Why is it helpful to examine a plant while it is still growing when diagnosing a disease?

Examining a plant while it is still growing is considered the best approach for diagnosing a disease because it allows a skilled diagnostician to observe the plant in its natural context.1

This method is helpful for several reasons:

• Contextual Assessment: A diagnostician can evaluate the plant’s local air and soil environment, as well as the specific cultural conditions under which it is growing.1
• Symptom Identification: Disease is often indicated when plant parts—such as leaves, stems, roots, or blossoms—appear abnormal (e.g., discolored, misshapen, or underdeveloped). Observing the plant in situ helps distinguish between infectious diseases and noninfectious issues caused by environmental factors, such as poor drainage, nutrient imbalances, or extreme weather.12
• Comparative Analysis: By looking at the plant in its environment, a diagnostician can compare it to nearby healthy plants. If multiple, unrelated plant species in the same area show similar symptoms, it is usually an indication of an environmental factor rather than a specific pathogen, as most infectious diseases are highly specific to certain plant species.1
• Observation of Signs: In addition to symptoms, the diagnostician can look for "signs" of disease, such as fungal fruiting bodies or bacterial ooze, which are more easily identified on a living, growing specimen.13