1. Biodegradable Mulches for Specialty Crops Produced Under Protective Covers Evaluating Biodegradable Mulches in Diverse Climates in the U.S. Annette Wszelaki, Plant Sciences, UT Carol Miles, Horticulture & Landscape Architecture, WSU Jeff Martin, Plant Sciences, UT Jeremy Cowan, Horticulture & Landscape Architecture, WSU Tom Walters, Horticulture & Landscape Architecture, WSU Russell Wallace, Horticultural Sciences, Texas A & M Debra Inglis, Plant Pathology, WSU

2. Biodegradable Mulches for Specialty Crops Produced Under Protective Covers Debra Inglis and Carol Miles (Project Directors) 1 ; Andrew Corbin, Ana Espinola-Arredondo, Annabel Kirschner, Karen Leonas, Tom Marsh and Tom Walters 1 ; Doug Hayes, Bobby Jones, Jaehoon Lee, Larry Wadsworth and Annette Wszelaki 2 ; Jennifer Moore-Kucera 3 ; Russ Wallace 4 ; Marion Brodhagen 5 ; and Eric Belasco 6 ; 1 2 5 SCRI Grant Award No. 2009-51181-05897 4 3 6

3. Introduction High tunnels have been shown to: – Increase crop yield – Allow for season extension – Shorten days to harvest for many crops – Modify growing environment Protect from rainfall and wind Increase temperature – Improve crop quality

4. Introduction Plastic mulch key component in specialty crop production in high tunnels Provides weed control, conserves soil moisture, increases crop yield, modifies soil temperature, and shortens the time to harvest Manufacturing from non-renewable petroleum feedstocks and inability to recycle raises concern about environmental sustainability

5. Introduction Biodegradable mulches (BDMs) could reduce the overall environmental impact BDMs must perform well under array of climatic conditions Several studies on BDMs in open field conditions Information lacking on BDM performance in high tunnels

6. Objective: To evaluate and compare mulch deterioration, weed control and tomato production among three mulch products marketed as biodegradable, one experimental product, black plastic mulch and a bareground control under high tunnel and open field production systems in three climatically diverse regions in the U.S.

7. Project Design Study locations: Mount Vernon, WA – marine climate; cool summer, moderate precipitation; Skagit silt loam, high organic matter Knoxville, TN – humid subtropical climate; mild winter; hot, humid summer; Dewey silt loam, low organic matter Lubbock, TX – Southern High Plains region; hot summer; low humidity and rainfall; high wind; Acuff clay loam, low organic matter

8. Project Design Experimental design: CRD (TX and TN) and RCB (WA) split-plot Main plots: High tunnel and open field production systems with four replications Haygrove ‘Solo’ Clearspan ‘Colassal’ Golden Pacific Windjammer Series 5000

9. BioAgri ® Ag-Film Cornstarch and non-disclosed biopolymers; biodegradable and compostable; 0.02 mm (BioBag, Palm Harbor, FL) BioTelo Agri Cornstarch and non-disclosed copolymers; biodegradable and compostable; 0.02 mm (Dubois Agrinovation; Waterford, ON, CAN) WeedGuard Plus ® Cellulosic; biodegradable control; 0.23 mm (Sunshine Paper Co. LLC; Aurora, CO) Sub-plots: Mulch treatment SB-PLA (NatureWorks LLC; Blair, NE) Experimental nonwoven spunbond, 100% poly(lactic acid); 0.64 mm Black Plastic Polyethylene plastic (control); 0.03 mm (Pliant Corp.; Schaumburg, IL) Bareground Non-mulch control

10. Project Design Mulches hand laid in 3 ft beds, plots 6 ft wide x 14 ft long Tomato cv. Celebrity – 6-9 week-old transplants planted 2 ft in-row spacing (7 plants/plot) Pruned, staked, managed organically Drip irrigated Insect and disease management practices varied by site

14. 2010 Field Schedule KnoxvilleLubbockMount Vernon HTOFHTOFHTOF Mulch laying 23 Mar.4 May7 May 25 May Planting 26 Mar.5 May7 May 27 May3 June Mulch removal 11 Aug. 8 Oct. 18 Oct.8 Oct. No. days mulch in place 14199154 146136

15. 2011 Field Schedule KnoxvilleLubbockMount Vernon HTOFHTOFHTOF Mulch laying 6 Apr.6 May15 Apr. 12 May24 May Planting 7 Apr.6 May15 Apr. 12 May31 May Mulch removal 5 Sept.3 Oct.15 Oct.15 Sept.12 Oct.5 Oct. No. days mulch in place 152150154183153134

16. Data Collected Total number of rips, tears, and holes (RTH) (5 ft x 2 ft area/plot) Percent visually observed deterioration (PVD) – 0% = fully intact – 100% = fully deteriorated Weed counts and weights (mulch removed in 2 ft x 3 ft area at tomato first- flower and after final harvest) Total and marketable fruit number (fruit·ha -1 ) and weight (kg·ha -1 ) Air and soil temperatures % relative humidity Photosynthetically active radiation (PAR) Average wind and wind gust speeds

17. Statistical Analyses All data were subjected to analysis of variance (ANOVA) using PROC MIXED in SAS (Version 9.2) Compared production system (main plots), mulch (subplots), and production system x mulch interactions Significantly different treatment means were compared using Fisher’s Least Significant Difference test (alpha level 0.05)

18. Results

19. Environmental Comparison 2010 Mount Vernon, WALubbock, TXKnoxville, TN HTOFHTOFHTOF GDD y (base 10 o C)10077401799166117951463 Ave. daily max. air temp. ( o C)24.221.131.932.634.233.5 Ave. daily min. air temp. ( o C)10.59.724.718.917.518.7 Ave. soil temp at 5 cm depth BioBag18.917.726.225.626.227.0 BioTelo19.318.125.926.627.026.8 SB-PLA-1018.717.024.924.626.526.6 WeedGuard Plus18.316.726.926.625.726.3 Black Plastic19.818.927.228.227.827.3 Bareground18.716.824.925.226.926.7 Ave. sol. rad. (µmol·m -2 ·s- 1 )0.360.440.350.540.410.57 Relative Humidity (%)79.781.366.266.774.179.2 Ave. wind speed (km·h -1 )1.13.30.26.40.01.9 Total rainfall (mm)0.0235.50.0333.50.0156.0

20. 2010 # of RTH/bed in WA High Tunnel16-Jun30-Jun14-Jul28-Jul16-Aug2-Sep15-Sep29-Sep BioBag 1.83.0 a2.5 a 7.3 a 7.8 b12.8 b14.0 b15.8 ab BioTelo 3.83.8 a4.3 a 9.5 a15.5 a22.5 a26.3 a28.5 a WeedGuardPlus 0.32.0 a2.3 a 4.5 b 5.8 b 6.0 bc 9.8 b 9.5 ab SB-PLA-10 0.00.0 b 0.0 c 0.0 d 0.0 c Black Plastic 0.30.0 b 0.0 c 0.8 c 1.3 c 1.5 c 1.5 b P value 0.06250.00110.0005<.0001 Open Field BioBag 0.5 yz1.3 y2.0 yz 9.3 x10.5 xy19.5 y20.8 y21.8 x BioTelo 1.5 xy1.8 y6.0 x13.0 x18.3 x17.0 y28.3 y33.5 x WeedGuardPlus 4.8 x5.0 x6.8 x 7.3 x 7.5 xy11.5 y25.0 y 72.8 w SB-PLA-10 0.0 z 0.5 z 0.8 y1.5 z 2.8 z 3.0 z Black Plastic 0.8 yz 2.8 xy 6.3 x 5.5 yz10.0 y10.5 z13.8 y P value 0.00690.00200.00430.00130.01040.00990.0009<.0001

21. BioBag Mount Vernon, WA Mulch Visual Evaluations June 17 August 1 September 2 October 10

22. 2010 BDM Percent Visual Deterioration

23. 2011 BDM Percent Visual Deterioration

24. Area Under the Deterioration Progress Curve TN 2010 WA 2011 TN 2011 WA 2010 a bc a y c c ab a z y x b a c y z x y y bc z x z y HT OF

25. SB PLA experimental mulch and cellulose mulch

26. 2010 Total Weed # (in 10 ft 2 plot -1 ) Weed # Knoxville, TNMount Vernon, WA First flower Final harvest First flower Final harvest Production system High tunnel 11.33.425.56.9 Open field 9.23.035.76.1 P value0.37670.50340.29510.5018 Mulch treatment BioBag 2.3 b 0.0 b 18.8 b 1.3 b BioTelo 2.1 b 0.0 b 10.4 b 2.4 b WeedGuard Plus 1.8 b 0.0 b 13.1 b 3.3 b SB-PLA-10 123.7 a 16.0 a 98.5 a 24.3 a Black Plastic 0.3 b 0.0 b 12.3 b 1.3 b P value <0.0001 0.0163

27. 2011 Total Weed # (in 10 ft 2 plot -1 ) Weed # Knoxville, TNMount Vernon, WA First flower Final harvest First flower Final harvest Production system High tunnel 1.7 b0.50.10.8 Open field0.8 a0.50.42.4 P value0.00870.22790.17160.0591 Mulch treatment BioBag 0.6 1.0 0.8 a4.1 BioTelo 0.7 0.1 0.0 b1.4 WeedGuard Plus 0.3 0.0 0.0 b1.3 SB-PLA-11 0.1 0.3 ab 0.6 Black Plastic 0.4 0.0 0.1 b0.5 P value 0.27090.4926<0.00010.0163

28. 2010 Total # and Weight for Tomato Fruit Knoxville, TNLubbock, TXMount Vernon, WA Fruit # (plot -1 ) Fruit wt. (kg plot -1 ) Fruit # (plot -1 ) Fruit wt. (kg plot -1 ) Fruit # (plot -1 ) Fruit wt. (kg plot -1 ) Production system High Tunnel175.2 a29.2425.2 a 45.0 a 72.7 a 18.7 a Open Field123.6 b28.1244.0 b 28.3 b 14.0 b 2.0 b P value<0.00010.5797 0.0001 0.00080.0005 Mulch treatment BioBag155.3 y 29.7 y 315.934.1 51.1 x 12.5 w BioTelo148.9 y 28.5 y 312.035.1 49.6 xy12.0 wx WeedGuard Plus152.6 y 29.3 y 315.532.542.9 xyz 10.0 xyz SB-PLA-10156.4 y 29.8 y 389.043.1 39.0 y 9.0 yz Black Plastic167.3 y 32.0 y 306.032.5 43.1 xy 10.1 wxy Bareground116.0 z 22.7 z 369.142.4 34.4 z8.3 z P value0.03970.02490.62090.39500.00830.0036

29. 2011 Total # and Weight for Tomato Fruit Knoxville, TNMount Vernon, WA Fruit # (plot -1 ) Fruit wt. (kg plot -1 ) Fruit # (plot -1 ) Fruit wt. (kg plot -1 ) Production system High Tunnel186.2 a29.288.5 a25.6 a Open Field158.3 b28.120.8 b 4.1 b P value0.02140.67520.00070.0041 Mulch treatment BioBag 177.8 34.5 56.5 x 15.2 x BioTelo 171.6 33.9 62.3 x 16.5 x WeedGuard Plus 172.4 34.2 46.6 y 12.7 y SB-PLA-11 175.6 35.6 47.8 y 13.9 y Black Plastic 170.1 36.1 59.8 x 15.8 x Bareground 166.1 33.1 55.3 xy 15.1 xy P value0.93780.82100.00360.0231

30. Conclusions WeedGuardPlus, BioTelo and BioBag showed the most deterioration at all sites in both years Values were greater in OF than HTs SB-PLA showed little deterioration at all sites and was equivalent to black plastic Weed growth at Knoxville and Mount Vernon was greatest under SB-PLA-10; minimal in 2011

31. Conclusions High tunnels out-performed open field plots in all locations in both years 2010: – Total # and total fruit weight were lowest for bareground at both Knoxville and Mount Vernon – BioBag had higher yields than the SB-PLA-10 and bareground plots in WA; equivalent to plastic 2011: – Yield did not vary by mulch treatment in Knoxville – BioBag, BioTelo and black plastic had higher yields than the SB-PLA-11 and WeedGuard plots in WA

32. Questions?