I am sending you photos of 3 different trees. The first is a lemon with black things, the second is an orange tree with orange or brown bugs (I dont know if it is San Carlos), and the third is what my rose's leaves looks like. Can I treat it with white oil? Thanks.
Certified GKH Gardening Expert
The second image looks like a scale insect infestation. Please see these articles for advice:
The first image is probably also a scale insect, black scale, attacking your lemon tree. This article will give you more information:
The third image might show the beginnings of black spot disease, a common problem with roses: