Sustainable Pest Management Approaches for High Tunnel Screenhouse Production in the Tropics
A summary of screenhouse for tomato, brassica and cucurbit crop productions from the collaborative works with 5 participating farmers were reported during a statewide extension agents training day. One field trial was completed to compare insect exclusion nets with different mesh sizes. Another field trial was added to examine insect exclusion nets as row cover without a screenhouse structure. Three extension articles that outline detail procedure and prices to construct insect exclusion screenhouses are published. Two YouTube videos were produced to provide specific information on what insectary plants are appropriate to attract beneficial insects to prey on different target pests. Three public clients’ workshops were presented to statewide extension agents in Hawaii as well as farmers associations (Hawaii Farm Bureau, HDOA, HARC, Monsanto Hawaii). Summary of how to use oil radish as a trap crop and biofumigant against plant-parasitic nematodes is posted online. All of these materials are accessible online and published in CTAHR Sustainable and Organic Agriculture Program quarterly newsletter, Hanai’Ai that reach out to ~1000 readers in Hawaii including all organic farmers in the State. This provides resources that are significant for organic farmers that are seeking non-chemical approaches for various pest management. This reduced farm input approach for pest management is also becoming increasingly important for the growing population of small-scale farmers in Hawaii (64% with farm income of < $10,000/year based on NASS 2014 report). Outputs of this project are well received by farmers.
Specific objectives of this proposed project are to:
- Compare crop yields and market values of produce from screenhouse (SH) vs open field (OF) production of each farmers.
- Monitor insect pest damage (pickleworms and fruit flies for squash, incidence of virus on tomato, flea beetle damage on eggplant, rose beetles on taro, imported cabbage worm or diamond back moth damage on lettuce), weed pressure, and nematode population densities in SH vs OF production.
- Evaluate the suppression of root-knot nematode population densities following “Dead-end Trap Crop” practice.
- Scout for diversity of beneficial insects visiting cash crops in SH vs OF production.
- Conduct workshops and field day events for “Do-it-yourself (DIY) screenhouse construction”, “Turn the Page”, “Adopt the Insectary” and “Dead-end Trap Crop” methods and evaluate farmers’ perception, adoption, and record their suggestions/inputs on the project. These workshops will be repeated for the University of Hawaii new farmers training program, GoFarm Hawaii, as part of their on-farm training lectures.
Objective 1 & 2: During this progress report period, we published extension and outreach materials with information related to: “Do-it-yourself (DIY) screenhouse construction”, “Turn the Page”, “Adopt the Insectary” and “Dead-end Trap Crop” and “Biofumigation” methods for nematode control. Besides evaluating the benefits of screenhouse production for managing various hard to manage arthropod pests using 17-mesh screen materials, we also extend our project to evaluate other screen materials with denser mesh size for insect pest exclusion.
A series of field trials were conducted inside and outside of Do-It-Yourself (DIY) screenhouse using 17-mesh insect exclusion net that we had assisted 5 farmers to construct. This design is posted in an online newsletter published by CTAHR Sustainable and Organic Agriculture Program, Hanai’Ai volume 28 (https://cms.ctahr.hawaii.edu/soap/HanaiAi.aspx). So far all the sreenhouses withstand gusty winds occasionally encountered. A report was summarized and presented to state wide extension agents and local farmers at the Sustainable and Organic Agriculture Program’s Extension and Research Update event took place at Waimanalo Experiment Station on November 9, 2016. More than 60 people attended the event. The data is summarized and posted at http://www.ctahr.hawaii.edu/WangKH/Downloads/2016_Organic_SPM.pdf.
These screenhouse prices range from $0.68 to $0.95 per sq ft., which is equivalent to $510 to $713 for a 15’ × 50’ × 6’ house. However, increasing numbers of small-acreage farms in Hawaii earning less than $10,000 a year (NASS, 2014) are asking for cheaper but more stable screenhouse designs for insect pest management. Thus, PIs from this project constructed another design of screenhouse in hoop house design. Though it cost $0.78/ft2, it is more stable than the $0.68/ft2 hoop house. Another challenge from the $0.95/ ft2 design is that although it can block larger insect pests, it allows the entrance of smaller insect pests such as aphids, whiteflies and thrips. Therefore, we conducted another experiment to compare prices and insect pest management effects of screenhouses using different mesh sizes (17, 40 and 75 mesh, 30% reflective shade). The results are summarized and published in Haina’Ai volume 28 as Part II of this report.
Comparing mesh sizes: Zucchini yield from this trial clearly demonstrated that all the insect exclusion screens (17, 40 and 75) protected zucchini fruits from the key pests of zucchini i.e. pickleworms and melon flies. This had resulted in higher marketable yield in hoop houses than the OF. Using shade materials, which are more readily available from local agricultural distributors in Hawaii compared to the 17-mesh size, mesh size is 2 times larger than the 17-mesh is not an alternative to insect exclusion nets if the grower’s interest are to protect the crop from insect pests. On the other hand, finer screen materials than 17-mesh (40- and 75-mesh) that cost more did not protect the crop from aphids but did slow down and reduce whiteflies and powdery mildew damage. High counts of aphids in 40-mesh could be due to cross contamination working in between screenhouses. While the effect of 40-mesh on aphid infestation need further evaluation, it is important to pay attention to sanitation working inside and outside of a screenhouse. 40-mesh screen is 2.8 times and 75-mesh screen is 6.8 times more expensive than the standard 17-mesh screen. Yet marketable yield of zucchini in this trial is better in 17 mesh than those in 40- and 75-mesh. However, previous kale trial conducted in a 17-mesh screenhouse resulted in an outbreak of thrips inside the screenhouse (Wang, K.-H., personal communication). Thus, effects of screen materials are pending on insect pests present. In addition, since the insect infestation inside the 17-mesh screenhouse was low, weekly insecticide spray rotation did not further protect the crops from aphids or whiteflies damage.
Overall, this zucchini trial demonstrated that a hoop house design with the 17-mesh screen is worthwhile for farmers to invest in. Previous 17-mesh screenhouse design used EZ corners and lumbers for the structure cost $0.95/ft2. The current hoop house design use 17-mesh screen costs $0.78/ft2. Although insect exclusion screens reduced light intensity compared to open field, zucchini growth and health was not compromised and in fact was stimulated in the 40-mesh hoop house. Plants in the 75-mesh house did show sign of elongated growth later in the season. However, reduction in light intensity in all the screenhouses resulted in more blossom end rots. None-the-less, blossom end rot did not contribute to major yield reduction.
Row cover: In the event that farmers still prefer to grow crop in open field but would like to just cover the planting row with insect exclusion net without having to construct screenhouse structure, Co-PI Sugano conducted another trial to evaluate effects of Proteknet “Biothrips” Insect Netting (Jonny Seed) as row cover, Enviromesh 17-mesh screen with hoops, and pesticide sprays against cabbage webworm (Hellula undalis). The 17-mesh screen with hoops reduced cabbage webworm as effectively as the commercial pesticide Coragen. Proteknet “Biothrips” Insect Netting without hoop structure cost $0.15/ft2 had been the least effective treatment in reducing webworm damage. Other OMRI certified organic insecticide tested in this trial included Pyganic, Debug Turbo, Crymax, and Entrust, among which only Entrust suppressed cabbage webworms comparable to Coragen and 17-mesh screen.
Objective 3. A graduate student examined the effects of oil radish for plant-parasitic nematodes and determined ‘Sod Buster’ oil radish (Raphanus sativus) can serve moderately effective as a trap crop to trap root-knot nematodes if terminated 1 month after planting. However, when oil radish was terminated by tillage, its biofumigation effect against the root-knot nematodes was not significant. Thus, the student is currently evaluating different cover crop termination methods to improve the biofumigation effect of oil radish. This result was also presented during the Sustainable and Organic Agriculture Program’s Extension and Research Update event on Nov 9, 2016 and available at http://www.ctahr.hawaii.edu/WangKH/Downloads/PWaisen_Waimanalo_2016.pdf.
Wang, K.-H., J. Sugano, S. Fukuda, J. Uyeda, D. Meyer, and S. Ching. 2017. DIY Screenhouse for insect management in the Tropics: Part I. HānaiʻAi Newsletter 28: Dec, Jan, Feb 2017. https://cms.ctahr.hawaii.edu/soap/HanaiAi.aspx
Wang, K.-H., J. Sugano, S. Fukuda, S. Ching, J. Kam, J. Uyeda, and D. Meyer. 2017. DIY Screenhouse for insect management in the Tropics: Part II Hoop Houses. HānaiʻAi Newsletter 28: Dec, Jan, Feb 2017. https://cms.ctahr.hawaii.edu/soap/HanaiAi.aspx
Kylie Wong1, Josh Silva1, Robin Shimabuku2, Steve Fukuda1, Jari Sugano2, Koon Hui Wang2, Jensen Uyeda1, Fred Reppun1, Shelby Ching2, Jonathan Kam2 and Ronald Mau2. Comparing Physical Barriers and Organic Pesticides for Controlling Cabbage Webworm on Daikon. HānaiʻAi Newsletter 28: Dec, Jan, Feb 2017. https://cms.ctahr.hawaii.edu/soap/HanaiAi.aspx.
- Wang, K.-H., S. Ching and J. Uyeda. 2016. Insectary settings for arthropod pest Part I and Part II. Hānai‘Ai Newsletter September, October, November, 2016. http://go.hawaii.edu/82j or at (https://youtu.be/BsN_3lC35wg and https://youtu.be/1stOru5I-a0).
Refereed Conference presentation/Published abstracts:
- Waisen, P., -H. Wang, Z. Cheng and B. S. Sipes. 2016. Developing effective management strategies against plant-parasitic nematodes using oil radish in Hawaii. Society of Nematologists/Organization of Nematologists in Tropical Agriculture, Montreal, Canada. July 18-22, 2016.
Field days and Workshops
- Ching, S.A., K.-H. Wang, J. Sugano, S. Fukuda, J. Uyeda, D. Meyer, J. Kam. 2016. Screenhouse for tomato, brassica and cucurbit crop productions. Sustainable and Organic Agriculture Program’s Extension and Research Update, Waimanalo Experiment Station, November 9, 2016 (attendance 60) http://www.ctahr.hawaii.edu/WangKH/Downloads/Screenhouse_insects_management.pdf
- Waisen, P., K.-H. Wang, J. Sugano, J. Uyeda, J. DeFrank. 2016. Managing plant-parasitic nematodes using trap cropping and biofumigation. Sustainable and Organic Agriculture Program’s Extension and Research Update, Waimanalo Experiment Station, November 9, 2016 (attendance 60) http://www.ctahr.hawaii.edu/WangKH/Downloads/PWaisen_Waimanalo_2016.pdf
- Sugano, J., K.-H. Wang, J. Uyeda, S. Fukuda, S. Ching, J. Kam. Screening to exclude agricultural pests. Vegucation Farmer Workshop: Farmers Field Day Experience. Hawaii Farm Bureau, HDOA, HARC, Monsanto Hawaii, Kunia, HI. Sept 14, 2016 (attendance 100).
Impacts and Contributions/Outcomes
Three extension articles that outline detail procedure and prices to construct insect exclusion screenhouses are published. Two videos to provide specific information on what insectary plants are appropriate to attract the beneficial insects to prey on different target pests are made available on YouTube. Summary of how to use oil radish as trap crop and biofumigant against plant-parasitic nematodes are posted online. All of these materials are accessible online and published in CTAHR Sustainable and Organic Agriculture Program quarterly newsletter, Haina’Ai that reach out to ~1000 readers in Hawaii including all organic farmers in the State. This provides resources that are significant for organic farmers that are seeking non-chemical approaches for various pest management. This reduced farm input approach for pest management is also becoming increasingly important for the growing population of small-scale farmers in Hawaii (64% with farm income of < $10,000/year based on NASS 2014 report).
More and more farmers are contacting our extension agents and PIs about constructing screenhouses or using row cover. We are organizing a field day and workshop for screenhouse production at the end of the month to reach out to wider audience and to make our publications widely available.
Since we are demonstrating DIY screenhouse with the farm coach of GoFarm Hawaii, new farmers’ training program, we are reaching out to a growing population of new farmers in Hawaii. In 2016, GoFarm Hawaii had graduated 163 from AgSchool, 51 from AgProfessional training, and created over 30 new commercial farmers. Many of these farmers are contacting PIs of this project about new and improved pest management approaches. The farm coach of GoFarm Hawaii, Jay Bost, who is collaborating on this project testified that “We love the screenhouse. We got basically no harvest of zucchini in the open field, but all marketable inside the screenhouse. For tomatoes, though comparable yields between inside and outside of screenhouse, but inside had no fruit flies and most tomato from open field have eggs/larva of fruit flies, making it hard to sell. I consider the screenhouse a big success and many GoFarm students are contemplating building their own”.
One major outcome of this project could be the reduction in pesticide resistance population of caterpillar pests in particular, diamondback moth, that have been a rising problem in Hawaii. Thus, over a long run, wiser use of insect exclusion screenhouse for crop production in Hawaii would not only reduce farmers’ reliance on pesticides, it would also improve the efficacy of existing insecticides. The implication of this project on sustainable pest management in Hawaii will be great.
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