(a) "Forest pest" means any insect, disease or closely related organism which is harmful, injurious, or destructive to forests or timber.

(b) "Forest land" or "forest" means land supporting a stand or potential stand of trees valuable for timber products, watershed or wildlife protection, recreational uses, or for other purposes.

(c) "Timber" includes forest trees standing or down, alive or dead, and shall include shade trees of any species around houses, along highways, within cities and towns, and any other locations which constitute insect and disease menaces to nearby timber trees or forests.

(d) "Control zone" means an area of potential or actual forest pest outbreak with designated boundaries clearly described in a manner to definitely identify the zone.

(e) "Outbreak" means the existence of populations of a forest pest in such proportions as to threaten forests or timber and the benefits derived from them.

(f) "Action programs" shall mean those programs which are necessary to detect, control, suppress or eradicate forest pests which are in outbreak proportion.