Got Nature? Blog

Figure 1: Drought stress can cause decline and, in some cases, death in trees.

Purdue Landscape Report: With recent rain storms across the state, watering may not be at the forefront of everyone’s minds. But as we head deeper into summer it is food to remember most of Indiana is in a state of abnormal dryness to moderate drought, continuing similar conditions from previous years. With that in mind, we should be thinking about the health of our trees (Fig. 1).

Understanding what drought is and its effects on trees can help to bolster care plans.  Drought is an extended time with little to no precipitation and can slow growth, reducing photosynthesis, and depleting energy reserves trees need to survive dormancy in winter.  Drought conditions can stress trees, making them susceptible to pests and diseases, reducing their ability to produce defensive chemicals, and in severe situations resulting in death (Fig. 2).

One simple task to protect your trees is watering. This is especially important in young and newly transplanted trees. A good industry guideline is the 5-plus-5 rule.

Figure 2a: Wilting in leaves and dieback in parts of the tree can indicate drought stress.

Figure 2b: Wilting in leaves and dieback in parts of the tree can indicate drought stress.

Apply 5 gallons of water plus 5 gallons for every diameter inch of the trunk. For example, a 4-inch tree would require about 25 gallons of water as needed. A good tactic to reduce water runoff from the hose is to take a large bucket and drill enough small holes to create a slow drip watering system. Also check moisture levels in your soil to see if conditions are dry, moist, or saturated.

Another way to maintain soil moisture is to mulch around the tree. Mulch rings should be at least 3 feet in diameter and 2-3 inches deep with a 2–3-inch space between the base of the trunk and the inner mulch ring. Mulching up to the trunk is called volcano mulching and causes issues like stem girdling root production and decay. Mulching reduces evaporation from the soil and helps maintain moderate soil temperatures. It also reduces competition with surrounding lawn and landscaping plants while protecting the trunk from mechanical damage caused by mowing and lawn care practices.

These little steps can go a long way to protect your trees, extending their life spans and your enjoyment with a healthy canopy. For a more detailed look at drought and trees, please have a look at the Purdue extension store here.

Original article posted: Summer Tree Care: Watering Your Trees.

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Resources:
Planting Your Tree Part 1: Choosing Your Tree, Purdue Extension YouTube Channel
Tree Planting Part 2: Planting a Tree, Purdue Extension YouTube Channel
Tree Installation: Process and Practices, The Education Store
Tree Pruning Essentials, The Education Store
Tree Pruning Essentials Video, Purdue Extension YouTube Channel
Drought Information​, Indiana Department of Natural Resources
Drought? Don’t forget the trees!, The Education Store
Tree Defect Identification, The Education Store
Tree Wound and Healing, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Surface Root Syndrome, The Education Store
Find an Arborist video, Trees are Good-International Society of Arboriculture (ISA)
Trees and Storms – The Education Store, Purdue Education’s resource center
Indiana Invasive Species Council
ID That Tree, Playlist, Purdue Extension – FNR YouTube Channel (Invasive White Mulberry, Siberian Elm, Tree of Heaven)
Fifty Common Trees of Indiana
An Introduction to Trees of Indiana
Native Trees of the Midwest, The Education Store
Subscribe – Purdue Extension-FNR YouTube Channel

Ben McCallister, Urban Forestry Specialist
Purdue Forestry & Natural Resources