Monday, March 19, 2018

Leaf Scorch and Wind Desiccation Damage

Recent extreme weather conditions have turned our region into brown and crinkly landscape of discoloured leaves and littered ground well before autumn colours should be turning.  It's a major bummer for gardeners, but a good opportunity to share a post about something that often catches folks by surprise - storm desiccation wind damage on plants despite concurrent heavy rainfalls.

Leaf scorch occurs where plants can't access enough moisture to sustain leaf hydration. This is typically associated with hot weather drought conditions, but leaf scorch can happen any time a plant is loosing water faster than it's roots and internal systems can replenish it out to the leaves.  This can happen because the plant is
  • loosing excessive moisture (heat, wind);
  • unable to access sufficient moisture (drought);
  • unable to take up enough moisture (limited root systems, root damage);
  • unable to effectively distribute moisture (damage, borer, pests), or 
  • under a combination of these stresses.   

Affected leaves will typically turn brown (or in some cases black) from the tips and margins of the leaf inwards. Where storm wind damage is a factor, the damage will be more extensive on the most exposed areas, and it is not uncommon to see areas of a tree or shrub substantially more damaged than sheltered parts. The sudden degree of damage can be rather shocking. In our recent example, it was like full autumn (although not quite as colourful) within a day or two of the storm, but that also helps a little with diagnosis since all of our gardens, parks, and green spaces were suffering degrees of similar looking damage. At least you can take solace in not being alone! 

A healthy hydrated plant with a strong and stable root system will be better equipped to deal with storm wind conditions. You can't avoid storms or protect your garden from everything nature may through it it, but you can help to reduce the risks with plant selection, general care, and storm contingencies.  Here are a few tips:
  • As with any good planting plan, the first step is to pick plant varieties that are well-suited to your local climate as well as the specific planting conditions/position in your garden. If you have a windy site or are in a storm prone location, choose options that are less prone to wind damage and (if you're near the ocean) don't forget the storm winds can carry coastal salt well in from the waterfront.  
  • Provide sheltered positions for plants that are vulnerable to wind-related issues and use frames or stakes to help reduce wind-rocking in young transplants or other shallow rooted specimens. Provide wind breaks if needed.  Relocate portable potted plants to sheltered areas during windstorms. 
  • Foster healthy root development and general plant health by planting in well-suited soil and maintain that soil quality over time with amendments if/as needed. In periods of dryness, where feasible, provide regular deep waterings and use a mulch or groundcover to help retain moisture. Help protect plants by ensuring they are well-hydrated before storm winds to reduce the risk of not only leaf desiccation but dry and brittle branches breaking.
  • Feed, prune, and/or provide provide other routine care as may been needed for plant health and keep watch for signs of disease, pests, or other problems. Be careful when digging or doing other mechanical work near your plants to reduce the risk of root damage.

Got scorched? On smaller plants with a few damaged leaves or wind-battered tips, it may be helpful to nip or prune (depending on the plant), but for broad-spread damage this is typically unfeasible. Scorched leaves will linger around until their natural cycle to fall; however, heavily affected leaves may drop and regrow or may drop prematurely without regrowth if you are approaching natural dormancy. Do a review of your affected plants. You might want to move a few plantings (or plan to transplant at a suitable future point), create additional shelter, and/or adjust your care cycle to try and reduce future vulnerabilities, but sometimes just things get a little battered no matter what. Nature is a powerful force! 

In the example photographed for this post, the winds that caused the damage came with heavy rain, but not enough to make up for the extreme sustained force of the storm winds.  The storm hit oat the end of a lovely sunny summer, but that also meant dry conditions and watering restrictions placing plants in a pre-storm stress position from sustained dehydration. Pampered plants survived with minimal damage (except the ones that cracked off and blew away!), but large trees all around town were heavily scorched.

Is your garden on an exposed site or in a stormy area? We'd love to hear your inputs, success stories, or tales of windy woe! Please leave a comment.

Note: There will be a brief pause in our usual posting cycle for Easter break. Regularly scheduled posting will resume the week after Easter weekend. Have a wonderful end of March, and we'll see you again in April!

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