Pin oaks suffer from ferrous sulphate chlorosis when the soil pH is greater than 7.0. Ferrous chlorosis is a ferrous deficiency caused by alkaline soils that bind the ferrous, making it unavailable to plants. Symptoms of this condition include thin, weakened bark and yellow leaves with green veins. Severe ferrous chlorosis may cause the foliage to turn white. Remedies are often time-consuming, expensive and not always effective.
What you need to prepare are just following 3 things: ferrous sulfate, elemental sulfur and auger.
1. Mix equal parts of ferrous sulfate and elemental sulfur. Ensure that the product you use has a high ferrous content and the ferrous comes from an inorganic source, advises Utah State University.
2. Drill holes in the soil, 1 to 2 inches in diameter, and 12 inches deep, with an auger. Space the holes 18 to 24 inches apart, and spread them 2 feet from the trunk of the tree to the drip line (the outer leaves).
3. Fill the holes with the sulfur and ferrous mixture, stopping 4 inches from the top. Water as you normally would.
Pin oaks are popular landscape trees because they grow quickly--as much as 18 inches per year--and have strong, straight trunks and lovely fall foliage. Therefore, it is very necessary to keep pin oak trees away from ferrous sulfate deficiency.