Tika Adhikari

The main goal of this proposal is to improve the resilience and sustainability of U.S. tomato farms through the identification and utilization of novel genetic determinants that confer resistance to Verticillium Wilt incited by non-race 1 isolates of Verticillium dahlia (Vdn). The pathogen can live for 20 years or more in the soil and rotation is not feasible for control of the disease because other crops are also hosts. We propose that the critical solution to mitigate VW damage may be host resistance and the most feasible and economic control is the use of verticillium-tolerant tomato cultivars. There are numerous resistant cultivars effective against race 1; however, no source of resistance to non-race 1 isolates is commercially available. Multiple on-farm trials in Vdn infested grower fields enabled us to successfully identify novel sources of Vdn resistant tomato germplasm. The following objectives express a two-tiered approach to achieve and deliver the proposed outcomes to the stakeholders. a) identify and fine-map Vdn resistant locus (loci) in three NCSU tomato breeding lines. b) Utilize Vdn resistance to develop new tomato hybrids stacked with additional disease resistances The addition of Vdn resistance will broaden the disease-resistant spectrum of the elite NCSU tomato cultivars minimizing economic risk for growers in the U.S. and worldwide. Improved cultivars will be selected in a farmers' participatory selection process and released for commercial use. Findings from this research will be published in relevant journals and may also provide a genetic tool to combat VW in other economically important crops.

The demand for organic tomatoes in the Southeast is high, but production is limited due to lack of regionally adapted high yielding varieties. Organic growers have requested research disease management practices including improved varieties with superior fruit quality so that they can take advantage of the ever increasing market demand. Our long-term goal is to develop sustainable approach of disease management for organic production by integrating organic disease management system and resistance breeding well-adapted to organically growing conditions in the Southeast. The proposed project will benefit farmers in the U.S. in general, and in the Southeast in particular, who need high-value crops that can be grown on small acreages. This proposal was developed through direct interaction with the organic growers. The objectives of this proposal are: 1: Determine genotypic differences for foliar and soil-borne fungal disease resistance, and fruit quality in heirloom tomato varieties grown under organic conditions 2: Production system: grafting for the management of major diseases and enhancing fruit quality under organic transition conditions 3: Identification of suitable tomato varieties for organic production through participatory variety selection for high yield, disease resistance, and fruit quality 4: Disseminate knowledge gained on tomato varieties and production systems grown in organic conditions to farmers, extension agents, industry, and the general public The proposed research is relevant to the Organic Transition program and will facilitate the development of organic agriculture production, biodiversity, and soil health by minimizing the pressure of soil-borne pathogens, and integrating novel technology into organic system.

The phasing out of methyl-bromide has left many agricultural systems vulnerable to soil-borne plant pests. Bacterial wilt and Verticillium wilt are existential threats to many crop systems. Addressing these threats requires a multifaceted approach. Understanding how to restore tired soils will involve researching how plant genetics, microbiomes, and grower inputs are interconnected. NC State has a large number of proprietary sequenced tomato lines and access to commercial lines with diverse genetic backgrounds known to improve soil health. To better understand how to utilize this rich source of genetics, we propose to study the impacts of these tomato lines on soil health in disease infested fields. Several locations with bacterial wilt and Verticillium wilt infested soils are available to us. In cooperation with growers, we propose to study the impact of this diverse tomato collection on soil health under various conditions [fumigated, non-fumigated, and anaerobic soil disinfestation (ASD)]. The utilization of these tomato lines will also be studied in grafted and non-grafted systems to allow growers the usage of cultivars with their preferred characteristics. Soil health will be assessed by measuring plant-available nutrient content, microbiome diversity, disease severity, and subsequent increases in yields.

Bacterial spot of pepper is a serious disease of peppers in the USA. This project seeks to conduct research and extension efforts related to 1) Population genetics of endemic and emerging bacterial pathogens (Xanthomonas, Pseudomonas and Clavibacter) of peppers and detection assay development; 2) Breeding for resistance. 3) Evaluating novel biologicals, biorationals and nanomaterials to manage critical bacterial diseases of peppers; and 4) conduct outreach to stakeholders to disseminate information for informed management decision making and increased economic benefits. NCSU personnel will be engaged primarily with objectives 1,2 and 4.

To improve the sustainability of the tomato production system and to reduce the dependence on pesticides, the combined use of anaerobic soil disinfestation (ASD) and the application of biological control agents (BCAs) are promising management alternatives for soil-borne pathogens of tomato in North Carolina. ASD has an incredible potential to complement other practices such as solarization, biological control, or grafting. More importantly, it is possible to combine them with the application of ASD. Our working hypothesis is that ASD treatment combined with BCAs application could be more effective than either treatment alone in reducing VW and BW in tomatoes. Our overarching goal of this project is to develop effective and sustainable management tools for emerging soil-borne diseases of tomatoes in North Carolina. We hypothesize that the combination of ASD treatment and biocontrol agent can be more efficient than either treatment alone in reducing VW and BW severities in tomatoes. The specific objectives of the project are to (i) select a carbon source for anaerobic soil disinfestation (ASD) based on its effect on Verticillium wilt (caused by Verticillium dahliae (Vd) race 3) (VW) microsclerotia viability, and bacterial wilt (BW) severity (caused by Ralstonia solanacearum (Rs) race 1) in tomatoes, and (ii) To determine the combined effect of ASD and application of new biological control agents (BCA) to reduce VW and BW in tomatoes. This project envision to provide growers, agribusiness companies, and extension agents with a sustainable and integrated management strategy for the soilborne pathogens in tomato production systems.

Soilborne pests such as soil-borne fungal pathogens, nematodes, and weeds limit strawberry production in SE-USA. Among these, soilborne pathogens such as Pythium irregulare, Rhizoctonia fragariae, and Pratylenchus penetrans which cause black root rot (BRR) complex. Although soilborne pests were effectively managed in strawberry production by the application of methyl bromide (MB), a pre-plant soil fumigant, it was phased out due to health and environmental concerns. Anaerobic Soil Disinfestation (ASD)���, also known as ���Biological Soil Disinfestation (BSD)���, is a non-chemical method used to manage soil-borne diseases, phytonematodes, and weeds in vegetable and fruit production systems. The main objective of this project is to conduct lab and greenhouse trials to examine the capacity of anaerobic soil disinfestation (ASD) with locally available labile carbon sources to advance a non-fumigant-based production system. Understanding the effects of locally available carbon sources that can initiate ASD has the promise and environmental benefits of non-chemical management of soilborne pests and continue to make this research project on this area both timely and of critical importance to improved soil conditions and agriculture sustainability in NC.

The strawberry breeding program at NC State University objective is to breed strawberries that adapted to climate and cultural growing conditions in North Carolina and the southern region of the US. In order to be successful in this region, cultivars need to have a minimal chilling requirement and a fruiting period that occurs primarily in a 2 month window the spring. Our primary objectives therefore are to develop strawberry cultivars with superior yield, fruit and horticultural plant traits adapted to this region. Ideal plants would also have resistance to insect and disease pressures that are common to this region.

This proposal develops an expandable infrastructure for the field testing and deployment of plant protection products. The project is focused on the management of botrytis in strawberries in the United States but with potential global application. The project includes: i) the identification of microclimate and phenological indicators for botrytis forecasting; ii) affordable, infield sensor arrays; iii) Deployment of improved Botrytis forecasting models���; and iv) Product testing in strawberry fields including integration of models, infield monitoring and product application. Initial product testing is planned in North Carolina, Florida and California.

The main goal of this project is to optimize and fill gaps in managing soil-borne pathogens of tomato using current fumigant practices and explore new opportunities to advance non-fumigant based IPM options for tomato growers in North Carolina. Tomato growers in NC face many challenges due to emerging diseases such as Verticillium wilt (VW) and root-knot nematodes (RKN) that limit crop yield and profitability. Specific objectives are as follows: 1) Optimize fumigant application rates, methods, and mulch types to enhance the efficacy of pest management in tomato, and 2) Advance host resistance and grafting to manage Verticillium wilt in the tomato production system.

The main objectives of this project are (i) to characterize and compare the structure and composition of the root and rhizosphere bacterial and fungal communities of strawberry and (ii) to identify key beneficial and symbiotic plant-associated microbes that can utilize carbon sources and suppress soil-borne pathogens of interest. Our long-term goal is to develop a next-generation microbiome-mediated strategy as a chemical alternative method for targeted soil-borne disease suppression and enhance strawberry plant growth and marketable yield in North Carolina.