Other fungicides can be used, but Kocide will do a good job. Cool, damp weather in the spring increaes the chance of this problem. So you may or may not have a problem next spring. Since aphids overwinter as adults, you can try using a dormant oil spray next spring before budbreak. This may reduce numbers although there are no guarantees.
Aphids can blow in and migrate for long distances so they are usually an annual problem.
For example, pH, how much Mg, Mn, N, P, K, Ca organic matter, etc. The preferred pH for most fruit crops is 6.5 - 7.0. Most nutrients are readily available at this level. Nitrogen is very low in Texas soils so it is rare to have any come back on the soil test report. Ideally there would be about 50 ppm nitrogen in the soil.