Tree turn yellow to soon
I have a question from my parents..they have four red maples (acre rubrum) on their blvd in Olivia Minnesota 56277. Mom says they are a cross of a silver maple and a Norway maple and their leaves turn red in the fall. They planted them five years ago and are about 8 or 9 years old. Two of them turn yellow and the other two stay green. The yellow leaved ones are about 1/3 the size around the trunk and a few feet shorter. They have visited a few nurseries and people have said dump iron and sulfur in the ground. They have done that but the problem continues. If this is how to correct this problem could you give nice instructions to how much be it liquid or granular and how often. Hopefully the pictures works for you.
The trees in the photo are probably a hybrid cross of red maple (Acer rubrum) and silver maple (Acer saccharinum). A number of hybrid cultivars have been bred this way. Autumn Blaze is one that's been widely planted in Minnesota.
What you have said suggests that the leaves of the smaller tree turn yellow in the fall. However, the recommended amendments, sulfur and iron, are usually prescribed for trees suffering from chlorosis. In that case, the leaves of the affected tree would be pale yellow all season.
Go here to learn about chlorosis and what can be done about it.