Optimizing management of a new invasive species, swede midge, on small-scale organic farms: Part II

Project Overview

Project Type: Partnership
Funds awarded in 2016: $14,999.00
Projected End Date: 11/30/2019
Grant Recipient: Cornell
Region: Northeast
State: New York
Project Leader:
Christine Hoepting
Cornell Cooperative Extension - Cornell Vegetable Program

Annual Reports


  • Vegetables: broccoli, cabbages, cauliflower, radishes (culinary), rutabagas, turnips, brussel sprouts


  • Crop Production: crop rotation
  • Education and Training: demonstration, extension, on-farm/ranch research, workshop
  • Farm Business Management: agricultural finance, budgets/cost and returns, feasibility study
  • Pest Management: cultural control, field monitoring/scouting, mulching - plastic, trap crops

    Proposal abstract:

    Swede midge (SM) is an invasive insect pest that threatens the viability of organic production of Brassica crops in the Northeastern US.  SM is quite small (< 2 mm) and its damage difficult to identify, so it is commonly misdiagnosed.  There is an urgent need to develop effective pest management tools and to conduct outreach/education to familiarize at-risk small-scale organic growers with SM diagnosis and best management practices to protect them from devastating SM outbreaks.  For this project, we seek to build on the success of our first year of study and will partner with 5 small-scale organic farms to continue our work in gaining tremendous insight into the population dynamics of SM as it relates to management practices via intensive pest monitoring, and optimizing the use of newly developed disruption tactics including insect exclusion netting and garlic oil repellant for managing SM. Through our educational and outreach efforts including on-farm demonstrations, informational website, newsletter articles and winter workshops, the majority of organic Brassica growers in the Northeast US will become aware of SM, be able to identify its damage and become knowledgeable on how to manage this pest effectively.  This is the first major outreach program targeting organic growers, and we anticipate that it will launch several more projects that seek to reduce economic losses caused by SM to organic growers. Ultimately, crop failures and economic losses caused by SM will no longer occur and the viability of the organic Brassica industry in the Northeast US will be sustained.

    Project objectives from proposal:

    Our objectives are to:

    1. Advance understanding of swede midge (SM) population dynamics on small-scale organic Brassica farms related to management practices.
    2. Optimize management strategies including newly developed disruption tactics (insect exclusion netting and garlic oil repellent), crop selection and rotation strategies.
    3. Increase awareness of SM and knowledge of its management among at-risk small-scale organic Brassica growers.

    We plan to build on the success of our first year study by partnering again with small-scale organic farms that suffer from SM infestations. Each farm will be a case study where we will monitor the SM population, and trial/optimize management strategies that are appropriate for each farm.


    Due to budget constraints, case studies will be conducted only in NY, which accounts for 79% of organic production of broccoli, cabbage and cauliflower in the Northeastern US. Educational efforts are planned to reach the entire Northeastern US.  This is the first major outreach program targeting organic growers, we anticipate that this project will strengthen relationships among growers, Extension and University researchers, and initiate several more projects that seek to reduce economic losses caused by SM to organic growers.  Ultimately, viability of the organic Brassica industry in the Northeast US will be sustained.

    We will partner with five swede midge (SM)-infested organic farms located in five NY counties, four participated in our project in 2015.

    SM monitoring: Five SM pheromone traps will be deployed on each farm (Fig. 8 & 9), one trap/site.  For example: spring emergence sites (where SM-infested Brassicas grew previous fall), spring, summer and fall Brassica plantings, and Brassica transplant production site.  Monitoring will occur from early-May until mid-October and traps will remain at each site for approximately 10 weeks.  Number of SM adults/trap will be reported to growers weekly.  At crop maturity, SM damage will be rated on a 4-point scale.  When multiple crops/varieties occur, each will be assessed separately.

                    Trap catch and damage information will help grower cooperators make real-time management decisions to the best of our current knowledge and advance our understanding of SM population dynamics as related to management practices.  For example, to indicate when spring emergence has completed and to determine when it is safe to plant a new Brassica crop.  At Fellenz farm, SM monitoring will be critical in their decision whether to restore their once lucrative fall broccoli production, a crop that they abandoned due to SM. Trap catch data from the same farms over multiple years will allow us to test our predictions, monitor annual variability and evaluate efficacy of implemented management strategies over time.  Additionally, to accurately determine completion of spring emergence, we will place our traps under a hand-made inclusion cage made of insect netting to capture only SM that emerge from the soil while excluding those that originated elsewhere.  Similarly, we will place such enclosed traps in the spring at sites where summer-harvested Brassicas were grown the previous year, to determine whether this is a safe rotation strategy.

    Optimizing use of insect exclusion netting (IEN): Some cooperating farmers may adopt IEN with mulch for managing SM, but first secondary benefits/detriments must be understood and optimized accordingly.  Muddy Fingers will trial landscape fabric, hay mulch and white plastic under IEN in fall broccoli to study effects on heat stress.  Hay and white plastic mulches may create a cooler microclimate less favorable for heat stress in the fall.  IEN/mulch trials are still underway as of 10/6/2015 at Canticle (Brussels sprouts) and Fellenz (kohlrabi) farms.  Both farms are expected to trial IEN with fall broccoli in 2016; exact treatments will be determined with growers after 2015 trials are completed. 

                    Due to the small-scale production of Brassicas on organic farms, randomized complete block designed (RCBD) trials with several replications may not be feasible.  Trialing IEN in many on-farm scenarios compensates for our lack of replication and is still highly valuable, as it was in 2015.  Treatments will include a minimum 20 plants/treatment-replicate and 3 replications.  IEN will cover the entire width of bed and be secured to exclude SM (Fig. 11).  A pheromone trap and temperature sensor (Onset Hobo pendant temperature data-logger) will be placed under the IEN in two replicates/treatment.  Traps will be serviced as per the monitoring project.  We will not risk the marketability of grower’s crops; if necessary to remove IEN temporarily/permanently to ensure crop quality, then data will be collected under this real-world situation, as appropriate.  At crop maturity, SM damage will be rated.  Other differences among treatments including plant size, maturity and other pest pressure will be quantified, when relevant. 

    Garlic oil repellant trials: Canticle and Blue Heron farms will host trials evaluating garlic oil repellant 1% (Bulk Apothecary), which will be trialed alone and with surfactants, Nufilm-P (Miller) and Silwet ECO Spreader (Momentine).  Trials will be set up in a susceptible crop (e.g. broccoli) at a site with high risk of SM-infestation. Trials will be arranged as RCBDs with minimum 3 replicates and 20 plants/treatment-replicate.  Treatments will be applied to individual plants to run-off using a spray bottle.  Treatment will commence within 1 week of transplanting and continue weekly until 2 weeks pre-harvest.  At harvest, SM damage will be rated.   

    Post-harvest SM monitoring: Studying SM population dynamics in relation to crop stage of both harvested crop and nearby crops will help us to understand the risk associated with not destroying a crop post-harvest.  Each week after harvest, the stage of the harvested crop with particular attention to development of secondary side-shoots will be recorded, and side-shoots inspected for SM-infestation.  The same data will be collected from nearby Brassica crops as well as SM damage rated.  Traps will be located in the harvested and nearby Brassica crops. 

    Evaluation of spring emergence following different mulch type. At the Cornell HTC Vegetable Research Farm, an intensive systems study is underway in cabbage that suffered SM-infestation in 2015.  The project is studying six tillage systems overlaid with three mulch types.  We have the opportunity to compare the effect of permanent straw mulch to compost mulch (essentially bare ground) with spring shallow tillage on SM spring emergence.  Our 2015 studies demonstrated that SM will emerge through straw , but it is unknown whether it would serve as a barrier to SM dropping to the soil to pupate.  We will set up enclosed SM traps in early May in each of 4 replicates per treatment, and continue to monitor SM until their emergence is complete.  Cabbage will be grown in this trial in 2017 and there may be opportunity to evaluate the effect of tillage practices on SM emergence in the future.  This project will be the beginning of a mutually beneficial partnership.

    Analysis: Data collected from replicated trials will be analyzed using General Analysis of Variance and means will be separated using Fisher’s Protected LSD test with 5% significance.  Monitoring data will be summarized and related to the unique circumstances of each farm.

    Economic analysis: Only differences in inputs relating to SM management will be considered including cost of IEN, garlic repellant, and labor requirements associated with treatments.  Yield data from the trials will be used, and growers will be asked to provide sale prices and input costs.


    Meet with grower cooperators to devise their individual case studies and on-farm trials: where monitoring traps will be placed, how exclusion netting and garlic repellency trials will be set up (crop type, which planting, plot size, whether exclusion netting will be with or without mulch, type of mulch, etc.) Hoepting, Hall and grower cooperators.  April 2016.

    Write and submit “Be on the lookout for SM” article to NOFA newspaper, The Natural Farmer and Small Farms Quarterly. Hoepting. April 2016.

    Order field supplies (pheromone traps supplies, etc.). Hoepting. April 2016.

    Deploy first monitoring traps. Hall. May 2016.

    Set up SM traps in mulch study at Freeville Organic Research Farm. Hoepting, Hall, Maher.  April 2016.

    Monitor traps, assess SM damage, quantify trap captures and disseminate information to grower cooperators. Spray garlic repellency trials.  Hall, Hoepting.  May to October 2016, weekly or bi-weekly visits.

    Harvest evaluations of trials. Hall, Hoepting. June to October, 2016, as needed.

    Conduct Twilight Meetings, as appropriate. Hoepting, Hall, Grower cooperators.  August and September, 2016

    Collect grower feedback and economic info from growers. Hoepting, Hall, growers. November 2016.

    Data entry, analysis and summary. Hall, Hoepting.  May-December 2016.

    Write and submit annual report. Technician, Hoepting.  December 2016.

    Present results at NOFA-NY winter conference. Hoepting. January 2017.

    Write and distribute project results in newsletter article, update SM website with latest information. Hoepting, Chen. February 2017.

    Present results at NOFA-VT winter conference. Chen. February 2017.

    Write and submit final report to NESARE. Hoepting. May 2017.


    We will aim for our educational efforts to reach the majority of at-risk organic small-scale Brassica growers in Northeastern US where broccoli, cabbage and cauliflower are grown on 364 farms.

    Hoepting will write an informational article designed to alert Brassica growers to be aware and on the lookout for swede midge (SM).  The article will include details about diagnosing and scouting for SM as well as preventative management tactics.  This will be distributed in the Northeast Organic Farming Association (NOFA) newspaper, The Natural Farmer and Cornell’s Small Farm Quarterly Summer 2016 issues, which should blanket Brassica growers in the Northeast US.  During the growing season, grower cooperators will host twilight meetings where SM management will be demonstrated.  It is expected that at least 40 small-scale growers at risk for SM invasion will attend these meetings. 

    Updates and recommendations for managing SM generated from this project will be summarized in another article that will be distributed in The Natural Farmer and Small Farm Quarterly in Spring 2017 issues, as well as through the CCE Cornell Vegetable Program’s newsletter and website (http://cvp.cce.cornell.edu/), “Swede midge information site for the US” website (http://web.entomology.cornell.edu/shelton/swede-midge/, originally developed by Cornell University) and other similar Extension newsletters/websites.  Hoepting and Chen will also present latest research results/recommendations at the NOFA-NY and -VT winter conferences, respectively, and will be available for one-on-one consultations with growers who require their expertise. Growers hosting on-farm trials will serve as resources to other interested growers.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.