Final answer:
The forestry department is using chemical control method by spraying pesticides on the tree leaves.
Step-by-step explanation:
The forestry department is using chemical control as a method to combat pests. In this case, they are spraying pesticides directly on the leaves of the trees. Chemical control involves the use of chemicals, such as herbicides or insecticides, to kill or control pests.
Chemical control is a common approach used in agriculture, forestry, and public health to manage pest populations. While it can be effective in reducing pest populations, it is important to use these chemicals in a targeted and environmentally responsible manner to minimize disruption to the ecosystem.