BEATING THE HEAT
· July 6th -119 degrees F for over an hour
here.
Many Plants Scorched.
In the following days trees, shrubs and woody plants start to defoliate.
Many Plants Scorched.
In the following days trees, shrubs and woody plants start to defoliate.
The Physiology of Heat Damage
·
PWP -mostly a problem with herbaceous plants.
·
Chloroplast damage -sets off a chain reaction in the
plant.
o Increased
production of protective proteins
o Increased
production of abscission hormones.
o Increased
production of damaging peroxides.
·
Leaf drop
·
Fruit drop
·
Flower drop
·
Twig drop
·
Leaf scorch
·
Trunk and branch scorch (citrus and avocados)
·
Limb drop in susceptible trees.
What to Do After
·
Mulch
·
Increase irrigation frequency (but do not
overirrigate)
·
Do not fertilize
·
Do not overwater
What if More Heat is on the Way?
·
Anti-transpirants?
o Work by
either plugging up the stomata or causing it to close.
o Can cause
overheating, decrease transpiration.
o Work best
in frost situations
·
Misters
o Are
expensive
o Can cause
fungal infestations
o Require installation
and $
o Cheap
barrel misters may be the best bet.
·
Shade-cloth
o Can injure
plants if just ‘draped’ on.
o Should be
installed as a permanent structure.
o Need to
choose right % for the plant.
o Do not
prevent all heat damage.
·
Kaolin
o Sprays on
o Helps
control some insects as well
o Irrigation
washes it off.
o Looks
terrible.
·
Modify Irrigation
o Check
Evapotranspiration Index
o Water
according to current ET number.
§ Make sure
you do irrigation measurement before you do this.
o Use coffee
cups and turn irrigation on for 10 minutes, measure depth in inches.
·
Plant Choices
o Plants with
blue-green coating (glaucous) do well.
o Plants from
South Africa and Madagascar do well.
o Plants form
the Southwest, South and Central America (not all).
o Many (not
all) Australian plants.
o Plants from
temperate areas do not usually do well.
·
Landscape Choices
o Remember to
put heat and sun resistant plants near walls and walks.
o Go with
climate appropriate plants.
o Build shade
structures.
o Consider a
mist system (for you, not the plants).
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