Early blight ate us up last year too. It was the WORST year ever for tomatoes. Many people I talked to said it was their worst year too, but I don't know if their trouble was early blight or something else. I was done way early and I usually have tomatoes until the first freeze.
I had never seen anything like it.
justsaymo

Hi Bill,

I've been growing tomatoes for as far back as my memory goes, first with my dad in his garden, and then later on in gardens of my own, and Early Blight has always been a problem.

Early Blight is a fungal disease caused by the microorganism Alternaria solani. I know of no tomatoes that are resistant to it, although there are some that are troubled less by it than others. The Alternaria spores can survive on plant debris in soil, on tomato seeds themselves, and in the soil. The spores can be carried by wind and water. The best "cure" is to prevent it from infecting your plants to begin with.

Some years I have a huge problem with early blight, but some years I have little trouble with it at all. The key difference appears to be the amount of rainfall, cloudiness and humidity. In wetter years, EB is a huge problem. In hotter, drier, less humid years, it is not as much of a problem as long as I don't get water on the leaves when watering the plants. (So, watering with a soaker hose or drip irrigation is obviously preferable to using a sprinkler.)

Here are some ways you can help minimize problems with Early Blight:

1) Use only clean seed saved from non-diseased plants if you save your own tomato seed. And, if you save your own seed, be sure to use the fermentation process to help eliminate disease.

2) Remove and dispose of all plant debris from the previous year because it can harbor spores of the fungus that causes Early Blight. Do not rototill the plant debris into the soil because that just spreads the spores throughout the soil.

3) Control (remove) volunteer tomato plants and weeds in the tomato plant area that sprout as they can harbor the spores.

4) Space plants properly for good air circulation and do not errect wind barriers. Good air flow helps plants dry off more quickly after rainfall or dew and this is important in preventing spores from germinating.

5) Orient your rows in the direction of the prevailing wind the garden receives durinng the growing season.

6) If you must use overhead irrigation, understand that every time you irrigate, you are likely to be creating conditions that encourage the spread of early blight. So, if overhead irrigation is a must, irrigate as early in the day as possible so plants can dry completely before nightfall.

7) Keep plants well-fed and well-watered, but not overfed or overwatered. Plants that have enough, but not too much, food and water are healthiest and most likely to survive early blight.

8) To the extent that you can, keep pests under control because they can spread the disease from one plant to another.

9) When you see affected foliage, which normally appears on older, lower leaves first, remove the foliage from the plants and dispose of the leaves away from the garden. Because you can spread the disease from plant to plant while removing the foliage, wash your hands before moving from one plant to another or, if using pruners, dip them in a water/bleach solution before moving from one plant to another.

10) Use varieties known to be more resistant or tolerant of Early Blight. Although no tomato variety is immune to this fungal disease, some varieties are said to be more resistant than others. Keep records from year to year to see if you can spot varieties in your garden that don't get Early Blight, or that at least seem able to "outgrow" it or otherwise overcome it. Many gardeners have found that Amelia, for example, resists early blight. Tomato leaves come in several varieties--the standard regular leaves that are most common, the potato-leaved tomatoes in which the leaves of the tomato plants look very similar to potato plant leaves, and the rugose leaves, often found on short internode plants, among others. Many gardeners believe potato-leaved tomato plants and rugose-leaved tomato plants seem better able to resist early blight. One line of thought is that both potato-leaved plants and rugose-leaved plants have thicker foliage that is harder for the spores to penetrate/infect.

11) Do everything in your power to keep ALL the moisture off the leaves that you can. This includes only ground watering via soaker hoses or drip irrigation and no overhead watering from sprinklers. As soon as the plants are in the ground, mulch the ground around them with 2" to 3" of mulch to keep soil-borne fungal spores from reaching the plants. Replenish mulch often. Some people like to scatter corn meal (a known antifungal) on the surface of their mulch to help prevent fungal spores from residing in the mulch.

12) Grow plants in the most upright manner possible. Stake them, cage them, trellis them using the Florida Weave or something similar, etc. Plants that sprawl on the ground usually get more early blight than those grown in a more upright manner.

13) You cannot "cure" Early Blight once your plants have it, although sometimes you can keep the plant growing vigorously enough that it outgrows the EB. So, the best cure is "prevention" and the best "prevention" is to spray your plants with chlorothalonil at 7-10 day intervals beginning the very first day the plants are in the ground. Spray the plants heavily, coating the stems and leaves and be absolutely certain that you spray the undersides of all leaves. Mix the chlorothalonil (Daconil) as directed on the package and be sure to dilute it as directed. If you spray with a heavier concentration than the package recommends, you can burn your plants and seriously harm/kill them. Spray at 7-10 day intervals from Day 1 and never miss a spraying. Basically, the chlorothalonil coats the leaves and stems and prevents the spores from infecting the plants. You can use other antifungals, but none of them are going to be as effective as Daconil. Copper sprays work great on some fungal problems, but not on early blight. Serenade (Bacillus subtillis) was first promoted as an anti-fungal, but even though I had good results the first year I used it, it hasn't seemed effective on early blight since then. It is a better pesticide than antifungal in my garden. Potassium bicarbonate is an organic antifungal, but isn't as effective as Daconil.

In the gardening world, many people prefer not to use Daconil because it is a chemical, and I understand that. I don't use it myself. However, if Early Blight is a severe problem for you, then it is the best solution.

I think early blight was so bad in so much of OK last year because of high rainfall, long periods of cloudiness and high humidity. Here in Love County where there was very little rainfall, fewer than the normal amount of clouds, and relatively low humidity all summer long, I had almost no early blight, and that is fairly rare.

While Early Blight is only one of the many tomato diseases found in Oklahoma gardens, it is probably the most common one although it often is accompanied by Bacterial Speck and Bacterial Spot too. For all the talk of verticillium and fusarian wilt, it is only Early Blight that causes me problems some years. It is important, though, to understand the symptoms of Early Blight and to be sure you are diagnosing it properly so that you are treating the plants for the right problem.

Hope this info helps.

Dawn

DAWN,
THANK YOU VERY MUCH FOR YOUR INFORMATION. AS USUAL YOUR INPUT IS MOST HELPFUL.
IN THE PAST I HAVE PUT 1 GALLON BUCKETS OVER THE TRANSPLANTS AND FILLED WITH WATER. I SUSPECT THAT THAT IS WHERE IT FIRST STARTS, AND THEN YOU GET THE SPLATTER OF RAINS ETC.
I HAVE BEEN TOLD TO START THE SPRAY SCHED AT BLOOM, BUT I LIKE YOUR SUGGESTION BEST. FROM DAY ONE.
TNX AGN FOR YOUR INPUT.
BILL - ANADARKO

Hi Bill,

You are welcome. I hope the info is helpful.

In a REALLY rainy year, if you are raising your own transplants indoors or in a greenhouse, I'd even spray them the first time a couple of days before taking them outside to start hardening them off. Being vigilant really, really pays off.

Dawn