf linden, Tilia cordata, to create Tilia x europaea, also known as Tilia x vulgaris, the common lime tree. This natural hybrid is vigorous, growing taller than both its parents,” Codit continued.
“So is it called the mediumleaf lime? And where is the fruit?” Electra’s eyes sparkled electrically as she nudged Codit in the ribs. Spring was in the air.
“You’re full of ‘vulgaris ’ humor this evening, aren’t you, Electra?” Ashley’s bright blue eyes glinted. “The name more likely comes from the genus’ preference for alkaline soils, which originate from limestone parent materials. Speaking of bedrock, I wish I could get the power lines in our city buried like they do here, but we lack the budget”
I pulled down a branch and bit off a leaf. The three of them eyed me oddly. “Young lime tree leaves make an excellent snack. Not as much flavor as sassafrass, but a very pleasant texture,” I said, as I chewed it over.
“Now’s the time to try them, if you must,” Ashley said, studying the tree while looking askance at me. “I see no aphids yet, so there’s no sooty mold. Ants can be an effective biocontrol for aphids. There’s not much soot from combustion either, internal or external.” I didn’t need the report, but it’s good for a loose cannon to have someone chock his wheels once in a while.
We walked under an ancient archway and up to an allee’ of young Tilia cordata. “These are the trees,” I said grimly, setting down my diagnostic kit. “What do you see?”
“Look at those orange streaks on the stems,” Codit noted. “The color is similar to the woundwood forming in those bark crevices years after we excised Armillaria infections on Quercus alba back home. Could the bark have been damaged by rough handling, and now it’s sealing the injury?”
“Maybe the coloration is from hybridization,” Electra speculated. “If ‘Rubra’ has red twigs, maybe the bark is getting reddish due to the same kind of hybridization”
“Could it be that the salt used on the sidewalk splashed onto the bark, or other pollution, or are girdling roots squeezing the circulation?” Ashley wondered as she dug with my trowel. “Scratch that last hypothesis —the flare looks good.”
“Let’s look higher, then,” I said, pulling off more leaves to chew.
“Gosh, all that tufted growth on the stem looks like witches’ broom,” Codit said. “That could have been caused by insect oviposition, mites or mistletoe.”
“Could be a virus, fungus, or phytoplasma,” Electra conjectured. She and Codit huddled together as they examined the growth with their hand lenses.
“Maybe it was hormones,” Ashley said, eyeing Codit and Electra. “If cytokinin interferes with auxin’s suppression , those dormant buds can grow like gangbusters. What do you think, Dendro?”
“I think it’s getting dark, so we should go back to hear some more music, and then sleep on it,” I said, spitting the leaves into my hand and looking them over. “We have several good theories, and the answers are in our sight—and in some cases, on our persons. Tomorrow we’ll meet with the forensic arborist who referred us. He may have clues you can use to crack this case.”
Do our diagnosticians have the answers? Turn to page gazillionty seven for the answer.
The next morning dawned brightly—too brightly. I rolled over to escape the glare, and met the floor head-on. I figured things could be no worse outside, so I grabbed my gear and sped to the jobsite. My Czech colleague was feeding the crew fresh kolaches, apple-filled pastries, and steaming mugs of coffee. Things were looking up.
“We saved one for you, Dendro,” Jack smiled as he handed me the last kolache. The spicy sweet smell of apples kicked my mind into gear. “Your crew tells me that they gathered a lot of data yesterday, but could not solve the mysteries of the burnished bark and the sprouting stems. Should I give them more information?”
“Ymfgd,” I bobbed my head up and down as I wiped apple filling off my chin. Ashley rolled her eyes.
“I was called as a forensic expert to decide whose fault this problem was. These trees were planted two years ago, with the stems covered by rattan. After eight months, the contractor removed the covering. The following winter was very mild with quick temperature changes. The bark damage is on the southwest side of the stems. The company was found liable because of lack of stem protection."
“But Dendro, you looked at the chewed leaves in your hand and told us that the answers were on our persons,” Ashley said. “What did you mean?”
“Your cheeks, dear Ashley, were sunburned after they lost their covering.” I gazed at her, and her cheeks reddened all the more. “Our ANSI standards only mention protection during transplanting, not afterward. The ISA’s Best Management Practices state that ‘Where sunscald or frost cracks are common, trunks of thin or smooth-barked trees are wrapped to prevent injury from the winter sun.’ Sunscald is a major problem in the USA. Despite the BMP’s we hesitate to protect our young trunks because trunk wrap can harbor destructive insects and create temperature differentials. Your rattan shields are fascinating. The air space between them and the stems does not provide habitat for pests. If these shields are standard procedure here, like specialized dressings that your government approves on certain wounds, we may be able to learn something from your practices.”
“They look nice, too.” Codit and Electra said as one.
“Thank you,” Jack said. “Also, according to our practices, an aggravating factor in these trees’ condition is the lack of thinning. Our publications recommend that interior twigs be removed per need to lessen the imbalance between water uptake and transpiration, which can mean decreased vitality of the whole crown. This is generally accepted in our conditions, so they also call for removing some of the epicormic shoots in the lower part of the crown .”