Yellowing leaves in the summer

This summer we are starting to see quite a few birch and other trees start to develop yellowing leaves.This yellowing of leaves is called chlorosis.  It is a function of a stressed root system that is having a hard time pulling up certain nutrients from the soil.  This is compounded by soil chemistry as well.  Birches tend to like soil that is slightly more acidic, while most of our soils are basic.  When soil is more acidic (with a lower pH level)  the tree roots can find it easier to pick up the lacking micro nutrients (usually iron)   Chlorosis can be a stubborn problem and there are a variety of ways to help correct it.
  • Watering- The simplest and easiest thing is to make sure to keep the tree well watered.  Birch trees have higher water requirements than most trees.  A good deep watering with a slow trickle with the house can help saturate the root system and allow the tree to rebound.  Watering your tree is a good way to prevent chlorosis from developing. 
  • Foliar spray with chelated iron- During the summer months it is possible to perform foliar spray treatments of iron that can help "green up the leaves".  These treatments can work well, but are not long lasting and are often complemented with other treatments such as fertilization of trunk injection.
  • Soil fertilization-  Soil injection fertilization treatments with acidifying agents can help deliver additional micronutrients and help lower the pH level of the soil.  It is a good practice with chlorosis susceptible trees such as birches and red maples to perform regular annual fertilization.  Over time the pH level of the soil is lowered and the tree roots become stronger and healthier. 
  • Trunk injections-  For trees that are showing more advanced chlorosis, a trunk injection may be warranted.  Iron is delivered into the vascular system of the tree by using a pressurized tank.  This direct injection product is most often done in the fall months and generally lasts 2-3 seasons before it may need to be repeated again. 

The severity of  the chlorosis determines which treatment types that our arborists recommend.  The best defense is to catch chlorosis early when it is easier to correct.  If you are concerned about  yellowing, pale leaves on your tree, our arborists can help.

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