We are in the height of the season for home gardens. Whether you’re a seasoned veteran gardener, or just establishing your green thumb, odds are you have questions. K-State Research and Extension is here for you during this process with science-based facts from the experts who really understand what’s going on. While you can always get information from Google, and some of it may be factual, it’s always a good idea to find information from a trusted, accredited source like your state’s land-grant institution. Our office has received many questions regarding tomatoes in recent weeks, so I’ll provide you a broad overview of blossom-end rot, tomato horn worm, fertilizing tomatoes and tomato fruitworm. 

Blossom-end rot: This is non-parasitic disorder can affect tomatoes, peppers, squash, watermelon and eggplant. It is characterized by a flat, leather area on the blossom-end of the fruit, opposite the stem. It’s usually first noticeable when the fruit is half-grown and it continues as the fruit matures. 

Blossom-end rot is caused by a calcium deficiency in the blossom-end of the fruit. When the fruit is growing rapidly, it requires large amounts of calcium. This could be the result of low calcium in the soil, but often times, is caused by a sharp change in weather from cool to hot, extreme soil moisture fluctuations, drought stress, root damage due to waterlogged conditions or excessive growth due to too much nitrogen fertilization. If the condition is caused by a limited roots system, the condition will correct itself as the plant adds more roots. In this case, remove affected fruit and continue to water the plant at its base. Additionally: 

• Maintain soil pH around 6.5 as shown by soil test. Do not assume that blossom-end rot is sure evidence that the soil lacks calcium. Other conditions that interfere with calcium uptake can cause calcium to be demanded in higher quantities than the plant can physically supply.

• Use a nitrate nitrogen fertilizer such as calcium nitrate rather than one that releases nitrogen in the ammonium form. Excess ammonium ions reduce calcium uptake. Also make sure that the plants are not over-fertilized especially when the fruit are small. Usually 1 1⁄2 pounds of a 10-20-10 fertilizer applied before planting is sufficient for tomatoes though sandy soils may need monthly side dressings.

Early Blight and Septoria Leaf Spot: These two common diseases can take place at any time during the growing season, but become more severe after blossom-set. They result in spots on the leaves that usually develop first near the ground. Early Blight and Septoria Leaf Spot can cause extensive deflation, sun scalding of fruit and reduction in the number of fruit produced.

These fungi overwinter in plant debris, on seed or on weeds. The spores of fungi may be splashed or blown onto tomato leaves. Warmer temperatures, abundant rainfall and high relative humidity are favorable conditions for disease development.

Both fungi overwinter in plant debris, on seed, or on weeds such as nightshade and horsenettle. Spores of these fungi may be splashed or blown to tomato leaves. Disease development is favored by relatively warm temperatures, abundant rainfall and high relative humidity.

To learn more about controlling pests in the garden or landscape, contact the Cowley County Extension Office at (620) 221-5450 or email Kelsey Nordyke (klnordyke@ksu.edu).


Original Source: Raymond A. Cloyd, Horticultural Entomology and Plant Protection Specialist, KSRE publication MF3474, “Bagworm: Insect Pest of Trees and Shrubs.”

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