Soilborne Diseases in Tomato High Tunnels: An Emerging Threat

Ohio vegetable producers are increasingly using high tunnels to produce high-value tomatoes as these structures allow for season extension and protection from adverse environmental conditions. The protected environment and lack of crop rotation inside these tunnels leads to the build-up of soilborne pathogens. A yield-limiting soilborne disease complex is present in Ohio high tunnels and includes corky root rot (Pyrenochaeta lycopersici), black dot root rot (Colletotrichum coccodes), Verticillium wilt (Verticillium dahliae), and root knot nematodes (Meloidogyne spp.). Soilborne diseases are often ignored until they preclude profitable tomato production as they are difficult for farmers to observe and researchers to diagnose. A survey of Ohio high tunnel soils was conducted in 2017-2018 to identify the incidence of these diseases across the state, proactively providing researchers with a better understanding of disease distribution and farmers with improved knowledge of the diseases present on their farms. Soils were collected from 68 tunnels from 34 farms in 17 Ohio counties. Pathogens were detected in soils using PCR-based assays and greenhouse bioassays. The most commonly detected pathogen was C. coccodes, present in 90% of high tunnels and 97% of farms. The next most commonly detected pathogens were P. lycopersici present in 47% of high tunnels and 50% of farms and V. dahliae, present in 46% of high tunnels and 74% of farms. Root knot nematodes were detected in 38% of high tunnels and 50% of farms. This information will aid in prioritizing disease management research and providing farmers with targeted soilborne disease management recommendations

Farmer-Focused tools to improve soil health monitoring on smallholder farms in the Morogoro region of Tanzania

A participatory approach was used to improve smallholder tomato farmers’ understanding of and access to soil health monitoring in the Morogoro Region of Tanzania. Baseline soil characteristics were gathered from 50 tomato fields in the region, local soil knowledge was elicited from farmers and used to de- velop a soil health card to qualitatively assess soil health, and farmers (n = 32) were trained on the use of a low-cost soil test kit to quantitatively assess soil health. Farmers most often described local indicators of soil health in terms of soil texture and tilth, soil color, soil water relations, and soil fertility. Following use of the soil test kit, farmers indicated increased awareness of soil testing services (Wilcoxon signed rank Z = –3.0, P = 0.001), more agreed they had access to soil testing services (Z = –2.7, P = 0.004), and more agreed that soil management recommendations were easy to understand (Z = –3.4, P < 0.0001) compared with pre-exposure results. Farmers continued to use the soil health test kit and soil health card based on a follow-up survey administered 1 year after project completion. Participatory soil health monitoring projects can improve farmers’ ability to monitor and manage soil health, potentially impacting sustained soil and plant health.United States Agency for International Development - United States Borlaug Fellows in Global Food Security and iAgr

Integrating ethnophytopathological knowledge and field surveys to improve tomato disease management in Tanzania

<p>The prevalence of tomato diseases and local smallholder farmer knowledge was assessed in five villages in the Morogoro Region of Tanzania during the rainy and dry production seasons. The most commonly occurring foliar diseases in both seasons were early blight (88 of 100 fields), bacterial spot/speck (49), viral diseases (42) and Septoria leaf spot (34). Bacterial spot/speck, tomato yellow leaf curl virus, other viral diseases, and late blight were present in significantly higher numbers of fields during the rainy season than the dry season, while significantly more plants per field were affected by early blight in the rainy season than the dry season. A root health assay was conducted to assess root knot nematode damage and root rot severity, and root knot nematodes were found in 44 of 50 fields surveyed. Farmers used local names for plant diseases, which tended to be associated with the symptomatology of the disease, concepts borrowed from other aspects of life, perceived causal agent or weather conditions. Identification of local names improved communication between farmers and researchers and elucidated how farmers perceived key diseases in the region. Extension materials were developed to improve farmers’ identification and management of key tomato diseases in the region. Farmers can better allocate limited resources to manage key diseases through an improved understanding of prevalent diseases and local plant disease knowledge. This study serves as an example of how plant pathologists can develop a baseline understanding of key regional plant disease constraints through the integration of field surveys and ethnophytopathological studies.</p