Where an insect infestation or disease infection is believed to exist on forestland within the state, the State Forester shall cause an investigation to be made. Whenever, upon investigation, he finds that an infestation or infection exists, he shall give notice in writing, by mail or otherwise, to each forest landowner within the affected area, advising him of the nature of the infestation or infection, the recommended control measures to be taken and offering him technical advice for methods of carrying out the recommended control measures.