Container Gardening

When I went to my mother’s house yesterday, I found her (in-ground) tomatoes suffering from a fairly severe case of early blight.  In my part of the world (Massachusetts), this has been an extremely wet June, leading to some delays in vegetable growth and some fun and exciting health problems for our plants.  Inspired, I’ve decided to talk about early blight in container tomatoes.

As with most vegetable diseases, this is more common with in-ground plants than it is with vegetables grown in pots.  Most plant diseases incubate in the soil, and the soil for in-ground vegetable gardens is more likely to be contaminated than the soil in containers, especially if you use fresh potting mix every year for your container garden.

However, the fact that it’s more common with in-ground tomatoes doesn’t mean you don’t see it when growing containers in pots.  So, what is early blight?

Early blight is a fungal infection that can affect eggplant, pepper, potato, and tomato plants.  It tends to do the most damage to potato and tomato plants.  It survives between hosts in the soil, living off the plant matter in the dirt.

Early blight can affect the leaves, the stem, and the fruit of tomato plants.  The symptoms vary depending on what part of the plant you are looking at.

Leaf Lesions

The first place you usually spot early blight is on the oldest leaves, near the bottom of the plant.  It will show as brown blotchy spots, surrounded by a yellow halo.  Eventually, the yellow will overtake the entire leaf, and it will wither and die.

If the damage spreads to the stem, it will show as dark, elongated patches on the stem.  Fruit can also be affected, with dark sunken lesions on the fruit.  These are leathery to the touch, and usually occur at the stem end of the fruit.

If you catch early blight when it first appears, it is usually correctable.  Early blight spreads up the plant from the lowest affected leaves, so when you see leaves with the characteristic lesions, remove them immediately.  Damaged stems will eventually kill off any plant growing beyond them, so if you have main stem damage, it is best to pull the entire plant and start over.  Any affected fruits should be picked and thrown away, letting the plant focus its energy on healthy tomatoes.

You can use a mild fungicide to catch early cases of blight.  Organic gardeners find that a milk spray (one part milk to 10 parts water, misted on the plant after every rain), helps prevent fungal infections or treat existing ones.

Preventing blight is usually easier than fixing it, however.  The most common way for tomatoes to develop blight is from infected soil splashing up onto their lower leaves.  To prevent this, make sure to tie up all leaves that hang close to the ground.  You can trim the lower branches entirely as the plant grows: these won’t get as much sun and will not thrive anyway.

You can also mulch over your soil, creating a barrier between the dirt and the plant.  This has the added benefit of keeping the soil more moist between watering sessions, which is always a challenge for container gardeners.

Tags: plant ailments, Tomato

This entry was posted on Tuesday, June 23rd, 2009 at 11:26 am and is filed under Tomatoes. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.