Last summer, one of my pine trees died as a result of this browning. Now all of my other pine trees are showing the same symptoms. A. UC master gardener Lori Murphy says that without knowing the age and species of pine, she can't positively identify the problem. Some pine species, such as the Monterey pine, are short-lived in our hot, dry summers, with a life expectancy of 15 to 20 years. Upon reaching this life expectancy, a Monterey pine will suddenly turn brown and die, she says.
Most pines are fairly drought- tolerant and can become stressed by overwatering.
This is a common problem for trees planted in areas with hardpan or heavy clay soils, or in lawn areas. Murphy says you should examine your tree for discolored bark and oozing sap. This is a symptom of root rot. Weakened trees can come under attack by bark beetles, which leave sawdust-like boring dust near the holes they have bored. Other causes of stress include old age, severe drought, pollution or injury.