Tomato Cultivar Specifics and Seed Source Ref. of LB/EB Rx (Year
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Performance of Tomatoes (all Solanum lycopersicum unless noted) (Hybrids, Open Pollinated and Heirlooms) for Late Blight (LB) and Early Blight (EB). – T. A. Zitter, Department of Plant Pathology Cornell University, March 2010. Tomato Cultivar Specifics and Ref. of LB/EB Genetic Comments Seed source Rx (year) resistance Fresh Market Reds Legend OP Det., rnd red, 14‐ Not tested locally; Reportedly Ph2 resistance will not 16oz; Territorial (dev. Dr. Baggett, tolerant for US8 provided resistance (9) OSU) (1) and US11; Ph2 for current isolates of only; EB res. LB. New Yorker OP Det., rnd red, 4‐6 Not tested locally; Resistance Ph1 Ph1 gene will not oz, early season; (dev. NYSAES, gene provide resistance for Online Geneva, NY) current races of LB. West Virginia 63 OP Indet., rnd red, Not tested locally; Reported as Ph2 gene will not 6.5oz;Online (dev. Dr Gallegly, Ph2 gene provide resistance for WVU) (5) current races of LB. JTO99197 F1 Det., large globe Suited for vine‐ripe shape; Johnny’s Resistant for EB (8) production. Heirlooms Aunt Ginny’s Purple Indet., pur/blk, Good resistance None reported Potato‐leaf plant. beefsteak, 16oz; US17 (2002, 2006) Online (4) Aunt Ruby’s German Indet., gr. Moderate resistant None reported Green beefsteak, 8‐18oz; US17 (2002, 2006) Online (4) Big Rainbow Indet., bi‐colored Good observations None reported beefsteak >16oz; US22 (2009) (10) Online Black Krim Indet., maroon, Mod. res. US17 None reported beefsteak ,10‐ (2002, 2006); 12oz; Online mixed performance US22 (2009), (4,10) Black Plum Indet., mahogany Highly resistance None reported plum, 2 in. US17 (2002, 2006) elongated; Online (4) Brandywine Indet., pink fruit, Moderate None reported Prolific potato‐leaf oblate 1‐2 lb.; resistance US17 plant. Johnny’s; Online, (2002, 2006) (4) Pruden’s Purple Indet., dk. pink, Moderate None reported Medium potato‐leaf >16oz; Johnny’s resistance US17 (7) plant. Slava Indet., red, 2 in.; Some resistance None reported Potato leaf variety, Online reported US17 (3) Eastern European Stupice Indet., red, 2‐3 in.; Some resistance None reported Potato leaf variety, Territorial (9) reported US17 (3) Eastern European. Tigerella (AKA Mr. Indet, bi‐color, 4‐ Observed good None reported Productive small Stripey) 6oz; Online tolerance US22, round fruits with (2009) (10) reddish‐orange skin and stripes. Saladette (large cherry), Plum Juliet, Plum cluster F1 Indet., 1 ½ ‐2 oz; Intermediate South Asia, Ph Larger sister variety of Johnny’s resistance for LB gene(s) likely ‘Santa’. (US17) and EB (2009) (3,7,8) Mountain Magic F1, Indet. 2oz size; Excellent with Heterozygous Limited or not Large Cherry Bejo (2), Johnny’s exposure to US22 for Ph2 and available in 2010; (2009); multiple Ph3; (dev. Dr Gardner, isolate resistance homozygous NCSU). US11, US17 (6,10) tolerant for EB Plum Regal F1, Plum Det.; Bejo (2) Excellent with Homozygous Limited or not exposure to US22 resistant Ph3; available in 2010; (2009); multiple Homozygous (dev. Dr Gardner, isolate resistance tolerant for EB NCSU). US11, US17 (6,10) Smallfruited Grape, Cherry, Pear (assorted colors) Red Currant, OP Indet., 3/8‐inch, Good resistance US None reported Vigorous growth and sweet (but slightly 17 (2002, 2006) many fruit. tart); Online (4,7) Red Pearl, Grape Indet., 1oz; in Intermediate None reported Compare to ‘Red clusters Johnny’s resistance for LB Grape’ F1, but larger US22 (2009) (8) fruit. Matt's Wild Cherry Indet., cherry, ½ Excellent None reported Rampant vines; Sm. Red Cherry He, S. in. borne in resistance US17 Probably Ph3; origin is lycopersicum var. clusters; Johnny’s, (2002, 2006); Hidalgo state in cerasiforme Online observed res. US22 eastern Mexico. (2009) (4,7,10) Yellow Currant, S. Indet., very small, Excellent tolerance None reported Regular leaf; fruit pimpinellifolium 1/2‐inch almost US17(2002, 2006) borne in cluster of 6‐8 translucent yellow (4,7) tomatoes. cherry; Online Yellow Pear, OP, He Indet., cluster; ¾ ‐ Excellent tolerance None reported Tall and vigorous vine 1 oz; Johnny’s; US17 (2002, 2006) with many fruit. Online (4) 1. Baggett, J. R. 2001. http://extension.oregonstate.edu/news/story.php?S_No=312&storyType=garden 2. Bejo Seed 2010. http://www.bejoseeds.com/gba/upload/pdf/347/Bejo%20Tomatoes%20Eastern%20U.S.%202009.pdf 3. Dillon, M. 2005. Public breeding for organic agriculture. Screening for horizontal resistance to late blight in tomato. http://ofrf.org/funded/reports/dillon_04s20.pdf 4. Fry, W. E. 2002, 2006. From trials conducted by Dr. Hilary Mayton formerly with Dr. W. Fry’s Lab Group (http://www.plantpath.cornell.edu/Fry/LB_Tools.html#heirloom) 5. Gallegly, M. E. 1960. Resistance to the late blight fungus in tomato. Proc. Plant Science Seminar. Campbell Soup Co., Camden, NJ. 6. Gardner, R. G. 2008. http://www.ces.ncsu.edu/fletcher/programs/tomato/releases/release‐notices/release‐ Mountain‐Magic.pdf; http://www.ces.ncsu.edu/fletcher/programs/tomato/releases/release‐notices/release‐ Plum‐Regal.pdf 7. Inglis, D., Gundersen, B., and Derie, M. 2001. Evaluation of tomato germplasm for resistance to late blight, 2000. Biological and Cultural Tests for Control of Plant Diseases 16:PT77. http://ipcm.wisc.edu/WCMNews/tabid/53/EntryId/875/Managing‐Late‐Blight‐in‐Tomatoes.aspx 8. Johnny’s Selected Seeds. 2010. http://www.johnnyseeds.com/c‐1‐vegetables.aspx; personal communication. 9. Territorial Seed Company. 2010. http://www.territorialseed.com/prod_detail_list/vegetable_seed 10. Zitter, T. A. 2009. Personal observations and correspondence. Keeping Late Blight in Your Rearview Mirror – Planning for 2010 – Home Gardener Version Tom Zitter, Department of Plant Pathology, Cornell University, Ithaca, NY 14853 [email protected] The 2009 season was very challenging for most home gardeners because of weather conditions unsuitable for many crops and for the widespread occurrence of late blight in much of the Northeast US and beyond. This was particularly true for tomato and potato production. Late blight (LB), the fungal‐like disease responsible for the Irish Potato Famine, occurred on tomato transplants much earlier in the season (mid‐June) compared with all previous recorded occurrences. Also environmental conditions in 2009 during June and July were very conducive for the occurrence and spread of late blight inoculum, since the organism responsible, Phytophthora infestans, prefers cool and wet conditions for its reproduction and spread. Plant pathologists at Land Grant Universities around the country (including Cornell University for New York State) have agreed to a numbering system to help identify the main characteristics associated with the current LB genotypes. Think of it as knowing what the seasonal flu virus will be for a given year, so that a seasonal vaccine can be developed to lessen the chance of getting the flu. And just as for humans where a seasonal vaccine will not protect you against 2009 H1N1 flu, how tomatoes respond to late blight can change depending on which isolate (genotype) of late blight is occurring. In 2009, the majority of losses for tomato in the Northeast was due to infections with genotype US22. This genotype is relatively new for the US, and in addition to infecting tomato, also infected potato and solanaceous weeds. As bad as late blight was in 2009, it could have been a lot worse if for tomato the plants had been exposed to US11 or US17 which are even more virulent for tomato, or in the case of potato, if US8 had been disseminated more widely, since it causes more damage than seen with US22 infections in 2009. Genetic resistance for plant pathogens, including late blight, is known and is being incorporated into tomato varieties using conventional plant breeding techniques. An accompanying table lists the performance of tomato cultivars for late blight, and includes the performance of reds, heirlooms, large cherry and small‐fruited types, some with known genes for resistance or tolerance for late blight. The most widely known genes for LB resistance are Ph1, Ph2 and Ph3. The Ph3 gene provides the strongest protection since it confers resistance for multiple LB genotypes including US22, unlike Ph1 or Ph2 which are genotype specific, and thus do not provide the necessary high level of protection. Where do we stand for the 2010 growing season? A listing of the performance of tomatoes for exposure to late blight (LB) is currently available, and may accompany this report. Choosing cultivars with resistance or tolerance is always a good starting point for disease control. For tomato growers in the affected areas (most of the Northeast in 2009), the slate is wiped clean in terms of survival of LB inoculum from last year. The late blight organism is an obligate parasite, meaning it must survive on living tissue. This source of inoculum can be LB‐infected potato tubers that were saved or survive in compost pills or appear as volunteers that overwintered in the soil from last year. In the case of potato tubers as a potential source, make sure none survive in compost piles or as volunteers, and if present, dispose of them properly before you begin preparing the soil this spring. Use clean tubers to establish your new crop in 2010. Tell your neighbors to do the same! The late blight isolate (US22) is not capable of surviving in the soil and is not seedborne in tomato. So growers do not need to rotate away from the planting area they used in 2009 specifically for LB control. However, I suspect most gardeners also have disease problems with two common fungal diseases, early blight and Septoria leaf spot, for which rotation is critical. A few cultivars on the tomato list also have good resistance or tolerance for early blight and should be considered. The development of triple resistant tomato varieties (LBR, EBR and SLSR) is currently underway at Cornell, with important field trials for selection of resistance and multiple fruit types set for 2010.