This study tested a certified organic method of managing the brown marmorated stink bug (BMSB) in okra, sweet pepper, tomato and summer squash. Commercially available stink bug pheromone traps were combined with a 3 ft wide sunflower trap crop perimeter that surrounded the cash crops. We observed a high degree of BMSB attraction to the sunflower trap crop, with > 2-fold increase in average BMSB densities in the trap perimeters, as compared to the cash crops. The trap crop perimeters also delayed BMSB colonization of the cash crops, resulting in lower BMSB densities for tomatoes and peppers late season (> 15 Aug). However, reduced BMSB densities in the cash crops did not translate into significantly lower crop damage or higher yields in the trap crop plots as compared to control plots. We found a 14-d earlier colonization and 2-fold higher density of BMSB in plots with prior history of vegetable production, as compared to plots previously in grain. No overall directional affect for BMSB colonization was found within fields, suggesting that presence of the cash crops in the previous year was a more important factor for BMSB.
Our results indicate that this system is effective for organic production but will require a BMSB-specific pheromone lure, or an organic mortality inducing agent, that can be incorporated within the trap crop perimeter in order to effectively reduce BMSB damage to the cash crops.
[see full results in presentation documents at end of report]
The Brown Marmorated Stink Bug (BMSB), Halyomorpha halys, is an invasive pest causing significant economic losses to farmers due to its extremely broad feeding range and lack of native natural enemies. BMSB was detected in Pennsylvania in 1998 and initially affected farms in the mid-Atlantic states most severely but since has spread rapidly and is now in every Eastern state (See http://www.stinkbug-info.org/index.php). All major vegetable and fruit crops are susceptible to BMSB, and the predominant management tactic being employed is frequent application of broad-spectrum insecticides that are toxic to beneficial organisms, disrupt biological control and lead to secondary pest outbreaks. At our farm, where BMSB has two generations, densities have exceeded 10 adults per fruit (in tomatoes), and annual losses due to BMSB have exceeded 30% of total revenues. This pest is threatening the economic viability of farms throughout the Eastern U.S., and to date, there are no viable sustainable management tactics.
Research and extension reports indicate that most insecticides have limited efficacy against BMSB (See http://njaes.rutgers.edu/stinkbug/control.asp). Yet in response to unprecedented BMSB damage levels, orchardists and farmers are spraying broad-spectrum insecticides at high rates and frequencies and spraying wooded and other adjacent habitats. This tactic is highly unsustainable, as these pesticides kill a wide range of organisms, including beneficials needed for pollination, predation and parasitism, disrupting biological control and IPM programs, leading to outbreaks of additional pests and necessitating more pesticides. Furthermore, introducing these toxins to the ecosystem beyond farm borders can result in soil and water contamination. Additionally, farmers report that the chemical approach is not economically sustainable, as entire annual pesticide budgets are being consumed by materials targeting BMSB (http://www.northeastipm.org/working-groups/bmsb-working-group/).
This research project tested a chemical-free approach that combined a sunflower trap crop perimeter with commercially available pheromone traps to manage BMSB. We tested this system in 2012 on four cash crops with previously high BMSB susceptibility: okra, sweet pepper, tomato and summer squash, in replicated field plots under USDA certified organic production.
The objective of this study was to develop an environmentally and economically sustainable BMSB management method that can be used on USDA-certified organic farms. The project specifically aimed to test a chemical-free system that combined a highly attractive trap crop buffer with baited pheromone traps in replicated field plots on a working certified organic farm.
Performance targets were as follows:
• Establish four replicates containing mixed vegetable field plots (okra, tomato, sweet pepper and summer squash) that adhered to commercial organic production techniques
• Determine if BMSB display directionality with respect to colonization of the plots
• Determine BMSB host-use preference, with respect to the four cash crops studied
• Determine the relative suitability (i.e., attractiveness) of species studied as trap-crop plants (green amaranth and sunflower)
• Evaluate the effectiveness of the trap crop system for protection of the four cash crops (i.e., BMSB densities on the cash crops, BMSB damage levels, and crop yields)
• Provide a Twilight Farm Tour, to demonstrate the trap cropping tactic and disseminate project results
• Disseminate research findings to a wide audience of farmers and agricultural professionals via publication of a Technical Bulletin, electronic publication on relevant websites, and presentation at professional meetings
A randomized complete block design (two replicates per block) was established at Redbud Farm (Berkeley County, WV, USA) to test the effectiveness of an integrated trap crop and baited pheromone trap system in protecting four economically important vegetable crops: okra (‘Clemson Spineless,’ High Mowing Organic Seed Co.), sweet pepper (‘Red Ace,’ Johnny’s Seeds), tomato (‘Big Boy,’ Johnny’s Seeds), and summer squash (‘Zephyr,’ Johnny’s Seeds). These crops were chosen based on their previously established high level of susceptibility to BMSB and their compatibility in terms of culture. The farm has two natural blocks based on previous use: Block 1 consists of two adjacent fields (~5 acres each) that had been planted in a highly diversified rotation of vegetables, flowers, herbs and small fruits since 1998; Block 2 consists of two adjacent fields (~10 acres each) that had been in a corn-soybean-hay rotation since 1998. Both blocks were adjacent to hardwood forest stands. Four study plots (900 sq ft each) were established within each block, for a total of eight plots. Each study plot contained 4 linear crop rows (each 3 x 36 ft) with aisles in between (3 x 36 ft aisles; See Fig. 1). Half of the plots within a block were randomly selected to receive BMSB treatment and the other half served as controls. The BMSB treatment consisted of a 3 ft wide border strip of trap crops [green amaranth (Amaranthus spp., Redbud Farm saved seed from 2011) and sunflower (open pollinated mixture, Johnny’s Seeds)] planted to form a perimeter around the vegetable crops (See Fig. 2: 1 replicate). The perimeter trap design was selected because, while it is generally thought that BMSB emerge from the woods in spring, we did not know for certain from which direction they would immigrate into the plots; therefore, we aimed to protect all sides of the cash crop plot. Control plots were exactly the same as treatment plots but did not have the order strip of trap crops. The study used a total of 8 field plots, with 4 designated as BMSB treatment plots and 4 controls.
Sweet pepper and tomato transplants were started from seed in the greenhouse in late February, 2012. Field plots was prepared (plowed and disked) on 15 May, and a total of four rows (3 x 36 ft) per plot were prepared with a 6 ml irrigation drip tape down the middle and covered with 3 ft wide black plastic (1 ml embossed, Martin’s Produce Supply) on 18 May. The sweet pepper and tomato seedlings were transplanted by hand (24” spacing with the rows) into the black plastic 18 May. Okra and squash were direct seeded into holes made in the plastic cover within rows on 21 May (4 okra seeds/hole, 2 squash seeds/hole, both at 24” spacing within the rows). The crop configuration (okra, tomato, squash, and then pepper) within the plots was identical and was designed to avoid shading by taller crops (Fig. 1). Tomato, okra, and sweet pepper plants will be spaced at 24 inches, totaling 17 plants per row; squash will be spaced 24 inches (total 17 plants per row). To protect the young seedlings, from 23 May to 11 June, crop rows were covered with floating row cover (AG19, 0.55 oz/sq yd) supported by wire hoops (3/16” high tensile steel, 76” long) placed every 3 ft. Tomato plants were caged on 19 June (36” high metal cage, 1/plant, Martin’s Produce Supply). The aisles between rows were mulched with straw to discourage weed growth (22 May). The 3 ft wide trap crop border was direct seeded on 23 May. Amaranth and sunflower seeds were broadcasted by hand to form the trap crop border strip [green amaranth (4 oz/plot) and sunflower (24 oz/plot)] and tamped with a garden rake.
Four ‘RESCUE’ stink bug traps (Sterling International, Inc.), using inverted funnel/pyramid design and baited with dual pheromone lures, were placed in the trap crop border of each treatment plot, 1 centrally located within each side of the trap crop perimeter (See Fig. 2), on 6 June. This timeframe corresponded with historical emergence of the first generation of BMSB in the panhandle of West Virginia. Control plots did not receive stinkbug traps. According to the manufacturer, a RESCUE trap is capable of attracting stinkbugs within a 20-30 ft radius; therefore, a minimum of 35 ft buffer area was maintained between any two study plots to avoid attracting BMSB out of control plots. Traps were hung from wooden stakes at a height of 3 ft and secured at the bottom to enable juvenile capture. Trap contents were emptied weekly through the season, and lures were replaced 12 July and 9 August.
Stink bug (BMSB and natives) densities were estimated in both the trap crop borders and the vegetable crops at weekly intervals (4 June – 21 September). For the vegetable crops, 3 plants per row were randomly selected, and the entire plant was visually examined (including underside of leaves) for up to 60 sec. The number of stink bugs (adults and nymphs) and number of egg masses per plant was recorded, and the average per crop type was calculated within the plot each day. Scouting occurred between 0600 and 1000 hr each day, to avoid high temperatures when the stinkbugs became more mobile. The order of sampling field plots was randomly determined each day.
Stink bugs captured in the RESCUE traps within the trap crop perimeters were counted weekly (4 June – 21 September). Trap contents were dumped into a 2 gallon bucket with soapy water to keep adults from flying away. The number of BMSB and native stink bugs (adult and nymph stages) per trap was recorded by trap location (i.e., north, east, south or west side of the trap crop perimeter), and traps were re-deployed.
Vegetable crop damage and yields were assessed weekly once the crops reached maturity (squash: 4 July, pepper: 18 July, okra: 19 July, tomato: 31 July), in conjunction with harvests. Three plants per row (per crop type) were randomly selected and the salable portion (e.g., fruits) was examined for signs of stink bug damage. The number of damaged fruits/plant was recorded, and the average per crop type was calculated within the plot each day. Damaged fruit was removed from the field to avoid re-counting in a subsequent sample. Salable crops were weighed and yield by crop type (lbs/row) determined weekly. Yield data was totaled by crop type across the season.
Individual data sets were subjected to visual examination and the univariate procedure (Shapiro-Wilks) to confirm normal distributions and homogeneous variances prior to statistical analysis. Separate mixed model ANOVAs tested for block and trap direction effects and block*trap direction interaction on BMSB densities (nymphs and adults combined) in RESCUE traps within each sample date. An additional ANOVA tested for block effect on BMSB collected in the RESCUE traps over the whole season (totaled over 16 sample dates). Separate mixed model ANOVAs by crop type were performed for BMSB densities (adults, nymphs and eggs combined) within sample dates, as well as seasonal BMSB densities, crop damage levels and yields. All statistical analyses used SAS software (SAS Institute).
Our study explored the effectiveness of a novel and sustainable approach to BMSB management, combining trap crop buffers with baited pheromone traps. This non-chemical approach prevents agricultural pollution and reduces environmental and health risks in agriculture by eliminating significant volumes of insecticides currently being applied to target BMSB. Furthermore, the tactic conserves biota and enhances soil and water quality through reduced pesticide runoff or percolation to ground water. The results of this study are useful in addressing the current void that exists with respect to economically viable and environmentally sustainable BMSB management tactics available for certified organic farming operations.
The project successfully tested a chemical-free system that combined a highly attractive trap crop buffer with baited pheromone traps in replicated field plots on a working certified organic farm.
Specific project accomplishments include:
• Successfully established four replicates containing mixed vegetable field plots (okra, tomato, sweet pepper and summer squash) that adhered to commercial organic production techniques
• Determined that BMSB did not display any overall directionality with respect to colonization of the plots; rather, the BMSB apparently were most affected by previous host-plant history in the plots, with greater pest densities in the field that traditionally produced vegetables, as compared to the field previously in grain production
• Determined BMSB host-use preference, with okra being most preferred, followed by tomato and then pepper; found that BMSB did not use summer squash when the other hosts were in the vicinity
• Determined the relative suitability (i.e., attractiveness) of sunflower as a trap-crop plant, finding a high degree of attraction that was season-long; the study did not evaluate amaranth due to crop failure in the interplant
• Successfully evaluated the effectiveness of the trap cropping system for protection of the four cash crops; gathered data on BMSB densities on the cash crops, BMSB damage levels, and seasonal crop yields
• Conducted outreach to disseminate research findings through a farm tour, two technical bulletins, website publication and three presentations at professional conferences
Education & Outreach Activities and Participation Summary
Outreach was achieved through a variety of tactics, as outlined below:
• Provided a Twilight Farm Tour (via collaboration with our county Extension Agent, Mary Beth Bennett, and our project Technical Advisor, Tracy Leskey, USDA Appalachian Fruit Research Station), on 30 August 2012, demonstrating the trap cropping tactic and presenting research findings; the tour was attended by Extension professionals, researchers from local universities, the USDA and the BMSB Working Group, and local growers; Technical Bulletins featuring preliminary research results were provided free of charge
• Disseminated research findings to a wide audience of farmers and agricultural professionals via a free Technical Bulletin featuring final research findings and via electronic publication of findings on our farm website (www.redbudfarm.com) and on the national BMSB Working Group website that is hosted by the Northeastern IPM Center (http://www.northeastipm.org/index.cfm/working-groups/bmsb-working-group/bmsb-information/)
• Disseminated research findings to >150 growers, researchers and Extension professionals in an oral presentation entitled ”Brown Marmorated Stink Bug Host-Use in Organic Vegetables with Trap Crop” at the Annual Meeting of the Northeastern IPM Center’s BMSB Working Group on 27 November 2012, in Winchester, VA
• Disseminated research findings to >40 researchers and agricultural professionals in an oral presentation entitled ”Integrated Trap Crop and Pheromone Trap System for Organic Management of Brown Marmorated Stink Bug” at the Annual National Meeting of the Entomological Society of America on 11 November 2012, in Knoxville, TN
• Disseminated research findings to ~25 university, extension and USDA ARS researchers in an oral presentation entitled ”Trap Crops for Organic Management of BMSB: 2012 Findings & Recommendations” at the Annual Planning Meeting of the OREI-funded project to develop organic stinkbug management tools on 7 January 2013 at the Rutgers Agricultural Research and Extension Center, Bridgeton, NJ
In addition, the research findings are being submitted for publication in a professional journal.
The findings of our study will significantly contribute to the current body of knowledge regarding trap cropping to reduce BMSB, as they provide much needed information regarding four key vegetable crops, as well as potential trap crop species. As this research was carried-out on a working farm that has been under organic management since 1998, the findings are critical to understanding how the trap crop approach works under real-life conditions. Our findings will be used to inform trap cropping field research methodologies for a recently launched multi-institutional effort to combat BMSB (“Whole Farm Management of BMSB and Endemic Pentatomids,” funded by USDA OREI) in organic agriculture. Once a species-specific pheromone lure becomes commercially available for use in traps placed within the trap crop perimeter, this system has the potential to significantly enhance farm productivity by reducing crop losses, ultimately increasing the economic viability of organic farms in the mid-Atlantic region. The tactic has wide transferability to agricultural practices throughout the Northeast.
Future research should focus on developing tactics for killing the BMSB in trap crop perimeters in adherence with USDA NOP standards, or incorporating a species-specific pheromone lure to trap both early and late season BMSB out of the trap crop. In addition, research into other trap crops would be useful in order to apply this tactic to other geographical areas in which sunflower might not be an ideal choice.