Wednesday, October 27, 2010
Problems ... already
Well, well, here's something interesting.
One of my growing experiments this year is using 5-gallon coconut coir grow bags. I bought the product from HydroGardens, and they're really cool. The coir comes in a little block in a bag. You add water, and the brick expands into a 5-gallon bag full of coconut coir grow medium. Coconut is a little bit different than peat ... it retains water better, and most importantly, it's completely sterile and pH neutral. With peat, we add dolomite lime to balance the pH (peat is acidic and dolomite lime is a base), but the dolomite has the added benefit of supplying calcium and magnesium for the plants. With coconut, however, you can't use dolomite because it will raise the pH since the coconut is already neutral. Tomatoes, like most vegetables, like a slightly acidic environment (around 6.0 to 6.5 on the pH scale), but not too much.
So how do you deal with the calcium/magnesium issue in coconut? If you can't get it from dolomite lime, then where? I mix agricultural gypsum in at planting (for calcium), and supplement weekly with magnesium. Additionally, I feed with a balanced fertilizer and add bone meal (for more calcium). This has worked for me, and I've gotten some great tomatoes from these coconut coir grow bags.
This year, though, something new and interesting and awful is happening. I'm growing yellow pear tomatoes in the bags. One plant is vigorous and huge and beautiful and already flowering (the bottom photo). The other is stunted, with severely curled leaves on the top of the plant (the top photo). I've inspected carefully for insects (there are none), and I don't think there's a problem with temperature, watering, or nutrients, which can all cause tomato leaf curl.
Instead, I believe this plant is infected with the tomato leaf curl virus. This virus causes stunted plants, curled leaves from the top of the plant down, and new growth that stands upright instead of laying flat. I've never had this problem before. According to my reading, infected plants can still yield tomatoes, but if they are infected young (as this one was), yields might be reduced or in some cases, completely non-existent. There is no cure for tomato leaf curl virus.
So sadly, to prevent the spread of this to my other plants, I'm going to have to destroy the plant. Which means fewer yellow pear tomatoes for me and one long face ...