There are so many different reasons why your tree could be turning brown: diseases, a lack of nutrition in the soil, dehydration, or an infestation. Each of those problems could lead you to another problem that you have to fix before you can save the tree. In winter, the culprit is likely to be soil that is too cold.
Once the needles or fronds turn brown, they stay brown. Depending on the cause of the browning, an evergreen may be able to generate new growth from the tips, but sometimes the tree ends up looking like a tree made up of bottle brushes. Many arborvitae trees succumbed to the drought of 2012.
Needle dropping on the inside branches of evergreens is to be expected through autumn. Brown needles at the tips and of new growth indicate a dying tree. Evergreens naturally lose some needles to reduce winter snow and ice damage.
Common factors include drought, high winds, and extreme temperatures. One of the top concerns for evergreen browning is water loss. While coniferous trees have adapted to retain moisture and nutrients in harsh conditions, there are times when the foliage doesn't receive enough water to keep up with its needs.
If you are not sure whether or not your tree has been overwatered, there are a few other signs to look for. For example, leaves that are yellow or wilted can be a sign of too much water. You should also check for any fungal growths around the base of the tree. These are often indicative of overwatering as well.
Yellowing leaves can be a sign of root rot, and the leaves may drop off. The leaves may also become distorted (smaller than usual, twisted, etc.). Once you do inspect the roots, you may find that they are a different color than normal (darker, reddish-brown, etc.) and stink with rot.
If it is too hot and you don't water your trees enough, they can turn brown to help preserve the water that they do have. In general, browning is just a cry for help from your trees.
You might be using incorrect tree health care practices, which could be what is causing the leaves on your tree to turn brown. Things like incorrect watering, unhealthy soil composition, and over-fertilization can cause a tree's leaves to turn brown.
Increase drainage and take measures to prevent pines from standing in water– if the tree is young, you may be able to trim the rotted roots away from the plant. Proper watering should allow this condition to correct itself over time, though the browned needles will never re-green.
Prune all evergreens, except pine, before new growth starts in the spring or during the semidormant period in mid-summer. When pruning, follow the general branching pattern to maintain the natural shape. Remove dead, diseased, or broken branches anytime.
A “complete” fertilizer — one that supplies the macronutrients nitrogen (N), phosphorus (P), and potassium (K) — is often recommended. A fertilizer analysis of 10-8-15 means the fertilizer has 10 percent nitrogen, 8 percent phosphorous, and 15 percent potassium.
Evergreens end up looking like tall stalks of celery. Dead limbs won't regrow, so they should be cut off. That can be done at any time of year. Winter dormant season is as good as any.
Some of the issues are general, including hotter weather and soggy soil from excess rains. Others are species-specific, including needle cast diseases that attack Douglas firs and heat-loving spider mites which target the popular dwarf Alberta spruce.
Too Much Sunlight
Sometimes, there will be enough sunlight that your evergreen trees will dry out more quickly as well. If you've ever suffered a mild sunburn, then you know what it'll feel like when your evergreen tree suffers from sunscald. The needles and bark are both drying out.
Spruce and coniferous trees are susceptible to environmental, insect and disease problems that can cause the trees to discolor, lose needles and possibly die. Spruce in both urban and rural landscapes can be affected. Spruce trees can show brown needles starting from the lower limbs and progressing up the tree.
Soils with organic fertilizers remain loose and airy which can help a dying tree. Fertilizers are another item that can help your dilemma on how to save a dying tree. When using fertilizers, avoid sprinkling or spraying it too much to the trees.
Wilting leaves: The leaves on infected twigs and branches will bend backwards and wilt, first turning a grayish-green color and then brown or black. The leaves often appear scorched, hence the name tree blight, and they will remain on the tree.
Pine trees browning gradually from top to bottom may just be suffering from drought. You can fix this by giving your tree more water during the dry season. To confirm that it is a drought problem, stick your finger into the soil around your tree.
Irrigate established evergreen trees deeply during hot, dry periods of summer, when there has been no rainfall for four to six weeks. Continue to water evergreen trees until it rains or until the ground freezes.
Evergreen Tree Root Rot
The only way to treat root rot is to dig away all the damp soil around the roots and let it dry. Root rot is caused by too much water at the roots or from the soil moisture being too wet. Pick your planting site wisely as this can determine the life of your evergreen tree.
Signs of root rot are slow growth, mushy stems, and wilting, yellow, distorted leaves (especially when the plant has been well watered, as wilting leaves can also be a sign of a dry plant). Usually the soil will smell rotten and the roots will appear to be reddish brown.