Skip to content
Pocket Botanist
Get the app

Guides

Fig Rust

Disease

Fig Rust is a fungal disease caused by the pathogen Cerotelium fici that primarily affects the foliage of fig trees. It matters because heavy infections cause premature leaf drop, which weakens the tree and reduces its ability to produce a healthy harvest.

Symptoms by part

Leaves

Small, angular, reddish brown spots appear on the undersides of leaves, eventually turning dark brown or black. These spots may be surrounded by a yellow halo, and the upper leaf surface often shows yellowing or browning directly above the spots.

Causes

  • High humidity levels
  • Prolonged periods of leaf wetness from rain or overhead irrigation
  • Poor air circulation within the canopy
  • Warm temperatures that favor fungal spore development

Could be confused with

  • Leaf Spot · Leaf spot diseases typically show larger, more irregular lesions without the fine, dusty spore masses characteristic of rust.
  • Nutrient Deficiency · Nutrient issues usually cause uniform yellowing or patterns across the whole leaf rather than distinct, raised, rust colored spots.

Treatment

  1. 1. Remove and destroy all fallen leaves from beneath the tree to reduce the amount of fungus present in the area.
  2. 2. Prune out heavily infected branches to improve airflow through the center of the tree.
  3. 3. Apply sulfur to the foliage, ensuring thorough coverage of both the top and bottom of the leaves, follow the label.

Without chemicals

  • Prune the canopy to increase light penetration and air movement.
  • Water the soil directly at the base of the tree rather than using overhead sprinklers.
  • Clean up all leaf litter under the tree at the end of the season to prevent spores from overwintering.

Chemical options

  • Sulfur, apply as a spray to the foliage, follow the label.

Preventing it

  • Space trees far enough apart to ensure good air circulation.
  • Choose planting sites with full sun and good drainage.
  • Keep the area under the tree clear of debris throughout the growing season.

Season

The warm growing season, especially during humid or rainy stretches.

Spread risk

Moderate

Severity

Moderate

When to act

Act as soon as you notice the first reddish spots on the undersides of the leaves to prevent the infection from spreading across the entire canopy. If the tree loses its leaves prematurely for several years in a row, it may be time to consider replacing it with a more resistant variety.

Think it's Fig Rust?

This guide covers the general picture. Pocket Botanist looks at your actual plant from a photo and tells you what's really going on, how serious it is, and what to try first. Identification and a health check are free.

Download on the App StoreGet it on Google Play

Get the app · Or check it from a photo now, free

Questions people ask

Will fig rust kill my tree?
It is unlikely to kill a mature, healthy tree, but it can significantly stress the plant and reduce fruit production over time.
Can I eat the figs if the leaves have rust?
Yes, fig rust is a leaf disease and does not affect the safety or quality of the fruit itself.

Plants it affects

Back to all guides

This guide was generated with AI and is general information, not horticultural advice. Read about how we build these guides.