Progress 09/01/23 to 08/31/24
Outputs
Target Audience:Growers Pest control advisors Agronomists Extension personnel Government researchers Academic (university) researchers Seed industry Students Changes/Problems:The virus complex transmitted by whiteflies continues to grow at an alarming rate. At the same time, our field data indicate that elicitors are most effective against mosaic viruses transmitted by aphids. This is a very important discovery because it allows us to assess the limits of elicitors for control of virus complexes primarily composed of whitefly-transmitted viruses. Our data also clarify that breeding for resistance against whiteflies is probably the better route to address challenges from virus complexes, as this will limit the transmission of multiple viruses. We are therefore focusing our efforts on advancing whitefly resistant germplasm and potentially combining this with elicitors for mosaic virus control, while pausing some work on CYSDV resistant germplasm. What opportunities for training and professional development has the project provided?Three undergraduate students assisted the graduate student with phenotyping. They mastered whitefly phenotyping techniques and plant breeding protocols. One of the undergraduates performed an independent project to evaluate relationships between leaf structure traits (trichomes) and whitefly resistance. The graduate student presented his work to other researchers and successfully completed his qualifying examination. The undergraduate students will be co-authors on forthcoming publications and presentations describing QTL mapping efforts. How have the results been disseminated to communities of interest?Presentations on the project were delivered at grower events, academic meetings, and meetings catering to seed industry personnel. We integrated outputs of project activities with educational efforts of the Emerging Viruses in Cucurbits Working Group (https://ecucurbitviruses.org/). The details of these presentations and stakeholders addressed are listed in the "other products" section of this report. One open access publication was produced for the project during this reporting period and this is listed in the "publications" section of this report. What do you plan to do during the next reporting period to accomplish the goals?For Objective 1 - Complete genotyping by sequencing to identify QTLs and markers associated with whitefly resistance traits in PI 122847 - Continue advancing germplasm for whitefly resistance based on QTL analysis and development of markers For Objective 2 - Evaluate effects of priming on resistance traits in offspring of CYSDV-resistant individuals in the F2:3 population derived from PI 313970 - Evaluate cost effectiveness of implementing elicitors in an IPM program
Impacts
What was accomplished under these goals?
Project impact statement Over the last 30 years, muskmelon growers in the US have endured the repeated introduction and establishment of new insect vectors (transmitters of plant viruses) and new viral pathogens. This has resulted in intensive use of insecticides to control insect vectors, leading to negative environmental impacts, high costs, and only marginal virus control. Thus, important economic, ecological, and environmental motivations exist to develop alternative integrated pest management (IPM) approaches to manage the impacts of both viruses and vectors. Our project addresses this need through testing and validation of resistance based IPM tools that will provide flexible, sustainable virus control options compatible with reduced risk insecticide programs. Building on several years of research, funded by stakeholders, we are using traditional breeding techniques to create new muskmelon cultivars with virus and vector resistance, then combining these with immunity priming to improve and broaden resistance traits. During the current project period, we conducted a large-scale phenotyping experiment to identify whitefly resistance traits in a set of wild melon x cultivated melon crosses known as a mapping population. We also made available, through an open-access publication, new tools to drastically improve breeding for whitefly resistance in melon and three additional crops plagued by whitefly attack. We discussed our project with numerous stakeholders, produced publications on our work to inform others of our research, and trained the next generation of agricultural science researchers. Our project activities are key steps to providing a suite of safe, effective tools for virus management. Obj. 1. Identifying resistance to CYSDV and B. tabaci. 1) Major activities CYSDV resistance Activities related to virus resistance focused on further understanding the virus complex into which resistance traits will be deployed. Ongoing stakeholder-supported surveys indicate yet another whitefly-transmitted virus, watermelon chlorotic stunt virus (WmCSV), is now spreading in key melon production areas. Whitefly resistance Phenotyped 1410 individual melon plants in the F2:3 mapping population representing 130 F2 families (mean of 10.8 individuals per family) Phenotyped 47 melon plants of each parent line Extracted genomic DNA from leaf tissues of 126 F2 plants in the mapping population and the two parent lines 2) Data collected and 3) Results CYSDV resistance We completed work on surveys to document new virus incursions into the areas where germplasm will be deployed. Surveys were conducted in the low desert region of CA and AZ in collaboration with partners on this project. Whitefly resistance During the previous project period, the main graduate student working on the project optimized our whitefly phenotyping protocol. During this project period, the student published this novel method in the journal Plant Methods and applied it to phenotyping a mapping population derived from PI 122847 x Top Mark crosses. The methods for phenotyping the mapping population are available in the publication (open access) 4) Key outcomes We identified a new whitefly-transmitted virus spreading throughout the region (WmCSV) and published this finding. We also discussed implications of this discovery in meetings with growers, researchers, and seed industry representatives. Our continued documentation of extensive co-infections among multiple whitefly-transmitted viruses suggests that breeding for whitefly resistance is the better option to pursue because breeding for resistance to one virus will simply create opportunities for other resident viruses to cause similar damage (even with immunity priming). We therefore focused on whitefly resistance breeding, as resistance to the vector will result in reduced infection success for all whitefly-transmitted viruses. We successfully completed phenotyping of the mapping population derived from the melon germplasm with the strongest whitefly resistance (> 1400 plants phenotyped using the new method we developed). Genome sequencing to identify quantitative trait loci associated with resistance is ongoing. Obj. 2. Immunity priming. 1) Major activities We completed testing the efficacy of priming agents under field conditions using conventional cultivars. In previous project periods we documented the efficacy of the commercially available products in the greenhouse and completed some initial field testing. During this project period we repeated field testing of selected products. 2) Data collected and 3) Results Compounds were tested through field applications according to label rates (Regalia) and plant-safe rates established by our group (Actigard) (Kenney et al. Viruses 2020, 12, 257). Plants in treatment plots received two applications of each product spaced out by 7 days, starting at the 1-2 true leaf stage. We previously tested compounds twice in the low desert area, and once in an area with typical Central Valley conditions. During this project period we ran a second experiment in the Central Valley conditions using zucchini yellow mosaic virus (ZYMV) as the challenge pathogen. We hand-inoculated this isolate to plants in plots at the two true leaf stage then assessed symptom incidence and progression over the season, yields, and fruit quality. In 2023 we found that both Actigard and Regalia slowed disease progression and improved fruit quality (sweetness) to fall within acceptable standards (virus infection without elicitor treatments resulted in fruit quality scores below the USDA standard). In 2024, we also saw evidence of reduced symptom expression but did not see the same improvement in fruit quality due to elicitor applications. 4) Key outcomes We confirmed that elicitors attenuate disease symptoms in the field against mosaic virus pressure. However, impacts on yield and fruit quality were variable between 2023 and 2024. In 2024, weather events (heat waves) may have influenced plant responses to elicitor applications, overriding benefits. Abiotic influences on plant responses to virus infection and elicitors should be evaluated moving forward. Obj. 3. Field evaluations/economic analysis. To be addressed in future project periods once resistant germplasm is amplified for field testing.
Publications
- Type:
Peer Reviewed Journal Articles
Status:
Published
Year Published:
2024
Citation:
van Raalte, B., Watrous, K., Lujan, M. et al. Evaluation of a low-cost staining method for improved visualization of sweet potato whitefly (Bemisia tabaci) eggs on multiple crop plant species. Plant Methods 20, 75 (2024).
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Progress 09/01/22 to 08/31/23
Outputs
Target Audience:Growers Pest control advisors Agronomists Extension personnel Government researchers Academic (university) researchers Seed industry Students Changes/Problems:The phenotyping process for advancement of whitefly resistance has taken longer than anticipated, but this challenge is common in this type of research and is one of the main reasons we do not have commercially available cultivars of any crop with whitefly resistance. During the project period, our efforts to improve phenotyping by oviposition measurements revealed remarkable inconsistencies in egg counting when eggs are not stained to improve visualization. As all previous applications of egg counting for phenotyping use unstained eggs, this is likely reducing heritability and impeding germplasm advancement. We are confident that investing time in improving this approach will have broad benefits for our project and the other crops on which we validated the approach (tomato, cowpea, sweet potato, and casava). The main downside of this delay is that we have not yet tested germplasm from our lines in the field alone or with elicitors. However, due to the quality of the graduate student involved in the project, we have been able to obtain merit-based support from UCR programs for student salaries for all but two summer periods. As a result, we have not only the trained personnel but also the funds to continue the project with a no-cost extension period should this be required to complete field experiments. We also continue to receive in-kind support from stakeholders, including the California Melon Research Board, who are very interested in seeing this germplasm deployed and incorporating elicitors into their management approaches. What opportunities for training and professional development has the project provided?One graduate student mastered whitefly phenotyping techniques and plant breeding protocols. This graduate student presented his work at numerous venues and engaged in conversations about the project with all stakeholder groups indicated on this report. The graduate student secured a one-year internal fellowship based on his performance, as well as merit-based funding from the UC Riverside graduate division and a UCR Department of Entomology US Dept. of Education grant. Two undergraduate students were trained in whitefly phenotyping protocols and both students will be co-authors on a forthcoming publication. How have the results been disseminated to communities of interest?Presentations and posters on the project have been presented at grower events, academic meetings, and meetings catering to seed industry personnel. The details of these presentations and stakeholders addressed are listed in the "other products" section of this report. Publications are listed in the "publications" section of this report. What do you plan to do during the next reporting period to accomplish the goals?For Objective 1 - Advance the six resistant lines derived from PI 122847 through production of fruit/seeds - Perform genotyping by sequencing to identify QTLs and markers associated with resistance traits in PI 122847 - Complete phenotyping of F1, F2, and backcross lines of PI 122847 and PI 313970 for whitefly resistance - Perform genotyping by sequencing to identify QTLs and markers associated with whitefly resistance traits For Objective 2 - Evaluate effects of priming on resistance traits in offspring of CYSDV-resistant individuals in the F2:3 population derived from PI 313970
Impacts
What was accomplished under these goals?
Project impact statement Over the last 30 years, muskmelon growers in the US have endured the repeated introduction and establishment of new insect vectors (transmitters of plant viruses) and new viral pathogens. This has resulted in intensive use of insecticides to control insect vectors, leading to negative environmental impacts, high costs, and only marginal virus control. Thus, important economic, ecological, and environmental motivations exist to develop alternative integrated pest management (IPM) approaches to manage the impacts of both viruses and vectors. Our project addresses this need through testing and validation of resistance based IPM tools that will provide flexible, sustainable virus control options compatible with reduced risk insecticide programs. Building on several years of research, funded by stakeholders, we are using traditional breeding techniques to create new muskmelon cultivars with virus and vector resistance, then combining these with immunity priming to improve and broaden resistance traits. During the current project period, we identified six more advanced breeding lines with virus resistance and evaluated priming compounds for efficacy against different virus pathogens under field conditions. We also performed final validation of tools to drastically improve breeding for whitefly resistance in melon and three additional crops plagued by whitefly attack. We discussed our project with numerous stakeholders, produced publications on our work to inform others of our research, and trained the next generation of agricultural science researchers. Our project activities are key steps to providing a suite of safe, effective tools for virus management. Obj. 1. Identifying resistance to CYSDV and B. tabaci. 1) Major activities CYSDV resistance 1. Screen parents and F1, F2, and reciprocal backcross populations for resistance to infection and systemic spread by CYSDV. During this project period we focused on lines derived from PI 122847, along with advanced breeding lines developed from PI 313970, which are also used as a comparative resistance source. 2. Screen parents and F2:3 families for resistance to infection and systemic spread by CYSDV. Completed screening of F2:3 families derived from PI 122847 (see data collected below). Resistance markers identification is in progress. Whitefly resistance 1. Screen parents and F1, F2, and reciprocal backcross populations for resistance to whiteflies. This work is on hold while we completed validation of the oviposition method for phenotyping. A graduate student completed this validation and produced a manuscript draft that is ready for submission. The manuscript draft is being reviewed by his academic committee members (a requirement of our graduate program) prior to submission to the journal Plant Methods. 2) Data collected and 3) Results CYSDV resistance Evaluations focused on evaluating F2:3 lines of the accession PI 122847, which showed high resistance to CYSDV in the laboratory and field. We also screened lines derived from PI 414723, which shows CYSDV tolerance. Screening methods followed those described in the report for the prior project period. Six lines derived from PI 122847 showed strong CYSDV resistance as measured by quantitative RT-PCR. Marker identification for these lines is in progress. Six lines derived from PI 414723 showed reduced virus titers relative to the susceptible control but were still infected. Based on these results, lines from PI 122847 are the most promising for advancement. In addition to breeding-related activities, we completed work on surveys to understand the dynamics of CYSDV and a related crinivirus, CCYV, in areas in which germplasm will be deployed. We collected a portion of the samples for this work during the prior project period (Fall 2021) and in this project period, completed a manuscript documenting CYSDV-CCYV co-infection dynamics (Mondal et al. 2023). Whitefly resistance During the previous project period, we recruited and trained a graduate student. The student identified several areas of the phenotyping approach that needed improvement, which were detailed in the previous project period report. During this project period, the student addressed all of these issues and optimized the protocol. The student created new clip cage designs for housing whiteflies during trials, improved whitefly handling and rearing protocols to produce sufficient numbers of females, optimized whitefly sexing protocols, designed handling protocols to increase throughput, evaluated a staining procedure that significantly increases egg counting precision, and demonstrated that our phenotyping workflow is especially effective for melons, but can be applied to numerous crops. The student will shortly submit this work for publication in the journal Plant Methods. We used this phenotyping method to validate resistance in parent PIs and explore age-related changes in resistance among parent PIs. Our results indicate that resistance in TGR-1551 is minimal and not easily phenotyped using our method or traditional, low throughput methods. Therefore, we will focus on PI 122847 and PI 313970. 4) Key outcomes Our project activities advanced six additional breeding lines for CYSDV resistance derived from accession PI 122847. We clarified and communicated virus community dynamics as they relate to the durability and usefulness of single virus resistance in elite germplasm. Phenotyping protocols were optimized and finalized for use with melons. A manuscript on the new phenotyping protocol is ready to submit pending final suggestions from the student first author's committee members. Obj. 2. Immunity priming. 1) Major activities As we await completion of CYSDV-resistant lines for field experiments, we continued to test the efficacy of priming agents under field conditions using non-resistant cultivars. In the previous project we documented the efficacy of the commercially available Actigard and Regalia products in the greenhouse. During the project period covered by this report, we tested these in the field. 2) Data collected and 3) Results Compounds were tested through field applications according to label rates (Regalia) and plant-safe rates established by our group (Kenney et al. Viruses 2020, 12, 257). Plants in treatment plots received two applications of each product spaced out by 7 days, starting at the 1-2 true leaf stage. Compounds were tested twice in the Southern desert area (Fall planting and Spring planting) and once in a production area typical of Central Valley conditions. For desert experiments, crinivirus pressure was sufficient for field testing without intervention. For the experiment in the non-desert environment, disease pressure is variable. Therefore, we collected and amplified a local isolate of a mosaic virus that causes losses in the Central Valley region (ZYMV) and hand-inoculated this isolate to plants in plots at the two true leaf stage. We assessed symptom incidence and progression over the season, yields, and fruit quality. We found that elicitors had little effect on disease outcomes for a virus-susceptible cultivar under the high crinivirus inoculum pressure present in the Southern desert production areas. In contrast, for the experiment with ZYMV pressure, both Actigard and Regalia slowed disease progression and improved fruit quality (sweetness) to fall within acceptable standards (virus infection without elicitor treatments resulted in fruit quality scores below the USDA standard). 4) Key outcomes We determined the efficacy of elicitors under field conditions and against specific types of viruses. Our results suggest that elicitors should have the strongest benefits when combined with virus or vector resistant germplasm in areas affected by mosaic viruses in the genus potyvirus. Obj. 3. Field evaluations/economic analysis. To be addressed in future project periods once CYSDV-resistant germplasm is amplified for field testing.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Mondal, S., Jenkins Hladky, L., and Wintermantel, W.M. 2023. Differential seasonal prevalence of yellowing viruses infecting melon crops in southern California and Arizona determined by multiplex RT-PCR and RT-qPCR. Plant Disease 107: 26532664.
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Progress 09/01/21 to 08/31/22
Outputs
Target Audience:Growers Pest control advisors Agronomists Extension personnel Government researchers Academic (university) researchers Seed industry Students studying entomology, plant pathology, and plant breeding Changes/Problems:We experienced some slight delays in finalizing breeding lines for whitefly resistance phenotyping. These are now completed. We identified some areas of the whitefly phenotyping protocol that required improvement as we attempted to scale up this protocol to much larger experiments. We also identified the presence of age-related resistance against whiteflies in at least one breeding line. These findings caused us to revisit the phenotyping protocol to implement improvements and to revise experiment protocols to incorporate a time series element (which will lengthen the duration of each experiment). Additionally, we are performing experiments to determine if we can use immunity priming as a means of eliciting resistance traits at earlier phenological stages of plant development. Although the overall progress of whitefly resistance phenotyping has been delayed by these discoveries, addressing them ensures that we can consistently and accurately phenotype material, which is necessary for advancing breeding lines with these traits and evaluating responsiveness to priming products. Additionally, revision of the phenotyping protocol will lead to an additional publication providing guidance and tools (e.g., software) for using this protocol in other specialty crops. What opportunities for training and professional development has the project provided?One graduate student was trained in whitefly phenotyping techniques and plant breeding protocols. Two graduate students attended the Fall Vegetable Crops Update and the Emerging Viruses in Cucurbits Working Group meetings and participated in conversations with stakeholders about virus problems, solutions, and future challenges. Two undergraduate students were trained in virus handling/inoculations, diagnostics, and phenotyping How have the results been disseminated to communities of interest?Progress on the project was discussed with representatives of the specialty crop industry in California at the Specialty Crop Technical Council meetings (Mauck - grower/policymaker audience), the Entomological Society of America Annual meeting (Co-PI Wintermantel - academic/researcher audience), the Cucurbitaceae meeting (Wintermantel - seed industry, academic/researcher audience), the International IPM Symposium (Mauck - academic/researcher audience), and the CA Melon Board virtual symposium (Mauck - grower audience). Project progress discussion was also part of activities of the Emerging Viruses in Cucurbits Working Group (Mauck, Wintermantel). This group includes researchers, government/policymakers, and industry representatives. An extension presentation that covered some aspects of this project (plant priming, emerging viruses) was delivered to growers, pest control advisors, and agronomists at the Fall vegetable crops update held in Five Points, CA (Mauck, Wintermantel). What do you plan to do during the next reporting period to accomplish the goals?For Objective 1 - Complete CYSDV resistance phenotyping of F1, F2 and backcross lines of PI 122847 - Perform genotyping by sequencing to identify QTLs and markers associated with resistance traits in PI 122847 - Finish production of fruit from select CYSDV-resistant individuals in the F2:3 population derived from PI 313970 - Complete phenotyping of F1, F2, and backcross lines of PI 122847, PI 313970, and TGR-1551 for whitefly resistance - Perform genotyping by sequencing to identify QTLs and markers associated with whitefly resistance traits For Objective 2 - Evaluate effects of priming on resistance traits in offspring of CYSDV-resistant individuals in the F2:3 population derived from PI 313970 - Determine how priming affects the magnitude and timing of resistance against whiteflies
Impacts
What was accomplished under these goals?
Project impact Over the last 30 years, muskmelon growers in the US have endured the repeated introduction and establishment of new insect vectors (transmitters of plant viruses) and new viral pathogens. This has resulted in intensive use of insecticides to control insect vectors, leading to negative environmental impacts, high costs, and only marginal virus control. Thus, important economic, ecological, and environmental motivations exist to develop alternative integrated pest management (IPM) approaches to manage the impacts of both viruses and vectors. Our project addresses this need through testing and validation of resistance based IPM tools that will provide flexible, sustainable virus control options compatible with reduced risk insecticide programs. Building on several years of research, funded by stakeholders, we are using traditional breeding techniques to create new muskmelon cultivars with virus and vector resistance, then combining these with immunity priming to improve and broaden resistance traits. During the current project period, we identified advanced breeding lines with virus resistance and screened priming compounds for efficacy against different virus pathogens. We also refined a method for evaluating resistance against vectors and are working to make this available for use in other crops. Our project activities are key steps to providing a suite of safe, effective tools for virus management. Obj. 1. Identifying resistance to CYSDV and B. tabaci. 1) Major activities CYSDV resistance 1. Screen parents and F1, F2, and reciprocal backcross populations for resistance to infection and systemic spread by CYSDV. Lines proposed for evaluation through these experiments include those derived from PI 122847, along with advanced breeding lines developed from PI 313970, which are also used as a comparative resistance source. Screening of PI 122847 is in progress. 2. Screen parents and F2:3 families for resistance to infection and systemic spread by CYSDV. Completed for F2:3 families derived from PI 313970 (see data collected below). Resistance markers have been identified for breeding lines derived from this accession and these facilitated exploration of relationships between the previously identified QTL and resistance traits. Whitefly resistance 1. Screen parents and F1, F2, and reciprocal backcross populations for resistance to whiteflies. Crosses were completed to produce F2:3 families derived from three sources of whitefly resistance (PI313970, PI122847, and TGR-1551). A graduate student was recruited and trained on methods for phenotyping whitefly resistance. Methods for whitefly resistance that we previously developed were refined. 2) Data collected and 3) Results CYSDV resistance Evaluations focused on evaluating F2:3 lines of the most promising source of resistance that is closest to commercialization - PI 313970. Screening of the next most promising line (PI 122847) is currently in progress. Whiteflies were provided an acquisition access period (AAP) of 48 hours on the CYSDV-infected source plants. Clip cages containing 50 viruliferous whiteflies were attached to the underside of melon seedlings for a 48-hour inoculation access period (IAP). Following transmission, plants were treated to remove whiteflies then transferred to cages in growth chambers, and CYSDV titer was evaluated by RT-qPCR at 6 weeks post inoculation. Plants with low titers and limited or no symptoms were transferred to a whitefly-proof cage in a greenhouse for further development and for collection of fruit, with continued sampling for virus titer every 21 days. All susceptible plants (Top Mark) were symptomatic and infected. Several plants of different 313970 progeny lines were promising because virus was not detected, foliar symptoms were absent, and one or both markers for the resistance locus were present. For example, a few plants of F2:3 line 36902 had low CTs indicating virus accumulation; however, most lines exhibited high CTs indicating these plants did not become infected with CYSDV. Other promising progeny were also identified from this cross and are being propagated for further evaluation. In general, virus accumulation and symptom expression were reduced in plants with one or both putative markers and heterozygous lines. Low-titer plants with flanking PI 313970 markers and asymptomatic/mild symptoms will be advanced to the next generation. Whitefly resistance Crosses to produce advanced breeding material were completed by collaborator McCreight. Whitefly phenotyping is in an earlier stage than CYSDV phenotyping for all lines. We previously developed an oviposition-based resistance phenotyping approach and validated this with the use of externally applied resistance elicitors. Female whiteflies extract fewer nutrients from resistant plants and produce fewer eggs within a defined area, which can be counted by the researcher. This method is a large improvement over prior methods. We recruited/trained a graduate student with phenotyping experience to carry out this approach on the completed lines. However, the student noticed some areas that needed improvement to ensure accuracy. Optimization of egg counting - the student optimized a mid-throughput staining procedure to visualize eggs laid on melon leaves. Staining improves accuracy of egg counts and allows photographing for automated egg counting. The student also trialed different photography techniques and equipment set ups to identify one that accurately shows all eggs in the field of view (stacked images). Automation of egg counting - the student wrote and tested a computer program to automate egg counting. The student identified features associated with eggs and trained the program to be able to discriminate eggs from residual leaf features that did not fully clear during staining. Optimization of whitefly synchronization/mating - the student improved methods for synchronizing emergence of female whiteflies and ensuring mating status prior to use in experiments. Identification of plant age as a factor underlying the magnitude of whitefly resistance in melon - The student used parental germplasm of TGR-1551 to validate phenotyping method progress. The student discovered that for this accession, plant age plays a role in the strength of whitefly resistance. This is an important discovery as it changes our phenotyping approach to include a time series element. 4) Key outcomes Our project activities produced knowledge toward advancement of breeding lines for CYSDV resistance and phenotyping for whitefly resistance. Whitefly resistance phenotyping methods will be published and can be used for other specialty crops (anticipated Spring 2023). Obj. 2. Immunity priming. 1) Major activities We screened five priming agents for efficacy in preventing infection and/or attenuating symptoms/titer of CYSDV and a mosaic virus (zucchini yellow mosaic virus). 2) Data collected and 3) Results Plants were treated with elicitors then challenged with virus infection by vector inoculation (for CYSDV) or rub inoculation (ZYMV). We collected data on infection rates, symptom severity, and virus accumulation in plants (titer). Actigard, Regalia, and a laminarin formulation all reduced symptom severity. No compound fully prevented infection. We will focus on using these active ingredients and evaluate against additional viruses. We also found that priming is more effective during warmer periods with longer day lengths of natural sunlight. We will follow up on this work with additional experiments in ensuing project periods. We will also evaluate efficacy of priming agents as inducers of resistance against whiteflies. 4) Key outcomes We identified which priming agents and pathways are active against viruses, and variation in efficacy due to seasonality. This knowledge is necessary for selecting the right options for IPM practices. Obj. 3. Field evaluations/economic analysis. To be addressed in future project periods.
Publications
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