alnmcn
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Tomato Plants Failing

Hi,

I have just joined the forum in order to seek some advice from anyone who has had experience in growing tomatoes...

I have bought and built a greenhouse this year and started off growing tomatoes along with peppers and courgettes. The tomato plants were growing well until around a 7-10 days ago when the leaves on the bottom started to go yellow and more recently the stems and fruit have begun to discolour.

A local garden centre has suggested that the greenhouse being overcrowded may be the cause so today some of the plants were moved out in order to create more space.

One thing that bothers me is that one of the courgette plants which is outside the greenhouse and was doing well has now began to show similar symptoms.

Hopefully the pictures below will give some clues.

Any help or advice would be much appreciated,

Thanks.
IMG_6022.JPG
IMG_6021.JPG
IMG_6020.JPG
IMG_6019.JPG

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rainbowgardener
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Oh dear.... I'm really sorry to say, those are pretty classic images of late blight.

Image

Late blight is about the worst disease your tomatoes can get. It kills them pretty quickly, it spreads quickly, and it spreads to other plants besides tomatoes, especially other nightshade plants like potatoes and eggplant.
The fungus, (Phytophthora infestans), that causes late blight is aptly named: phytophthora in Latin means "plant destroyer." Infected plant tissue dies. Outbreaks spread quickly under favorable conditions because the pathogen can produce huge numbers of wind-dispersed spores. Once a plant is infected, it must be destroyed.
https://www.gardeners.com/how-to/prevent ... C=XNET9465

"favorable conditions" definitely includes a greenhouse with increased humidity and decreased air circulation (compared to outside).

Note that the article is titled "how to prevent late blight," not how to treat it. Once it has progressed this far, there is usually no treatment. Here is an article about treating late blight:
https://www.planetnatural.com/pest-prob ... te-blight/

but you note that most of the steps are really about prevention and all the treatment steps say things like " applying before infestation gives the best results."

I am really, really sorry to be the bearer of such bad tidings, but I think your best course would be to destroy all your tomato and eggplant plants and do a thorough cleaning of the greenhouse. :( :shock:

BUT please don't embark on this destruction just on my say so. Take your plant sample to a good local nursery or somewhere else knowledgeable (university ag dept? county extension?) and get this confirmed.

Hopefully others with more expertise than I will chime in on this.

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rainbowgardener
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Note USA Blight https://usablight.org/ tracks late blight in this country. They give information here
https://usablight.org/managing about managing/preventing late blight and information about diagnostic clinics to have your blight confirmed.

alnmcn
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Hi,

Many thanks for the replies, I think that you are correct, the symptoms seem to fit. Oh well I will try and quarantine the plants that appear to be ok and get rid of the others then clean the greenhouse as suggested.

I'll have to do some more research and hopefully next time will be more successful. :)

Thanks again for taking the time to help out.

Kind Regards,

Alan.

imafan26
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Greenhouses are great tools but it is a environment that needs to be controlled. Once pests and disease gets in, the crowded conditions can spread the problems quickly. Use a thermometer and humidity meter.
https://www.greenhousemegastore.com/prod ... ring-tools

Know the ideal conditions for the plants you are growing and you need to use the greenhouse vents and fans to try to mimic that environment. Where I am glass houses are not practical since they get too hot and high humidity and poor air circulation breeds fungal problems. The shade houses we have usually have shadecloth or opaque phylon because the clear glass amplifies the sun which is good in a northern climate but bad in a tropical one.

You have to be more diligent in a greenhouse to try to make sure no pests get in because there usually are no predators in a greenhouse. Watch your plant spacing and make sure you isolate or remove any sick plants from the greenhouse to protect the rest.

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rainbowgardener
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alnmcn wrote:Hi,

Many thanks for the replies, I think that you are correct, the symptoms seem to fit. Oh well I will try and quarantine the plants that appear to be ok and get rid of the others then clean the greenhouse as suggested.

I'll have to do some more research and hopefully next time will be more successful. :)

Thanks again for taking the time to help out.

Kind Regards,

Alan.
Yup, get rid of all affected plants AND the soil they are in (NOT in the compost pile). Clean all pots and tools with bleach solution. Then monitor remaining plants very carefully to be sure they don't have it. Start spraying them with anti-fungals NOW, not when they show disease signs. Anti-fungals include hydrogen peroxide straight from the bottle, baking soda solution, diluted milk or commercial preparations like Actinovate or Serenade.

Make sure the plants are well spaced. My tomato plants are caged, so I prune out branches growing into the center of the cage to help maintain good air flow. Keep a fan going in the greenhouse for air circulation. Water only the soil, not the leaves.

Best Wishes for being able to save some of your plants!

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rainbowgardener
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It is very disappointing and frustrating to have to trash your plants :( :( . But don't take it personally.

If you bought those as transplants (vs. starting them from seed), it is possible that they were infected already when you got them. The blights have been spread a lot by nurseries. Here's a little article from last year about that:

https://www.northeastnursery.com/blogs/ ... d-potatoes

AND a greenhouse, especially in summer, is a very difficult and tricky environment to work with. It is great in late winter/early spring for getting things started. But once warm and humid weather arrives, your plants are much better off being outside.

I don't think you have said where you are located? it always helps to tell us where in the world you are. There are hardly any garden questions that can be discussed without regard to location/ climate. In this case, what your summer conditions are like is relevant to this discussion.

CherylNelson740
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sorry to hear that. I know how it feels to see your labor of love didn't turn out to be what you expected. but we all learn from our mistakes right? :)

Cheryl from SiouxFallTreeService.org



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