Tomato Blight
July 7, 2009 by Doug
Filed under Vegetables
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Unfortunately, there are three kinds of “blight” that you’re likely to see in your garden at this time of year. The first one and most common is “Septoria leaf spot”. This particular problem appears roughly around the end of July and starts out as small round black or brown rotting marks on the lowest leaves. It works its way up the plant to hit all the leaves but it starts from the bottom first. You’ll get fruit if you have this problem.
The second most regularly seen is Early Blight. It usually appears about the same time as the Septoria but it has concentric target-shaped marks. In other works, the spots on the leaves look like targets with circles within circles. This too spreads all over the plant and you’ll get fruit but the yield will be reduced.
The least common of these blights is the Late Blight but it has appeared this year (it's already on Long Island) and the experts tell us with the wet, cold year it can be expected to run rampant in gardens. The only slow-down mechanism that home gardeners have is a Bordeaux mix - if you're in an area with this problem, start spraying according the directions on the label and continue. It will delay but not prevent the problem and you may get some small harvest.
Late Blight appears later than the first two and the first symptoms are a watery type of lesion on the lower leaves. If you get this one, you won’t have to ask what you have because the elapsed time from the time you first see it to the time the plant wilts and dies is about a week. If your tomato plants simply shrivel up and die with big brown spots on the leaves – and it seems to happen almost overnight – your plants are suffering from Late Blight.
The interesting thing about the blights is that they are not regular. There are a multitude of causes and seasonal variations and you think you’ve got the problem solved and the next year’s weather will come back, change, and create the problem all over again. I do note that the older tomatoes – the heirloom varieties – do tend to be more susceptible to blight problems than the newer hybrid cultivars.
So if you have the problem now, what can you do? Generally if you’ve already seen the problem, there’s not a lot you can do. A preventative spray of lime-sulphur or Bordeaux mix will slow down the spread of Septoria and Early Blight but the real key is in the prevention of the problem
Next spring, mulch your tomatoes. Mulching will reduce the stress on the plant but more importantly it will prevent “splash-back” from the ground to lower leaves during rainstorms. If you’ve ever noticed the lower leaves on tomato plants tend to be dirt splashed, it is because rain or overhead irrigation tends to splash dirt up. This dirt can contain the spores for blight and it is this inoculation that we want to avoid.
Install drip irrigation or use individual watering bottles (I’ve written about them before) with pinholes in the tops to water each plant. The trick is to prevent the splashing while ensuring the plant has enough water.
Do not water in the evening. We want our leaves to be dry going into the evening. Damp leaves and dark conditions are ideal for spore starting and keeping those leaves dry is the way to keep them healthy.
I’ve said this before but too many folks try to crowd tomatoes together. You really do need to space them apart. I find that staking the plants and giving them at least two square feet each is the best way to keep those leaves dry. I also prune off the lower leaves once the plant has set that bottom cluster of fruit. This lets the air and sunlight into the fruit and it also removes those lower leaves that can be water-splashed.
If the dew is on the plants, you’ve just watered, or it has just finished raining, do not work around the plants. Your hands and activities around the plant can spread the problems as quickly as anything can. While I’ve written this advice before, I’m about to do so again. Do not plant any crop in the same place more than one year. Planting in the same spot from year to year is simply an invitation to problems. They build up in the soil and there’s little you can do to prevent them using your tomatoes as a food source. Also do not plant peppers, potatoes or eggplant in that garden region as they will act as alternate hosts and be just as quickly wiped out by the problem.
If you have plant debris and you’ve had a problem, do not compost this material. The average home composter is not working at a high enough temperature to knock back the overwintering spores so the best thing you can do is bag up the dead leaves and stems and send them to the dump or municipal composting facility where the compost temperatures are high enough.
If you do see a branch with a problem, prune it out immediately. Do not let is sit on the plant to infect all other parts of the plant and reduce your yield. Similarly, remove weeds from around your tomato plants. They reduce air circulation, scavenge nutrients your plants need and can act as a host for the blights.
If you have a problem with blights, then do plant modern cultivars with disease resistance. Look for letters after the name of the plant in seed labels that might say “V” for verticillium resistant, or “F” for fusarium resistant. While not specifically blight resistant, they do have better overall resistance to diseases than those without those initials.
In the case of blights, the cure rests in good gardening techniques rather than any kind of magic spray.
If you have questions about tomato blight, you'll find a box to ask them right here
Blight….I was told I had a calcium prob and to put eggshells in the soil…..a waste??? I only get it with one plant…every year…same spot.
@mary -
Eggshells are indeed a waste of time if you have blight. And if you get the same problem every year in the same spot, let me suggest you don’t have blight – and you might consider crop rotation.
HA! You’re so right! Only 2nd year planting tomatoes and thought it was a freak last yr. Other plants huge and producing so well her in So. Cal. Thanks for the help!
At last! The answer to what the H is wrong with my tomatoes. It sounds dead spot on for the late blight symptoms.
I did cut the bottom leaves off yesterday but darned if I can remember where I threw them now. Might have been the compost.
My local nursery owner, who I highly respect, tried to tell me it was because they were not in a sunny enough location. I bought that till I came home and ound some volunteer tomatoes in the same location (so same light conditions in a pot on the patio, NOT in the ground. They were doing just fine thanks.
That eases my troubled mind. I was thinking there was something dreadfully wrong with the soil in that bed….and maybe there is.
My asparagus died, my cucumbers and zucchini are 2 inches tall with yellow leaves the size of a quarter, the basil is not thriving, onions and garlic are looking skinnier than they should.
Thanks again Doug.
@Jane Brunton -
Get the Bordeaux going and let us know how it works for you
This is on tomato blight maybe coming to my area…
I use a gallon of water to a tsp of dish detergent…
and I put a 2 tbsp of epson salts in it…
Would that help me with the blight….>>>?????
I have used this for years on beans and peppers also…
Now another question….My tomato plants always get huge….
I do a lot of suckering…but the plant is huge..Everyone
comments on them wondering why they get so big…
I don’t have an answer for it because mine have alway done
so….Some times I have a big yield…and sometimes not…
People don’t think it is a good thing…but I do not have
the problems others have with tomato blight and drop blossom…and tomato turning white inside….or cracking…
Why it wrong with huge plants…>>??????? They are
beautiful and standing…I will have Beef steak in another
week…and that is a late tomato for around here.!!!
Thank you for your websight and your messages to my
e mail…I can say I love you because you send great
articles out to us all..God Bless…..Marilyn
@Marilyn Hook -
The epsom salts and dish detergent are not likely going to stop this Blight. Sorry. A healthy plant is your best defense and it sounds as if you have that. Size of plant might be because of the way you water and feed (heavily it sounds like) so that’s all to the good. A bit too much nitrogen might lower your harvest because you’re producing too many leaves at the expense of food.
Go easy on the Epsom salts – that’s simply magnesium and it’s one of the big garden myths – if your soil is deficient in this element, it’s going to help. If not, then you’re not doing anything but if it makes you happy – keep it up.
Nothing wrong with big strong plants as long as you’re giving them a balanced fertilizer.
In your article about tomato blight, you suggest not crowding the tomato plants. Giving plants at least 2 square feet (1′ x 2′ = 2 sq.ft.). Do you mean 2 feet square(2′ x 2′= 4 sq.ft.)per plant? My tomatoes are in raised beds surrounded by 16″ cement blocks and they are planted at every 2nd block giving them lots of space and air. I’ve been the crowded tomato route with accompanying blight but this more generous spacing along with pruning the lower and ‘inner’ leaves yields healthier plants and more fruit. I garden in NW PA.
@Marian Johns -
Commercially we aimed for the 1×2 or 2 square feet per plant at a minimum distance. I know a lot of gardeners who crowd way more than that but that’s the minimum.
some of my tomatoes plants are 5.5 ft tall with a GREAT yield.
Only problem is staking.
@mary -Thank you Mary….
I have always had tall plants….even when I planted
50 plants in a huge garden…yes…staking is a big problem..
Mine are in a raise garden, and it makes them look even larger…I have chicken wire to keep out the critters around it….and tall cages doubled…and stakes all around..It looks like a jungle..but they are 2 feet apart…
Thank you Mary..we would make a good pair…Marilyn
My neighbor plants tomatoes by the corner of his house- not a lot of space. His bush tomatoes look ok but then he planted another variety in front and they have a problem. They are small and have curling leaves on the top of the plant. The plant is still green but the leaves are like balls. Barely recognizable as a tomatoe. I advised removing these plants. I have never seen this problem before. Have you?
Thanks,Lillian
@Anonymous -
Yes – and it could be several things – from a heavy aphid infestation to one of the viral problems. Take it to a good local garden center (not box store) or contact your local extension services for a diagnosis.
Doug, What can I do, I want vine ripened tomatoes but the dang birds are beating me to it. I’ve tried the fake owl trick bur the birds use it to land on to decide which tomatoe they want.
@Mike Decatur -
put up netting – easy and inexpensive
Had’nt thought of it. But does sound like it will work great. Thanks
On another web site I found a name for my neighbor’s strange tomatoe disease- tomatoe leaf curl virus (TLCV) But what to do about it. I gave him a lecture on watering the base of the plant and not sprinkling the leaves, but we still don’t know what else to do about this. I then went home and looked at my tomatoes after washing my hands and found a little of the same thing on the top of an heirloom tomatoe. I cut that out well below the problem and am watching it.
Lillian
@Anonymous -
If it is indeed the tomato leaf curl virus – your home treatment option is to control the insect vector (the insect that carries the problem) which is the whitefly. You do this by regular sprayings with insecticidal soap (real label for directions). You also reduce all stress on the plant by watering deeply twice a week and feeding weekly to help the plant outgrow the problem. You’ll get a reduced yield but you should get some fruit.
Doug,
Can you explain the individual watering bottles that you use to water your tomatoes with? thanks
@Dianna
Take a large plastic bottle with screw-top lid. (a big soda bottle works fine). Poke pinhole in lid (use hot needle) Fill with water. Put on lid. Turn upside down in garden next to tomato. The bottle will slowly leak out and keep the area around it damp. Two things to note – you have to adjust the size of the hole to get the drip rate you want. And you have to put the bottle close enough to the main stem so the water can reach it.
After reviewing Blight for what it is and how it works, I have come to the conclusion that it was sprayed from air planes. It could not have spread though my whole State as fast as it has without help. The blight was in the rain along with other chemicals that the Government spray’s from planes. Why, I’m not so sure other than they are all crooks and sick individuals! When you research cloud seeding with the understanding that population reduction is under way, the picture is very clear! It is going to be the most interesting decade in a long long time! Good luck all and better luck with your gardens next year ( in a green house)?
@photomaineac – you know this explanation had never crossed my mind, has never appeared in the literature, has never been suggested on any other gardening website that I know of. Thanks for the start to my day.
After all said and done, I have had a lot of tomatoes off of my 4 plants
of variety, one of which is a herloom plant….I had volunteers come up and not knowing what they are, they are in abundance….A blight did come but
did not do the damage until after the tomatoes set on….Next year, I will rotate the garden as I always do….
The blight did not hit the volunteer tomatoes…These tomatoes are nice,
and plump but I am still trying to figure what kind they are….I had
better results this year, and more pleased with my garden, even chasing the
ground hog and the deer away from eating all of the bounty….but they
have to eat too….so I guess I can share….I never give up on planting
and growing. When I do, I will no longer be able to play in the dirt..
and that is more important to me then all the bushels of tomatoes in
the world….! Happy growing….!
Hi – could you post the information (again?) about your drip watering system? I have been searching your website and have been unable to locate it – Thanks –
PS – I have (indeed) late blight – you aint just a kidding that it moves FAST!! I ‘had’ 57 plants and deceasing daily. I am just sick with the thought of this happening. What can I do to kill the blight (I live in Wisconsin) and prepare the ground for next season? – I want NO chance of this terrible thing happening EVER again! – thank you for your time -
I believe I have late tomatoe blight as all my tomatoe leaves are dying. All the leaves are turning brown and some of the tomatoes are rotting from the stem out. Is it ok to pick off the green tomatoes that have no marks on them and let them ripen inside to then eat or can; or do we just bag up the whole thing and dispose of them? Thanks, Yvonne from Northern NH.
@yvonne
The tomatoes will likely rot as well when you try to store or ripen them
Great info, Thanks! Noone else said anything about there being three types. I was ready to give up on my plants and pull them out as they recommended on the news, but now I know that they have the first blight that you listed and not the late blight.
I too have the Septoria leaf spot. Plants were doing extremely well (may have been too busy to notice any early problems developing) and loaded with tomatoes before our vacation, but upon returning home (of the 7 days away, it had rained 4) we discovered a huge change with our 24 plants dying from the bottom up. I’ve removed 10 of the worst looking and lowest producing plants. Of the remaining “healthier” plants some tomatoes are rotting in the green stage, some are rotting in the ripening stage, while the rest of the produce (thus far) appear healthy and without any flaws, even though the leaves are brown and dead on the bottom 3/4 of each plant. I am bringing some of the produce indoors in the green stage and in the ripening stage to see what happens and leaving the rest to mother nature. My question is this: If some of the produce does ripen, is it edible? If there is a small darkened area on a ripe tomato, can that area be cut away and the remainder safely eaten? In your explanation on this type of blight you state: “It works its way up the plant to hit all the leaves but it starts from the bottom first. You’ll get fruit if you have this problem”, can we assume that the tomatoes are safe to eat? Actually, I’ve eaten some and not gotten sick, but my husband refuses to eat any. Thank you for your response.
@Linda
If the tomatoes ripen – they’re good to eat – no problem.
It’s August 30th, 50 miles southwest of Chicago, and we have lost our entire
tomato crop to late blight. I guess all we can do is start over next year with better spacing and pruning practices. It was a cold, wet summer and we live in the Fox River valley where winds are low and the air moves very little. Lots of fog and heavy dew. thanks for the good info.
@Lin – sorry to hear about the crop – it’s a major pain in the garden to be sure.
I have the late tomato blight in Central Ky. It has pretty much destroyed my tomato patch in less than two weeks. Found pictures on the web that could have been taken of my tomato plants that were confirmed late blight. I got a lot of tomatoes before it hit so it is not a total loss. I’ve read that they think it could have been commercial plant growers that have sold infected tomatoes. You and others indicate that it comes from the soil. My plants were grown from seed. They were grown in a patch of my yard that had never had anything but grass on it before. I moved my garden because of a lack of light. This happened so fast I thought it might have be sprayed with weed-b-gone or something.
@Ken – I said it *could* have overwintered or been in the soil – not to imply that it always comes from the soil and that new soil won’t have it. As I said, there’s a multitude of reasons that this problem occurs – not to repeat the article here.
Growing tomatoes: It is like the mysteries that comes with planting and growing anything in the garden..Most of us grow to save on our grocery bill, and some of us grow and plant because it is in our blood. Some of looks
for that juicy red tomato that makes our mouths water….WE understand
that not everything is going to be perfect…We look for the imperfections andtry to correct it next year..This year, so many of us had problems with planting our tomatoes. In part I did. I had volunteers to come up, and nothing happened to them. The plants I purchased ended up with the blight or a ground hog got into them….But over all, my garden did really I do all container and above ground gardening…
Now to plan for next year…I am always lookingfor that perfect year…I always plant one new plant of something for next year…I always try
a couple of heirloom plants to fit into my small area…I am so happy
when spring has sprung, and I am able to get my fingers into the soil…
I love that more then anything else in life..Getting back to nature and
watching the seed sprout and shoot forth it’s bounty for us to enjoy.
Thank you so very much for this sight…Thank you Doug!
Can you cut away the bad spots on the tomatos and eat them safely?
3/4 of my 6 tomato plants rotted. I thought maybe I could save a few.
@Cindy – if you have blight – then the rot on the tomatoes is pretty much going to be right through the fruit – not worth saving. The fruit will be mush.
What is the best way to deal with infected plants now that the season is done? Bury them? Burn them? Wait for the freeze and then till them under? Don’t want to bag them if at all possible.
@Laura – bag and remove from the garden. Do not bury or till in (infection lives in soil) Get them off the property
Is it safe to plant other plants in the same spot that the blight occured? I know I can’t do tomatoes there again, but can I do something else?
Folks – rather than continuing to answer questions in this article - I’ve answered most questions right here If you check out that page and your question isn’t asked – then ask it in the form there. Easy and most questions have been answered there.