This site is for people who like plants -- growers, enthusiasts, aesthetes, novices and professionals, those who appreciate wild things and those who appreciate the cultivated. I garden in Chelsea, and I've been visiting people's yards for 20+ years in the course of my work. My goal is to make this blog a community project, so if you share my interests, please consider becoming a participant and contributing content -- Guerin. Info: firstname.lastname@example.org
Thursday, May 3, 2012
Big bad diseases on landscape conifers
I suppose something should be said about spruce trees which are declining in great numbers throughout our area. The situation is a complicated mess. A number of fungal agents appear to be involved, and questions remain as to which are causal agents and which are incidental. Until a few days ago, we were happy to lump them all together as 'needlecast' diseases, in hopes that a few judiciously timed sprays each year would keep the problems at bay. Thus it was disconcerting to read the following headline in a recent bulletin from Michigan State University Extension: "Michigan awash with Phomopsis cankers on spruce trees." The bulletin continues to state that "we now know that a group of Phomopsis strains of unknown species are at the center of the current landscape spruce problems . . and is now causing mature tree defoliation, branch death and, in some cases, tree death." Making things more difficult is the fact that symptoms appear much like needlecast, and it is necessary to skin off a lot of thin bark to determine the presence of the canker. The final paragraph begins "it appears we are in a cloud of Phomopsis spores, the likes of which we have never seen before." Trying to treat spruces with fungicides is becoming a shot in the dark.