Regional Gardening Reports :: National Gardening Association

In the Garden:
Southern California Coastal & Inland Valleys
August, 2011
Regional Report

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Cherry tomatoes are the best of all snacks - healthy, tart-sweet, and juicy!

Tomato Problems #2: The Fruit

The August 11 column dealt with common tomato growing problems. Now we consider problems with the fruit.

Symptom: Light-colored cloudy spots with pithy or corky areas just below the skin.
Problem: Stink bug punctures.
Solution: Remove by hand and destroy. Spray with insecticidal soap. Keep down weedy areas if bugs have been persistent. Plant smaller sections of crop, rather than large areas.

Symptom: Large holes or completely hollowed out.
Problem: Slugs.
Solution: Stake tomatoes and place mulch or boards under fruit to get them off the soil. Harvest frequently.

Symptom: Hollow fruit.
Problem: Poor pollination caused by low light (dark, cloudy days), too much nitrogen, heavy rainfall, temperatures that are too high (over 90 degrees) or too low (below 58 degrees), or too much hormone fruit-set spray.
Solution: Set tomatoes out later in season and modify environment with hotcaps. Shade in hot weather. Use less fruit-set spray.

Symptom: Cracks -- concentric circles around stem or in lines radiating from center.
Problem: Sudden, rapid growth during high temperatures (over 90 degrees) and high rainfall or heavy irrigation, especially after a dry spell. Ripening fruit and fruit exposed to the sun are most affected.
Solution: Plant less-susceptible varieties. Keep soil evenly moist with proper watering techniques and mulches. Do not remove leaves from plants. Do not irrigate just before harvest.

Symptom: Black mold along growth cracks.
Problem: Damaged, cracked tissue developing under warm, moist conditions.
Solution: Prevent fruit cracking (see above). Handle fruit carefully.

Symptom: Catfacing -- misshapen, puckered, swollen areas; cavities lined with scar tissue.
Problem: Incomplete pollination due to 1) weather being too cool or hot, 2) bees not being available, or 3) overhead irrigation during blossoming that makes blossom cling to itself, resulting in abnormal shaping of the fruit. Common on early fruit of varieties that produce large-size fruit.
Solution: Plant less-susceptible varieties, including those bearing smaller fruit. Encourage bee activity. Irrigate under foliage.

Symptom: Circular sunken spots on skin that enlarge and darken.
Problem: Anthracnose.
Solution: Plant in well-drained soil. Destroy plants and fruits (do not place in compost pile).

Symptom: Blossom-end rot -- watersoaked area on blossom end which darkens and becomes larger, sunken, and leathery.
Problem: Related to lack of calcium due to lack of water when plants have grown rapidly during the early part of the season and then are subjected to hot dry weather when the fruits are in an early stage of development. More severe in sandy soils and soils with a high salt content.
Solution: Plant less-susceptible varieties. Refrain from planting in very cool soils. Calcium is not available to plants at a low soil pH, so incorporate dolomitic limestone at time of transplanting. The finer the grade of limestone, the faster it breaks down in the soil, and the sooner it raises the pH and enables the calcium to be utilized. Keep soil evenly moist with more thorough irrigation. Stake tomatoes or mulch beneath them to get fruit off ground.

Symptom: White or yellow patches on parts of green or ripening fruit that face the sun; become blister-like and form large, flattened, grayish-white areas with a dry, paper-like surface.
Problem: Sunscald; most frequent during hot dry weather and on plants which have lost foliage from pruning or disease.
Solution: Some varieties with little foliage are more tender and sunscald more easily. Do not remove leaves from plants. Where fruits are exposed, put a light covering over the clusters to diffuse the direct sunlight.

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