Jaipi Sixbear is an established author of hundreds of helpful online articles. Jaipi learned to garden at an early age. She has old and new tips and tricks for growing your best garden ever.
Late blight on tomatoes in Denver? It does happen, although not often. Occasional monsoon like spring weather in this usually hot, dry community brings up the question of fungus. Fungus like that which causes late blight tomatoes grows well in such wet weather.
Denver gardeners should watch for signs of late blight tomatoes and potatoes. This fungus spreads quickly and can damage a whole field crop. A gardener with late blight tomatoes should act quickly to see that the fungus does not spread.
Late blight tomatoes can be recognized by lesions on the leaves, fruit and stems. These lesions begin with a green appearance but turn black in damp weather. Late blight tomatoes will often develop a white mold which may disappear in dry weather.
Note: New gardeners might mistake blossom end rot for late blight on tomatoes. Blossom end rot differs in that it involves a rotten spot on the base of tomatoes, rather than fungus throughout the entire plant. Blossom end rot signifies the need for more calcium in the soil and is easily remedied with supplementation.
Late blight tomatoes are a greater concern in Denver now due to a strain of late blight from Mexico which first appeared in the early 90’s. This late blight tomatoes disease strain is more resistant to fungicides than previous strains.
Another problem is that big box stores are selling tomato plants that are already infected with the fungus. This, combined with unusual moisture can be a double whammy.
In a rainy season, gardeners should take care not to over water their plants. In Denver, gardeners are used to taking measures to retain water, not work to keep plants dry. So, when unexpected rains fall, it’s important to know what to do.
Raised bed gardening with good drainage should keep late blight from developing. Raised beds or containers that drain well allow soil to dry between waterings. Soil that retains water makes it easier for tomatoes and potatoes to grow fungus.
Controlling late blight may ironically mean more frequent watering. This is due to quick draining and drying containers. Excess water usage is a thorn in the side of Denver organic gardeners. Still, when the alternative is throwing away good food the choice is clear.
Do not add discarded, diseased tomatoes to the compost bin. The fungus thrives in warm wet compost. Throw late blight tomatoes, potatoes and plants out with the trash to prevent infection of next years crop.