What type of sprayer is commonly used to apply treatments to large trees and shrubs?

A hydraulic sprayer is specifically designed to apply treatments to large trees and shrubs, making it the most suitable choice for this context. These sprayers utilize a pump to create high pressure, which allows for the efficient application of pesticides and other treatments over greater distances and vertical heights. The pressurized spray can reach the canopy of tall trees and ensure that the entire plant is adequately covered.

In comparison, insect growth regulators, horticultural oils, and insecticides are types of products or controls rather than specific application equipment. While they can be used in various treatments for pests and diseases, they do not pertain to the method of application. Therefore, they do not answer the question regarding the type of sprayer commonly used for large trees and shrubs.