Podcast: How to handle root rot in avocados

Root rot in avocados is a problem that has been plaguing farmers across the country for years. In this episode of Farmer’s Inside Track, Jacques Swanepoel from AECI Plant Health unpacks this fungal disease and shares advice on how to best deal with root rot affecting avocado trees.

Swanepoel is the AECI Plant Health technical advisor for Limpopo and the Laeveld region of Mpumalanga, where avocado production has traditionally been concentrated in the warm subtropical areas of the two provinces.

Root rot is a fungal disease caused by the pathogen phytophthora cinnamomic and it is soil-borne, Swanepoel explains. However, the disease can easily spread in water, soil, and organic materials containing the pathogen.

Found in dams and rivers

“The pathogen is found in dams and rivers in the most avocado regions due to contamination from the run-off from infected orchards. According to literature it affects approximately 5 000 different plant species,” he says.

This includes crucial tree crops for the economy including citrus, avocado, macadamia, and stone fruit. The feeder roots are severely harmed by this pathogen’s infection, which will eventually stop the plant from absorbing nutrients.

Swanepoel explains that a gradual dieback of the shoots occurs as well as yellowing of leaves. “Eventually the tree will be completely defoliated in severe cases. Smaller and less fruit might be produced with sunburn damage due to a less dense canopy of leaves that can’t protect the fruit from the sun,” Swanepoel says.

Containing root rot

According to the 2021 Census, total avocado plantings in South Africa stood at 15 439 hectares showing a growth of 747 hectares from 2020 to 2021. If this virus is not contained, many of these plantings will eventually perish, Swanepoel cautions.

In this episode, Swanepoel also discusses: