Many citrus orchards all over northern Thailand are in serious decline. I've heard different explanations, but at least one factor involves a disease known as citrus greening. Maybe someone else more knowledgeable can elaborate, but this tree and hundreds of others in this plantation are victim, and apparently once the disease reaches this stage, it only has one or two years left. In fact the owner of this orchard is going out of business and is looking to sell his land. Some large scale farms are turning to rubber plantations as an alternative.