Iron chlorosis is one of the most common reasons a bald cypress tree will start turning yellow. This is a fairly common disease for this tree but is more likely to occur if it's grown in alkaline soil.
Iron deficiencies are common in bald cypress trees. However, low amounts of magnesium can cause leaves to turn yellow. There is also the possibility that high phosphorus levels are preventing your tree from absorbing iron. Before you start amending your soil or adding nutrients to your plant, you should be sure that you're adding the proper nutrients.
Dry soil and high temperatures can cause bald cypress leaves to yellow and droop, indicating water or heat stress. Neglecting to address the issue can lead to orange leaves and leaf loss, starting from the tips.
Bald cypress trees are commonly found in wet environments and unlikely to be overwatered. If grown in water-logged soil, they develop cypress knees which may aid in root aeration and anchoring. Removing the knees is a divisive topic among gardeners, with some considering it safe for small and distant knees, while others advise against causing stress to the tree.
To revive a cypress tree, ensure proper watering, nutrients, and remove diseased or broken branches. Test soil for pH, nutrients, and hydration levels, and amend as needed. Limit pruning to avoid harm, but if necessary, trim before new growth in spring.