Keep tomato plants healthy to avoid problems in the garden

One of summer’s delights for me is eating fresh garden tomatoes at least once a day. There’s nothing like the old-fashioned flavor of vine-ripened tomatoes, especially if they come from my garden. While they taste so good, they do not always look like the perfect red, unblemished tomatoes I see at the grocery store. 

Tomato plants and fruit have their share of diseases, but what about those imperfections we find on tomatoes in our vegetable garden? What causes them? Are the tomatoes safe to eat? Most of the problems are cultural; and yes, the fruit is generally edible after removing damaged portions.

One of the most common problems is Blossom End Rot (BER). It appears as a flat, dry, sunken, brown rot on the blossom end of the fruit. It is caused by the lack of calcium in cell walls due to environmental stress. BER results from inconsistent or shallow watering at times of rapid plant growth, which affects the calcium uptake of the plant. 

Another frequent problem is fruit cracking. Cracks can develop in the skin of fruit that is reaching maturity. During periods of abundant moisture, particularly following dry conditions, cracks can appear. It can often be avoided by picking ripening fruit ahead of forecasted rain.

Due to foliar diseases by this time of the summer, there is a loss of leaves on tomato plants and the hot, direct sunlight can affect the fruit. Sunburn spots on tomatoes are common. Another effect is Yellow Shoulder, a condition in which the top of the fruit never ripens properly and is tough and poorly flavored. High temperatures inhibit the production of red pigment in tomatoes, called lycopene. The “shoulder” of the fruit is the part most often exposed to direct sun. This problem is most often seen when potassium levels in the plant tissue become deficient.

Another problem that can result from inadequate potassium, combined with other conditions, is Blotchy Ripening. Contributing factors can be compacted by overly wet soil, high nitrogen rates and high temperatures coupled with high relative humidity and low light levels. Sometimes the blotchy ripening of fruit is not cultural, but it is the sign of Tomato Spotted Wilt Virus, a disease transmitted by very tiny insects called thrips.

More common is damage caused by stink bugs, which puncture plant tissue to feed on the sap. The damage appears as irregular yellow blotches on the skin of the tomato and white blotches on the fruit under the skin.

Maintain healthy tomato plants by following these tips: 

• Soil testing to optimize the correct soil pH and fertility. 
• Grow tomatoes in full sun.
• Apply regular water in the absence of rain, ideally using a drip hose. 
• Provide good air circulation by staking plants to keep them off the ground.
• Remove suckers to minimize high humidity and increase drying.
• Mulch to conserve moisture and prevent leaves and fruit from soil contact. 
• Practice good sanitation. Do not compost diseased plants or save seeds of diseased plants. Control weeds that can harbor damaging insects.

There is nothing like harvesting those delicious tomatoes from your own back yard. It takes a bit of effort, but it is so very worth it! For more information, go online. 

If you have any gardening or landscape questions, contact us at 478-310-5350 or email us at bibb.extension@uga.edu.