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Cold snaps — IPM driver (protected crops)

Cold snaps — IPM driver (protected crops)

Summary

Cold snaps rarely “solve” pest problems in protected crops, but they can create instability: crop growth slows while some pests persist, and beneficial performance can drop. The main risk is loss of control continuity.

What this driver controls

  • Crop growth tempo slows (less flush, slower recovery, delayed canopy fill)
  • Beneficial activity and searching may reduce (temperature-limited behaviour)
  • Condensation risk rises (high RH events) → disease/IPM interaction
  • Management volatility (reduced venting, altered irrigation)

Pest fingerprints

Thrips

  • Can persist even when growth slows, especially indoors with some heat/light.
  • Pressure can become “background persistent” and then surge when warmth returns.

Spider mite

  • Population growth slows, but established hotspots may remain.
  • Risk returns strongly when temperature/VPD rebounds (post-snap step-change).

Aphids

  • Colony expansion slows with reduced growth tempo.
  • However, mild protected conditions can still sustain colonies; watch for rebound on flush after recovery.

Beneficial stability / failure modes

  • Parasitoids/predators may be less active; establishment can stall.
  • If beneficial momentum is lost, rebound conditions (warming + flush) can reopen the predator lag window.

Monitoring signals

  • Sudden drop in night temps; increased overnight RH/condensation events
  • Crop slowing: reduced transpiration, altered irrigation demand
  • “Rebound risk” forecast: snap ending + warming + increasing light

Stabilising actions

  • Maintain continuity: keep baseline beneficial presence rather than pausing completely.
  • Avoid over-wet substrates during low transpiration periods (sciarid risk).
  • Treat the “warm rebound” as the key risk: increase scouting and pre-empt releases ahead of recovery.

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