High soluble salt levels are caused by the excessive use of fertilizers, frequent applications of fertilizer, and the incorrect use of fertilizer concentrates.
Symptoms of fertilizer toxicity
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The typical symptoms are browning or dieback of the leaf tips and margins. But can include reduced growth, lower leaf drop, dead root tips, and wilting.
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Sometimes yellowing or stunting may occur. The root systems will also show dieback and decay.
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Fertilizer salts may also accumulate on the surface of the potting media as a white crust, especially if bottom watered, and cause stem collapse at the soil line.
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Salt deposits may be visible on the outsides of pots.
Management
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Use the proper fertilizer analysis at the correct rate and frequency.
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Large pots with growing media that have excessive salts can be flushed or leached by irrigating with clear water.
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Allow the water to run out the bottom of the pot and repeat the several irrigations with a volume at least that of the pot size.
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Smaller pots with media high in salts should have the growing media replaced.