Answer: Several things could cause yellowing leaves. When young leaves (those near the end of shoots) turn yellow, we ususally consider an iron deficiency to be the cause. High pH, high phosphorous and of course low soil iron levels all can result in iron deficiency symptoms. If older leaves are yellowing, nitrogen may be deficient.
Root problems are another cause of yellowing leaves. Root rot infection, physical damage to roots, drought and overwatering (soggy, waterlogged soil) can all cause leaves to turn yellow and fall.
Try to determine which of the cultural problems listed above may be the cause and take steps to alleviate it. If a root rot disease is present, there may be little that you can do at this time other than to avoid overwatering which tends to make things worse.
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