Q: My plant is yellow! What can I do?A: If I had a nickel for every time that I have heard that complaint I would be a rich man. Yellow plants seem to be a way of life in this area where we have high pH soils. Most yellowing of plants, if pests are not involved, is caused by lack of iron in the plant. Such an iron deficiency in a plant can be caused by the plant's inability to utilize available iron in the soil or simply the lack of iron in the soil. Because most soils in this area of Texas contain an abundance of calcium which cause an alkaline soil condition, many of the minor elements such as iron are not in a usable state for plant consumption even if they do exist in the soil. As a rule, iron deficiencies tend to diminish as temperature increases and soil moisture decreases. Improved aeration encourages greater microbiological activity with greater root growth and exposure to soil iron. But unadapted plants NEVER recover regardless of temperature or moisture. Without extensive soil amendments, gardenias, azaleas and blueberries will be eternally yellow and shrink instead of grow.
Some of our most treasured, fruiting plants suffer from iron chlorosis. Grapes, peaches, pears and apples can turn yellow and eventually perish because of iron chlorosis. One of the best defenses against iron chlorosis is to plant adapted varieties. Plants which are native to the alkaline soil conditions have the ability to extract enough of the sparse and tenacious iron molecules to avoid the yellowing, weakening effects of iron chlorosis. If these adapted plants can be utilized, addition of iron, acidification of the soil and the constant struggle to maintain a green plant color can be alleviated if not totally eliminated. These adapted, native plants also have resistance to soil-borne pathogens which can annihilate non-indigenous types.
Unfortunately most of the adapted native species do not produce as good quality fruit as desired. For optimum growth and quality production, a combination of native and improved must be accomplished. Such combinations are accomplished by grafting.
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