I am assuming early blight is destroying my tomato plants. All the lower and inner leaves have turned brown. The outer growth is pretty green, and aside from some anthracnose spots the fruit is mostly OK.
Does that sound like early blight? It started about three weeks ago when we were getting constant daily rains.
I know there isn’t much I can do now, so a couple questions:
Going forward, what are some good fungicide sprays that help prevent it? Organic or synthetic is fine by me, as long as it WORKS.
Am I better off trying to let the fruits ripen on the vine as long as possible, or yank them and let all the fruit ripen in the garage? I hit “peak production” about a week ago, and it seems to have sloughed off a bit already.
If your plants resemble below it is Verticillium wilt. A soil fungus which builds up over in the soil. Crop rotation is the recommended so no tomato family in that spot for at least 2 years. Brassicales is a good choice, encourages a diffrent group of soil bacteria.
Yeah it’s probably early blight. Their are some spray you can use, but only as a preventative. chlorothalonil is the most common. Copper too. Usually lesions on tomatoes are bacterial spot. I didn’t spray this year, and have it too. I usually spray the first month or two weekly. After that I don’t care as plants are along enough not to reduce production. Some are very resistant like Tim’s Black Ruffles. It will get the blight but weeks after all else has it, so really needs no sprays.
Acidic water in spray tank usually helps product stay effective days longer.
In this case, it is probably NOT early blight. There are four big fungals that infect tomatoes. They are Early Blight, Late Blight, Gray Mold, and Septoria. Do a quick search and there are disease keys that show symptoms of each. Given the description that lower leaves and leaves on the inside of the plant have turned brown, the most likely culprit is Septoria. This is by elimination because Late Blight leaves a stinking tangle of dead plants, Early Blight affects new and old leaves indiscriminately, and Gray Mold tends to affect random leaves near the bottom of the plant but not ALL leaves at the bottom of the plant. This leaves septoria as the probable plant killer. Septoria tends to spread from the bottom of the plant going up. It affects all leaves near the bottom and inner leaves where air circulation is poor. It is spread by rain splash from the soil, is endemic throughout most of the U.S. but is especially damaging in East central and Southern states.
I’ve been working on septoria tolerant genetics which is difficult because there are no sources of strong resistance. It requires concentrating several small effect genes that are not highly effective even when all of them are homozygous.
That said, you might look for a variety called BBXEPB or Big Beef X Eva Purple Ball which is a line I released about 7 years ago. It tends to have fairly strong resistance to septoria. It still gets disease, but will produce a full crop of tomatoes before going down. Heidi is a paste variety that also produces a heavy crop. Iron Lady was released a few years ago with supposed septoria resistance. Based on my own results and reports from numerous other growers, it does not have enough resistance to make a difference.
Azoxystrobin containing fungicides are fairly effective against septoria. Chlorothalonil can help but only if the plants are sprayed consistently and even then can have some side effects. Copper is totally ineffective. Neem oil will delay it some but won’t stop it.
Tim’s Black Ruffles seems to have resistance to septoria, best I have seen.
I have observed that some strange things with tomatoes. Like for some reason certain soils or possibly surrounding plants seem to help. Tomatoes grown in my blackberry patches seem never to get it, or get it very late in the year. This might be just an observation of stress. The ones by blackberries are less stressed being in ground. My potted plants seem to always get it first, the most stressed of my tomatoes. Combining genes of drought resistance with septoria resistance might make a super plant?
Doesn’t work that way. Septoria is a disease that a plant can grow out of to some extent. Reduce the fruit load and the plant can devote more energy to rapid growth. Drought resistance in tomato is more a function of having a large root system. This gets down to having a vigorous plant. Graft onto a very vigorous rootstock and septoria damage will be significantly lower. Again, this is not due to an inherent resistance, it is a more vigorous plant that can produce more alkyl sugars which promote leaf health. It is correct to say that breeding for a more vigorous plant is making a super plant, but the effect on septoria is indirect.
If you dig around online, you can find a study from Brazil showing several lines of wild species with significant resistance. S. Chilense and S. Peruvianum in particular have much better overall disease resistance than domestic tomato. Unfortunately, crosses to these two species require embryo rescue which I am not set up to perform.
I’d like to say that there is a ready genetic solution to septoria, but the reality is that it is going to take a lot of work and probably some genes from wild potato species to do something significant. Crosses to diploid potato are possible via somatic fusion. Worth noting that pepper is generally immune to septoria. Unfortunately, the genetic barriers with pepper are far higher than with other tomato species.
Including Solanum lycopersicum, there are currently 13 species recognized in Solanum section Lycopersicon. Three of these species—S. cheesmaniae, S. galapagense, and S. pimpinellifolium—are fully cross compatible with domestic tomato. Four more species—S. chmielewskii, S. habrochaites, S. neorickii, and S. pennelli—can be readily crossed with domestic tomato, with some limitations. Five species—S. arcanum, S. chilense, S. corneliomulleri, S. huaylasense, and S. peruvianum—can be crossed with domestic tomato with difficulty and usually require embryo rescue to produce viable plants. The Lycopersicon section has not been fully sampled within wild species in the South American range, so new species may be added in the future.
Solanum section Lycopersicoides and section Juglandifolium are represented by two species each that are considered bridge species genetically intermediate between tomato and non-tuber bearing potato species. S. lycopersicoides can be crossed with domestic tomato and introgression lines have been developed. This species was significant in moving the domestic tomato from separate genus status into the Solanum group because it directly links the tomato into the potato family.
This year my tomato plants are the healthiest they have been in a few years but the tomatoes aren’t. Looks like anthracnose on mine. We have had frequent rain and high humidity through most of July and August. Only watered once or twice when we had two weeks of dryer weather.
Here is a good source of tomato disease information and photos:
The fruit issue (which I can get a pic of later) is a sunken round spot. Some of them eventually develop a white mold on them, or at least on the inside wall of the fruit if you cut off the spot, there will be a fuzzy white fungus.
What you said, is what i was trying to say, to break it down, stress is a contributing factor.
Interspecific crosses are being done and cultivars being developed. It will be fun to see what comes out of it.
What we call early blight here is more gradual than that with lots of yellowing in the interim to brown.
Didn’t get it when I first started gardening in S. NY state but then it arrived and took some of the fun out of growing tomatoes. It comes every season, early or late depending on how wet summer is. Some varieties don’t lose that much productivity to it, but most of the best heirloom types do.
I spray copper soap until fruit gets close to ripe, which seems to extend the baring season in spite of my over-sheltered excessively dewy site.
Country Taste, Sungold and Chocolate Gold are three available varieties that crank out tomatoes almost as long as they would without the blight for me. I also have a discovery Brandywine type that seems far more productive and resistant than Brandyboy and other Brandywine type hybrids I’ve grown.
I have dubbed it Sweet Rachel, but think I will change it to Ethiopian queen.
Your description is more consistent with septoria. If the plant develops yellow leaves near the base of the plant that gradually go up the plant, it is probably septoria. Early blight shows up on leaves throughout the canopy and usually has a few leaves with typical bullseye target appearance. Septoria and early blight are often found on the same plant.
My tomatoes are looking better than ever this year.
As far as sprays go, I gave my tomato plants a squirt of immunox mixed at the ratio for apples, since I had it left over. The Immunox label has instructions for tomatoes and if I recall correctly, they call for a stronger mix for tomatoes than they do for apples.
I am also being more conscientious than I was in previous years. Each part of the garden got their full of manure, each hole got a couple handfuls of tomato tone mixed in, I mulched, and I watered almost daily. This ensured healthy plants. Trimming the lower leaves is supposed to keep the blight from getting onto the plant in the first place and I have mine trimmed almost a yard high. Also, inside the cage I thinned out the plants to ensure good airflow.
So it’s either the shot of immunox, actually using good gardening practices, luck, or a combination of the above that led to me having this much success this year. Could also be that I picked the right varieties. I have “Early Girl” that turned out to be an unknown mislabel, Celebrity, Better Boy, and Jersey Devil.
Alan, my description was of septoria. It starts at the bottom of the plant as yellowing leaves and gradually progresses up the plant. Septoria shows up as lots of small black specks on the leaves. Early blight is different in that it occurs throughout the canopy and there are always at least a few leaves with the typical bullseye pattern typical of early blight. Gray mold and bacterial spot are two more diseases we contend with each year.
This disease guide does not show septoria, but it does have early blight, late blight, and gray mold. Please look carefully at the leaf shown. It clearly shows the bullseye pattern typical of early blight. Early blight of tomato | UMN Extension