Tomato plant disease?

Asked April 10, 2018, 6:09 AM EDT

Hi - I wanted to find out the diseases of tomatoes that are prevalent in northern MN (I'm in Bemidji). Every summer around early August - just when fruit is starting to ripen - the plants start dying from the bottom up. First the leaves start yellowing, then browning, and soon the entire plant is dead and brown. Is this late blight or other disease? I notice it only in the plants that are outside - not in my small greenhouse, so I am guessing this is a water-borne disease like blight. I do rotate my plants each year, and mulch the base of the outdoor plants to try to keep dirt off them. I water at the base of plants, but the outdoor ones do get rain. Any thoughts you have on this, I apprecaite! Thanks - Diana

Beltrami County Minnesota tomato diseases horticulture

2 Responses

The most likely culprits are septoria leaf spot and early blight - they are the two most common tomato "blights". Late blight is a devastating disease that kills the plant and rots the tomatoes within a week. It is not common here (thankfully) but it was around last year.

Prevention is the best option: don't water overhead or at night, don't work around wet plants, mulch to prevent splash up of soil, plant disease resistant varieties (and avoid heirlooms), space plants, keep them off the ground and on stakes or trellises, clean up debris in the fall and rotate crops. Read here:
http://www.extension.umn.edu/garden/yard-garden/vegetables/septoria-leaf-spot-of-tomato/
http://www.extension.umn.edu/garden/yard-garden/vegetables/early-blight-of-tomatoes-and-potatoes/
http://www.extension.umn.edu/garden/fruit-vegetable/plant-diseases/late-blight-tomato/

Also look here:
http://www.extension.umn.edu/garden/yard-garden/diseases/#vegetable



Thank you much, Dennis. This information is very helpful. I think the likely culprit is probably septoria. I will take additional precautions this year!
Diana