avocado cercospora spot

Plants affected

• avocado

Easily confused with

• anthracnose

  How to tell them apart: Colletotrichum gloeosporioides (avocado anthracnose) starts as small brown-to-black spots on leaves that turn into sunken, water-soaked lesions; on fruit it forms round, sunken dark spots that develop salmon-pink to orange spore masses (acervuli) in the centre under humid conditions. Pseudocercospora purpurea (cercospora spot) makes smaller, angular spots that stay flat and often have a distinct purplish-brown to violet border, frequently confined by leaf veins and giving a speckled blotchy look. Look for sunken texture plus pink-orange spore dots to call anthracnose; look for flat angular purple-edged spots without sunken centres to call cercospora.

• avocado scab

  How to tell them apart: Pseudocercospora purpurea (avocado cercospora spot) makes small, flat, angular-to-irregular brown lesions on both leaf surfaces and on fruit; the spots stay sunken or level with the skin, often have a faint purplish margin, and on fruit they may crack and join into larger dark blotches without ever rising above the surface. Sphaceloma persae (avocado scab) instead produces lesions that quickly become raised, corky and rough: on fruit you see scattered brown-to-purplish spots that turn into hard, scabby, often star-shaped corky islands you can feel with a fingertip, and on leaves the spots are smaller, oval and tend to drop out leaving shot-holes along the veins. The decisive test is texture: run a finger over the lesion. Cercospora is smooth and flat; scab is rough and raised. Scab is worst on young expanding fruit and flushing leaves in wet, humid spring weather, while cercospora spotting builds up later on older leaves and maturing fruit.

Common questions

Do I have to report avocado cercospora spot?

No. avocado cercospora spot is not a notifiable organism, so there is nothing to report to an authority. Treat it as a normal garden problem.

How is avocado cercospora spot 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.