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Sunday, September 1, 2013

Do your trees have leaf scorch?

     I'm seeing it just about everywhere I look:  leaf scorch... where the outer margins of a tree's leaves turn brittle and crumble when touched.  I'm seeing it at the big box stores.  I'm seeing it at the gym.  I'm seeing it in lots of parks and median strips.  And most of it could have been prevented if the trees had been better cared for.

A textbook example of leaf scorch
    Leaf scorch is common when a tree's roots have been damaged and can't deliver enough water once the heat of summer sets in.  The roots' ability to supply the needed moisture is limited because many of the roots dried up and died over the winter. Come summer, the roots system can't take in enough water.  The end of the "supply line" is the  outer-most edges of the leaves, and they pay the price.

Winter watering

     The leaf scorch damage we're seeing now could easily have been caused last winter.  "Winter watering" is one of my favorite soapbox topics.  A lot of gardeners and homeowners just don't fully appreciate how important winter watering can be for keeping our plants healthy.  Back in my Master Gardener days, "winter drought" was easily one of the most common problems that would prompt homeowners to call the Master Gardener helpline in July and August, when the temperatures climb into the 90's and above. Most of the time, the callers had no idea that the damage began months earlier.

Good care now could save this tree

     Our trees and shrubs are dormant during the winter, but they're not completely shut down.  If we don't have a good, wet soaking snow at least once a month in the winter, it's up to us to keep the roots of our trees and shrubs (and even our lawns) healthy. We need to drag out the hoses or the buckets on a warm morning and put down an inch or so of water to make up for what Mother Nature isn't delivering.

     Winter drought  is one of the most common causes of root damage, but other things can kill the roots, too.  Watering too much or too little, especially on younger trees, can destroy roots and eventually show up as leaf scorch.  Again, the roots are damaged and can't perform their job.  Construction like trenching, use of heavy equipment over the roots and paving can create problems, too.

So what's the answer?

Too late for any T.L.C.

     If you're seeing leaf scorch on your trees, there's no way to repair the leaves that have already been damaged.  But regardless of what caused the damage, the "answer" is pretty basic:  give the tree or shrub the best and most appropriate care you can now.  Don't try to over-compensate with excessive watering or fertilization.  That's not the answer, and could actually make matters worse.

     The staff at Tagawa's can offer lots of advice on what "best and most appropriate care" means, given your particular plants and growing conditions.  We encourage you to take a few pictures of the tree or shrub and bring them into our nursery experts for detailed advice.

     Leaf scorch doesn't have to happen.  Even when we start out the gardening season with watering restrictions as we did this year, good basic care is still possible.  The folks at Tagawa's will be happy to show you how.



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