Garden Notes : Trees for West Tisbury?
The demise of the elms has left West Tisbury town center bereft of their sheltering presence and looking barren. Their disappearance, like the loss of old friends, saddens me, and many of my fellow townspeople as well. The trees were but a remnant of a once-lengthy tunnel of stately elms in West Tisbury, planted possibly just after the Civil War. This visual feast of trees used to stretch from the store to the garage, and out along Music Street as well - the heart, soul and lungs, figuratively and literally, of town.
While the taxpayers over the years have spent large sums to treat and maintain the elms, undoubtedly disease and the coincidence of the town hall renovation provided the rationale for doing away with them. Though a street lined with American elms is a tough act to follow, still it is my earnest hope that planning and funding are underway to replant and recreate the next generation of shade trees for a leafy, well-treed town center.
Photo by Susan Safford
Speaking of tough, "street tree" is a tough job description. Parameters for street trees are different than for yard trees: they must fit where sited and also with respect to overhead wires or two-story tour buses. Street trees must tolerate pollution; heat; dry, compacted, or poor soils; road salt - conditions generally harsh and inhospitable to large, long-lived green organisms. Nonetheless much has been done in recent years to find, select, or breed trees that are up to the job.
Genera that I would be looking at, as possible replacements for the West Tisbury trees, or other situations where a street tree is needed, would include lindens (Tilia), sycamores (Platanus), zelkovas, oaks (Quercus) and elms (Ulmus). Maples, while beautiful and beloved by many and especially so at this time of year, are shallow rooted and as a genus are one of those most at risk from climate and air quality changes; as street trees they are currently a poor investment.
Photo courtesy of the Martha's Vineyard Museum
Tar spot on maples
Thanks to an Oak Bluffs resident for the inquiry about tar spot on Norway maples, which has been prevalent this season. The UMass Extension landscape message had this to say about it:
"Tar spot on maple is visible on Norway maple leaves as black, tar-like fruiting structures massed within rounded, yellow-tan leaf spots. Spores from the fungus, Rhytisma [acerinum], infected the developing leaves last spring when there were extended periods of mild, wet weather. This provided optimal conditions for the Rhytisma fungus to infect the leaves. Tar spot infections do not threaten the fitness of an otherwise healthy tree. Most of the leaf area remained green throughout the summer, so the tree had plenty of leaf area to photosynthesize and produce what it needs to thrive. Reduce the potential for next year's infections by collecting and disposing of diseased leaves as they fall. This reduces the amount of inoculum available when conditions are cool and moist next spring and the fungus spores released from the fruiting structures can infect young maple leaves. Except to preserve the appearance of high value trees, applications of protective fungicides are unnecessary."