Tomato plant problem? - Ask Extension
For the last 2 weeks I have noticed a change in some of the leaves on my tomato plants. I was wondering if you might be able to identify the cause of...
Knowledgebase
Tomato plant problem? #873896
Asked June 20, 2024, 9:41 AM EDT
For the last 2 weeks I have noticed a change in some of the leaves on my tomato plants. I was wondering if you might be able to identify the cause of the browning and dying of these leaves. Is it a fungus? I have mulched my plants this year with straw to hopefully confine the soil borne illnesses.
Fairfield County Ohio
Expert Response
Hi Cyndy,
It sounds like you certainly had the right idea about trying to head off issues with your tomatoes. Fungi overwinter in plant debris, on seed, and on weeds such as nightshade and horsenettle. Spores may be splashed up from the soil or
blown by the wind onto tomato leaves. Mulching, plant spacing, watering methods and timing, and general plant management can all help.
Unfortunately, even the best practices sometimes fail. Disease development is favored by relatively warm temperatures, abundant rainfall, and high relative humidity. All of these conditions have been widespread in Ohio this year.
It does indeed appear that your tomatoes are being attacked by a fungal disease.
Two of the most common diseases in Ohio are early blight and Septoria leaf spot. Both diseases may occur anytime during the growing season, but they generally become more severe after blossom-set.
Based on your photos, my money is on Septoria leaf spot as the culprit. I didn't see the 'target' formation that indicates early blight and I thought I could see the spores that characterize Septoria. However, the resolution of your photos didn't allow me to enlarge them enough to get a really good look.
Here is an excellent overview from Rutgers University of several of the most common tomato diseases including early blight, late blight, and Septoria leaf spot.
https://njaes.rutgers.edu/fs547/
Referring to the article above and the two that follow, examine your plants thoroughly - leaves, stems, and any fruit - to see if you can make a more definitive diagnosis. It is not impossible for more than one disease to be present.
https://extension.wvu.edu/lawn-gardening-pests/plant-disease/fruit-vegetable-diseases/early-blight-of-tomatoes
https://extension.wvu.edu/lawn-gardening-pests/plant-disease/fruit-vegetable-diseases/late-blight-tomatoes
As you plan for next season - or maybe yet this season - you may want to select tomato varieties based on their disease resistance. Cornell University has put together quite an exhaustive list of varieties and the diseases they can fight:
https://www.vegetables.cornell.edu/pest-management/disease-factsheets/disease-resistant-vegetable-varieties/disease-resistant-tomato-varieties/
You might also want to consider crop rotation - another very important management practice, particularly for tomatoes. If you have room, rotate the location of your tomatoes each year to an area that has not had tomatoes or related [nightshade] crops, such as, peppers, potatoes, eggplant, or tomatillos, for several years.
If rotation is not feasible, fungicides may be helpful. Read directions carefully to make sure you are applying the product properly and that it is safe to use on vegetables. Be sure to start protecting plants as soon as disease symptoms appear. It is virtually impossible to stop fungal disease on heavily infected plants. The articles linked above all include additional information about managing these diseases.
I hope this information is useful and you have lots of tomatoes for your BLTs. Good luck and good harvest!
It sounds like you certainly had the right idea about trying to head off issues with your tomatoes. Fungi overwinter in plant debris, on seed, and on weeds such as nightshade and horsenettle. Spores may be splashed up from the soil or
blown by the wind onto tomato leaves. Mulching, plant spacing, watering methods and timing, and general plant management can all help.
Unfortunately, even the best practices sometimes fail. Disease development is favored by relatively warm temperatures, abundant rainfall, and high relative humidity. All of these conditions have been widespread in Ohio this year.
It does indeed appear that your tomatoes are being attacked by a fungal disease.
Two of the most common diseases in Ohio are early blight and Septoria leaf spot. Both diseases may occur anytime during the growing season, but they generally become more severe after blossom-set.
Based on your photos, my money is on Septoria leaf spot as the culprit. I didn't see the 'target' formation that indicates early blight and I thought I could see the spores that characterize Septoria. However, the resolution of your photos didn't allow me to enlarge them enough to get a really good look.
Here is an excellent overview from Rutgers University of several of the most common tomato diseases including early blight, late blight, and Septoria leaf spot.
https://njaes.rutgers.edu/fs547/
Referring to the article above and the two that follow, examine your plants thoroughly - leaves, stems, and any fruit - to see if you can make a more definitive diagnosis. It is not impossible for more than one disease to be present.
https://extension.wvu.edu/lawn-gardening-pests/plant-disease/fruit-vegetable-diseases/early-blight-of-tomatoes
https://extension.wvu.edu/lawn-gardening-pests/plant-disease/fruit-vegetable-diseases/late-blight-tomatoes
As you plan for next season - or maybe yet this season - you may want to select tomato varieties based on their disease resistance. Cornell University has put together quite an exhaustive list of varieties and the diseases they can fight:
https://www.vegetables.cornell.edu/pest-management/disease-factsheets/disease-resistant-vegetable-varieties/disease-resistant-tomato-varieties/
You might also want to consider crop rotation - another very important management practice, particularly for tomatoes. If you have room, rotate the location of your tomatoes each year to an area that has not had tomatoes or related [nightshade] crops, such as, peppers, potatoes, eggplant, or tomatillos, for several years.
If rotation is not feasible, fungicides may be helpful. Read directions carefully to make sure you are applying the product properly and that it is safe to use on vegetables. Be sure to start protecting plants as soon as disease symptoms appear. It is virtually impossible to stop fungal disease on heavily infected plants. The articles linked above all include additional information about managing these diseases.
I hope this information is useful and you have lots of tomatoes for your BLTs. Good luck and good harvest!
