- Agronomic: sunflower
- Vegetables: tomatoes
- Crop Production: intercropping, tissue analysis
- Education and Training: farmer to farmer, on-farm/ranch research
- Farm Business Management: feasibility study
- Pest Management: biological control, disease vectors, field monitoring/scouting, physical control, row covers (for pests)
- Production Systems: permaculture
Heirloom tomatoes are a popular crop for many small-scale organic growers, bringing both a price premium and attracting numerous customers in search of old-fashioned tomato flavor. Our company, TomatoCulture LLC, is part of a fast-growing market for sustainable, locally produced food. We target local chefs, caterers and farmers’ market patrons who increasingly want to know the origin of their food and seek out organic and unique products characterized by taste, quality and nutrition. Maximizing yield is critical to growing heirloom tomatoes profitably. The demand for our sustainably produced, colorful and flavorful heirloom tomatoes exceeded our supply in 2015, due in large part to significant losses from Beet Curly Top Virus (BCTV). BCTV is a very destructive tomato pathogen, widespread in multiple strains across the semi-arid regions of the Western United States. It can wreak havoc on small-scale farms that rely on income from high-value heirloom tomatoes. TomatoCulture LLC (the Producer) is a case in point. In 2015, BCTV caused a 40% loss in potential heirloom tomato yields, reducing cash flow by over $10,000. A fellow New Mexico (NM) farmer reported pulling nearly 100 BCTV-infected plants per day at one point during the season. Small-scale farmers are not the only ones impacted. A severe 2013 outbreak of BCTV in California’s San Joaquin Valley caused tomato losses that exceeded $100 million (CA Tomato Growers Association, UC Davis, 2014). The beet leafhopper (Neoaliturus tenellus) is the only known vector of BCTV. According to plant pathologists at New Mexico State University (NMSU), and confirmed by several other Western universities, BCTV is very difficult to control, with no known resistant tomato varieties. High BCTV percentages in crops are consistently related to high October and November rainfall in NM (Romney 1939; R. Creamer, unpublished data). Adult leafhopper populations increase in mid-April, remain high through the summer, and decrease in the fall (Creamer et al., 2003). Young plants are highly susceptible and, if infected, bear no fruit and die prematurely. Stress factors later in the season, like blazing sun, heat and drought, can cause symptoms to emerge in older plants. Management strategies for large-scale tomato growing have focused on spraying herbicides to control the various weeds on which the beet leafhoppers overwinter and feed, and using insecticides to control the leafhopper itself. Researchers suggest controlling the major host weeds as the most sensible area-wide approach to managing N. tenellus because these weeds serve as virus reservoirs (Creamer et al. 2003), as well as leafhopper hosts. However, N. tenellus is a very mobile disease vector, obfuscating the benefit of weed control efforts. Spraying for the leafhopper has also proven ineffective, although may prevent some infield spread on large acreages (NMSU publication H-106). Other recommended controls pertain mostly to home gardeners and include cultural practices that reduce the attractiveness of tomato plants to the leafhoppers. A publication from Oklahoma State University indicates that the beet leafhopper is most attracted to “widely spaced, vigorous plants grown in open areas where the plants sharply contrast with the surrounding soil.” Defensive strategies include weed control, dense planting, row covers, shading, living mulches and intercropping. NMSU suggests that home gardeners plant tomatoes in light shade, as beet leafhoppers prefer to feed in bright sunshine. But how practical are these strategies for farmers growing at a larger scale? This grant request seeks to address this question. Through this project, TomatoCulture will test an integrated approach to beet leafhopper control and reduced incidence of BCTV in its tomato fields. Control strategies will include: dense spacing; row covers; weed barrier; living mulches; insectary plantings for natural leafhopper enemies; and a shading system. The shading system is the primary variable to be evaluated. TomatoCulture will design and manage a test to compare and contrast the efficacy of two innovative shading strategies: 1) A fabric shade cloth, suspended above the rows using infrastructure already in place for trellising the tomatoes; and 2) Inter-planting with wild sunflowers (Helianthus annuus L.), which grow taller than the tomatoes, providing dappled shade. In this experiment, TomatoCulture will: Divide the field into three equal blocks with three strips each; Cover rows of tomatoes with shade cloth in strip one throughout the season; Interplant sunflowers with the tomatoes in strip two; Provide no shading in strip three; Distribute these treatments randomly within each of the three blocks; Cover all rows of tomatoes with a light row cover suspended by hoops to protect plants during the first 30 days; Apply equally to all rows, reflective weed barrier, fertilization, watering, and organic treatments for foliar diseases; Plant flowering insectary rows approximately every 20 feet to attract natural beet leafhopper predators and parasitoids, avoiding any known hosts of the pest; Employ detailed data collection and tracking in the field to determine rates of BCTV infection, plant health, plant mortality, and yield. The Producer hopes to demonstrate an economically feasible and environmentally sustainable approach to controlling BCTV, one that will enhance the availability and quality of culturally important heirloom tomatoes and provide value to other farmers. Outreach and education will be a very important part of this project. TomatoCulture will use video to capture and present the experiment as it unfolds. Additionally, we will create and distribute collateral material, post the research findings on our Website and present the results through multiple events through the Rio Grande Farmers Coalition, NM Western SARE, and the annual NM Organic Farming Conference.
Project objectives from proposal:
- Determine if light shading deters the beet leafhopper from feeding on tomato plants and spreading the BCTV infection. Working with the Bernalillo County Extension service, TomatoCulture will monitor plant infection and mortality rates for each of the test plots and periodically send plant tissue samples to the plant diagnostics lab through NMSU to confirm BCTV infection.
- Compare shade cloth with inter-planted sunflowers to see which shading system works best in terms of effectiveness and cost. If we can confirm protection from shading, it will be valuable to understand if inter-planting tall sunflowers (assumed to be more cost effective) provides the same, less or greater benefit as fabricated shade cloth.
- Measure and compare plant yields to determine if there is a positive ROI for the increased labor and material cost associated with each shading system. Monitoring and comparing the fruit yields across the three different test plots will provide valuable information about the feasibility of an environmentally sound approach to a pest that can be very destructive to high-value cash crops.
- Determine if shading to control BCTV has other impacts, good or bad, on overall plant health and tomato yield. Some believe that shading sun-loving tomato plants slows plant growth, delays flowering and reduces yield. This experiment will allow us an easy way to test a secondary hypothesis: that shading in NM, which is at higher elevations and has high solar radiation, actually leads to less stressed plants, greater fruit set, and lower disease pressure overall.