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Departments » UW Extension » Urban Horticulture & Natural Resources
General Information

Welcome to Extension Brown County's

Urban Horticulture
Natural Resources Pro


Article of the Week
(Originally published in the Green Bay Press-Gazette on July 1, 2018)

Preventing Tomato Diseases and Disorders
Tomatoes are one of the most popular, relatively easy growing, and rewarding vegetable crop for many gardeners. But tomatoes are also one of the most vulnerable crops to many diseases (like septoria leaf spot, early blight, and late blight) and physiological disorders (blossom end rot) that arise during the mid-growing season. With proper diagnosis and adapting preventive measures at the right time, one can minimize the disorders affecting the tomato plant.
1. Inspect your tomato plants every day. Warm, moist weather condition during the mid-summer season is ideal for septoria and early blight fungal disease. Check for any circular leaf spots or blotches on your plants, especially the lowest leaves. Both diseases can defoliate your tomato plants and can ruin the quality of the fruit if not prevented at the early stage. Remove the leaf at the first sign of infection and bring the sample to the Brown County UW Extension office for proper diagnosis. Fungicides for vegetable crop use containing copper or cholorothalonil as an active ingredient can be sprayed at the early stage before infection spreads. Read the product label carefully and follow its direction.
2. Avoid overhead irrigation to prevent the spread of foliar diseases. Use a soaker hose, drip irrigation or place the watering wand of your hose at the base of the plant without wetting the leaves. Early morning is the best time to water the plants. Tomato plants need at least one inch of water per week barring any significant rainfall. Check the soil moisture by poking a finger an inch deep in to the soil before watering the plant. A good soaking water on a regular basis will minimize physiological disorders like blossom end rot.

3. Mulch your tomato using rice hulls, crushed corncobs, clean straw or hay, or shredded newspaper (black ink) to about 1 inch thick. Mulches will act like a barrier preventing the spores splashing from the soil to the leaves. Don’t use treated lawn clippings for mulch. It is also a wise idea to prune off the lowest leaves to encourage air flow and minimize the leaf infection.

4. Tomatoes are highly vulnerable to herbicide drifts injuries. Take caution when spraying your lawn weed control products and follow the label directions. Avoid spraying lawn herbicide products when the weather is windy and temperature is above 85 F.

5. Indeterminate tomato varieties can grow as a bushy shrub and can trap humidity around them. To encourage better air flow around the plant, stake the plant using a tall tomato cage or in a trellis system.

6. Don’t over fertilize your tomato plant as it triggers excess foliage growth leading to foliar diseases and physiological disorders. Generally, tomatoes are fertilized twice during the growing season (using a complete fertilizer like 10-10-10) – before transplanting and side dressing after the first fruit set (golf ball size). Do not sprinkle the fertilizer on the leaves, rather spread it 6 inches away from the base of the plant and water it thoroughly.
Tomato Trellis

For horticulture-related questions and advice, contact Extension Brown County's Horticulture Help Desk at 920-391-4615 or

Fall 2018 Master Gardener General Training
This session is now in progress and closed until July 2019.
For more information about becoming a N.E.W. Master Gardener Volunteer please follow: Becoming a Certified Master Gardener Volunteer


Horticulture Help Desk Services
We offer free consultations on lawn care advice, insect and disease diagnosis, and plant and insect identification. We also address tree and shrub problems as well as help you select the plants that are best suited to your needs and site. Soil tests and advanced diagnosis services are available for a fee.

Bring your live or digital specimen to the Horticulture Help Desk:

Extension Brown County
210 Museum Place, Green Bay, WI 54303
Hort Help Desk Phone: 920-391-4615

The UW-Extension Office is open Monday through Friday from 8 AM to 4:30 PM.
If a horticulture staff member is not available when you call or visit, messages and samples can be left with UW-Extension reception, and a staff member will contact you.

We are here to serve you by connecting the University system, Master Gardener volunteers, and you - Northeast Wisconsin residents - to help things grow.

Contact:  Vijai Pandian - Horticulture Educator
Phone: 920-391-4611
Fax: 920-391-4617
Click here to email
Mailing Address:  Extension Brown County
210 Museum Place
Green Bay, WI 54303
Hours:  Monday - Friday, 8 AM - 4:30 PM
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