Frost Protection - UTL Repository

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F R O S T P R O T E C T I O N : F U N D A M E N T A L S , P R A C T I C E A N D E C O N O M I C S
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Trunk painting and wraps
The bark of deciduous trees sometimes splits when there are large fluctuations in
temperature from a warm day into a frost night. Painting the trunks with an
interior water-based latex white paint diluted with 50 percent water in the late
autumn when the air temperature is above 10 °C will reduce this problem. White
paint, insulation and other wraps are known to improve hardiness against frost
damage in peach trees. The paint or wraps decrease the late winter high cambial
temperatures due to daytime radiation, which improves hardiness. Wrapping tree
trunks with insulation (i.e. materials containing air spaces that resist heat
transfer) will protect young trees from frost damage and possible death. Critical
factors are to use insulation that does not absorb water and the trunks should be
wrapped from the ground surface to as high as possible. Fibreglass and
polyurethane insulation wraps with higher resistance to heat transfer provide the
best protection of commercially available wraps. Typically, the trunk wraps are
removed after 3 to 4 years. Wrapping young citrus tree trunks with water bags
was reported to give even better protection than fibreglass or polyurethane foam.
The main drawback to trunk wraps is increased potential for disease problems,
so the bud unions should be at least 15 cm above the ground. Applying
fungicide sprays prior to wrapping helps to reduce disease problems.
Bacteria control
For freezing to occur, the ice formation process is mostly initiated by presence
of INA bacteria. The higher the concentration of the INA bacteria, the more
likely that ice will form. After forming, it then propagates inside the plants
through openings on the surface into the plant tissues. Commonly, pesticides
(copper compounds) are used to kill the bacteria or competitive non-icenucleation
active (NINA) bacteria are applied to compete with and reduce
concentrations of INA bacteria. However, this frost protection method has not
been widely used; for further information refer to Chapter 6.
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