Begonia: powdery mildew rex vs cane
Quick answer
On Begonia, powdery mildew rex vs cane usually comes down to this: Cane begonias (angel wing types like 'Don Miller', 'Lucerna') exhibit higher genetic susceptibility to powdery mildew than rex begonias due to denser foliage architecture that traps moisture and reduced cuticle thickness on newer growth. Rex varieties develop thicker waxy cuticles as defense but require higher humidity (70-85%) which can paradoxically increase mildew risk if airflow is inadequate. The infection threshold differs: cane types develop mildew at 60%+ humidity with stagnant air; rex types require 75%+ humidity for spore activation.
Start here:
- 1. For cane begonias: Maintain strict 50-60% humidity ceiling using dehumidifier; run oscillating fan 8+ hours daily; space plants 18+ inches apart
- 2. For rex begonias: Allow 65-75% humidity but mandate constant airflow; position fan to create gentle leaf movement without causing dessication
How to tell these apart on Begonia
Begonia spp.
Cane begonias (angel wing types like 'Don Miller', 'Lucerna') exhibit higher genetic susceptibility to powdery mildew than rex begonias due to denser foliage architecture that traps moisture and reduced cuticle thickness on newer growth. Rex varieties develop thicker waxy cuticles as defense but require higher humidity (70-85%) which can paradoxically increase mildew risk if airflow is inadequate. The infection threshold differs: cane types develop mildew at 60%+ humidity with stagnant air; rex types require 75%+ humidity for spore activation.
What to do for Begonia
- 1
For cane begonias: Maintain strict 50-60% humidity ceiling using dehumidifier; run oscillating fan 8+ hours daily; space plants 18+ inches apart
- 2
For rex begonias: Allow 65-75% humidity but mandate constant airflow; position fan to create gentle leaf movement without causing dessication
- 3
Preventive spraying: Apply neem oil + baking soda solution bi-weekly to cane varieties during humid seasons (spring/fall)
- 4
Early detection: Inspect cane begonia new growth weekly—mildew manifests first on tender shoots; rex varieties show mildew first on older shaded leaves
- 5
Treatment differentiation: Cane begonias recover faster from defoliation if root system healthy; rex begonias retain more foliage but recover slower due to rhizome energy storage priorities
Avoid mixing these up on Begonia
Select mildew-resistant cane cultivars when possible; group rex varieties with shared airflow systems rather than cane types; maintain species-specific humidity zones; avoid growing high-humidity rex varieties in same enclosure as cane types requiring drier conditions