Definition of "spotting"

Symptoms consist of various foliage spottings and blotchings.

1954, Thomas H. Everett, The American Gardener's Book of Bulbs, page 161

Although the NVA went to great lengths to conceal the locations of their artillery, they had to expose them at the time of firing. Less reliable than visual spottings were electronic intercepts […]

2009, “Close Air Support and the Battle for Khe Sanh”, in Marine Corps, US, page 100