From the Director's Desk: Update on Oak Wilt and Landis

By Fred Breglia

Oaks are our lega­cy here at the Lan­dis Arbore­tum, what with the land orig­i­nal­ly known as Oak Nose Farm” after the 500-year-old Great Oak” that once stood over­look­ing the Schoharie Val­ley. Oaks are a big part of our func­tion­ing ecosys­tem, which includes plants, fun­gi, and wildlife. When the approach of oak wilt was report­ed, we stood by hop­ing it would not reach the Arbore­tum, and so far, so good. That being said, oak wilt has been iden­ti­fied in neigh­bor­ing Sch­enec­tady County.

Bretziella fagacearu
Bret­ziel­la fagacearu 

Oak wilt is a sys­temic, lethal dis­ease caused by the fun­gus Bret­ziel­la fagacearu (pre­vi­ous­ly known as Cer­a­to­cys­tis fagacearum). The fun­gus is spread via root grafts and bee­tles feed­ing on sap at open wounds or on the leaves of healthy trees. Once inside the tree, the fun­gus begins to repli­cate, even­tu­al­ly pre­vent­ing the uptake and move­ment of water. Symp­toms of the dis­ease first appear near the top of the canopy. The out­side of the leaves turn bronze, brown, or dull green, usu­al­ly start­ing at the top of the leaf, while the base of the leaf remains green. Some leaves curl and begin to drop soon after symp­toms appear.

It is more like­ly to affect red oak than white oak. An infect­ed red oak typ­i­cal­ly dies with­in two months, while a white oak can live with the dis­ease for sev­er­al years. If infect­ed, a tree will begin to show symp­toms in mid-summer.

In the past, pre­ven­ta­tive mea­sures includ­ed trench­ing between tree roots, prun­ing only dur­ing hard win­ter, and remov­ing dis­eased trees. Today, focus­ing on reduc­ing mono­cul­ture plant­i­ngs, restor­ing soils, and apply­ing fungi­cides in urban envi­ron­ments are proven to be more effec­tive. It is impor­tant to note that there are ways to con­trol” the dis­ease rather than just con­tain” it. Con­tain­ing it means to cre­ate a bar­ri­er and hope it doesn’t spread. Con­trol­ling the dis­ease takes more effort and involves going with­in the bar­ri­er to remove the oaks, allow­ing native species to regrow. In essence, you woule remove all oaks, espe­cial­ly in a mono­cul­ture set­ting.

Oak wilt could impact Landis. 

At Lan­dis, we have sev­er­al species of trees and plants mixed in with our oak forests, which would prove help­ful in mit­i­gat­ing the spread of the dis­ease should it occur. While our his­toric oak col­lec­tion is at risk as the roots make con­tact, they are also mature and strong, which might help them sur­vive. Sad­ly, if oak wilt were to occur at Lan­dis, in essence, we would remove all oaks from our prop­er­ty in order to pre­vent the spread of the dis­ease to oth­er locations.

There is hope, how­ev­er. Oak wilt was recent­ly found in South Bris­tol, NY (Ontario Coun­ty). After removal of infect­ed trees and root trench­ing efforts to pre­vent spread­ing, the dis­ease site is now receiv­ing a clean bill of health. Work­ing togeth­er, the Depart­ment of Envi­ron­men­tal Con­ser­va­tion and the landown­er were able to erad­i­cate the dis­ease and pre­vent neigh­bor­ing forests from being destroyed as well.

We will con­tin­ue to mon­i­tor the sit­u­a­tion, con­tin­u­al­ly check­ing the health of our oaks. While we hope no action will be nec­es­sary, we also are com­mit­ted to pre­serv­ing the greater for­est envi­ron­ment, both inside and out­side the Arbore­tum boundaries.

Summer 2019

Volume 37 , Number 2

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