The answer to 'why is my irrigation system disease' is that there are several common causes for irrigation system issues, including clogged or damaged sprinkler heads, leaks in the pipes, and problems with the controller or valves. Symptoms can include uneven water coverage, standing water, or reduced water pressure. The solutions will depend on the specific issue, but may involve cleaning or replacing sprinkler heads, repairing leaks, or troubleshooting the electrical components.
For minor issues, you may be able to address them yourself with some basic troubleshooting and DIY repairs. However, for more complex problems or if you're not comfortable working on the system, it's best to call in a professional irrigation technician who can properly diagnose and fix the problem.