Tomato Plant Blight - What an evil disease!

Asked June 1, 2016, 12:58 PM EDT

Hello and thank you for the time in reading my message. I moved into my house four years ago. The property is old farm land and has, what I would think would be dark, healthy soil. The first year I was in the house, I planted five tomato plants along the back side of the property in full sun. They were planted simply in holes that I had dug in the grass, using new garden soil and surrounded with mulch. The variety that was planted, and has been since (for the purpose of this discussion) was the Better Boy and Big Boy varieties. The first year, the plants flourished. I watered them frequently with Miracle Grow and by the time the season was over, the plants had reached over eight feet in height and had produced a very large yield of healthy tomatoes. The following year, I decided to expand the garden to approximately 10' x 15'. The area was tilled while removing most of the grass and weeds prior to planting. Shortly after planting, I noticed the bottom leaves of each of the tomato plants having spots on them (dark spots, surrounded by gray and ultimately yellow. See attached picture). Before I knew it, the majority of each plant was nearly skeletonized and barely hung on for the remainder of the season. The rest of the garden (peppers, green beans, cucumbers) seemed to be unaffected. Last year, I decided to move the tomato plants out of the main garden and away from the affected area (approximately 40 feet from garden). This time, I planted the tomatoes the same way I did the first year. Simply dug a large hole, filled with a mixture of new garden soil with native soil. Shortly after planting, I noticed the same thing taking hold of the plants. I could not stop it. The plants were, once again, barely hanging on for the duration of the growing season. This year, I planted tomatoes in the same area, away from the garden and used an organic fungicide that would supposedly help the plants resist blight (or whatever it is). I covered the area around each plant with a wide bed of mulch, with the hope that this will aid in the blight prevention. No use. The attached picture was taken less than two weeks after I planted the once healthy plants. With this being said, I need help! My wife and I long for the taste of good home grown tomatoes. I feel absolutely helpless at this point. I have read tons of information regarding "solarizing" the garden soil with plastic prior to planting and even feeding the plants 325 mg of aspirin to a gallon of water. While I am now trying the aspirin (after removing all of the affected leaves), I did not try to solarizing method. I guess I would like to get some information from an expert as to how I might get back to having large, wonderful tomato plants and not feel like I am fighting a losing battle. I understand that it may be too late this year, but I will try anything to turn things around for next year. Any help you could provide would be wonderful. Thank you in advance, Tracy


1 Response

Unfortunately, it is not possible to diagnose your tomatoes from a photo. The yellowing around the brown/black spots is indicative of several different fungal diseases. There could also be pH or nutritional issues as well, a soil test would answer those questions.

You can bring in a complete infected plant for us to send to the plant pathology lab as well.

In general, tomatoes and other plants in the solanacea family do need a little more consideration when deciding what and where to plant. (These include peppers, eggplant and potatoes.) Whether you start them from seed or purchase them as bedding plants remember:

Disease resistant varieties are best! Tomatoes should have the letters VFFNTA. These letters represent disease and nematode resistance.

a) V – Verticillium wilt.

b) F – Fusarium wilt, FF indicate 2 most common fusarium strains.

c) N – Nematodes (microscopic plant parasite)

d) T – Tobacco mosaic virus.

e) A – Alternaria leaf spot.

Disease resistant is not disease proof so good gardening sanitation and practices are still necessary!

Indeterminate or determinate? Determinate tomatoes tend to ripen all at once, are bush like and are great for canning. Indeterminate varieties ripen off and on through the season, are vine like and the plants live a bit longer.

Rotate the crop. Do not plant them in the same place within a 3 year period. This includes any plants in the solanacea family!

Use a fertilizer labeled for tomatoes or veggies low in nitrogen but higher in potassium and phosphorus.

Better yet, get the soil tested and follow or recommendations for your particular garden plot.

Be prepared to mulch the plants for soil moisture and temperature control. Mulching also creates a layer between the soil and plants which can aid in disease control.

Be consistent with the watering.

If you decide to start your plants from seed next year:

*Read the seed packets closely and compare recommended planting and harvest dates.

* Disease resistance is worth the effort as it can save you both time and money.

*Check to see if there are any specific or unusual plant needs.

* Decide on the square footage of your garden.

*Note the space each plant will need.

*Most veggies need to be started 6 to 8 weeks before our frost- free date of May 13.

* Use clean seed starting mix, pots and clean tools before using.

*Be sure to save the seed packets for reference!

Common diseases on tomatoes in Kentucky:

Feel free to contact our office if you have other questions.

Let me know if I can help you further!

Carol Wilder
Horticulture Technician
Jefferson County Cooperative Extension Service
810 Barret Ave
Louisville KY 40204