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Funded Project

Funding Program: Regional IPM Competitive Grants - Northeastern

Project Title: Combined Resistance to Late Blight, Early Blight, and Septoria Leaf Spot in Tomato, and Complementary Fungicides for Northeast and Other Temperate U.S. Production Zones

Project Directors (PDs): Martha Mutschler [1] Thomas A. Zitter [2] Charles Bornt [3] Barbara Liedl [4] Kelly Ivors [5] Steven Rideout [6]

Lead State: NY Lead Organization: Cornell University

Cooperating State(s): North Carolina, Virginia, West Virginia

Extension Funding: $10,720

Research Funding: $123,000

Start Date: Sep-01-2009 End Date: Aug-31-2012

Pests Involved: early blight, late blight, septoria leaf spot, fungus, fungi

Site/Commodity: tomatoes

Area of Emphasis: resistance, breeding, organic

Summary: This Research & Extension project targets improved control, with reduced pesticide load, of early blight (EB), late blight (LB), and Septoria leaf spot (SLS), the 3 main fungal diseases of tomatoes in the eastern US. These diseases occur in all NE states to the Southern region and are repeatedly listed as priority items. Another priority is strobilurin resistance found in EB isolates in NY, NC. This project unites breeders, pathologists, horticulturists, and conventional & organic growers in 4 states and two regions to meet priorities by developing LB/EB/SLS resistant tomatoes (adding SLS resistance to a LB/EB resistant line), and testing disease response of these lines with reduced sprays of low EIQ fungicides. Severe SLS damage across the NE in 2008 demonstrates the need for this resistance. We address strobilurin resistance by selecting appropriate replacements, scheduling use (TOM-CAST), and assess how reduced sprays and plant resistance can improve control and reduce grower costs. Conventional and organic grower-cooperators will serve as multipliers. Objectives: Research Objective 1: Combine SLS resistance with LB and EB resistance in high quality tomato line Research Objective 2: Testing disease response and horticultural type in triple-resistant lines and hybrids. Research Objective 3a: Determining the efficacy of four fungicide treatments (a reduced spray schedule, TOM-CAST-18 and TOM-CAST-25 and an organic treatment) for the control of SLS with or without genetic resistance. Research Objective 3b: Compare the performance of the best subset of fungicide timings on tomato lines with & without EB/LB/SLS resistances. Extension Objective 4: Field work in Albany/Columbia Cos. NY and in other VA, NC, and WV in Years 2 and 3 Research Objective 5: In years 2 and 3, the triple-resistant lines and hybrids will be used for replicated trials in organic production with a commercial line as a control. Plants and fruit will be characterized for horticultural characteristics in multiple organic locations in years 2 and 3 of the project. Trials will be conducted at least two locations with organic certification or production standards and scheduled IPM scouting. If necessary, fungicide programs will be implemented using data from Objective 3a above and OMRI approved products. The data from the plants and fruit grown at these sites will guide the release of the tomato lines and assist in developing recommendations for organic production with these disease resistance plants, or indicate what additional modifications of the lines will be necessary to gain acceptability. Proposal USDA CRIS research data USDA CRIS extension data

Interim Report: Dec-01-2011

Outcomes A trial in the Cornell Organic Farm in Freeville produced data on both SLS control and fruit characteristics. Disease development started in July, but was slow to advance due to the hot dry conditions that are unfavorable to EB and SLS. However disease development intensified with the cooler much wetter conditions in august. Disease and defoliation was marked in the susceptible controls, the cultivar Mt Fresh Plus, and the LB/EB hybrids that lacked SLS resistance (denoted as SLS-S in Fig. 1), but much slower in the SLS resistant hybrids. As a result, on August 23rd, the defoliation of Mt Fresh and of the LB/EB hybrids was >85% and >75% respectively, while the defoliation of the LB/EB/SLS hybrids was <12%. Defoliation of the LB/EB/SLS hybrids started to rise thereafter, starting on plants closest to neighboring susceptible entries, and reaching 50% after another 2 weeks. This appears to parallel defoliation possible when SLS resistant lines are subjected to extremely heavy artificial inoculation (spraying to run off with suspension of ca 500,0000 spores per ml). The lesions on SLS resistant lines are very small, but if they are present in extreme number, defoliation still results. We postulate that isolating SLS resistant plants from susceptible plants would greatly extend the disease free or very low disease period. We will be testing this hypothesis in the 2012 season. Early Blight tolerance is associated with smaller fruit, so we compared fruit size and yield of LB/EB/SLS hybrids with LB/EB hybrids with same male parents to determine if SLS resistance has any affect on fruit or yield. The results indicate that the fruit weights of LB/EB/SLS hybrids no smaller than that of LB/EB hybrids (Table 1). Fruit weights of the LB/EB (166 to 179g) and LB/EB/SLS hybrids (150 to 186g) are moderate, ranging between that of Legend (146g) to less than that of Mt Fresh (254 g) Fruit size and yields of the SLS/LB/EB lines and hybrids does not indicated linkage drag issues with SLS resistance gene The yield of LB/EB/SLS hybrids was also no smaller than that of LB/EB hybrids. The LB/EB/SLS hybrids also tended to have less BER, higher % marketable fruit. However we do not know if this will be a typical result, since the year itself was not typical. The percentage culls in this trial was unusually high due to blossom end rot, a physiological disorder caused by water stress in July, followed by heavy rains in August. Additional trials of these LB/EB/SLS hybrids were performed at other locations under conventional production conditions. Similar results for fruit and yield analysis were obtained in the large parallel trial performed by Dr. Kelly Ivors in NC at a NCSU farm in Fletcher NC. The results for Total Tons/Acre, Marketable tons per acre, % total radial cracking, and % total weather checking were similar for most of the LB/EB/SLS hybrids and the commercial control Mt Fresh. These results, and those of the Freeville trial, are very favorable to the use of LB/EB/SLS resistant hybrids to control these three major foliar diseases. Results from trials in Freeville NY in 2011 for work related to Objective 3a and 3b substantiated those seen in 2010 despite more challenging plant growth and environmental extreme issues. Using spreader rows rather than direct infection of each plant for the two diseases worked well for disease spread, although rows immediately adjacent to the spreader row had higher disease ratings. Clearly the use of homozygous or heterozygous material performed better than the susceptible hybrid in the absence of fungicides. The newer reduced-risk fungicides offer a good tool to reduce the need for additional sprays and are much safer for the applicator and the environment. PRESENTATIONS * VBI Field day, Ithaca NY. Presentations by both Martha Mutschler and Tom Zitter Aug 29, 2011 * Organic Twilight meeting, Freeville, NY Presentation by Martha Mutschler (Aug 4, 2011) * Presentations at 26th TDW Oct. 12, 2011 Presentations by both Martha Mutschler and Tom Zitter. Abstracts and slides for both presentations (number 16 and 17) available online at: http://vegetablemdonline.ppath.cornell.edu/TDW/agenda.html * Ag-Inservice Training for extension educators. Presentation by Tom Zitter, (November 2011) DID GRANT SERVE AS SEED MONEY FOR OBTAINING ADDITIONAL GRANTS * NY Specialty crop block grant which will extend horticultural quality of the LB/EB/SLS lines was granted to Mutschler and Zitter, starting late 2010. ENHANCED COLLABORATION: * Additional cooperators not on original grant are now participating in testing the LB.EB.SLS resistant tomato hybrids, including Meg McGrath, Long Island, NY, and Randy Gardner and Dilip Panthee, NCSU. * An exciting new opportunity has arisen, interacting with a major multiple university project funded by the USDA, called SOLCAP. SOLCAP is creating a new set of molecular tools for use in breeding solanaceous crops, including tomato. SOLCAP began with a request for breeding programs to submit materials for use in a panel of tomato germplasm. A series of the LB/EB/SLS resistant lines were submitted for analysis two years ago, along with parental lines for controls. The results were just released, providing a genetic characterization by over 7,000 molecular markers for these lines. Analysis of the data has identified the putative location of SLS resistance gene to a 20 cM segment (which is less than 2% of the entire genome). The SOLCAP project also called for submission of mapping populations. This spring, the SLS mapping population, created using one of the same LB/SB/SLS lines being used in this project, was also accepted by SOLCAP for free full SNP analysis, both enhanced collaboration and leveraged funding, through this in kind service. That data, due before Jan 1, 2012, will allow the confirmation, with greater precision, of the location of the SLS resistance gene, and the creation of a simple marker for rapid, routine screening for the SLS resistance gene in small seedlings. This will enable seed companies to more rapidly deploy SLS resistance in tomato varieties.

Impacts Tomato is a significantly important crop for most Americans. Thus any meaningful research in this area literally affects thousands of people. Tomato diseases can be a limiting factor for tomato production and frequently requires use of fungicide sprays for disease control. By combining the use of genetic resistance to three important foliar diseases and by utilizing reduced-risk fungicide sprays we can make production more sustainable and more environmentally friendly.

Report Appendices Progress Report 2011 [PDF]

Final Report:

Outcomes A trial in the Cornell Organic Farm in 2011 Freeville produced data on SLS control. Disease development started in July, but was slow to advance due to the hot dry conditions that were unfavorable to EB and SLS. However disease development intensified with the cooler much wetter conditions in August. Disease and defoliation was marked in the susceptible controls, the cultivar Mt Fresh Plus, and the LB/EB hybrids that lacked SLS resistance but much slower in the SLS resistant hybrids. As a result, on August 23rd, the defoliation of Mt Fresh and of the LB/EB hybrids was >85% and >75% respectively, while the defoliation of the LB/EB/SLS hybrids was <12%. Defoliation of the LB/EB/SLS hybrids started to rise thereafter, starting on plants closest to neighboring susceptible entries, and reaching 50% after another 2 weeks. This appears to parallel defoliation possible when SLS resistant lines are subjected to extremely heavy artificial inoculation (spraying to run off with suspension of ca 500,000 spores per ml). The lesions on SLS resistant lines were very small, but if they are present in extreme number, defoliation still results. We postulate that isolating SLS resistant plants from susceptible plants would greatly extend the disease free or very low disease period. We tested this hypothesis very successfully in 2012. The goal for the 2012 experiment was to determine the impact of the SLS resistance on the rate of SLS spread in the absence of high inoculum loads, either applied directly or from a preponderance of highly diseased susceptible plants surrounding the SLS resistant plants. For this study we included three genotypes: the SLS homozygous resistant line 108257-4, the SLS susceptible line NC33EB-1, and their heterozygous hybrid 101256 x 101251. Each of the genotypes was represented by one row of 12 plants each per rep. In the center of each row between the 6th and the 7th plants, one susceptible plant (NC33EB-1) was added to act as a pathogen source plant. The distance between plants was 2 ft, and the orientation of the rows was west to east, the direction of the most common prevailing winds. Each of the four replicates was planted 30 ft. apart and each row in a replicate was separated by 15 ft. The pathogen source plants were spray-inoculated on June 25 with a SLS suspension of 105 spores/ml, applying 30 ml of the spore suspension per plant. After the inoculation and for the next two consecutive days, plants received approximately 5 mm of overhead irrigation at dusk to facilitate infection. The field was also irrigated twice a week to maintain plant growth during this rather dry season. The results showed that SLS disease progress was very strongly reduced in homozygous and heterozygous SLS resistant plants compared to susceptible plants. Plants at all distances in the susceptible line were more than 90% defoliated nine weeks after inoculation. However, none of the plants of the SLS homozygous or heterozygous resistant entries showed this level of defoliation, not even in plants immediately adjacent to the centrally placed inoculated susceptible source plants. Plant to plant SLS spread was strongly slowed / delayed in homozygous and heterozygous SLS resistant plants compared to susceptible plants. This significantly reduced the final defoliation and area under disease progress curve values (AUDPC) in resistant plants at all distances from susceptible sources plants. There is a steep reduction in AUDPC in resistant plants away from the source plant not seen in the susceptible ones at later dates. In the homozygous resistant plants, the AUDPC at 4 ft. from the source plants was reduced by 4.3 times, meanwhile this reduction was only 1.5 times in the homozygous susceptible plants. Data for the heterozygous SLS resistant hybrid are similar to that of the homozygous SLS resistant lines, suggesting that the resistance is fairly dominant. Based on these results, and considering the characteristics of SLS and mode of dissemination of S. lycopersici, the value gained in testing SLS resistance will be maximized if tomato plants are planted separately from fully susceptible genotypes, which are the major source of spores for secondary and tertiary cycles in the SLS epidemic. The distance for separation would not need to be that great, most likely on the order of 20 to 30 feet if SLS resistant plants are situated upwind. Fruit size. The 2011 Freeville plot provide information on fruit size in LB/EB/SLS hybrids. Early Blight tolerance is associated with smaller fruit, so we compared fruit size and yield of LB/EB/SLS hybrids with LB/EB hybrids with same male parents to determine if SLS resistance has any affect on fruit or yield. The results indicate that the fruit weights of LB/EB/SLS hybrids no smaller than that of LB/EB hybrids. Fruit weights of the LB/EB (166 to 179g) and LB/EB/SLS hybrids (150 to 186g) are moderate, ranging between that of Legend (146g) to less than that of Mt Fresh (254 g) Fruit size and yields of the SLS/LB/EB lines and hybrids does not indicated linkage drag issues with SLS resistance gene The yield of LB/EB/SLS hybrids was also no smaller than that of LB/EB hybrids. The LB/EB/SLS hybrids also tended to have less BER, higher % marketable fruit. However we do not know if this will be a typical result, since the year itself was not typical. The percentage culls in this trial was unusually high due to blossom end rot, a physiological disorder caused by water stress in July, followed by heavy rains in August. Additional trials of these LB/EB/SLS hybrids were performed at other locations under conventional production conditions. Similar results for fruit and yield analysis were obtained in the large parallel trial performed by Dr. Kelly Ivors in NC at a NCSU farm in Fletcher NC. The results for Total Tons/Acre, Marketable tons per acre, % total radial cracking, and % total weather checking were similar for most of the LB/EB/SLS hybrids and the commercial control Mt Fresh. These results, and those of the Freeville trial, are very favorable to the use of LB/EB/SLS resistant hybrids to control these three major foliar diseases. Results from trials in Freeville NY in 2011 and 2012 for work related to Objective 3a and 3b substantiated those seen in 2010 despite more challenging plant growth and environmental extreme issues. Using spreader rows rather than direct infection of each plant for the two diseases worked well for disease spread, although rows immediately adjacent to the spreader row had higher disease ratings. Clearly the use of homozygous or heterozygous material performed better than the susceptible hybrid in the absence of fungicides. The newer reduced-risk fungicides offer a good tool to reduce the need for additional sprays and are much safer for the applicator and the environment.

Impacts Tomato is a significantly important crop for most Americans. Thus any meaningful research in this area literally affects thousands of people. Tomato diseases can be a limiting factor for tomato production and frequently requires use of fungicide sprays for disease control. By combining the use of genetic resistance to three important foliar diseases and by utilizing reduced-risk fungicide sprays we can make production more sustainable and more environmentally friendly. A series of tomato lines possessing the Ph2 and Ph3 late blight resistance genes, early blight tolerance, and strong septoria leaf spot resistance (LB/EB/SLS lines) were released to seed companies, who are using them to transfer this unique combination of fungal resistances to new tomato lines and hybrids. The interest in this combination of resistances is so strong, that one organic seed company (High Mowing) is selling for use in the 2013 growing season a new LB/EB/SLS hybrid Iron Lady, based upon one of the Cornell LB/EB/SLS lines. Other seed companies are also testing hybrids. Therefore the fungal control blight program is already reaching growers and will soon reach consumers. Safeguarding human health and the environment: Deploying genetic resistance for plant disease control is the most effective method for disease control and therefore has the potential to be used on thousands of acres of this crop. We estimate that this would cover 23,000 acres in our regional area alone, plus much additional acreage for organic and homeowner plantings. We have documented a significant reduction in the number of sprays required and through the use of reduce-risk fungicides we can achieve better disease control and significantly reduce the environmental impact quotient (EIQ) to be safer for the applicator and the environment. We predicate that many operations can reduce their fungicide sprays to a quarter of the number currently applied, and the sprays can be applied following a disease forecasting model (Tom-Cast) that growers already know. Since we began to illustrate to growers how quickly EIQ values can begin to increase with each unnecessary spray, they have become more knowledgeable as to which fungicides could be selected to reduce their overall EIQ units for a given crop. This is the first time that we feel that growers and becoming better participants in crop production practices for themselves, their farms and for the people that purchase their produce. One of the largest seedling producers in the United States (with over 50 production facilities) with distribution to thousands of garden centers now relies on information provided by this project to foster the use of tomatoes with resistance to diseases. This has a direct impact on a problem that surfaced during the 2009 season, when late blight was pandemic in the NE region. Thus thousands of gardeners are impacted by providing the latest research information available. Economic benefits: POSSIBLE ECONOMIC BENEFIT: Control of late blight alone will reduce sprays costs by 3/4ths and the remaining sprays can be reduced again by as much as a half. These are direct cost savings by the individual grower in pesticide costs, not to mention reduced labor inputs, fuel costs and wear on farm machinery. Implementation of IPM: VALIDATION OF IPM STRATEGIES AND SYSTEMS: Deployment of genetic resistance, use of reduced-risk fungicides, and reduced spray applications are all key IPM strategies. These hold true for either conventional or organic operations. This project includes trials on organic and conventional grower locations in 3 states. NUMBER OF GROWERS/PERSONNEL TRAINED Educational information on this project has been covered at numerous venues including twilight meetings, grower talks, and professional meetings over the past 3 years. At least 750 growers have been exposed to our three prong approach (genetic resistance, reduced-risk fungicides, reduced application times) WEBSITE: Educational materials were delivered via the educational web site called Vegetable MD Online, which can be accessed at (http://vegetablemdonline.ppath.cornell.edu/). This website continues to be a very robust source of valuable disease control and varietal information, suitable for use by conventional and organic growers as well as backyard gardeners. The site in 2010 received over 4.8 million hits (12,597 hits per day), an increase of 3.5 million inquires in just 5 seasons. The tomato crop continues to receive the most inquires and the highest usage is during the months of June, July and August. The platform serves a vegetable resource worldwide. Known performance of tomatoes for their susceptibility for late blight and early blight was downloaded a total of 12,000 times. Information on tomato genetic resistance is now more commonly found in commercial seed trade catalogues with emphasis on LB and EB resistance.

Report Appendices Final Report [PDF]

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