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Home > Plants, Pests & Pest Control > Pest Management > Invasive Plant Pests > Pathways Survey

Pathways Survey for Early Detection of New and Emerging Pests


What is the Pathways Survey?

The Pathways Survey monitors for invasive pests and pathogens in our local agriculture through a combination of pheromone-baited insect trapping and visual inspection. Minnesota Department of Agriculture (MDA) staff visit survey sites biweekly throughout each growing season to monitor for pests and pathogens and interact with growers. The Pathways Survey was first conducted in 2014 and has been repeated each year since. Funding for this multi-organism, early detection survey comes from the U.S. Department of Agriculture (USDA) Farm Bill.

Who is Involved?

The survey is conducted at community gardens, community supported agriculture (CSA) farms, and small immigrant farms across Minnesota in both urban and rural areas. Emphasis is placed on population centers, where new pests are likely to be introduced due to the number of pathways by which invasive species can be moved by humans.

How is the Survey Conducted?

The MDA works with the USDA and the University of Minnesota (U of M) to identify insects and pathogens that might pose the greatest risk to Minnesota agriculture. Pests are assessed using criteria such as the following:

  • Likelihood of introduction in the near future
  • Host prevalence within Minnesota’s agricultural crops and natural ecosystem
  • Climactic suitability and cold hardiness

Each year, the list of target species that are monitored for in the Pathways survey is revised as new information becomes available.

Pheromone-baited traps and visual inspections are used to monitor for insect species, insect life stages, and host damage. Plants are also inspected for symptoms of plant diseases, and tissue samples are removed from plants showing symptoms of target pathogens for diagnostic lab testing.

Photo by Angela Stoddard, Minnesota Department of Agriculture (MDA).
Leaf symptoms of Clavibacter michiganensis subspecies michiganensis in tomato, photo by MDA.
Bacterial wilt and
canker of tomato
A brown marmorated stink bug trap. Photo by Angela Stoddard, MDA.
Brown marmorated stink
bug trap
Leaf symptoms of late blight on tomatoes, photo by MDA.
Late blight in tomato

What happens after a detection?

Not all pests pose the same level of threat to Minnesota agriculture; as such, when a pest is found our response varies.

  • Some pests are not regulated. If we find pests that are not regulated, we focus on education and outreach to growers about the pest(s) of concern.
  • Some pests are regulated, either locally or federally. If we find pests that are regulated, a number of things could happen, including:
    • Restrictions on the movement of plants and goods
    • Limitations on exports
    • Efforts to control and/or eradicate the pest(s)

In addition to education, outreach, and potential regulatory consequences upon finding a new pest, the MDA also works to track pests after they have arrived in Minnesota to determine their spread and scope within the state.

Survey Finds by Year

In 2014, the following organisms were included in the survey: golden twin spot moth (Chrysodeixis chalcites), Swede midge (Contarinia nasturtii), old world bollworm (Helicoverpa armigera), tomato fruit borer (Neoleucinodes elegantalis), bacterial wilt and canker of tomato (Clavibacter michiganensis michiganensis), Goss's wilt and blight of corn (Clavibacter michiganensis nebraskensis), bean bacterial wilt (Curtobacterium flaccumfaciens), cucumber green mottle mosaic virus, cucurbit beetle (Diabrotica speciosa), stem and bulb nematode (Ditylenchus dispaci), fruit piercing moth (Eudocima fullonia), brown marmorated stink bug (Halyomorpha halys), late wilt of corn (Harporphora maydis), wheat bug (Nysius huttoni), downy mildew of basil (Peronospora belbahrii), downy mildew of corn (Peronosclerospora maydis), late blight of tomato/potato (Phytophthora infestans), large white butterfly (Pieris brassicae), downy mildew of cucurbits (Pseudoperonospora cubensis), southern bacterial wilt (Ralstonia solanacearum Race 1 and Race 3 Biovar 2), brown stripe downy mildew of corn (Sclerophthora rayissiae var zeae). A total of 66 sites were monitored during 2014. The only target organism found during this year was basil downy mildew which was confirmed at multiple sites.

In 2015 the organisms targeted were similar to 2014, but old world bollworm was discontinued because of concerns that the traps were too attractive to pollinators common near vegetable farms and gardens. Spotted wing drosophila (Drosophila suzuki), blueberry maggot (Rhagoletis mendax) and clubroot (Plamodiophora brassicae) were added as targets. This was the first year that traps were used for brown marmorated stink bug monitoring in Minnesota. The targets detected during 2015 were bacterial wilt and canker of tomato (Clavibacter michiganensis subsp. michiganensis), late blight of tomato and potato (Phytophthora infestans), and spotted wing drosophila (Drosophila suzukii). Bacterial wilt and canker of tomato (CMM) was found in 16 counties. This pathogen is not regulated in Minnesota but can cause significant loss and further spread could impact commercial growers of tomatoes, peppers, and other solanaceous plants. Late blight of potato and tomato was detected at the end of the season in tomato crops in two counties. This disease can be a concern particularly for potato growers if the pathogen is able to overwinter in potato tubers in the ground or in cull piles. The MDA will continue to monitor for late blight, paying close attention to the seasonal timing and host species of any new detections. Spotted wing drosophila (SWD) was monitored in a separate U of M-affiliated MDA program via a dedicated network of small fruit grower volunteers. The traps set by Pathways inspectors broadened the scope of SWD monitoring and identified SWD activity in three additional counties in community gardens.

In 2016, vineyards were added to the survey and a total of 101 sites (nine primarily producing berries, eight primarily producing grapes and the rest mostly vegetables) were monitored during the growing season. The following organisms were added to the list of targets: Pierce's disease (Xylella fastidiosa), Australian grapevine yellows (Candidatus Phytoplasma australiense), allium leafminer (Phytomyza gymnostoma), spotted lanternfly (Lycorma delicatula), leek moth (Acrolepiopsis assectella), European grape berry moth (Eupoecilia ambiguella) and European grapevine moth (Lobesia botrana).During the course of the 2016 survey season, bacterial wilt and canker of tomato (CMM) was detected in 21 samples at eighteen sites in community gardens, CSAs, and immigrant farms in five counties. Prior to 2015, when this survey first detected CMM in Minnesota, it was unknown how frequently this pathogen occurred in Minnesota vegetable growing farms and gardens. Follow up monitoring in the subsequent years and providing the findings to affected sites has helped them to better understand and manage the pathogen. One pathogen of the Brassica group was detected, Plasmodiophora brassica (clubroot). Clubroot was detected in one sample from a garden site in Ramsey county. This is the first time that clubroot has been reported in Minnesota to our knowledge. In this instance the plant affected was mustard, but there are concerns about impacts of clubroot on other, more economically important crucifers in Minnesota. This find bring additional attention to this pathogen and will hopefully help to avoid any growers being surprised by it in the future. Swede midge was detected at one site in Hennepin and one site in Ramsey County. These are the first confirmations of this insect in Minnesota and potential impacts on growers of susceptible crops are substantial. These finds bring awareness to these potential impacts and provide the impetus for additional monitoring and outreach efforts to prevent any growers from being surprised by damage from this insect. Brown marmorated stink bug was found at one site in Dakota County. Minnesota is at high-risk from this insect and monitoring efforts have detected population increases over the last year. This continues to be a very important pest for growers of fruits and vegetables. Spotted wing drosophila was found at 22 sites in 13 counties. This insect is having major impacts on growers of soft fruits in Minnesota. Monitoring through this survey helps to bring awareness to growers of how to monitor which is key to knowing when to begin management efforts to avoid impacts.

In 2017, a total of 70 sites are being monitored with apple orchards being included in the mix this year. Twenty sites are primarily orchards, thirteen are primarily vineyards, nine are primarily berry farms and the rest are primarily vegetables. A related project is monitoring an additional 25 vegetable farms for high priority targets such as Swede midge. New pests added to the list this year are Egyptian cottonworm (Spodoptera littoralis), cotton cutworm (Spodoptera litura), Japanese beetle (Popilla japonica), several Candidatus Phytoplasma and Rotbrenner disease (Pseudopezicula tracheiphila).

How To Help

The Pathways survey allows for meaningful interaction between growers, the public, and the MDA in regards to invasive species. It is our hope that the survey will continue to facilitate a partnership with the community to protect our local agriculture systems. Additionally, an early detection of a new pest provides the best opportunity for mitigating its impact on our state.

Last Updated: July 21, 2017