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Old November 22, 2020   #39
Fusion_power's Avatar
Join Date: Feb 2006
Location: Alabama
Posts: 2,154

That is a surprisingly easy question to answer. Look at the way Septoria spreads. It is usually splashed from the soil into aerosol droplets that are blown by wind to land on leaves and grow. The amount of Septoria inoculum in the soil is off the charts therefore it will always find a way to spread. From this perspective, it will be impossible to totally prevent Septoria.

With that said, there are a lot of things you can do that will limit or reduce the impact on your plants.

1. Start with varieties that have at least a little resistance. I only know of a few that are currently available though more are due to be released this year. Iron Lady was ineffective in my climate, but is better further north. Jasper is a cherry tomato that is available from a few places. Mountaineer Delight and Mountaineer Pride are out of West Virginia. I have not yet grown them, but will trial this year from Southern Exposure. Lorelei red cherry tomato will be available from Sandhill as soon as Glenn gets his website updated. Some readily available varieties have a little resistance. These include Eva Purple Ball and Burgundy Traveler. I also grow Tropic because it is an adapted variety in my climate that is resistant to grey mold and has some Septoria tolerance.

2. Understand how Septoria resistance works. It is mostly based on acyl sugar accumulation in the plant. As fruit load increases, nutrients are sucked out of the leaves leaving them vulnerable to infection. Fertilize heavily just as the first fruits reach the diameter of a quarter.

3. Use cultural methods to reduce the amount of inoculum on leaves. This includes use of fabric/mulch, trimming bottom leaves, and most important, getting the plants up off the ground and exposed to as much air flow as possible. There are some other methods that get progressively more expensive such as growing in high tunnels to prevent rain splash.

4. Don't confuse Septoria with other diseases. This is particularly easy to do with bacterial spot and speck. If spot or speck is a problem, most of the things you can do for septoria will be ineffective.

5. Consider using chemicals if acceptable to you. Quadris or a few other fungicides are effective.

Last edited by Fusion_power; November 22, 2020 at 03:30 PM.
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