From the Ground Up: Tomatoes take hard hit this year

Many gardeners across Eastern Iowa are now enjoying the rewards of the tomatoes planted last spring, but not all of those tomatoes are perfect. Tomatoes have a lot of enemies in the garden, even deer! But more common are the fungus and bacterial diseases of tomato plants.

I am experiencing a lot of blossom-end rot and fruit cracking in my garden this season, which are two common issues attacking the fruit of the tomato plant. Both are caused by a calcium deficiency that is related to wide fluctuations in watering. Iowa soils contain plenty of calcium, so the addition of calcium doesn't solve the problem, but a consistent supply of moisture does.

Tomato blight and leaf spot is common and attacks foliage, particularly the lower leaves. Early blight, Septoria blight and Late Blight all have the overall effect of leaves turning yellow, brown, then withering and dying. These are all caused by a fungus that overwinters on plant debris in the soil. Fungal spores splash onto the plant's leaves by raindrops or watering. Wet spring and wet early summer weather favors development of foliar diseases on tomatoes.

There are also bacterial spot diseases that behave the same way as the fungal diseases, which can affect foliage and fruit. Bacterial spot, bacterial speck and bacterial canker are some common ones.

Then there are the wilt diseases, most common are Fusarium and Verticillium wilt. Plants infected by Fusarium wilt show leaf yellowing and wilting initially on one side of a leaf, branch, or plant, spreading to the remainder of the plant. Verticillium wilt causes yellow blotches on lower leaves; the leaves rapidly turn completely yellow, wither, and drop

off. Both wilts affect the water-conducting tissue in the stems.

Good cultural practices in the garden help avoid some of these issues. Iowa State Extension recommends rotating tomatoes in the garden every year, and not planting them in the same spot for three years. This helps to destroy the pathogens that live in the soil. That's hard to do in a small home garden.

Other tomato tips include:

' Space plants at least 3 feet apart, allowing good air circulation for faster drying of foliage.

' Staking tomatoes. Don't let them sprawl along the ground.

' Mulch tomatoes with at least a 2-3 inch layer of mulch which helps prevent the soil from splashing onto the plant.

' Avoid getting plant foliage wet when watering. Apply water directly to the ground around plants with a soaker hose, slow running hose or watering can. Water only in the morning so the foliage doesn't stay wet all night.

' Don't work with plants when foliage is wet.

' Remove diseased leaves to reduce the spread of the spores and remove all plant debris in the fall.

' Plant disease free and disease resistant varieties of tomatoes.

' Lisa Slattery is a Linn County Master Gardener. For gardening questions, call the Linn County Extension Hortline at (319) 447-0647 with your questions.