Ask Mr. Smarty Plants

According to this USDA Plant Profile Map, Diospyros texana (Texas persimmon) is native to Hays County. We always check this first in case the problem cited might be a result of climate or rainfall, as well as incompatible soils, that is causing that problem.

Because the symptoms you describe could be caused by several different problems, we are going to link you to some articles and pick out some material to quote that seems to address your particular situation:

eHow Home Persimmon Tree Diseases and Pests

"Leaf Spot

• Another disease that infects common persimmon is leaf spot. Leaf spot, or anthracnose, is caused by the fungus colletotrichum. Although not deadly to adult trees, leaf spot does cause black spots to appear on the surface of leaves, and may sometimes affect fruit as well. It can also lead to early dropping of leaves--this is most noticeable in August, for the North, and September, for the South. Sprays containing baking soda or sulfur, or the pesticide Bordeaux mix, are commonly used to control it.

University of Kentucky Cooperative Extension  American Persimmon (as opposed to non-native Oriental Persimmon)

"There is interest in varieties that have leaf spot resistance. Persimmon wilt, a fungal disease due to Cephalosporium diospyri, has caused considerable damage in the south."

All that having been said, we have suspected aphids from the beginning. This article from the University of California Integrated Pest Management on Aphids includes this statement:

"Low to moderate numbers of leaf-feeding aphids aren't usually damaging in gardens or on trees. However, large populations can turn leaves yellow and stunt shoots; aphids can also produce large quantities of a sticky exudate known as honeydew, which often turns black with the growth of a sooty mold fungus. Some aphid species inject a toxin into plants, which causes leaves to curl and further distorts growth. A few species cause gall formations."

This article also has information about control. Notice that the presence of ants on the tree usually indicates aphids. The ants don't damage the plant, but they are farmers, gathering the "honeydew." The last line on the paragraph on Management is:

"Managing ants is a key component of aphid management."

Since we are not plant pathologists, we recommend you contact the Texas A&M AgriLIFE Extension Office for Hays County.