Yes, Blight-Free Tomatoes are Possible!

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Tomates showing tell-tale symptoms of late blight.

New strains of late blight of the tomato (Phytophthora infestans) appeared out of nowhere a few years ago, taking both seed suppliers and gardeners by surprise. This is an old disease, the one that caused the Irish potato famine in the late 1840s (other strains of the same disease attack potatoes), and we all thought that the disease was pretty much under control, since most modern potato and tomato varieties are resistant to the original strains. But the new strains that have appeared, notably US-22 and US-23, are much more virulent than the older strains and particularly harmful to tomatoes. In fact, in climates with fairly humid summers, where late blight is most prevalent, late blight of the tomato is now that plant’s most devastating disease.

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Late-blight lesions on tomato leaves.

You can recognize late blight by its symptoms. First, it shows up in late summer (it’s not called “late blight” for nothing!). At first, brown spots appear on the lower leaves and grow quickly in size. White cottony growths may appear under the affected leaves… if the air is humid. The disease rises successively upwards, affecting leaf after leaf. Often stems also turn brown. Worse, just when the fruit is almost ripe, soft brown or black depressions form on it and it begins to rot. Soon it is only good for the trash.

Resistant Varieties

There are now however tomatoes with genetic resistance to late blight. Don’t panic: these are not OGMs. Natural resistance to the new strains of the disease has been found in certain tomatoes, notably wild cherry tomatoes, and has been bred into garden varieties by the same old-fashioned methods our ancestors used to create heirloom tomatoes like ‘Brandywine’ (which is terribly susceptible to late blight, by the way). Just buy and sow varieties that are resistant to the disease, and follow normal tomato cultural directives (grow them in full sun, practice crop rotation, leave space for aeration, water the roots, not the leaves, etc.) and you ought to be able to get a bumper crop of tomatoes!

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‘Defiant’. Photo: Johnny’s Selected Seeds.

  1. ‘Berry’
  2. ‘Brandywise’
  3. ‘Cherry Bomb’
  4. ‘Clou OP’
  5. ‘Cloudy Day’
  6. ‘Damsel’
  7. ‘Defiant PhR’
  8. ‘Defiant’
  9. ‘Fandango’
  10. ‘Fantasio
  11. ‘Fantastico’
  12. ‘Ferline
  13. ‘Foronti’
  14. ‘Golden Currant’
  15. ‘Golden Sweet
  16. ‘Iron Lady’
  17. ‘Jasper’

    ‘Fantastico’. Photo: All-America Selections

  18. ‘JTO-545’
  19. ‘Latah’
  20. ‘Legend’
  21. ‘Lemon Drop’
  22. ‘Lizzano’
  23. ‘Losetto’
  24. ‘Manalucie’
  25. ‘Manyel’
  26. ‘Matt’s Wild Cherry’
  27. ‘Merlice’
  28. ‘Mountain Fresh Plus’
  29. ‘Mountain Magic’
  30. ‘Mountain Merit’
  31. ‘Mountain Supreme’
  32. ‘Mr. Stripey’ (‘Tigrella’)
  33. ‘Oh Happy Day’
  34. ‘Old Brooks’
  35. ‘Plum Regal’

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    ‘Matt’s Wild Cherry’. Photo: Johnny’s Selected Seeds.

  36. ‘Pruden’s Purple’
  37. ‘Quadro’
  38. ‘Red Alert’
  39. ‘Red Pearl’
  40. ‘Resi’
  41. ‘Romello’
  42. ‘Rote Murmel’
  43. ‘Rote Zora’
  44. ‘Santa’
  45. ‘Stellar’
  46. ‘Striped Stuffer’
  47. ‘Sweetheart of the Patio’
  48. ‘Tommy Toe’
  49. ‘Tropic’
  50. ‘Sweetheart of the Patio’
  51. ‘Wapsipinicon Peach’

Sow tomatoes indoors 6 to 8 weeks before the last frost date. That date tends to be in mid to late May in most regions (it’s about June 15th in mine!).

Or Buy Disease-Resistant Plants

If you’re not into growing tomatoes from seed, look for tomato plants resistant to late blight in local nurseries. Things have improved considerably since the early 2010s, when the average garden center employee didn’t seem to know late blight even was. There are now late-blight resistant tomatoes being sold in garden centers in most areas. And if there is a local specialist in tomato plants, the kind of place that always offers many varieties, they’ll almost certainly offer several resistant tomato plants.

Bring Your List

I suggest you print this list or put it on your smart phone. You’ll want to have with you the next time you shop for tomato seeds or plants.

For more information on tomato diseases, read Disease-Resistant Tomatoes.

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