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Thursday, April 4, 2013

Three Tips to Preventing Soil Harboring Tomato Diseases: Mulching, Pruning & Watering

Tomatoes are subjected to many diseases and pests. There are strategies you can use preemptively to reduce the risks of disease. While I can’t guarantee you won’t get a disease in your garden, these three steps will make it more difficult for soil born diseases to establish themselves. The main disease in my area is Early Blight. Follow these three steps for a better year of gardening.

Three Tips to Preventing Tomato Diseases:


Mulching: A Disease Barrier

Mulching is used to create a barrier between your tomato plant’s leaves and the soil. Early Blight is often soil born. Leaf Spot spores can harbor in the soil.  Many diseases are soil born and over-winter. Yes, they can also be passed in the air and by hand or by buying infected plants. The spores go from the ground to the lower leaves of your tomato plant. You may have noticed how diseases progress upward through a tomato plant.

Absolutely mulch. It is your first line of defense against tomato diseases. Mulch covers the soil and spores and creates a barrier. I suggest, as in the pictures below, you use grass clippings. Always use freshly cut grass and you will reduce the smell factor. Add 2 inches of green grass clipping beneath your tomato plant and in the surrounding area. When that grass dries and yellows, add another 2 inches of green grass clippings when you cut the grass next time. You can continue this throughout the year.

If you don’t have grass. You can use hay, hardwood mulch, and even newspaper. One effective strategy I recommend is putting a layer of newspaper down as a solid barrier and then putting the green grass clippings or other material on that. Mulch creates a disease barrier.


Pruning: A Disease Gap

I prune the bottom leaves off my tomato plants as they grow. I often create a 12-18 inch gap of no leaves between the soil and the first leaves on my tomatoes. This is a gap to prevent disease. It is your second line of defense against tomato diseases. As stated, many diseases like Early Blight are spread through spores.

The spores harbor in the soil and wait to make contact with the leaves of tomatoes. Creating a gap between the soil and first set of leaves on your plants, makes it harder for the spores to get a foothold on your tomatoes.

In this picture you see the 'Delicious' tomato variety. It has not been pruned and you can see how low the leaves are to the ground. A disease ladder waiting to happen.

Mulched but Not Bottom Pruned

You can’t have issues pruning back your tomatoes. I know it seems wrong to remove lush growth. It isn’t. That lush growth will become disease fodder. You can cut or snap off the unwanted growth. I cut a little more then I typically would for the picture as an example. This is the gap you want to establish. You can do it in stages. Two rows of bottom leaves and then wait for more top growth and then remove some more bottom leaves.
Bottom Leaves are Pruned

You can see the pile I removed. It was a lot. I removed suckers and leaves. The tomato is well on its way to being pruned to create at least a 1 foot barrier between the ground and its first leaves. I will prune it again after some more growth. I stopped at this point to give it another weeks worth of development. You don’t want to over prune to quickly.

Watering: The Main Trigger

Water is the main mechanism that gets the spores from the ground to the tomato leaves. Human hands and wind can also do it. Hard rain and over-head watering splashes soil up onto the leaves of the tomato. It is that simple. Splashing spreads spores. The mulch and pruning creates defenses against soil splashing. You can help your cause of disease prevention by making sure you water from the bottom of the plants and don’t splash soil onto your tomatoes.

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  1. Great tips! Thanks so much.

  2. Thanks for the great tips! Will make sure I prune the bottom leaves of my tomatoes next summer!

    1. It makes a difference. You dont have to rush it. Just take a few off now and again.

  3. I agree! I have planted only two heirloom tomatoes.... but have learned to cut those suckers and do not wet the leaves.

    I am in Florida so I have an early start, but lots of humidity and rain... (so far so good).

    I am trying a new method of pest control using Kaolin Clay. Apparently, pests do not like this clay which is sprayed in a water mixture onto the plants. It produces a sticky substance that pests hate crawling over. Everything I have read about this method sounds wonderful. First time trying this so I will let everyone know how it goes. It also prevents sunburn in the south... I am hopeful! You can also add organic neem oil in the mix for an extra boost!

    1. That sound interesting. If you can let us know how it goes. I havent heard anything about Kaolin Clay or that angle of controlling pests. I hope it works.


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