What exactly do you see in plants?

What exactly do you see in plants?

At this point, it is important to inject a “reality check” in the diagnostic process. Are you on the right track? After stepping back to consider the overall health of the plant, force yourself to step back again to reconsider in more detail Question What do you see that looks abnormal? The key to diagnosis is often in such details, sometimes related to others who help with the diagnosis, such as a diagnostic lab technician or coworker in your company.
It is very important to note the pattern of damage. Is the damage on older leaves, newer leaves, or both? Is the damage only on the lower part of the plant, upper part of the plant, or throughout the plant? Do symptoms appear to be located on a particular part of the leaf? A good example of this is the difference in symptoms between maple anthracnose and physiological leaf scorch of maple.
To the casual observer, both problems involve blotchy, scorchy, brown discoloration of the leaves. However, the details are quite different. With anthracnose, caused by a fungus, the blotched areas are more of a reddish brown than a tannish brown, but more importantly, are concentrated along the leaf veins. With physiological leaf scorch, caused by excess evaporation of water from leaves due to a variety of factors, the blotches are not concentrated along the leaf veins and are typically more to the outer margins of the foliage. Knowledge of this difference in symptoms is the sort of fine-tuning that diagnosticians develop as they improve their observational and reporting skills.
As can be seen with this maple example, noticing where symptoms are occurring is critical. Diplodia (Sphaeropsis) tip blight of pine is characterized by browning and stunting of new growth on young Austrian, red, Scots and mugo pine shoots, in addition to dieback of this new growth (the growth farthest out on the branch). This disease typically occurs on the bottom branches of the tree first and works its way upward over the years. Compare this to the normal seasonal loss of inner needles from previous years that occur on pines. Every fall, many people become worried about the yellowing, browning, and falling needles on pine, even though loss of older needles is normal. Each evergreen species drops needles of different ages, so good plant identification and knowledge is essential. Careful observation of the details of whether the browning needles are on new or old growth is crucial for good diagnosis.
Diagnosing animal damage often depends on looking for details associated with how the animal feeds. Deer do not have upper front teeth. They have lower front teeth, and a tough pad instead of upper front teeth. When deer feed, they pinch-and-pull plant material between their lower teeth and the pad. This typically produces ragged edges rather than clean cuts on foliage, and tips of twigs may look like toothpicks because the outer bark has been pulled off. Rabbits have very sharp upper and lower front teeth and when a rabbit bites, their incisors cross at a 45 degree angle. So, they produce clean cuts that are angled at 45 degrees.