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Milberger's Nursery and Landscaping
3920 North Loop 1604 E.
San Antonio, TX 78247

Three exits east of 281, inside of 1604
Next to the Diamond Shamrock station
Please click map for more detailed map and driving directions.

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Questions for the Week

by Jerry Parsons, Ph.D.
Horticulture Specialist, Texas Agricultural Extension Service in San Antonio

Folks are CRITICALLY UPSET at this time of the year.

Things are going wrong with their precious plants. I guess that people thought that all there is to growing plants in Texas is planting them and waiting for a bountiful harvest. The most common disaster is yellowing plant foliage. This affects everything from gardenias to beans, and peas to photinias (for some reason folks do not want yellow - tipped photinias!). The answer to this yellowing condition is iron chlorosis, or the lack of sufficient iron that the plant can use. The condition is endemic to this area of Texas. The soils here contain huge quantities of calcium carbonate (lime) which cannot be easily neutralized.

What is the answer to this dilemma? The best answer is to plant only recommended, adapted (to local soil conditions!) plants. There is a list of such plants for every region at:

and specifically for South Central Texas at:

You WILL NOT find such plants as azaleas, dogwood trees, gardenias, loblolly pines, muscadine grapes or any of those Southeastern plants on the list for South Central Texas. Folks who insist on planting such problems-waiting-to-happen should realize that sooner or later the "old yellow" syndrome will occur. When non-adapted plants are small, a micro-environment modified with peat moss can enable the plants to survive for a brief period of time in a seemingly healthy condition. But sooner or later, the alkaline water and alkaline soil will provide an inhospitable environment and the plant will turn yellow, leaves will exhibit the severe iron chlorosis symptoms of browning around the edges of the leaves and will eventually weaken and die.

I have recommended the use of organic matter (leaves, grass clippings, etc.) and compost in vegetable gardens. Mulching around "problem" trees and shrubs can also alleviate the situation. Any organic material can and should be used as a mulch around established plants.

If huge quantities of non-decomposed organic material is used, additional amounts of nitrogen fertilizer will have to be added to compensate for nitrogen use during decomposition. Maintain a 3- inch mulch around plants to help control weeds and grass, stabilize soil temperature and conserve moisture. Do not apply mulch directly against plants. "Artificial" remedies, such as copperas (iron sulfate) and iron chelates (Sequestrene) furnish an available iron source for plants and can also be used to correct the yellowing problem.

Growers may as well accept the fact that this problem is here
to stay because of our alkaline soil conditions, and should treat it accordingly each year. Plants will exhibit symptoms of "iron deficiency"- with yellow leaves and darker green veins. This condition will only grow worse and the affected plant will decline and die if not corrected with generous quantities of iron sulfate mixed with organic material. Alkaline soils in this area of the state require frequent summer applications of iron-containing products to correct or prevent iron deficiency of plants. The products Ironate (has supplemental nitrogen) and green sand seem to be effective. Mulches can be used to increase the availability of iron for plant uptake in the soil by making a synthetic iron chelate. If iron is applied directly to the soil, calcium in the soil causes the iron particles to be unavailable for plant uptake. Gardeners can make a synthetic chelate with mulch by mixing one cup of iron sulfate (copperas) to each bushel of mulch applied. Iron particles will adhere to the surface of the mulching material and will be released to the plant as decomposition occurs around plants. Iron sulfate treated mulches are also effective when incorporated into the soil. Iron sulfate (copperas) or chelated iron as a foliar spray can provide a rapid-but-temporary green-up.

Bloom drop is also causing concern this time of the year. Whether the blooms are tomato, beans, squash, or pepper, what can be more disastrous after all your hard work than losing the plant's producing potential? The problem is the plant's environment-both existing and imposed. The imposed bloom-drop environment involves those folks who have chosen to ignore the FIRST COMMANDMENT OF SUCCESSFUL GARDENING and planted in the shade.

If you cannot sunbathe in your garden area for 8 to 10 hours daily, then DO NOT expect maximum yields from tomatoes. Some vegetable crops tolerate shade but none produce to their optimum in the shade. If your plants grow tall and spindly and drop blooms, then you have the plant growing in too much shade!

Another problem may be variety selection. Some indeterminate varieties such as Big Boy, Better Boy, Beefmaster and other ridiculously large-fruit varieties drop early blooms profusely. Recommended tomato varieties for large fruit types include Heatwave, SunMaster and Surefire. Such recommendations are based on at least 3 years of field tests including spring and fall conditions.

Tomato blooms leave such a pronounced stem when they fall from the bloom cluster that many gardeners think the blooms have been eaten by insects. Some of this poor fruit set can be caused by cloudy weather conditions and its direct relation to improper pollination of blooms. Tomato flowers are pollinated by either wind or mechanically so gardeners don't have to have bees. Sticky pollen caused by cloudy, damp weather conditions cause a lack of pollen shattering and, consequently, poor pollination.

Since we are discussing such sensual topics as pollination and fertilization, we may as well deal with the subject of squash. Is everyone upset about their squash blooms falling off? Are the falling blooms of the male or female gender- What? You don't know the difference? I will try to explain the difference even in fear of censorship. To begin with, there are male blooms and female blooms. The female blooms can be distinguished from male blooms by the fact that they have a small squash fruit attached. All of the males, which bloom profusely at first, will dry up or fall off. This is true for pumpkins, cucumbers, and watermelons. Any further lessons in sexology can be arranged by appointment only!

When male and female blooms are both present, and female blooms with small fruit attached continue to fall off, then you have a pollination problem. Pollination means the transfer of male parts to the female part. This task usually is accomplished by bees or insects visiting the flowers. If you don't have a source of such pollinating insects, or continually kill them by spraying insecticides during flight periods, inadequate pollination and fruit drop will occur. During peak pollination seasons, spray insecticides late in the afternoon to avoid problems.

If you do not have bees, you can hand-pollinate blooms. This involves taking a male bloom, removing the petals and rubbing the stamen (the pollen-containing male part) in a female bloom early in the morning, before 10am. This will effectively transfer the male pollen to the female bloom. I told you gardening could be fun and exciting!

Squash sex may not be the only issue creating production problems. Planting in the shade will cause lack of fruit set, as will overwatering. Water plants growing in sandy soil more often and with a lesser amount. Check the soil around plants by digging with your finger to determine if moisture is present. If moisture is present, DON'T WATER! REMEMBER -- MORE PLANTS ARE KILLED BY OVERWATERING THAN BY NOT ENOUGH WATER. Don't try to "hurry" plants into production with excessive watering; all you are accomplishing is the "hurrying" of plants to death.

These are a few of the "growing" problems that many gardeners are experiencing. There will be more--after all, if growing vegetables was easy, everyone would be a vegetable farmer. When the blooms are dropping, the fungus is attacking, and the insects are rampant, just be glad that your garden is 10- feet wide and 10- feet long and not 400 acres!