Fungal diseases bloom in cool, wet spring – Medford News, Weather, Sports, Breaking News

Hardy sycamores also struggle with southern Oregon’s heat and drought

[Photo by Rhonda Nowak] A sycamore with anthracnose, a fungal disease, has fewer new spring shoots. The disease will stop spreading with warmer temperatures and new leaves will develop.

[Photo by Rhonda Nowak] Spots on this sycamore leaf indicate infection with anthracnose, a fungal disease.

“For an enormous plane tree, indeed, with a whitish and gnarled trunk, thicker than that of any other in the garden and, I believe, of the whole province, the admiration (of Micol Finzi-Contini) bordered on reverence.” – Giorgio Bassani, “The garden of the Finzi-Contini”, 1962

While waiting their turn to play on the tennis courts during the warm autumn of 1938, Giorgio Bassani, author and narrator of his semi-autobiographical novel, “The Garden of the Finzi-Contini”, and Micol Finzi-Contini explored his family’s 20-acre garden by bicycle. Micol was particularly fond of the many trees in the park, some of which had dominated the landscape for centuries. She liked to ask her companion about his knowledge of trees and made fun of him for his ignorance.

Bassani writes: “It seemed to him absurd that there could exist in the world someone like me, who did not feel for the trees, ‘for the tall, calm, strong, pensive trees’, his own feelings of passionate admiration .

Micol liked to believe that the giant plane, or sycamore, tree in the garden had been planted by his aristocratic ancestor, Ercole I d’Este, Duke of Ferrara (1431-1505). “It’s almost 500 years old,” Micol told Bassani. “Imagine what he must have seen, how many things, since he was born!”

Reviewing the film adaptation of the 1970 book, the late film critic Roger Ebert wrote in 1971 that Micol seemed to believe that if the sycamore “has stood all these years in this garden, there’s cause for concern in the world outside?” Micol, and the rest of the Finzi-Contini family, could not imagine the horrific outcome of Mussolini’s fascist regime.

Micol’s cherished plane tree could have seen half a millennium go by as these deciduous giants, which can grow to over 100 feet, are known for their longevity. An Old World sycamore tree (Platanus orientalis) in Crete is estimated to be around 2,400 years old based on the circumference of its huge, gnarled trunk that spans over 78 feet.

It is not uncommon for healthy sycamores to live over 500 years. In Ferrara, where Bassani’s novel is set, there are still a few Old World sycamores that were planted during the second half of the 16th century and the first decades of the 17th century.

American sycamore (Platanus occidentalis) is native to eastern and central regions of North America where it often grows in riparian and moist areas. However, this species was planted extensively as an ornamental shade tree in my east Medford neighborhood in the late 1940s and early 1950s.

I have two sycamores in my garden that are about 70 years old. Towering over maples and fruit trees, they provide much-needed protection during the hot summer months. We depend on these two vigorous trees to keep our air conditioning bill from skyrocketing in July and August.

I agree with Micol Finzi-Contini that our sycamores provide a feeling of reassuring stability. They stood guard over this house as its various occupants came and went. Imagine what the trees must have seen — how many things — since they were born!

Unfortunately, the feeling of comforting permanence that my sycamores give me may be as mistaken as that of the Finzi-Contini. My two sycamores, as well as the sycamores in my neighbors’ gardens, are suffering from anthracnose, a fungal disease that causes leaf drop, twig dieback, and the sudden death of over 90% of new tree growth. American sycamores are more susceptible to anthracnose than P. orientalis or P. x acerifolia, the London plane.

Other common shade trees that often have anthracnose include ash, birch, black walnut, elm, maple, and oak.

Our cool, wet spring provided ideal conditions for anthracnose to flourish, so now, in mid-June, my trees have much less leaf than normal. Every day I collect small young leaves covered with yellow spots and brown angular spots along the leaf veins. Every day I look up at the sparse canopy of trees and worry about the protection the sycamores will be able to provide during triple-digit temperatures this summer.

It turns out, however, that anthracnose rarely causes the death of trees. Leaf spots and distortion do not cause permanent damage to trees. Fungicides, which are difficult to apply effectively to large trees and require precise timing, are not needed unless the trees have been nearly completely defoliated from anthracnose for several consecutive years.

The best way to manage anthracnose is to reduce the stress on the infected tree as much as possible. It is important to recognize that fungal pathogens, including anthracnose, are always present in the environment. Healthy trees resist disease better, while stressed trees, like my heat and drought stressed sycamores, are more vulnerable. When my sycamores were planted 70 years ago, prolonged summer heat waves and winter dry spells were less common than they are today.

During hot and/or dry periods, it is a good idea to provide additional water even for established trees. Although the root systems of my sycamores extend several feet below the soil surface, most of the small, moisture-absorbing feeder roots are in the top 12 to 18 inches of soil. The root zone of these 60+ foot trees extends throughout my garden, so my sycamores take advantage of them every time I water the garden plantings thoroughly.

Besides watering when needed, other anthracnose management strategies include raking and removing dead leaves (I don’t use them for compost or mulch), and pruning trees to get rid of infected twigs and branches and to increase sunlight and air circulation throughout. the tree canopy.

The anthracnose is not going away and the weather will likely continue contributing to less than ideal growing conditions for my sycamores. They may not live as long as Micol Finzi-Contini’s beloved plane trees, but I will gratefully take refuge in their shade for as long as possible.

Rhonda Nowak is a Rogue Valley gardener, teacher, and writer. See Literarygardener.com or email him at Rnowak39@gmail.com.