carob powdery mildew

Symptoms

White powdery patches on young leaves and on the rachis of catkins, distorted growth of new shoots, reduced and deformed pod set, mild defoliation in heavy years.

Plants affected

• carob tree

Easily confused with

• white mango scale

  How to tell them apart: A whitish coating that is actually a colony of armored scale insects: each female sits under a flat, circular, opaque-white waxy cover about 1.5-2 mm across, often with a slightly off-centre yellowish-brown spot. The covers form raised, crusty encrustations clustered along midribs, leaf undersides, fruit and bark, and they do NOT rub off as a smooth dust — you must scrape or flick them off, leaving a small dimple. Look for sooty mould and yellow leaf spotting where insects have fed. A true powdery mildew: a fine, flour-like white-to-greyish bloom that lies superficially on young leaves, shoots and flower clusters and wipes away easily with a finger, leaving green tissue beneath. It spreads as expanding circular patches and felted films rather than discrete bumps, favours warm dry weather with humid nights, and causes distortion or yellowing of new growth. There are no individual hard scales or covers to scrape off — it is a continuous mealy film.

Common questions

How do I recognise carob powdery mildew on carob tree?

White powdery patches on young leaves and on the rachis of catkins, distorted growth of new shoots, reduced and deformed pod set, mild defoliation in heavy years.

Do I have to report carob powdery mildew?

No. carob powdery mildew is not a notifiable organism, so there is nothing to report to an authority. Treat it as a normal garden problem.

How is carob powdery mildew 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.