Tuesday, March 20, 2007

Tomato issues in northern Dutchess County, NY

I have a home with a raised bed in which I grow a few vegetables. I go every year to the local nursery and buy a few different breeds and plant them. They do well the first few weeks, then they begin to look sick. They get these small, round, pale dots on the lower leaves. Sometimes with a black spot in the middle. The leaves turn brown and wither. Eventually the whole plant turns brown and dies. I do get a few tomatoes, but I've been used to robust plants that I used to grow in Brooklyn with a tremendous yield. On the internet I found a resource that said this was a mold or bacteria or something and the answer was to keep the lower leaves dry and not wet them when watering. This I did with no good results. They get plenty of sun and water. Not too much water. What do you think? Should I get those VGP disease resistant plants? How can I grow robust plants in northern Dutchess county?

Your situation certainly sounds to me like a fungal disease and not a bacteria or virus. Viral infections show a completely different set of symptoms, typically bizarre mosaic patterns on the foliage and stems, and it does not sound like that is the case at all. The black spots developing on the lower foliage and slowly moving up to take over the entire plant definitely sounds like a the spreading of fungal spores. If I had to narrow it down I would go ahead and guess one called Verticillium Wilt, which is known to be worst here in the northeast. The other close relative is Fusarium Wilt, but that fungus growers typically find further south.

To answer your question, yes, you should consider buying cultivars of tomatoes that are known to be more disease resistant. Since new cultivars seem to come out every year I cannot give specific names, but if the plant label has a capital “V” after the cultivar name then you can be sure that it is has been bred for better disease resistance. Otherwise, there is the homemade recipe for a foliar spray for fungal diseases and I am not sure if you are familiar with that. Using 1 gallon of water, mix in 2 tablespoons of baking soda and a drop of dish soap (to add a little viscosity), and once mixed use it as a foliar spray to cover as much of your crop as possible. Like with your watering, this should be done early in the day so that it cleans the leaves and evaporates before the scorching midday sun or the wet and cool evenings. Most people use this mix to combat powdery mildew and other issues, but I know plenty of people that use it on their veggie crops as well.

To cover all the bases, I’m also curious to know more about the raised beds you are using at your new home. Since you have experience growing successful tomatoes and other vegetables at your previous home in Brooklyn, I can’t help but wonder if the raised beds have adequate drainage. What do you think? Have all of the other vegetables you have grown in those same beds done well? I may very well be barking up the wrong tree, but perhaps the beds need to be double-dug to properly aerate and loosen the soil. If the soil in the raised beds is nice and loose but the soil from the ground level down has never been tilled then you could easily have a “perched water table”, and that water not being able to adequately drain all the way will only help further fungal issues.

Lastly, a couple tomato books that I have read here at our library suggest rotating your crops and growing your tomatoes in a different spot each year. I wonder if that would make a difference.

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