How to Control & Prevent Diseases & Problems on Tomatoes

August 22, 2019

By Matt

How To Control and Prevent Diseases/Problems in Tomatoes

There is nothing sweeter than biting into a ripe tomato right off the vine. Caring for tomatoes can be difficult when the plant becomes plagued with disease and problems. Now is the time to arm yourself with information about threats that can attack tomatoes! Having the knowledge in your arsenal gives you the upper hand to tackle problems. 

Where Did the Tomato Come From?

The tomato dates back to the 15th century where it grew wild in the Andes region of Peru, Ecuador, and Bolivia. A prehistoric migration of Indians carried species of tomatoes from the Andes to Mexico. The tomato eventually reached North America and Native Americans began cultivating them.

The early settlers transported the tomato back to Europe where it gained momentum traveling the world. However, when European aristocrats ate tomatoes, they soon became sick and even died! The tomato was nicknamed “poison apple” because of this. What they didn’t know was that the pewter dishes they served tomatoes on contained lead. Tomato acid caused uptake of lead into the tomato causing lead poisoning. Whoops!

Later in the 18th century, tomatoes caught on around the world becoming a widely consumed item. Today there are many varieties of tomatoes grown in the U.S. where tomatoes are a staple of many people’s diets!

Tomato Problems: Prevention Is Key 

Unfortunately, as most gardeners know, growing great tomatoes can be difficult because they are prone to a wide variety of diseases and problems. 

However, there is hope! Knowledge and prevention play large roles in the defense of possible diseases. It’s vitally important to be one step ahead of problems.

The first defense in keeping disease and problems at bay is prevention. Prevention includes being proactive with good cultural practices and chemical treatment when necessary. Educate yourself on diseases and problems. This will equip you to be able to look for any issues.

Some good preventative practices are:

  • Check your plants daily for any signs or symptoms.
  • Plant cultivars that are resistant to diseases.
  • Rotate planting areas each season.
  • Use fungicides before disease can hit.


That said, many diseases and insects will still push through no matter how hard you attempt to prevent them. At that point, it is essential that you identify the issue properly and use control techniques specific to that disease or insect.

For the remainder of this article, we will look at some common tomato problems and give you some control mechanisms for each one.

When in doubt, shoot us an email or contact your local extension service for more information or help.

Tomato Diseases and Problems

Without further ado, here are some of the worst diseases of tomatoes! 

Anthracnose

Paul Bachi, University of Kentucky Research
and Education Center CC BY-NC-3.0


Damage/Impact Meter: 7/10
Type of Disease: Fungus
Pathogen: Colletotrichum coccodes
Symptoms:
  • As tomatoes ripen, they develop indented regions.
  • As they mature, the tomato’s center becomes dark.
  • Infection site has spots that grow larger and begin to spread down into the tomato.
How The Disease Is Spread:
  • Spores from infected plants are spread by splashing plants with water, irrigation from overhead, or through rainfall.
  • Spores overwinter and remain in soil. When soil is disturbed, the spores become airborne.
  • Insects feeding on plant/fruit will spread fungus.
Favorable Conditions:
  • Warm/moist/humid weather.
Cultural Control:
Keep in mind that even with the best cultural controls in place, disease can still hit.
  • Plant in a sunny area.
  • Spread tomato plants out to avoid overcrowding.
  • Stake/cage tomato plants upright to ensure good airflow.
  • Keep area free of weeds.
  • Mulch area to create barrier between soil and plant.
  • Remove dead/decayed plant matter from ground. Do not compost it but throw into garbage.
  • Clean/sanitize all gardening tools to prevent the spread of the disease.
  • Plant cultivars that are resistant to disease.
  • Rotate crop/garden to a different area for a minimum of 1 year.
  • Pick tomatoes immediately after ripening.
  • Remove all plant debris after growing season. Do not compost.
Chemical Control: Bonide Fungonil
It’s best if used before anthracnose hits because it stops spores from germinating. Fungicides are best as a protectant and should be used BEFORE disease strikes.
  • Fungonil will control this disease once it has started.


Bacterial Wilt

Bacterial wilt of tomato (Photo courtesy of C. Allen, University of Wisconsin)





.



Damage/Impact Meter: 10/10
This disease is severe causing fatality in plants. Once it takes hold of a plant/garden, it is impossible to eradicate. Using a chemical control as a preventative may keep contaminated insects from spreading the disease.
Type of Disease: Bacteria
Pathogen: Ralstonia solanacearum
Symptoms:
  • Wilting
  • Withering
  • Stunting
  • Shriveling
  • Oozing
  • Discoloration of leaves (yellow, brown)
How The Disease Is Spread:
  • Through contaminated insects that feed on the tomato plant.
  • Bacteria overwinter in the soil. Contaminated insect eggs are laid in the soil emerging as new carriers.
Favorable Conditions:
  • Heat
  • Moist soil
  • Sunlight
Cultural Control:
A few cultural controls will help to impact this disease. 
  • Remove all dead/decaying plant matter immediately and discard in trash. Do not compost.
  • Sanitize garden tools to prevent the disease from being spread to other plants.
  • Rotate planting areas. The bacteria survive in the soil for a few years, so it’s important not to plant in the same area every year.
  • Stay ahead of the disease by controlling pests.
Chemical Control: Bonide Eight
  • This chemical will not kill bacterial wilt but will eradicate any contaminated insects feeding on the plant that may carry the disease.


Fusarium Wilt

Fusarium Wilt in Tomatoes, (Photo courtesy of: Clemson University). 


Damage/Impact Meter: 8/10
Type of Disease: Fungus
Pathogen: Fusarium oxysporum
Symptoms:
  • Leaves turn brown/yellow
  • Wilting
  • Stunted growth
  • Seedlings die
  • Rotted roots
How The Disease Is Spread:
  • Spores overwinter in soil.
  • When soil is disturbed, the spores become airborne.
  • Splashing water from watering or rainfall.
  • Contaminated garden tools and hands.
Favorable Conditions:
  • Dry heat
Cultural Control:
Bacteria can remain in the soil for up to 20 years
  • Soil Solarization.
  • Replace or treat contaminated soil.
  • Remove all dead/decaying plant matter immediately and discard in trash. Do not compost.
  • Sanitize garden tools to prevent the disease from being spread to other plants.
  • Rotate planting areas. The bacteria survive in the soil, so it’s important not to plant in the same spot.
  • When watering, be careful not to splash.
  • Spread tomato plants out to avoid overcrowding.
  • Stake/cage tomato plants upright to ensure good airflow.
  • Keep area free of weeds.
  • Mulch area to create barrier between soil and plant.
  • Plant cultivars that are resistant to disease.
Chemical Control: Bonide Infuse
  • Soil solarization should be used in addition to chemical control approach.
  • Infuse is designed to treat disease that is present in the soil. 


Early Blight

Early Blight In Tomato (Photo courtesy of 
Yuan-Min Shen, Taichung District Agricultural Research and Extension Station) 


Damage/Impact Meter: 5/10
Type of Disease: Fungus
Pathogen: Alternaria tomatophila and A. solani
Symptoms:
  • Brown lesions on leaves. These areas grow larger and appear like a bulls-eye. Yellowing is evident around the bulls-eye.
  • Lesions on stems cause girdling that lead to collar rot.
  • Lesions on tomatoes. Infected fruit drops.
  • Yellow leaves-especially on bottom of plant.
How The Disease Is Spread:
  • Spores overwinter in soil from plant debris.
  • Spores become airborne if disturbed in soil.
  • Contaminated seeds.
Favorable Conditions:
  • Heat
  • Humidity
Cultural Control:
  • Spread tomato plants out to avoid overcrowding.
  • Stake/cage tomato plants upright to ensure good airflow.
  • Keep area free of weeds.
  • Mulch area to create barrier between soil and plant.
  • Remove dead/decayed plant matter from ground. Do not compost it but throw into garbage.
  • Clean/sanitize all gardening tools to prevent the spread of the disease.
  • Plant cultivars that are resistant to disease.
  • Rotate crop/garden to a different area for a minimum of 1 year.
    Pick tomatoes immediately after ripening.
  • Remove all plant debris after growing season. Do not compost.
  • Don’t use overhead irrigation or splash water when watering.
Chemical Control: Bonide Fruit Tree & Plant Guard
  • Contains fungicide and insecticide.
  • Top-of-the-line for preventing and controlling insects and disease.
  • Best to spray before you see symptoms.


Late Blight

Late Blight In Tomato (Photo courtesy of Gerald Holmes, California Polytechnic State University) 




Damage/Impact Meter: 9/10
Type of Disease: Fungus
Pathogen: Phytophthora infestans
Symptoms:
  • Lesions appear on leaves.
  • Leaf spots enlarge and develop white mold.
  • Yellowing leaves- especially on bottom of plant.
  • Defoliation 14 days after onset of symptoms.
  • Fruit develops olive-colored lesions that are glossy.
How The Disease Is Spread:
  • Spores overwinter in soil from plant debris.
  • Spores become airborne if soil disturbed.
Favorable Conditions:
  • Cool temperatures
  • Wet climate/conditions
Cultural Control:
  • Spread tomato plants out to avoid overcrowding.
  • Stake/cage tomato plants upright to ensure good airflow.
  • Keep area free of weeds.
  • Mulch area to create barrier between soil and plant.
  • Remove dead/decayed plant matter from ground. Do not compost it but throw into garbage.
  • Clean/sanitize all gardening tools to prevent the spread of the disease.
  • Plant cultivars that are resistant to disease.
  • Rotate crop/garden to a different area for a minimum of 1 year.
  • Remove all plant debris after growing season. Do not compost.
  • Don’t use overhead irrigation or splash water when watering.
Chemical Control: Bonide Fruit Tree & Plant Guard
  • Contains fungicide and insecticide
  • Top-of-the-line for preventing and controlling insects and disease


Leaf Spot

Leaf Spot In Tomato (Photo courtesy of  Bruce Watt, University of Maine)
Damage/Impact Meter: 4/10
Type of Disease: Fungus Pathogen: Septoria lycopersici
Symptoms:
(will not affect fruit)
  • Lower leaves begin to exhibit small spots with dark bordering and beige centering.
  • Tiny black specks are present in the center of the spots.
  • Yellowing of leaves.
  • Defoliation.
How The Disease Is Spread:
  • Splashing plants either through watering, overhead irrigation, or rainfall.
  • Overwinters on plant debris.
Favorable Conditions:
  • High humidity
Cultural Control:
  • Spread tomato plants out to avoid overcrowding.
  • Stake/cage tomato plants upright to ensure good airflow
    Keep area free of weeds.
  • Remove dead/decayed plant matter from ground. Do not compost it but throw into garbage.
  • Clean/sanitize all gardening tools to prevent the spread of the disease.
  • Plant cultivars that are resistant to disease.
  • Rotate crop/garden to a different area for a minimum of 3 years.
    Remove all plant debris after growing season. Do not compost.
  • Don’t use overhead irrigation or splash water when watering.
Chemical Control: Bonide Fungonil
It’s best if used before leaf spot hits because it stops spores from germinating. Fungicides work best as a protectant and should be used BEFORE issues strike if possible.

Blossom End Rot

Blossom End Rot In Tomato (Photo courtesy of Brenda Kennedy, University of Kentucky)

Damage/Impact Meter: 7/10
Type of Problem: Calcium Deficiency
Symptoms:
Tomatoes develop a sunken rotted spot near the stem.

Causes:
  • Soil lacks calcium
  • Low pH levels in the soil affect the calcium uptake
  • Fluctuations in too much/too little water
  • Drought
  • Stress
  • Over-fertilizing
Cultural Control:
  • Test soil
  • Don’t over fertilize
  • Don’t over/under water
Organic Control: Espoma Tomato Tone
  • Natural/organic ingredients
  • Enhanced with living microbes
  • Prevents blossom end rot by adding calcium to soil
  • Continuously feeds plants
  • Formulated to produce juicy tomatoes

Conclusion

As you can see, tomato diseases are a real problem! While there are resistant varieties of tomatoes that can be planted, giving you a little more peace of mind, these cultivars vary in their resistance to disease. Unfortunately, there aren’t any tomato hybrids that are 100% resistant to all diseases.

That said, good cultural practices in place will help ward off the heavy hitters of disease and problems in tomato plants. When you do encounter disease, we hope this helps give you the knowledge and the tools in place to fight back!

References

Blake, J., Keinath, A., Kluepfel, M. (2018 December 13) Tomato Diseases & Disorders, Clemson Extension Home & Garden Information Center, Retrieved from:

https://hgic.clemson.edu/factsheet/tomato-diseases-disorders/

Smith, A. (2013 June 18) Why the Tomato Was Feared in Europe for More Than 200 Years, Smithsonian, Retrieved from:

https://www.smithsonianmag.com/arts-culture/why-the-tomato-was-feared-in-europe-for-more-than-200-years-863735/

Egel, D. (n.d.) Five Steps For Healthy Garden Tomatoes, Purdue Extension, Retrieved from:

https://www.extension.purdue.edu/extmedia/bp/bp-184-w.pdf

(n.d.) Fusarium Wilt, UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries, Retrieved from: http://ipm.ucanr.edu/PMG/r280100811.html

(n.d.) Conquer Blossom End Rot, Bonnie Plants, Retrieved from:

https://bonnieplants.com/gardening/conquer-blossom-end-rot/

(n.d.) Resistant Varieties, Vegetable MD Online, Cornell University, Retrieved from:

http://vegetablemdonline.ppath.cornell.edu/Tables/TableList.htm

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