Please don't let these tomates go!

June 29, 2009 2:50 PM

Tomato Plants showing some mold (SoCal)

Last year our tomato plants were a complete bust. They all molded away from the marine layer that invades our area come June (gloom). I live in Venice, CA about 1/2 mile from the ocean.

This year we did things right, built amazing four foot deep raised beds filled with all organic soil and compost from a gardener who was moving out of town. Many pictures of the boxes, the dirt moving and the voluptuous growth can be seen on this photo gallery Dimmy and Dewick Garden. We started our plants from seed and all along the way everything did great!

We got plants growing out of our ears and everything is vibrant and healthy. That is until about 10 days ago when we started noticing some mold on the tomato plants. Yes, this coincided with a fair amount of over cast June gloom weather, so now I am reaching out to the hive mind on what to do about it, if anything?

I trimmed back the damaged leaves and branches, but somehow I don't think that is going to take care of the issue, I know a bumper crop is out there and I feel very hopeful about this year, but I want to do what I can to make these lovely plants fruit.

In case you do not want to visit the entire garden photo gallery, here are a few shots of the issue at hand.

Healthy plant

Moldy leaves

Let me know if these links are an issue, it is my first time trying "little snapper"

Henry

posted by silsurf to Home & Garden (5 answers total)

I believe you've got powdery mildew, my friend.

Here's some organic treatment strategies. I'd thin out the plants and maybe select a different variety next time around.
posted by electroboy at 3:03 PM on June 29, 2009

That looks like powdery mildew. The most important thing is to make sure there's good air circulation around the leaves. You might need to prune the plants some in order to increase air flow, if your plants are as bushy as most tomato plants.

You can treat it later with a fungicide if you're really concerned. But for now it's best just to remove affected leaves, ensure good circulation, and make sure that you don't get the leaves wet when you water.

You'll find lots of advice on dealing with powdery mildew if you Google.
posted by mudpuppie at 3:03 PM on June 29, 2009

Yep, third vote for powdery mildew. Good ventilation and not letting the leaves get wet are the best preventative measure. There's no real (organic) cure, other than removing all affected leaves/plants and keeping the remainder dry and well-aired.
posted by le morte de bea arthur at 3:10 PM on June 29, 2009

Also, just in general, you tend to get better production and healthier plants if you don't let your plants go all crazy growing new branches. Here's a quick tutorial.
posted by electroboy at 3:39 PM on June 29, 2009

I've had good luck with neem oil on other plants with powdery mildew. I buy neem at the health food store, but not every place has it so call ahead. You can also try Indian grocery stores. It is also sold at garden centers but is more expensive.

Use 1/2 tablespoon of neem in one quart of water, add a few drops dish soap. Spray in early morning or evening to prevent sunburn. Mix up only what you are going to use, and store your neem oil in the dark.
posted by oneirodynia at 6:15 PM on June 29, 2009