There are several significant pathogens and pests impacting avocado, such as Phytophthora root rot, White root rot,  and most recently, Fusarium Dieback, caused by the PSHB and its fungal symbiont Fusarium euwallaceae. The ARP at FABI offers a disease clinic to avocado growers for the identification of avocado diseases. A consultation fee will be charged accordingly.




How to sample?

  • Take a photo of the symptoms, if possible
  • Samples should be taken from 4-5 randomly selected plants in an infection site.
  • Place the samples separately in a paper bag (Never use a plastic bag!!)
  • Seal the bag and label with the following: Collectors name, date, sample number, locality and cultivar

Specific tissue sampling

  • Collect individual leaves, place between blotting paper (paper towel) and in an envelope
  • Collect a sample that spans the diseased area, including +/- 2cm of healthy tissue on either side of the lesion
  • Place in a paper bag
  • Collect 200g of soil from under the diseased tree at a depth of 10-15 cm, place in a paper bag
  • Collect root pieces (healthy and diseased) from the soil and place in an envelope


Online submission: ARP Disease diagnostic clinic:

Additional information regarding sample submission:


Information Sheets


Avocado Sunblotch Viroid

Send the samples by fast mail or courier to the Avocado Disease Clinic @ FABI and give us a phone call to let us know to expect a parcel from you.

Prof Noelani van den Berg

Group Leader

This email address is being protected from spambots. You need JavaScript enabled to view it.

74 Lunnon street
Avocado Research Programme
University of Pretoria
(012) 420 3177

New Publications

Hlongwane NL, Dzomba EF, Hadebe K, van der Nest MA, Pierneef R, Muchadeyi FC. (2024) Identification of signatures of positive selection that have shaped the genomic landscape of South African pig populations. Animals 14:235. 10.3390/ani14020236
De Vos L, van der Nest MA, Santana QC, van Wyk S, Leeuwendaal KS, Wingfield BD, Steenkamp ET. (2024) Chromosome-level assemblies for the pine pitch canker pathogen Fusarium circinatum. Pathogens 13(1):70. 10.3390/pathogens13010070
Joubert M, van den Berg N, Theron J, Swart V. (2024) Global transcriptomic analysis in avocado nursery trees reveals differential gene expression during asymptomatic infection by avocado sunblotch viroid (ASBVd). Virus Research 339:199263. 10.1016/j.virusres.2023.199263. PDF
Anbu SP, Swart V, van den Berg N. (2023) Unmasking the invaders: NLR-mal function in plant defense. Frontiers in Plant Science 14:1307294. 10.3389/fpls.2023.1307294 PDF
Backer R, Naidoo S, van den Berg N. (2023) The expression of the NPR1-dependent defense response pathway genes in Persea americana (Mill.) following infection with Phytophthora cinnamomi. BMC Plant Biology 23(1):548. 10.1186/s12870-023-04541-z PDF