Needles over … Brown spot needle blight causes needle spots, browning and needle loss on pine trees. Drought. The Southern pine beetle, for example, is a highly destructive pest that affects pines in the Southern U.S., and often the only “cure” is to remove the infested trees. Pine Trees Affected: This disease causes the most damage to Austrian pine and Ponderosa pine. Pine trees are evergreen, so you don’t expect to see dead, brown needles. Check out this list to identify your pine tree’s symptoms and find suggested treatments. In the summertime, your tree is likely combating intense heat from the sun, as well as dry soil. But there are easier, less radical solutions to other problems. Drought weighs heavily on trees like the arborvitae, and watering during this season is essential. Needles are shorter than normal, needle tips turn brown, and the overall tree canopy becomes sparse. Ponderosa and Scots pines are severely damaged by this disease in Minnesota. Infected trees have slow growth and often have bare lower branches. Look for sunken infection sites on the tree trunk. If you find dead needles on lower pine branches only, you are probably not looking at normal needle shed. Red, mugo, and Scotch pines are also susceptible. Tree browning and death follow. Both of those issues can cause your arborvitae to turn brown. It you see dead needles on pine trees, take the time to figure out the cause. Note yellowing needles that brown and fall and follow down their branches to look for lesions. The most common cause of brown pine needles occurs in the fall and is normal. Pines shed older needles similarly to other trees’ fall foliage drop. The disease can eventually kill young trees … Drought-like conditions are another cause of arborvitae turning brown. Start by noting the season and which part of the tree is affected. Several factors related to growing conditions are involved in white pine decline. … Declining trees tend to be in sites with several or all of the following characteristics: High soil pH. Symptoms: Between March and April, the needles on the lower part of the tree begin to turn brown.