Effects of High Tunnels and Biodegradable Mulch Use on Fruit Quality and Yield in High-value Crops

High tunnels enhance and extend crop production by increasing air temperature and protecting the crop from rainfall. In high tunnel production systems, weeds are often controlled with plastic mulch. There is a desire to reduce non-recyclable waste by using biodegradable mulches (BDMs) that completely biodegrade in situ without detrimentally affecting yield, fruit quality, or the ecosystem. In 2010 and 2011, tomatoes were grown in high tunnels and open field plots at WSU Mount Vernon NWREC utilizing six mulch treatments: 1) BioBag (BB); 2) BioTelo (BT); 3) an experimental spun-bond non-woven composed of 100% polylactic acid (SB-PLA); 4) cellulose paper mulch, completely biodegradable standard; 5) 1.0 mil embossed black polyethylene (PE) plastic; and 6) bare ground as a non-mulch control. In 2010 and 2011, tomato fruit number and weight tended to be higher with the application of plastic mulch films, regardless of biodegradability, though these differences were not consistent in both years. Percent marketability of harvested fruit was significantly lower in mulch plots, especially plastic films, than in bare ground plots. Total number and weight of harvested tomatoes were 4 to 9 times greater, respectively, when grown in high tunnels as compared to open fields. In 2010, juice content was greatest for bare ground and BioTelo plots, and soluble solids (oBrix) was lowest in bareground plots. The same trends in fruit quality were observed as in 2011, however these differences were not significant. In 2010 there were insufficient fruit to compare between high tunnels and open field, but in 2011 juice content and pH of fresh harvested fruit were greater in high tunnels as compared to open field while soluble solids and titratable acidity (% citric acid) were lower. In stored fruit, juice content was also higher in high tunnels than in the open field.

Grant Information

  • Project ID: 079
  • Project Status: Complete


  • Principal Investigator(s): Miles, C.
  • Investigator(s): Andrews, P., Inglis, D., Leonas, K.
  • Grant Amount: $22,000
  • 2010 Progress Report (PDF)



J. Moore-Kucera, M. Davinic, L. Fultz, J. Lee, C.A. Miles, M. Brodhagen, J. Cowan, R.W. Wallace, A. Wszelaki, J. Martin, J. Roozen, B. Gundersen and D.A. Inglis. 2011. Biodegradable Mulches: Short-term degradability and impacts on soil health. HortScience 46(8):in press.

Wallace, Russell W., Carol Miles, Annette Wszelaki, Debra A. Inglis, Jonathan Roozen, Jeffrey Martin and C. Joel Webb. 2011. High tunnel lettuce variety yield and quality when grown in different US climates. HortScience 46(8):in press.

Inglis, D., C. Miles, E. Belasco, M. Brodhagen, A. Corbin, A. Espinola-Arredondo, D. Hayes, R. Jones, J. Lee, K. Leonas, H. Liu, T. Marsh, J. Moore-Kucera, L. Wadsworth, R. Wallace, T. Walters and A. Wszelaki. 2010. Biodegradable mulches for specialty crops produced under protective covers. HortScience 45(8):S208-S209.

Cowan, J., C. Miles, D. Inglis, K. Leonas, J. Moore-Kucera, A. Wszelaki, R. Wallace, D. Hayes, and L. Wadsworth. 2010. Evaluating potential biodegradable mulches for high tunnel and field vegetable production. Agricultural Plastics Congress, July 31-August 1, Palm Desert, California.

Miles, C., C. Beus, A. Corbin, R. Wallace, A. Wszelaki, H. Saez, T. Walters, K. Leonas, M. Brodhagen, D. Hayes and D. Inglis. 2009. Research and extension priorities to ensure adaptation of high tunnels and biodegradable plastic mulch in the United States. Agricultural Plastics Congress, July 13-16, College Station, Pennsylvania.

Miles, C., D. Inglis, and A. Foren. 2010. SCRI Project on High Tunnels and Biodegradable Mulch. SCRI grant public Web site, http://mtvernon.wsu.edu/researchprojects/hightunnels/.

Miles, C., D. Inglis, and A. Foren. 2009. Biodegradable Mulches for Specialty Crops Produced under Protective Covers. SCRI grant project management Web site, http://vegetables.wsu.edu/SCRI/index.html.

Corbin A., C. Miles, D. Hayes, J. Dorgan, and J. Roozen. 2009. Suitability of biodegradable plastic mulches in certified organic production. HortScience 44(4):1040.;Miles, C., M. Taylor, G. Sterrett, P. Kreider, S. Johnson, K. Hasenoehrl and J. Cowan. 2011. Marketable tomato quality testing protocol. Vegetable Horticulture Program, WSU Mount Vernon NWREC.

Miles, C., M. Taylor, G. Sterrett, P. Kreider, S. Johnson, and J. Cowan. 2010. SCRI project – tomato harvest protocol. Vegetable Horticulture Program, WSU Mount Vernon NWREC.

Plasticulture webpage http://plasticulture.wsu.edu/ was updated to include new information on biodegradable mulches, high tunnel suppliers and costs of high tunnel production.

Additional Funds Leveraged

USDA SCRI, $1,999,002, 2009-2012;USDA-SCRI – $68,000 secured


Short-Term: developed standard protocols for measuring fruit quality in high tunnels and with BDMs. Measured the impact of BDMs and high tunnels on tomato fruit quality during one field season and are preparing this information for dissemination to colleagues and producers through state and national meetings.

Intermediate-Term: Producers will gain knowledge and understanding of the impacts of high tunnels and BDMs on tomato fruit quality. If results are favorable, we expect that 20 producers will transition to the use of high tunnels and BDMs by 2012.

Long-Term: While it would be presumptuous to assume that polyethylene plastics would be completely replaced by BDMs, positive fruit quality responses will increase the likelihood that both the industry and growers will transition to this more sustainable technology by 2015. Likewise, positive crop responses with high tunnels, including enhanced fruit quality, longer seasons and greater crop diversity, will facilitate the adoption of high tunnels in Washington by 2015.