Research priorities

The Minnesota Invasive Terrestrial Plants and Pests Center (MITPPC) uses a prioritized funding model to identify terrestrial invasive species that pose the greatest threat to Minnesota. This guides how to direct limited funding resources for research. The goals of our approach are to be fair, transparent, and responsive in our assessment of terrestrial invasive species that threaten Minnesota.

We focus on terrestrial invasive invertebrates (like insects and earthworms), plant pathogens (viruses, bacteria, fungi, phytoplasmas, nematodes, and parasitic plants), and plants that harm valued plants. The top 15 most highly rated in each category are the species we prioritize for future research projects through a regular  request for proposals.

How we rank invasive species

We use a systematic, science-based ranking system to evaluate terrestrial species of concern. The process has 17 criteria that would be most useful to measure the threat an invasive species might pose to Minnesota if left unmanaged.

Each species is rated for each criterion. We then put all the ratings into a computer program that calculates an overall ranking for a species, relative to all other species evaluated. The higher the ranking, the greater the threat a species may pose.

Ranking criteria

Some examples of the criteria used to rank species include:

  • Suitability of Minnesota climate
  • Presence of hosts/habitats in Minnesota
  • Annual reproductive potential
  • Negative impacts to recreation or real estate in Minnesota
  • Negative impacts to ecosystem services

Species evaluations

When we evaluate a species for the potential threat it poses to Minnesota, we make the compiled information available for anyone to access. If new information becomes available or ratings change, we’ll update the evaluation document. We have evaluated over 210 species.

View all MITPPC evaluations

Updates to the rankings

We continually evaluate additional species and refine our process for completeness and accuracy. At least every 2 years, we update our list of rankings. The update reflects new species that have been evaluated and any new information that may affect the ratings of previously evaluated species. We welcome your feedback to inform these updates. 

Comment on an existing evaluation

Submit a new species for evaluation

Detailed description of our process

screenshot of the first page of the prioritization research paper

The following paper provides deeper insight about our prioritization methods and results. It is free to download: 

A participatory method for prioritizing invasive species: Ranking threats to Minnesota's terrestrial ecosystems (Journal of Environmental Management, 2021)

Top-ranked species

The following tabs list the species (or groups of species) of plants, plant pathogens, and invertebrates that our process has currently ranked as top threats. These species are eligible for funding from MITPPC.

The lists also include links to the evaluation document for each species that describes the information used in calculating their rank.

Top-ranked plants and evaluations listed alphabetically by scientific name
Scientific name Common name and evaluation link
Amaranthus palmeri Palmer amaranth evaluation
Berberis x ottawensis (B. thunbergii x B. vulgaris) Ottawa barberry evaluation
Bromus inermis; Poa pratensis Smooth brome evaluation; Kentucky bluegrass evaluation
Centaurea stoebe subsp. micranthos; C. diffusa Spotted knapweed evaluationdiffuse knapweed evaluation
Cirsium arvense Canada thistle evaluation
Euphorbia esula Leafy spurge evaluation
Frangula alnus; Rhamnus cathartica Glossy buckthorn evaluation; common buckthorn evaluation
Gypsophila paniculata Baby’s breath evaluation
Lonicera maackii; L. morrowii; L. tatarica; L. japonica Amur honeysuckle evaluation; Morrow's honeysuckle evaluation; Tatarian honeysuckle evaluation; Japanese honeysuckle evaluation
Lupinus polyphyllus Large-leaved lupine evaluation
Microstegium vimineum Japanese stiltgrass evaluation
Phragmites australis subsp. australis European common reed evaluation
Robinia pseudoacacia Black locust evaluation
Tanacetum vulgare Common tansy evaluation
Typha x glauca; T. angustifolia Hybrid cattail evaluation; narrow leaf cattail evaluation
Plant pathogens
Top-ranked plant pathogens and evaluations listed alphabetically by scientific name
Scientific name Common name and evaluation link
Aster yellows phytoplasma

Aster yellows evaluation

Ceratocystis fagacearum Oak wilt evaluation
Cronartium ribicola White pine blister rust evaluation
Geosmithia morbida Thousand cankers disease evaluation
Globodera pallida; G. rostochiensis Pale cyst nematode evaluation; golden cyst nematode evaluation
Heterobasidion irregulare Annosum root rot evaluation
Heterodera latipons, H. filipjevi Cereal cyst nematode (H. latipons) evaluation; cereal cyst nematode (H. filipjevi) evaluation
Hymenoscyphus fraxineus Ash dieback evaluation
Macrophomina phaseolina Charcoal rot evaluation
Ophiostoma novo-ulmi Dutch elm disease evaluation
Phyllachora maydis Corn tar spot evaluation
Phytophthora ramorum Sudden oak death evaluation
Raffaelea quercivora Japanese oak wilt evaluation
Ralstonia solanacearum, Race 3, biovar 2 Potato brown rot evaluation
Tilletia controversa (cereal strain)     Dwarf bunt of wheat evaluation


Invertebrates and insects
Top-ranked invertebrates and insects and evaluations listed alphabetically by scientific name
Scientific name Common name and evaluation link
Agrilus plannipennis; A. biguttatus

Emerald ash borer evaluation; oak splendor beetle evaluation

Anoplophora glabripennis Asian longhorned beetle evaluation
Aphis glycines Soybean aphid evaluation
Dendroctonus ponderosae Mountain pine beetle evaluation
Drosophila suzukii Spotted wing drosophila evaluation
Eupoecilia ambiguella European grape berry moth evaluation
Halyomorpha halys Brown marmorated stink bug evaluation
Helicoverpa armigera Old world bollworm evaluation
Lumbricus rubellus; Amynthas spp. Leaf worm evaluation; jumping worms evaluation
Lymantria dispar dispar; L. dispar asiatica Spongy moth evaluation; L. dispar asiatica evaluation
Popillia japonica Japanese beetle evaluation
Scolytus schevyrewi; S. multistriatus Banded elm bark beetle evaluation; European elm bark beetle evaluation
Sirex noctilio Sirex woodwasp evaluation
Spodoptera littoralis Egyptian cottonworm evaluation
Tetropium fuscum Brown spruce longhorned beetle evaluation


Research priority themes

Funded research projects must address one or more priority species AND one or more of the following priority themes.

Expand all

Theme 1: Detection and distribution of invasive terrestrial species

Strategic and tactical decisions for the statewide management of terrestrial invasive species depend on accurate, detailed information about the geographic distribution of those species.

Currently, many agencies and organizations in Minnesota are gathering information about the distribution of terrestrial invasive species to support internal decision-making. There is a growing recognition of the value of sharing information about the distribution of invasive plants and pests more broadly. Some tools already exist for this purpose. For example, EDDMapS ( has been used as a clearinghouse for terrestrial invasive plant data for some state agencies. Such tools are useful for collecting presence points but do not “connect the dots” to show the complete, potential distribution of an invasive plant or pest. Maps that depict where terrestrial invasive species are present and abundant across the state are essential to coordinate regional terrestrial invasive species management plans and to evaluate the effectiveness of the activities conducted under those plans. 

Some terrestrial invasive species may not be reliably detected with typical approaches. Ground-based surveys are time and resource-intensive and are frequently limited to relatively small areas. Aerial surveys for widespread woody species, such as buckthorn, have been attempted but have yielded too many false positives to be useful. New approaches to reliably detect and identify priority species are needed.

Theme 2: Response of invasive terrestrial species to future conditions

Temperature and moisture conditions, land use patterns, and global trade activity in Minnesota have been changing over the past 100 years and are projected to continue to change. Each of these future conditions can directly or indirectly affect the distribution, abundance, and/or impact of terrestrial invasive species that are already present or might arrive in the state. Tools are needed to describe which terrestrial invasive species are likely to become more widespread, abundant, or damaging and which are likely to experience geographic range contractions, become less abundant, or have less impact in the next 30–100 years. These descriptions should be as spatially explicit as possible.

Theme 3: Effectiveness of management alternatives for invasive terrestrial species

A variety of cultural, physical, mechanical, biological and chemical approaches are being used alone and in combinations to control terrestrial invasive species in Minnesota. Invasive species managers face a two-part challenge when choosing a course of action.

First, managers must contend with difficult questions about what constitutes successful management. For example, while the timely application of appropriate herbicides is likely to kill targeted plants, is the treatment “successful” if seeds are so plentiful that the plant readily re-establishes itself in the following year or if the composition of the plant community does not “improve”? Similarly, at what time- or spatial-scale should management be considered successful, for example, only within the treated area or over the entire range of the plant within the state?

Second, managers frequently have little information about the effectiveness of novel management tactics. For example, the use of large grazing animals (e.g., sheep, goats, and cattle) increasingly is proposed as a strategy for invasive plant management, yet reliable information about the effectiveness of generalist grazers is limited. New control options are needed, and their effectiveness rigorously evaluated, to ensure management goals are being met.

Theme 4: Human dimensions of priority invasive species issues

Socio-economic factors and human dimensions play a major role in the likelihood of new species arriving, the effectiveness of management strategies, factors motivating landowners and others to implement management strategies, and the consequences of new invasions. Research is needed to identify and measure the strength (i.e., propagule pressure) of different human-mediated pathways that might bring new species to Minnesota. This research will inform regulatory decisions to help prevent the arrival of new species and direct early-detection surveys to areas where initial introductions are most likely. 

In addition, decision-support tools are needed to determine the relative effectiveness of eradication, containment, or suppression strategies under various conditions, while accounting for uncertainties in our knowledge about an invading species and/or its response to management. 

More information is needed about the effectiveness of various educational, regulatory, economic, or other interventions to promote the implementation of management treatments by landowners. In other words, once effective treatment options are identified, what strategies are most effective to promote their implementation by landowners? Hypothesis-driven research is needed to understand what motivates landowners to invest in treatments individually or through partnerships. 

Finally, the economic impacts from invasive species frequently depend on micro- and macroeconomic forces and often dictate the appropriate level of investment in a management response. Research is needed to better characterize the realized and potential economic impacts of invasive species in Minnesota and to incorporate this information and associated uncertainties into scalable budgeting tools for management decisions.