Hollyhock rust 

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🔍 is a common fungal disease caused by Puccinia malvacearum, and it particularly affects hollyhocks (Alcea spp.) and other members of the mallow family.

Symptoms

• Orange-brown pustules on the undersides of leaves.
• Yellow spots on the upper surface.
• Leaves may become distorted, wither, and fall prematurely.
• Can also affect stems and flower stalks in severe cases.

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⚠️ Why It’s a Problem

• Weakens the plant, reducing flowering and vigour.
• Highly contagious — spreads via wind, rain splash, and contaminated tools or debris.
• Often reappears year after year unless actively controlled.

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✅ Control & Prevention

1. Cultural Controls

• Remove infected leaves as soon as seen (dispose in household waste, not compost).
• Cut back plants hard in autumn and dispose of all debris.
• Avoid overhead watering.
• Improve air circulation by spacing plants and thinning stems.

2. Resistant Varieties

• Some hollyhocks and closely related species show more resistance (e.g. Alcea rugosa or Alcea ficifolia).
• Avoid over-hybridised strains which may be more susceptible.

3. Crop Rotation

• Don’t plant hollyhocks in the same spot every year.

4. Fungicides (UK)

• There are no fungicides explicitly approved for amateur use against hollyhock rust in the UK, but:
  • General-purpose fungicides for ornamentals (e.g. based on myclobutanil or tebuconazole) may help if labelled for rusts.
  • Use as a preventative at the first signs in spring.
  • Always follow label instructions and check legal approval.

5. Organic/Non-chemical Options

• Regularly inspect and prune early.
• Neem oil, sulphur sprays, or homemade baking soda solutions may help reduce spread, though effectiveness varies.
• Companion planting with onions or garlic may slightly deter fungal spread (anecdotal).

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🧤 Autumn Cleanup

• Vital to reducing re-infection:
  • Remove all old stems and leaves.
  • Don’t compost infected material.
  • Mulch in spring to cover any spores in soil.

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