OAKS--FERTILIZINGOak trees need an acidic soil (pH 4.5 to 6.0) for proper growth. Available iron will be tied up with pH approaching a neutral or alkaline level. Iron chlorosis, a yellowing of leaves with bright green veins, results from a high soil pH, even though sufficient iron may be available in the soil.
To minimize iron chlorosis, oak tree should be fertilized with a fertilizer containing chelated iron after modifying the soil with the use of sulfur.
For information on fertilizing trees, refer to University of Illinois Horticulture Fact Sheet "Fertilizing Woody Plants", (NC-9-84).