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.
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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