Read TableOfLateBlight&EarlyBlightResistantTomatoCultivarsForHomeGarden.pdf text version

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 Fresh Market Reds

Legend OP

Specifics and Seed source

Det., rnd red, 14 16oz; Territorial (9) Det., rnd red, 46 oz, early season; Online Indet., rnd red, 6.5oz;Online Det., large globe shape; Johnny's Indet., pur/blk, beefsteak, 16oz; Online Indet., gr. beefsteak, 818oz; Online Indet., bicolored beefsteak >16oz; Online Indet., maroon, beefsteak ,10 12oz; Online Indet., mahogany plum, 2 in. elongated; Online Indet., pink fruit, oblate 12 lb.; Johnny's; Online, Indet., dk. pink, >16oz; Johnny's Indet., red, 2 in.; Online Indet., red, 23 in.; Territorial (9) Indet, bicolor, 4 6oz; Online

Ref. of LB/EB Rx (year)

Not tested locally; (dev. Dr. Baggett, OSU) (1) Not tested locally; (dev. NYSAES, Geneva, NY) Not tested locally; (dev. Dr Gallegly, WVU) (5) Resistant for EB (8) Good resistance US17 (2002, 2006) (4) Moderate resistant US17 (2002, 2006) (4) Good observations US22 (2009) (10) Mod. res. US17 (2002, 2006); mixed performance US22 (2009), (4,10) Highly resistance US17 (2002, 2006) (4) Moderate resistance US17 (2002, 2006) (4) Moderate resistance US17 (7) Some resistance reported US17 (3) Some resistance reported US17 (3) Observed good tolerance US22, (2009) (10)

Genetic resistance

Reportedly tolerant for US8 and US11; Ph2 only; EB res. Resistance Ph1 gene Reported as Ph2 gene


New Yorker OP West Virginia 63 OP JTO99197 F1

Ph2 resistance will not provided resistance for current isolates of LB. Ph1 gene will not provide resistance for current races of LB. Ph2 gene will not provide resistance for current races of LB. Suited for vineripe production. Potatoleaf plant.


Aunt Ginny's Purple Aunt Ruby's German Green Big Rainbow Black Krim None reported None reported None reported None reported

Black Plum Brandywine Pruden's Purple Slava Stupice Tigerella (AKA Mr. Stripey)

None reported None reported None reported None reported None reported None reported

Prolific potatoleaf plant. Medium potatoleaf plant. Potato leaf variety, Eastern European Potato leaf variety, Eastern European. Productive small round fruits with reddishorange skin and stripes.

Saladette (large cherry), Plum

Juliet, Plum cluster F1 Indet., 1 ½ 2 oz; Johnny's Indet. 2oz size; Bejo (2), Johnny's Intermediate resistance for LB (US17) and EB (2009) (3,7,8) Excellent with exposure to US22 (2009); multiple isolate resistance US11, US17 (6,10) Excellent with exposure to US22 (2009); multiple isolate resistance US11, US17 (6,10) Good resistance US 17 (2002, 2006) (4,7) Intermediate resistance for LB US22 (2009) (8) Excellent resistance US17 (2002, 2006); observed res. US22 (2009) (4,7,10) Excellent tolerance US17(2002, 2006) (4,7) South Asia, Ph gene(s) likely Heterozygous for Ph2 and Ph3; homozygous tolerant for EB Homozygous resistant Ph3; Homozygous tolerant for EB Larger sister variety of `Santa'. Limited or not available in 2010; (dev. Dr Gardner, NCSU). Limited or not available in 2010; (dev. Dr Gardner, NCSU).

Mountain Magic F1, Large Cherry

Plum Regal F1, Plum

Det.; Bejo (2)

Smallfruited Grape, Cherry, Pear (assorted colors)

Red Currant, OP Red Pearl, Grape Matt's Wild Cherry Sm. Red Cherry He, S. lycopersicum var. cerasiforme Yellow Currant, S. pimpinellifolium Indet., 3/8inch, sweet (but slightly tart); Online Indet., 1oz; in clusters Johnny's Indet., cherry, ½ in. borne in clusters; Johnny's, Online None reported None reported None reported Vigorous growth and many fruit. Compare to `Red Grape' F1, but larger fruit. Rampant vines; Probably Ph3; origin is Hidalgo state in eastern Mexico.

Indet., very small, None reported Regular leaf; fruit 1/2inch almost borne in cluster of 68 translucent yellow 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. 2. Bejo Seed 2010. 3. Dillon, M. 2005. Public breeding for organic agriculture. Screening for horizontal resistance to late blight in tomato. 4. Fry, W. E. 2002, 2006. From trials conducted by Dr. Hilary Mayton formerly with Dr. W. Fry's Lab Group ( 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. MountainMagic.pdf; PlumRegal.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. 8. Johnny's Selected Seeds. 2010.; personal communication. 9. Territorial Seed Company. 2010. 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 fungallike disease responsible for the Irish Potato Famine, occurred on tomato transplants much earlier in the season (midJune) 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 smallfruited 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 LBinfected 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. Two fungicides which worked well in our research plots last year for all three diseases were chlorothalonil and copper. Home gardeners who choose to spray have both available in the state; for example Bonide Fungonil Multiple Purpose concentrate (chlorothalonil) and Bonide Copper Fungicide (Bordeaux Modern Replacement).


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