Disease of the Month - Frost Injury

 
  Hort Snacks - April 2017
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 Causal Organisms:
Not biotic – caused by exposure to cold environmental conditions

Crops Affected: all crops are susceptible to some degree, depending on growth stage, crop type, etc.

Disease Cycle:

  • May occur in either spring or fall (or any other season), when environmental conditions shift from above to below zero
  • May be either a general drop in temperature or the movement of cold air into lower areas, resulting in localized damage
Symptoms:
  • Highly variable – depends on severity of temperature drop, duration of exposure to frost conditions, sensitivity of plant part(s) to cold and other conditions
  • Branches may fail to leaf out or flower
    • Leaf and/or flower buds may fail to break or open
  • Growing tissues may appear somewhat wilted and somewhat darker in colour, turning brown or black as tissues die
    • Tissues may have a water-soaked or papery appearance (depending on the plant part)
    • Damaged areas may dry up after a period of time
  • Internal tissues may have blotchy discolorations
  • Frozen tissues may become soft, spongy and watery, often eventually developing secondary infections (such as bacterial soft rots)
  • Tissues or the entire plant (all parts) may be damaged or completely killed
  • Flower buds and fruit may not develop properly
  • Apparently undamaged flowers may have a brown or blackened centre
  • Flowers or fruit may abort and fall off
Frost Damaged Saskatoon berries (green fruit stage) - frozen fruit = pink/purple discolouration - drop off when touched
.
Frost damaged chokecherry bush - growing points brown, wilted and dying
Frost damaged chokecherry flowers - note slight brown discolouration
Photos by Robert Spencer
Management:
  • Ensure that plants are planted on a slight slope, to allow cold air to drain off and not collect in an area of the field
  • Avoid blocking the flow of cold air, creating a frost pocket
  • Avoid low areas or depressions that are prone to cold air collection
  • Plant hardy or frost tolerant plants
  • Avoid late plantings
  • Plant perennial plants in areas that are somewhat slower to warm in the spring, preventing premature emergence and dormancy break
  • Apply sprinkler irrigation to protect sensitive plants for short periods of frost
  • Cover crops with row or field covers – may provide a small amount of protection, depending on thickness of material
  • Harvest crops prior to frost, if possible
  • If frost tolerant plants (such as cole crops) are exposed to frost, allow them to slowly and completely prior to harvesting
  • Grade out frozen or damaged product

Protection against Frost Damage – Agdex document
 
 
 
 
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For more information about the content of this document, contact Robert Spencer.
This information published to the web on March 27, 2017.