Progress 06/01/05 to 05/31/08
Outputs
OUTPUTS: In Year 1, all of the lines with resistance to LB and EB were evaluated in trials in NY under standard and organic practice and PA under standard practice. The trials were successful, allowing a subset of the best lines to be selected for testing in year 2. The results of the Year 1 Early Blight trial also confirmed that the Cornell lines were fixed for the early blight resistance. Another critical result was the demonstration of consistent control of stem lesions, but a considerable variation for foliar disease development and degree of defoliation among the EB resistant lines. This could have been due to differences among these lines for maturity and fruit load/development, rather than any true difference for resistance. This also underscores the importance of combining the EB resistance with supporting mild sprays for optimal EB control. The year 2, the best subset of LB/EB resistant lines were tested in expanded trials in NY and PA, and also tested these lines in disease trials with modest input of chemical controls to extend control of foliar symptoms of early blight. The tolerance levels for EB were similar to those in Year 1. The resistance of the lines for EB/LS tolerance/resistance and for earliness was confirmed. This, and evaluation of fruit characters, permitted final selection of a subset of fully resistant lines for the creation of experimental hybrids with full EB/LB tolerance resistance, moderate maturity and larger fruit size. Hybrid seed production, in the winter of 2006/2007, involved the cross of a series of Cornell EB/LB lines with one of two EB/LB line created by Dr. R. Gardner of NC. All these lines carry the same EB/LB resistance, so that hybrids are also homozygous for the resistance genes, like the parental lines. However the parental lines from the two programs differ, and complement, each other for important horticultural characteristics such as fruit size and maturity. The resulting series of hybrids was field tested in summer 2007 at multiple sites using either conventional or organic practices. Of the two NC lines used NC33EB1 produced hybrids with larger fruit than NC45EB2. Of the 7 Cornell lines used as the second parent of the hybrids, 071002 and 071008 tended to produce the hybrids with better fruit size. The two best hybrids in NYS were 071002 x NC33EB1 and 071008 x NC33EB1. However in the NC trial of the hybrids, the crosses 071009 x NC33EB1 and 048143-7 x NC33EB1 had the best fruit size and type. The best hybrid (NC06115) performed better in the presence of severe early blight pressure than the standard susceptible control hybrid in two seasons. Foliar defoliation was further significantly reduced with a conventional fungicide program (chlorothalonil) as well as the use of a biological product (Bacillus subtilis) teamed up with a product that induces systemic acquired resistance (acibenzolar-S-methyl). The information on the lines producing superior hybrids and seed of the Cornell lines (07-1002, 07-1008, 07-1009 and 048143-7) were released to seed companies for use in creation and release of LB/EB resistant commercial hybrids. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Integration of genetic resistance and reduce risk fungicides and biological controls are urgently needed for control of Early Blight and Late Blight in tomato. For the NE growers to use this approach, these resistant lines and strategies must also fulfill the needs of the shorter, cooler season characteristic of the NE growing regions. Work to date has finalized development of the tomato lines with resistance to LB and EB, and selected the best lines for development of hybrids. Hybrid seed was generated, and the hybrids were tested in 2007 in multiple locations using either conventional or organic production practices. Some tomato lines were released to seed companies in Winter of 2007/2008, and the remaining lines will be released Winter of 2007/2008, along with information regarding optimal use of the resistance in hybrid tomato varieties. Information on the use of resistant hybrids in a coordinated total disease control program for NE tomato production has been summaries and publications will be submitted winter of 2007/2008. A consistent issue with the use of EB tolerance is the tendency for reduced fruit size in homozygous lines. This is reflected in the trials of these homozygous EB experimental hybrids. Whether the tendency for small fruit is pleiotropic or the result of linkage drag not known. Since EB gene not mapped, one cannot determine size of introgression, and whether it is located in region of one of the many reduced fruit size genes that have been identified and located. The best long term fix to this issue would be to locate the EB introgression, to see if the fruit size issue is due to a linkage drag that can be eliminated by reduction of introgression length. However, the differences in fruit sizes between the two NC lines used as male parents and also among the hybrids demonstrate that this tendency for smaller fruit can be modulated to produce commercially acceptable fruit, even in the absence of a map location for EB tolerance. Resistant lines can also be later in maturity, but the hybrids were no later, and some were possibly earlier, than the control hybrids. Therefore compensation for this tendency is also possible. A goal of this project was to demonstrate that reliance on a conventional fungicide program could be modified when hybrids with the highest level of genetic resistance were available for testing. We demonstrated that products that are more environmentally friendly can be utilized in conjunction with the best genetic resistance to optimize disease control. Therefore, as this genetic resistance is more fully utilized in new commercial hybrids across the NE, we will be able to prescribe if any fungicide applications are needed, and how they can be selected based upon the properties that they are more friendly to the environment and biological in nature.
Publications
- Mutschler, M., Zitter, T. A., and Bornt, C. 2006. Effectiveness of genetic resistance and lite fungicides for disease control. Proceedings 21st Annual Tomato Disease Workshop, Asheville, NC. (online)http://cherokeereservation.ces.ncsu.edu/fletcher/programs/pla ntpath/2006-11-tomato-disease/TDW06proceedings.pdf
- Zitter, T. A., and Drennan, J. L., 2008. Using host resistance and lite fungicides to control early blight and Septoria leaf spot on tomato, 2007. Plant Disease Management Reports (online) Report 2:V061. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
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Progress 06/01/06 to 05/31/07
Outputs
The results of the trials in year 1 (summer 2005) allowed the selection of tomato lines with the good horticultural characteristics as well as resistance to Late Blight (LB) and early blight (EB). The year 2 season (2006) tested this subset of LB/EB resistant lines in expanded trials in NY and PA, and tested these lines in disease trials with modest input of chemical controls to extend control of foliar symptoms of early blight. The establishment and growth of the trial plots was initially very favorable, however the wet growing conditions ultimately impacted plant horticultural performance. The tolerance levels for EB were similar to those in 2005. The disease screens eliminated from consideration a few lines that were either contaminated or were still segregating for LB resistance. The resistance of the other lines for EB/LB tolerance/resistance and for earliness was confirmed. This, and evaluation of fruit characters, permitted final selection of a subset of fully
resistant lines for the creation of experimental hybrids with full EB/LB tolerance/resistance moderate maturity and larger fruit size. Hybrid seed production, in the winter of 2006/2007, involved the cross of a Cornell EB/LB line with a EB/LB line created by Dr. R. Gardner of NC. All these lines carry the same EB/LB resistance, so that hybrids are also homozygous for the resistance genes, and so should have the same levels of resistance as the parental lines. However the parental lines from the two programs differ, and complement, each other for important horticultural characteristics such as fruit size and maturity. The resulting hybrids are being field tested in summer 2007 at multiple sites using either conventional or organic practices. The season is progressing well, but slower due to cool temperatures.
Impacts
Integration of genetic resistance and reduce risk fungicides and biological controls are urgently needed for control of Early Blight and Late Blight in tomato. For the NE growers to use this approach, these resistant lines and strategies must also fulfill the needs of the shorter, cooler season characteristic of the NE growing regions. Work to date has finalized development of the tomato lines with resistance to LB and EB, and selected the best lines for development of hybrids being tested in 2007 in multiple locations using either conventional or organic production practices. This work will result in the release of the resistant tomato lines with proven ability to create acceptable hybrids, and information on their use in a coordinated total disease control program for NE tomato production. This program will provide more reliable disease control and also significantly reduce reliance on chemical control.
Publications
- Mutschler, M. A., Zitter, T. A., and Bornt, C. 2006. Effectiveness of genetic resistance and lite fungicides for disease control. Proceedings of the 22nd Annual Tomato Disease Workshop, NCSU, Mountain Horticultural Crops Research and Extension Center, Fletcher, NC
- Foolad MR, A Sharma, H Ashrafi, and GY Lin. 2005. Genetics of early blight resistance in tomato. Acta Hort 695: 397-406.
- Foolad MR and GY Lin. 2006. Breeding tomatoes for early blight and late blight resistance, improved fruit quality, and adaptation to PA. Proc. of the 2006 Vegetable and Small Fruit Field Day. pp 7-10.
- Foolad MR, HL Merk, H Ashrafi and MP Kinkade. 2006. Identification of new sources of late blight resistance in tomato and mapping of a new resistance gene. Proc. 22nd Annual Tomato Disease Workshop, North Carolina State University, Fletcher NC, Nov. 9-10. pp. 4-7.
- Foolad MR. 2007. Genetics and breeding of disease resistance and improved fruit quality in tomato. In: Proc. Mid-Atlantic Fruit and Vegetable Convention, Hershey, PA (published as supplement).
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Progress 06/01/05 to 05/31/06
Outputs
Year 1: In the first field season, all of the lines available were evaluated in trials in NY under standard and organic practice and PA under standard practice to determine the best lines to include in more extensive trials in the second field season. The trials were successful, and a subset of lines with confirmed resistance to LB and EB and the best horticultural characteristics were selected for testing in year 2, and for creating hybrids to be tested in year 3. Therefore this objective has been accomplished The results of the Early Blight trial confirmed that the Cornell lines were fixed for the early blight resistance. The results of this early blight trial also demonstrated the difference in the degree of disease control the resistance provides on stems vs. on the foliage. The stem ratings on all of the resistant lines are uniformly very low (from 0.0 to 0.2), in contrast to the ratings of the susceptible controls (greater than 4.0). However foliar symptoms, as
measured by the percent defoliation on the last reading date (19 Sep) or by area under the disease progress curve (AUDPC), were not as well controlled as the stem symptoms. There was also considerable variation among the resistant lines for foliar disease development. This could have been due to differences among these lines for maturity and fruit load/development, rather than any true difference for resistance. The results of the trials allowed the selection of lines with the best horticultural characteristics in addition to disease resistance. The better inbreds in terms of production, fruit size, as well as fruit characters such as shape, smoothness, blossom end scar (data not shown) have high production levels, through fruit size was smaller than that of the hybrids. Year 2: The year 2 season is currently underway. The subset of LB/EB lines selected in year 1 is being tested in expanded trials in NY and PA summer 2005. We are also testing these lines in disease trials with modest
input of chemical controls, in addition to the resistance, to extend control of foliar symptoms of early blight. The establishment and growth of the trial plots have been very favorable. Data collection is proceeding.
Impacts
Integration of genetic resistance and reduce risk fungicides and biological controls are urgently needed for control of Early Blight and Late Blight in tomato. For the NE growers to use this approach, these resistant lines and strategies must also fulfill the needs of the shorter, cooler season characteristic of the NE growing regions. This work will finalize the development of the tomato lines possessing resistance to LB and EB, and test the best of these lines under traditional and organic growing systems. This work will result in the development of a coordinated total disease control program for NE tomato production using the genetic resistance to provide more reliable disease control and also significantly reduce reliance on chemical control. It will allow reduction in the reliance on and use of chemicals for control of these two diseases.
Publications
- Zitter, T. A., Drennan, J. L., Mutschler, M. A., and Kim, M. J. 2005. Control of early blight of tomato with genetic resistance and conventional and biological sprays. Acta Hort (ISHS) 695: 181-190.
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