mulberry leaf spot (popcorn disease)

Symptoms

Pale brown angular spots between leaf veins, spots darken and develop pale centers, premature leaf yellowing and drop in late summer, slight yield loss.

Plants affected

• white mulberry

Easily confused with

• mulberry bacterial blight

  How to tell them apart: Mycosphaerella mori (fungal mulberry leaf spot / 'popcorn' false mildew) and Pseudomonas mori (bacterial blight of mulberry) both start as small dark spots on mulberry leaves. Mycosphaerella mori spots are roundish, brown to grey-brown with a darker margin and stay scattered across the blade; in humid weather tiny black pinhead fruiting bodies (pycnidia/perithecia) and a whitish-grey felty bloom appear on the spot surface, and the lesion edge is diffuse rather than vein-bound. Pseudomonas mori spots are instead angular and water-soaked, sharply confined by the leaf veins, often with a translucent yellow (chlorotic) halo; in wet conditions they exude sticky bacterial ooze, turn the leaf greasy/blackish and run along petioles and young shoots as dark sunken streaks, with no powdery growth or visible fungal bodies.

Common questions

How do I recognise mulberry leaf spot (popcorn disease) on white mulberry?

Pale brown angular spots between leaf veins, spots darken and develop pale centers, premature leaf yellowing and drop in late summer, slight yield loss.

Do I have to report mulberry leaf spot (popcorn disease)?

No. mulberry leaf spot (popcorn disease) is not a notifiable organism, so there is nothing to report to an authority. Treat it as a normal garden problem.

How is mulberry leaf spot (popcorn disease) treated?

Mainly with biological and cultural measures — removing affected material, changing the conditions that favour it, and treating with agents approved in your country. The exact steps and their timing depend on the plant, the season and where you live: Dr. Phyto works them out in a free diagnosis.