In order to stand upright and crisp, plants fill their cells and tissue with water that forms what is called turgor pressure. If there is not enough water present for the plant to maintain this pressure, the plants will begin to wilt.

Wilt may be caused by many different factors. The most obvious one is the lack of water in the soil because of drought or the excessive loss of water because of hot weather. Sometimes these causes can be overcome simply by providing more water to the roots.

However, there are times when irrigating the plant is not enough. Remember that water moves through a plant in "pipes" of varying sizes. These have been developed over the eons to provide enough water to that species of plant during a "typical" growing season in the local region. On days with exceptionally high temperatures and low humidity, there may just not be enough capacity in the pipes to keep up with the water loss through the leaves by transpiration.

Wilt Diseases - There are a handful of diseases which are truly life threatening to trees. Most plant diseases tend to be chronic and cumulative over years but a few are relatively quick killers and these commonly fall into the category of wilt diseases.

Plant diseases that fall into this category are primarily caused by fungi. Once inside the tree, they are very, very difficult (sometimes impossible) to cure or control. Wilt diseases tend to kill trees by one of two ways:

1. Disease Kills the Tree - Most of the diseases produce gooey substances that will clog the xylem and phloem. This prevents the transport of water and nutrients so the part of the tree served by those blocked tissues must die. Eventually, the main trunk is totally affected and the entire tree dies.

2. Tree Kills the Tree - One of the ways trees survive is by having the ability to "compartmentalize" parts of the tree that are suffering from disease. Once a rot or other internal infection is sensed by the tree, it can set up an impenetrable barrier around the problem. This is why trees can have areas of rot but generally do not completely rot away. When certain wilt diseases get started, the tree's self-defenses may kick in the tree itself will block parts of its water transport system.

Here are some of the more common wilt diseases:

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

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