Vigilance remains key to rooting out the rot

5 November 2024

Key Points:

Root and crown rot is a general term for plant diseases that affect the roots, lower trunk, or branches near the soil line.
Root and crown rot pathogens are difficult to detect, and vigilance is key as there is no cure once plants are infected.
Grow Help Australia, supported by levy investments in the Hort Innovation Nursery Fund, is offering all production nurseries six free diagnostic samples per year.

We encourage growers to remain vigilant as the industry faces ongoing and significant challenges from root and crown rot pathogens.

Early detection of the pathogens can be difficult as their symptoms can easily be mistaken for other issues. During the initial stages of infection, plants may appear healthy, showing only minor signs like leaf spots or slight root rot, but infections can quickly escalate, leading to leaf dieback, petiole wilting and plant death.

Preventing root and crown rot

With no cure once plants are infected, prevention is critical. Important management practices include:

only use clean or properly disinfected irrigation water
where possible opt for plant varieties that have traditionally shown resistance to these pathogens
schedule irrigation appropriately and maintain optimal environmental conditions
grow seedlings and runners in soilless media rather than in ground to reduce disease risk.

Fungicides cannot eliminate existing infections and will only suppress symptoms. Even if you apply fungicide, symptoms may emerge and, if the conditions are favourable, the disease is likely to recur.

It is therefore crucial to sell only healthy plants to minimise the risk of spreading these pathogens.

Diagnostic testing

If you suspect your plants are showing root or crown rot symptoms and need confirmation, you can submit samples for diagnostic testing. Grow Help Australia, a service that helps identify pests, is offering all production nurseries six free diagnostic samples each calendar year until the end of 2025.

For more detailed guidance on preventing root and crown rot in production nurseries, check out the:

Preventing disease factsheet – www.nurseryproductionfms.com.au/preventing-disease-in-propagation-hres-final · Crown rot management plan – www.nurseryproductionfms.com.au/vascular-wilt-and-crown-rot-mgmt-plan-high-res-final
Root rot management plan – www.nurseryproductionfms.com.au/pest-management-plan-soilborne-root-pathogens