Early Blight on Tomato Plants

This tomato plant has severe Early Blight as it has worked its way up the plant

Now that the monsoons are in full blast, tomato fungal diseases are showing up with all the moisture. One of them is Early Blight. It is caused by a fungus called Alternaria solani. Early Blight is a fungal disease that attacks tomato plants starting on the bottom leaves of the plant and works it’s way upwards. The leaves start turning yellow and get blotchy. If left unchecked, it can take over your plant killing it although it won’t die immediately. Where does it come from? It comes from water splashing soil up on the lower leaves, allowing the fungal spores to colonize on the leaves. The culprit is a bad soil fungus (there are good soil fungus as well). That’s why you always see it start on the bottom leaves. Early Blight should not be confused with Late Blight which is prevalent in northeastern United States. We don’t have Late Blight out here in the southwest (at least not yet).

Here is a close up of Early Blight on the leaves

-There are several things you can immediately do to help with this disease if you get this. The first thing you do is trim off the affected branches where the leaves are yellow. Keep trimming up your plant as needed and spray with an organic fungicide like Serenade.

-Disinfect your shears between plants by dipping the shears and your hand in a container of water with about 10% bleach solution. Alcohol also works. Be sure to disinfect your shears between plants because you can spread Early Blight.

-I like Serenade, an organic fungicide which provides protection from a broad spectrum of common fungal and bacterial diseases. It is a biological fungicide, meaning it uses other spores that crowd out the Early Blight spores. Spray it on when the leaves are dry. It is rainproof, non-toxic for bees and other beneficial insects. Respray every 5-7 days. Spray all parts of the plant-both on top and underneath till dripping. Serenade is also good to spray on other vegetables. Spray for powdery mildew on squash, cucumbers and melons and leaf rust on beans. I use it for all my vegetables. Don’t wait till you get the disease—it works best as a preventative but you can control many fungal diseases with Serenade.

-In addition to trimming the affected leaves, trim off any branches or leaves that touch the ground. I never let any leaves or branches touch the ground, trimming them up about 12 or more inches.

-Another option is to stake or tie up any branches that might touch the ground.

Mulch with straw underneath the plant so the soil can’t splash up on plant when it rains or if you water overhead. This is key to help prevent Early Blight on your tomatoes. I do it the minute I plant my tomato plants in the spring and add more straw as the plant spreads till eventually the whole bed is covered with straw. If you didn’t do it this year, you can still add straw now. Besides it’s also great for keeping moisture from evaporating in our hot sun.

-If space allows, rotate susceptible crops every 3 years. Just change where you plant tomatoes every year.


Holy Cow! Hail the size of quarters and bigger!


Wednesday we got two huge storms where hail was between the size of quarters and ping-pong balls in some places. I’ve never seen hail that big here in Santa Fe. Sorry for the blurry picture but our hands were shaking! Lots of damage was done in many people’s gardens, destroying or severely damaging many vegetables and fruits. Whole leaves were torn off or plants shredded. Most of mine were spared as I had the vegetable plants covered with row cover, and it took the hit instead of the plants.

Believe it or not some plants will come back and be ok for those of you hit hard. We will be a couple of weeks behind but the season is not necessarily over. Check your plants and if the center of it where new growth comes from is intact, it will probably grow back so don’t be so quick to pull it. I will wait for about a week to see if they show signs of new growth. If they do, I will trim back the damaged foliage but not before. Remember their root systems were not hurt so they have a good chance to recover.

Meanwhile I would spray a fungicide on them as they are weakened and more susceptible to disease, especially fungal diseases like early blight and powdery mildew with all this wet weather. You could use Neem, OR Copper spray OR Serenade to help ward off fungal diseases. All are organic.

Tomato Disease-more info on Early Blight

Early BlightSomeone replied to my last post on Early Blight, “Will this contaminate the soil (for next year)?” Great question. Here is more info on this subject.

If you have a garden, it’s pretty much in the soil. One key is to provide a barrier between the soil and your plant, hence I add straw as a mulch around them to act as a barrier and use fungicides to catch it early or before it starts.

Some years are better as they are drier but when you have a wet summer, it can be a problem. I’m not sure if you took out the soil if that would help because who can remove all the soil? Unless you put them in pots-maybe that would work.

You should consider crop rotation, not growing in the same spot for 2 years and then coming back to it 3 years later. Crop rotation is used to control diseases that can become established in the soil over time. Changing your tomato crops to a new bed or area tends to decrease the population level of the pathogens.  That is why I have 3 sections in my garden so I can rotate the tomatoes to a new section each year. If you have raised beds, you could rotate the tomatoes to a new bed each year coming back to the original bed 3 years later to get the same effect.

I don’t look at Early Blight as a major killer of tomato plants if we do close monitoring and take action. By using fungicides early on and crop rotation every year, we can usually control it.

Also good clean-up in the fall after the garden is done is important. Do not compost the dead plants but bag them and put in the garbage.

You can read the first post about Early Blight here.


Tomato Disease-Early Blight

early blight_plant

This is a tomato with severe Early Blight. Notice it has worked it’s way up through the plant. I should have removed the diseased leaves while it was till on the bottom leaves and then sprayed with Serenade. I may not be able to save it.


Early Blight is a fungal disease caused by the fungus Alternaria solani  which lives in the soil. When rain or water splashes the soil up on the lower leaves, the fungal pathogen gets on the plant. It starts as some yellow mottling on the lower leaves which left unattended, then proceeds to work its way up the plant branch by branch on the leaves as shown on the photo above. It is contagious to the other tomato plants next to it so you should get on this pronto if you see any sign of it. Some tomato plants are more susceptible to it as well.

Early Blight

Closeup of Early Blight on lower leaf

With all this cool rainy weather (we got 1″ on Tuesday night!) I have noticed more plants starting to get it especially as the season goes on. The older plants (just like people) get more susceptible to diseases as they get older. Here is a closeup of what it looks like on the leaves.

tomato plant trimmed

Tomato plant trimmed off of all diseased leaves-notice there are hardly any leaves

If you see any of this going on, you should immediately trim off all the branches that show signs of it. Be sure to disinfect your cutting trimmers between plants so as not to spread it. Your plant may not have many leaves  left like this one.

bleach water

Use a 10 % bleach solution in water to disinfect trimmers

I use a small container, pour some water in it to cover your trimmers and put some bleach in the water – 10% is good. But I don’t measure. I just pour some in-much less than if you were to put it in your laundry. The key is to dip the trimmers and your hand or hand in glove into the bleach solution and dry them off before I go to the next plant so not to pass the disease on to a healthy plant.

tomato fungicides

I Start with Serenade and then move to Copper Fungicide if it gets worse. Be sure to wash your tomatoes really well if you use the copper fungicide. Both are organic but the copper fungicide is stronger.

After you’ve trimmed off all the bad stuff,  you need to spray with a good organic fungicide like Serenade to help slow it down. Also Copper Fungicide works but be careful using it. They are both organic fungicides. It’s best if you start the season spraying your tomato plants early BEFORE you ever have signs of Early Blight because then it’s a preventative but you may be able to control it if it hasn’t gotten out of hand, maybe not depending how bad it is.

Some of my plants (about 5 have it bad and don’t have many leaves left on because I trimmed them all off but they are loaded with tomatoes and the disease won’t hurt the fruit so I’m letting them stay in till I harvest and then I will pull the plant. It is interesting to note I only have one double row of tomatoes where it started with one plant and has now spread to 7 plants. (I already pulled out 2 others that showed it real early) Now I’m up to 7 plants out of 12 in the bed that have it. The rest of the beds look pretty good. I wish I followed my own advice but was crazy busy in the garden this year and wasn’t paying attention.

How to deal with Early Blight

1. After you plant the tomato transplants and make a well and add your drip system (if you have one), put straw all around the base to keep water from splashing the soil up on the plants. This applies for either hand watering or even if you have them on a drip system because of the rain. And just because you put straw around your plants doesn’t mean it won’t get the disease, but it helps most plants.

2. Start spraying ALL YOUR TOMATO PLANTS with Serenade as a preventative right away. It has a bacteria that won’t let the Early Blight bacteria colonize on the leaves thereby thwarting the disease. Plus it doesn’t wash off as the good bacteria attach themselves to the leaves. Do spray about every 2 weeks even if it doesn’t rain as a preventative.

3. Once it starts raining, spray weekly. Be sure to add more straw if soil starts to show.

4. When you first notice the lower leaves yellowing, cut away any branches with the disease present.

5. Disinfect with bleach water between cutting limbs off different plants so not to spread it. You can use bleach water as mentioned above or alcohol on the blades. I use bleach as I have a lot of plants and it’s cheaper.

6. Spray immediately after trimming but I would wait to trim if rain is in the forecast for that day. I like to let the spray dry and let those good bacteria attach to the leaves so I don’t trim on rainy days.

7. If your plant continues to go downhill, keep trimming and spraying and of course you should be spraying ALL of your plants not just the infected ones. You can move to Copper Fungicide if you have to but I always take the least toxic organic methods first. And just because it’s organic doesn’t mean it can’t be toxic. Copper is organic and yet is toxic in great amounts but doesn’t last long on the plant so just wash your tomatoes before you eat them. You can also pull the plant early if it only has tiny fruit on it or wait if it’s loaded with bigger fruit but be aware it might pass it on to other plants nearby, especially those that it touches.

This might not help as much this year but keep this info for next year.

PS—Early Blight is not like Late Blight found on the East Coast. Early Blight if caught early can be controlled. Late Blight is always terminal for a tomato plant if it gets it. Luckily we don’t get Late Blight out here in the Southwest. It is currently confined to the North East part of the US.