Necrosis in plants is generally considered a sign rather than a symptom. In botanical terms, a "sign" refers to a measurable or observable indicator of a disease or condition, while a "symptom" refers to the manifestations or changes that the host organism experiences as a result of the disease.
Necrosis involves the death of plant tissues, which can be observed as dark brown or black spots or areas on leaves, stems, or other plant parts. Therefore, the presence of necrotic tissue is an observable manifestation of underlying issues such as infections (fungal, bacterial, or viral), environmental stress, or other pathological conditions.