DROUGHT OR DISEASE?

    It has been dry as a bone in Fredericksburg lately and some mighty sick plants are coming through the door at our store these days.  I am not a plant pathologist nor is the average person, which leaves us all at a bit of a loss when faced with a plant exhibiting potential disease symptoms.  A couple of weeks ago, I wrote a column on diseases with some hesitation because of the complexity of the subject.  Here we go again...

    If you have ever run out of gas while driving, you know how little warning you get.  Sure the gas gauge warned you, but the engine didn't "kinda" run out of gas - it just stopped promptly.  Likewise, a plant may wilt from lack of water, but when the vascular system has exhausted all resources of moisture, death arrives as rapidly as a car's engine dies without fuel.

    The key word here is "wilt."  Drought causes wilt as do many vascular diseases.  Vascular diseases usually interrupt or destroy the vascular flow of water and nutrients rendering a wilted, dry appearance.  In the case of drought, the vascular system may be reasonably intact and simply devoid of life-sustaining moisture.

    The presence of disease in conjunction with drought can spell disaster for the health of a plant.  In the last 5 years,  our area
has experienced abnormal extremes in weather - too much rain or no rain.  All of this takes its toll on the root system of a plant and can lead to an invasion of the root system by fungi such as Verticillium or Phytophthora. If these conditions exist, then the plant may be more susceptible to drought damage due to a diminished root system.

   Phytophtora is a naturally occurring fungus that moves or multiplies in water, attacking the fine feeder roots.  The disease clogs the roots, thus causing the top of the plant to wilt.  Verticillium enters the roots and systemically moves up through the body of the plant, destroying the vascular system.  Once the disease makes way to the twigs and leaves, rapid death occurs with the leaves, usually drying between the veins first.  Generally, one branch at a time will be affected.  Neither of these diseases responds well to chemical controls.  Once again, right plant in the right place.  Proper drainage is important.

    Drought usually dries the leaf from the tip back, but can simply show up as a rapid, mysterious death, mimicking a disease.  Do not be alarmed by the descriptions of these various diseases.  Remember to use common sense.  If it hasn't rained in "a dog's age", try the water hose first with a deep drench to ward off drought.  If it has been "pouring buckets", don't water.  At this point in time, I am more suspect of drought than disease.

    I will be on vacation from July 30-August 3.  I will have my next column posted on Monday, August 6.

    Have a great week.