Time Frame

• The timing of the needle discoloration is a large indicator of the problems that may be occurring. Pine trees can contract fungal diseases almost any time of year. Cyclaneusma needle cast inflicts pine trees in almost any season, but generally in the spring. Dothistroma needle blight is a late summer to early fall fungal disease. Pine needle rust almost always occurs in the fall. Gardeners must monitor their pines throughout the year in order to spot early pine fungal diseases.
  
  

Other Symptoms

• Yellowing of pine needles is typically not the only sign that the pine tree has a fungal disease. Other symptoms may include browning of pine needles, branch dieback, needle drop and fungal spores that look like small fruiting bodies. Stunted growth is another strong indicator that the pine has a fungal disease such as lirula needle blight. Diseases common to the region may help the gardener determine what type of fungal disease is infecting the pine. For example, rhizosphaera needle cast is a common disease to inflict North Dakota spruces, according to the University of North Dakota.
  
  

Natural Causes

• Not all yellowing of pine needles indicates a health concern. White pines shed their 2- to 3-year-old needles in the fall every year. Gardeners may see their needles turn yellow and then drop from the tree. Though this is a normal process, it can be a fungal infection. If the needles turn yellow near the middle of the branch it is likely normal. Yellowing that does not take on a uniform pattern on the tree is another indicator that this is a normal process.
  
  

Treatment

• Treatment for fungal diseases often includes fungicide sprays. Because it is important to diagnose the exact cause of the yellowing, gardeners should cut off a portion of the tree and take to their local county extension office laboratory to get a diagnosis. One application of a fungicide is generally not enough. Fungicide labels will indicate when the next round of spray needs to be applied. It is important to choose days that are free of wind and rain for spraying in order raise the success rate of the spray.
  
  

Cultural Practices

• Thinning out the pine will aid in preventing the fungal disease from spreading. Downward 45-degree cuts into the candles (new shoots) to healthy growing areas will help rid the tree of the fungal disease. Dipping the pruning tool into a mixture of 70 percent denatured alcohol and 30 percent water in between cuts will also aid in reducing the fungal disease spread. Monitoring the tree especially in the spring will help gardeners to identify possible fungal disease concerns.