You don't want to be underneath this mistletoe: the Eastern Spruce Dwarf Mistletoe


by Fred Baker, Emeritus Professor and Forest Pathologist, Utah State University

Eastern spruce dwarf mistletoe is a disease that kills trees quickly, with most trees dying within 20 years. In Minnesota, this mistletoe typically affects black spruce, an important species to the state's forest products industry and landscape.

The dwarf mistletoe disrupts a tree's physiology in incredible ways. The most common sign is the formation of a witches' broom. In this process, the disease diverts the tree's nutrients to the broom and "starves" the rest of the tree. Ultimately, the tree will die because it's unable to process the lipids it needs to survive.

Witches brooms in a dwarf mistletoe-infested black spruce stand. Photo: Brian Anderson.

Dwarf mistletoe is a parasite. It flowers in March and is a safe bet to be the first "plant" to flower in the spring. Seed dispersal happens in late August and early September. When seeds disperse, dwarf mistletoes are unique because they can shoot their seeds up to 55 feet from a diseased tree! These seeds are covered with a sticky substance that attaches to a nearby spruce needle. During summer rainfall, this sticky substance rehydrates, and the seeds slide closer to the twig, where it germinates the following spring.

Although dwarf mistletoe can shoot seeds up to 55 feet, most only go a few feet. This results in a spread rate of about 2.4 feet per year through a forest stand. Research indicates that spread from large trees and small trees is about the same. Slightly more than half the spruce stands in Minnesota are thought to be infected with dwarf mistletoe.

Mistletoes are obligate parasites. This means that if you kill the tree, the parasite dies too. If timber harvesting is done in black spruce, removing all spruce trees during a harvest could minimize the risk of mistletoe infecting a future stand.

  691 Hits
691 Hits

ACD Leads the Way on Rare Plant Conservation in Minnesota

Birds-eye view of volunteers planting rare lance-leafed violets at Blaine Wetland Preserve

Anoka Conservation District (ACD) has partnered with the Minnesota Landscape Arboretum (MLA) and Critical Connections Ecological Services (CCES) to salvage thousands of rare lance-leafed violets (Viola lanceolata)—a Minnesota State Threatened species—from permitted construction sites in Blaine, MN. Thanks to the new MN Department of Natural Resources 'Permit for the Propagation of Endangered or Threatened Plants', volunteers and staff from the City of Blaine, ACD, MLA, CCES, and the surrounding community were able to take these rare plants, clean them to remove weed seeds, and then transplant them into the protected Blaine Wetland Sanctuary. The newly planted lance-leaved violet populations will be monitored over time to determine the effectiveness of transplanting.  

Opened seed head of the lance-leafed violet (Viola lanceolata)

"Salvaging threatened and endangered plants from development projects where they would otherwise be destroyed provides an important opportunity to explore transplant options and to collect critical information about these rare plants. We aim to develop salvage and management protocols and monitor the efficacy of transplanting rare plants," said Carrie Taylor of the Anoka Conservation District.

"We have seen the destruction of many rare plant populations over the past couple of decades due to development. We are grateful for the MN DNR's new 'Permit for the Propagation of Endangered and Threatened Plants' so that we can move these plants to protected areas and learn how best to manage them," said Chris Lord, of the Anoka Conservation District. 

(From left to right) Carrie Taylor, Amanda Weise, and Jason Husveth--architects of the Rare Plant Salvage project

Anoka County is home to many unique habitats and rare species. However, development is rapidly increasing in the County, causing fragmentation of the landscape and threatening rare plant populations. The construction sites received a DNR permit that allows for the 'Take of Endangered or Threatened Species Incidental to a Development Project.' As part of that permit, a compensatory mitigation is paid to fund activities that result in a net-benefit to the species. When the 'taking' or removing rare plants from a development project area is unavoidable, rare plant salvage is an alternative conservation practice undertaken to transplant those plants that would otherwise be destroyed. Jason Husveth, principal ecologist with CCES, credits the developer, The Excelsior Group, for helping to make this happen despite incurring addition time and cost.

While salvage of rare plant species occurs in many states, there is no established process for doing so in Minnesota. Critical Connections Ecological Services, Anoka Conservation District, and the Minnesota Landscape Arboretum are seeking funding to develop an ongoing Rare Plant Salvage Program for Minnesota.

  1002 Hits
1002 Hits