This summer has been a challenging one for many Indiana vegetable gardeners. It started with a prolonged cold, wet spring, was followed by a couple of weeks of intense heat and drought, and then followed by torrential rains!
Gardens that have been in a prolonged saturated condition may present some surprising symptoms, ranging from wilting, yellowing or drooping foliage to blossom-end rot.
When soil is saturated for an extended period, roots are deprived of much-needed oxygen. A damaged root system cannot keep up with the moisture needs of the plant. As the root system becomes compromised, symptoms above the ground may appear similar to those you would expect during drought: wilting of the foliage, blossom drop and blossom-end rot of certain fruits. High temperatures make it even more difficult for the plant to keep up with moisture needs, since plants are constantly losing water as vapor through the leaves.
In addition, lack of oxygen in the soil can lead to buildup of ethylene gas in the roots, causing even further damage. This ethylene can cause leaves and stems to suddenly droop, particularly near the top of the plant.
If waters recede quickly, many crops will make a comeback as soils dry and air returns. It will take some time for new roots to grow. In the meantime, plant damage symptoms are likely to continue, at least for a bit.
When roots are unable to adequately take up water, the mineral nutrients normally contained in that water will not be available to the plant. Deficiency symptoms, such as yellowing foliage, leaf drop and stunting, may progress until the plant has a chance to grow new roots.
Flowering and fruiting should also be affected by damaged root systems. Blossom drop and poor fruit set on remaining blossoms are to be expected when plants are under severe stress. For fruits that have already set but are still developing, blossom-end rot is likely. A physiological disorder common especially to tomatoes, but also zucchini and other summer squash, blossom-end rot begins as a dead area on the blossom end of the fruit opposite the point of stem attachment. In tomatoes, a black, leathery scar appears on the bottom of the fruit, whereas in squash the damage often remains soft, appearing water-soaked. This scarring is caused by a deficiency of calcium in the developing fruit, usually brought on by extreme fluctuations in soil moisture. However, once the damage is there, secondary rot organisms may enter through the damaged tissue and cause a soft rot to develop.
As conditions return to normal, surviving plants should be able to put on new growth. However, heavy rains will have washed away much of the available nitrogen that plants need. Gardeners should supplement crops with a side dressing of fertilizer applied to the soil around the plants and watered in. For a quicker response, try foliar feeding with a water-soluble product. There are many fertilizer formulations available, including both synthetic and organic products. Always read and follow the label directions to avoid plant injury.