Organic Options for Striped Cucumber Beetle Management in Cucumbers Katie Brandt Grand Valley State University
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Grand Valley State University ScholarWorks@GVSU Masters Theses Graduate Research and Creative Practice 6-2012 Organic Options for Striped Cucumber Beetle Management in Cucumbers Katie Brandt Grand Valley State University Follow this and additional works at: http://scholarworks.gvsu.edu/theses Recommended Citation Brandt, Katie, "Organic Options for Striped Cucumber Beetle Management in Cucumbers" (2012). Masters Theses. 29. http://scholarworks.gvsu.edu/theses/29 This Thesis is brought to you for free and open access by the Graduate Research and Creative Practice at ScholarWorks@GVSU. It has been accepted for inclusion in Masters Theses by an authorized administrator of ScholarWorks@GVSU. For more information, please contact [email protected]. ORGANIC OPTIONS FOR STRIPED CUCUMBER BEETLE MANAGEMENT IN CUCUMBERS Katie Brandt A thesis Submitted to the Graduate Faculty of GRAND VALLEY STATE UNIVERSITY In Partial Fulfillment of the Requirements For the Degree of Master of Science Biology June 2012 2 ACKNOWLEDGEMENTS Many thanks to my advisors, who helped me plan this research and understand the interactions of beetles, plants and disease in this system. Jim Dunn helped immensely with the experimental design and prevented me from giving up when my replication block was destroyed in a flood. Mathieu Ngouajio generously shared his expertise with organic vegetables, field trials and striped cucumber beetles. Mel Northup lent the HOBO weather stations, visited the farm to instruct me to set them up and later transferred the data into an Excel spreadsheet. Sango Otieno and the students at the Statistical Consulting Center at GVSU were very helpful with data analysis. Numerous farmworkers and volunteers also helped in the labor-intensive process of gathering data for this research. Tom Cary carried the responsibilities of winter planning for the 2011 Groundswell Farm season, so these results could be compiled and written. Anna Hoekstra was extremely helpful and accommodating while the research was conducted at our farm in 2009. Funding for this research was provided by a Presidential Research Grant at Grand Valley State University. iii 4 ABSTRACT Striped cucumber beetles (Acalymma vittata F.) are a serious pest of cucurbits, particularly on organic farms. These pests are the vector and overwintering host for bacterial wilt (Erwinia tracheiphila), which kills plants and can render cucumbers, melons and other produce unmarketable. During field research in 2009, row covers, compost tea and reflective mulch were compared on a commercial organic farm in Ottawa County, Michigan. I collected data on plant growth, incidence of bacterial wilt (Erwinia tracheiphila), marketable and unmarketable yields and profits. I found that row covers led to significant increases in plant growth, significant increases in marketable yield during the second harvest week (21-24 July 2009) and an increase in profits of $98.09 per 30.5 m (100 ft.) row as compared to controls. This would translate to 9062 more cucumbers per acre. Trends in the data also suggest that compost tea decreased bacterial wilt and the number of unmarketable cucumbers, but profits decreased due to high labor and supply costs. Reflective mulch reduced disease more than any other treatment, but lowered profits. Emergence of second-generation adult beetles coincided closely with recently-developed predictions of degree day development in this species. We recommend row covers to organic farmers as a first line of defense for striped iv 5 cucumber beetles, but also for increased yields and profits. This study also offers field data to confirm estimates of degree day development in striped cucumber beetles. KEY WORDS Acalymma vittata, Erwinia tracheiphila, Cucumis sativus, row covers, compost tea, reflective mulch v 6 TABLE OF CONTENTS LIST OF TABLES………………………………………………………… .. x LIST OF FIGURES………………………………………………………….xi CHAPTER I. LITERATURE REVIEW……….…………………………… 1 Striped cucumber beetle management…………………… 1 Life cycle and ecology…………………………………… 2 Cucurbitacins and other induced phytochemicals... 3 Agricultural impacts…………………………………….... 5 Bacterial wilt…………………………………….. 6 Measuring agricultural impacts………………….. 7 Organic control methods…………………………….…... 9 Exclusion………………………………………... 9 Boosting plant defenses…………………………. 11 Intercropping and trap cropping………………… 14 Biological control……………………………….. 15 Chemical and organic sprays……………………. 17 Research methods………………………………………... 18 vi 7 Sharing results with farmers…………………………….. 24 II. FIELD RESEARCH………… …………………………….. 27 Introduction……………………………………………... 27 Methods…………………………………………………. 30 Site and growing methods………………………. 30 Experimental design……………………………. 32 Treatments……………………………………… 32 Data collection…………………………………. 33 Statistical analysis……………………………… 36 Results…………………………………………………... 37 Early season beetle population………..……........ 37 Late season beetle population………………….... 37 Bacterial wilt……………………………………. 38 Yield…………………………………………….. 38 Leaf number…………………………………….. 40 Insect development…………………………….. 41 vii 8 Discussion………………………………………………. 41 Row covers……………………………………… 42 Compost tea…………………………………….. 43 Reflective mulch……………………………….. 43 Cucumber beetles……………………..………. 44 Confounding factors……………………………. 45 Statistical analysis……………………………… 46 Adoption by farmers……………………………. 46 Management implications……………………………… 47 III. ECONOMIC ANALYSIS.………………………………….. 58 Introduction…………….……………………………….. 58 Methods………..……………………………………….. 59 Results…………………………………………………. 59 Discussion……………………………………………... 60 Management implications……………………………... 65 References Cited………….……………………………………………. 72 viii 9 APPENDICES……………………………………………….………… 79 A. Photographs of research in progress and samples of marketable and unmarketable cucumbers…………………. 79 A1: Experimental Block 2……………………………. 80 A2: Flood-damaged leaves in Block 2……………….. 81 A3: Sticky trap placement in block 1………………… 82 A4: Examples of unmarketable and marketable cucumbers………………………………………… 83 A5: Increased growth rate under row covers…………. 84 A6: Downward-facing leaf growth in young transplants on reflective mulch…………………… 85 ix 10 LIST OF TABLES TABLE PAGE 2.1 Methods and data collection to evaluate striped cucumber beetle treatments in cucumbers in Ottawa County, Michigan……………… 48 2.2 Treatments for striped cucumber beetles in cucumbers…..………… 49 3.1 Expense list for experiment including 183 m (600 ft.) of cucumber plots……………………………………………………..… 66 3.2 Partial budget analysis of organic controls for striped cucumber beetles in cucumbers………...………………………………………. 67 3.3 Added profitability per 30.5 m (100 ft.) of cucumbers using various treatments…………………………………………………………… 68 3.4 Partial budget analysis of row covers for controlling striped cucumber beetles in cucumbers assuming optimistic, typical and pessimistic yields in a 30.5 m (100 ft.) row …………………………………….. 69 3.5 Partial budget analysis of row covers for controlling striped cucumber beetles in cucumbers with various prices in a 30.5m row……………… 70 x 11 LIST OF FIGURES FIGURE PAGE 1.1 Striped cucumber beetle………………………………………………... 1 2.1 Randomized plots comparing organic treatments for striped cucumber beetles in Ottawa County, Michigan………………..………. 50 2.2 Daily rainfall at field site of 2009 cucumber experiment……………… 51 2.3 Striped cucumber beetle population response to various pest controls………………………...………………………………………. 52 2.4 Striped cucumber beetle population on black and reflective plastic mulch in cucumber subplots…………………………………………... 53 2.5 Bacterial wilt infection rates using various treatments for its vector, striped cucumber beetles……….…………………….…. 54 2.6 Mean cucumber yield ± SE per 30.5 m (100 ft.) using various treatments for striped cucumber beetles………………………………………………. 55 2.7 Marketable cucumber yields per 30.5 m (100 ft.) row over harvest Season…………………………………………………………………. 56 2.8 Mean leaf number in cucumber plants is affected by various treatments for A. vittata. ……………………………………………… 57 3.1 Break-even analysis for using row covers in cucumbers, assuming a 30.5 m (100 ft.) row……………………………...………… 71 xi 12 CHAPTER I LITERATURE REVIEW Striped cucumber beetle management Striped cucumber beetles (Acalymma vittata F.,Coleoptera: Chrysomelidae) are ranked by organic growers nationwide as their most common and destructive pest problem (Walz 1999). This pest is the primary target for up to 10 annual insecticide applications on conventional farms, contributing to 35 confirmed pesticide residues on cucumbers (Hutchison 1994; Hollingsworth et al. 1998; Punzi et al. 2005). Organic farming can displace such chemical use, often while increasing farm profits. The $28.6 billion organic food and agriculture industry grew at 8% in 2010 and now represents 4% of retail food sales in the U.S. (Organic Trade Association 2011). Continued Figure 1.1 Striped cucumber beetle (Burkness & expansion of these environmental and economic Hutchinson, U. Minnesota http://www.vegedge.umn.edu/ benefits will hinge upon creative solutions to pest vegpest/CUCS/cucb.jpg) problems such as the striped cucumber beetle. Furthermore, less-toxic options for controlling striped cucumber beetles and other pests 1 can be used in conventional agriculture when they are shown to be more effective or less costly than chemical controls. Life cycle and ecology Striped cucumber beetles are the most damaging pest of cucurbit crops in Michigan, the Northeast and the Midwest (Grafius & Hooplingarner 1993; Latin 1993). High beetle populations defoliate young crops and transmit bacterial wilt (Erwinia tracheiphila, Enterobacteriales: Enterobacteriaceae),