Excesses of anything can cause problems. Too much water can kill trees as well as gardens - - most of us experienced the "too much" of water this spring.
Why are salts toxic to many plants and most of our crops species? There are several reasons. First is that when salts are dissolved in the soil solution the plant cannot absorb and use the water it needs to survive.
This is because the potential of the plant to pass water out of and into the root system must be lower than that of the soil's holding capacity instead of the other way around. Plants can wilt when given a heavy dose of fertilizer salts. In order for the plant to adjust to salinity it must absorb and accumulate salt inside or manufacture organic solutes sugars, organic acids, amino acids, etc. Fertilizer, any product that adds nutrients to plants, may sound like an ideal addition to your collection of gardening products.
But more often than not it is unnecessary and sometimes detrimental. Over-fertilization is a common -- and sometimes fatal -- mistake; too much of a good thing can become a bad thing. Among the most common issues with over-fertilization is fertilizer burn. Fertilizer often works by supplying nutrients to the plant in the form of soluble salts. Although salts dissolve easily in water, too much salt cannot dissolve.
Instead, the water evaporates and the salts stay in the soil, causing a major disruption in the makeup of the soil. Salts can burn the tender, young roots -- and sometimes stronger, mature roots -- of landscape trees, shrubs, perennials and vegetables. When the salts burn the roots off, the plant is unable to absorb water and other nutrients from the soil. The lack of water often results in scorched-looking leaves, stunted growth and plant dieback.
Fertilizer burn is more severe in drought-like conditions. There are several symptoms of excessive fertilizer application. Stunted growth, excessive growth of foliage with few blossoms, and discoloring on the edges of leaves are the most recognizable symptoms. The most severe damage occurs underground in the roots. Excess salt in fertilizers can "burn" the roots and limit moisture uptake.
The combination of burns and limited water uptake will quickly lead to a decrease in plant health. The affected roots will also become weakened against disease and cultural problems. Running the garden hose will leach excess fertilizer away roots. Excess nutrients and salt need to be removed by a process called "leaching. Leaching washes the extra nutrients out of the soil or below the root zone, allowing the plant to begin the recovery process.
Check the surface of the soil around the plant for a white crust. Soluble salts from the crust can make their way to the roots and cause more harm during leaching. The crust needs to be carefully removed from the rest of the soil. Remove no more than one-quarter inch of soil from the surface.
Sometimes the crust is hard enough that it can be picked out in large chunks. Be careful not to remove too much soil along with the crust. Removing too much can stress the plant even more. Leaching can begin once the crust is removed. Saving a plant from fertilizer damage is relatively simple and quick to do. For container-grown plants, use room temperature distilled water and fill the container to the top edge.
Distilled room temperature water is the best water to use because it contains no dissolved minerals and will not add further stress. Filtered water can be used if distilled water cannot be obtained.
Allow all the water to drain from the plant. Large containers will take quite a while to drain so have patience. Repeat this about 4 times. Excess fertilizers will be washed from the soil and drain through the bottom of the container. Place a garden hose at the base of the plant. Turn the water on just enough to produce a steady trickle.
Allow the hose to run for a while so that adequate water runs through the soil to leach the fertilizers past the plant's root zone. Foliage that is discolored and dying should be removed along with dead foliage. The plant will never be able to heal affected foliage and the plant should not waste any further energy on damaged foliage. New foliage will be produced once the plant begins to recover from fertilizer damage.
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