Goss’s wilt definitely in KZN too, but fewer reports than last year

Contrary to the national Department of Agriculture’s recent announcement, Goss’s bacterial wilt is indeed being observed in parts of KwaZulu-Natal’s maize production this year. However, it is to a lesser extent than last year, and the province’s maize farmers are not panicking about its presence.

By Lloyd Phillips, senior journalist at African Farming and Landbouweekblad

Dr Rikus Kloppers, the highly experienced and regarded plant pathologist with Robigalia CropCare, says he has had confirmed reports from both last season and the current season of Goss’s wilt in KwaZulu-Natal’s Midlands, northern and southern parts. Disease symptoms were observed and samples submitted for verification.

Kloppers believes the discrepancy between his information and that from the national Department of Agriculture’s delimiting survey teams is likely due to a combination of the random sampling for Goss’s wilt these teams undertake in KwaZulu-Natal, not all results of the sampling having been released yet, and the timing of the survey.

In contrast, agronomists and chemical agents in the private sector are often contacted directly by farmers, and by each other, to report and follow up on suspicious cases of Goss’s wilt, some of which are ultimately confirmed positive.

“From the industry’s side there will need to be follow-up discussions with the Department of Agriculture to align on this matter and to make sure communication from various role-players is correctly understood by growers in the different regions.”

Kloppers says there are fewer reports of Goss’s wilt in KwaZulu-Natal’s maize crops this year. He suspects this may possibly be because in previous seasons, farmers identified which hybrids were most attacked by this disease. For the 2025-’26 summer, many farmers may have planted hybrids they feel are less susceptible and that may indeed be so.

Multi-season Scientific Research Essential

“Research is continuing and seed suppliers are in the process to scientifically confirm which maize hybrids are either more susceptible to or that have greater resistance against Goss’s wilt. This will need at least more than one season’s data”

An agronomist in KwaZulu-Natal, who asked not to be named here, expressed similar experiences and views to Kloppers’.

“I’ve seen Goss’s wilt here and there, like in the Greytown and Swartberg districts, but nothing to the extent I saw last year. There seem to be some hotspots for it. I agree that more proper research is needed to clarify why there are these hotspots and whether some maize hybrids are more susceptible than others.”

Somewhat fortunately, infection by Goss’s bacterial wilt does not directly cause the quality of maize grain to be downgraded, nor does it release toxins that make the grain unsafe for human and animal consumption. Photo: Dr Rikus Kloppers

Combined Strategy Needed Against Goss’s Wilt

Kloppers says there is currently no single “silver bullet” to protect against Goss’s wilt. Rather, a combined strategy is needed.

“It’s a bacterial pathogen, so fungicides are not an option. In infected fields, the bacterium can survive for up to ten months on crop residues left on the soil surface. If these residues are worked into the soil, the pathogenic bacterium’s population reduces significantly in a few weeks. This does not always align with conservation tillage practises but might be necessary as an emergency sanitation practise where there was severe infection.”

Kloppers says the following summer this same field should be planted to a crop, like soybeans, that is not susceptible to Goss’s wilt. This will further reduce the bacterium’s populations. The third summer, a maize hybrid considered less susceptible to Goss’s wilt can be planted.

“It’s a process of managing this disease down.

Government Must Rethink Its Stance

“Fortunately for us here in South Africa, the USA has already identified and is growing maize germplasm that is significantly less susceptible to Goss’s wilt. Our seed companies source this germplasm for breeding, and to find and develop better options for us.

“To help the situation, the South African government needs to reconsider the regulatory status of new breeding technologies, such as CRISPR-Cas gene-editing technology. CRISPR-Cas has significant potential to speed up precision breeding to develop new crop varieties that are more tolerant against various diseases and conditions, like Goss’s wilt.”

South Africa’s grains and oilseeds crops are at risk from various diseases. For example, this maize plant was attacked simultaneously by both Goss’s bacterial wilt (left lesion) and by northern corn leaf blight (right lesion). Photo: Dr Rikus Kloppers

Kloppers reminds maize farmers that while Goss’s wilt can potentially cause significant yield losses, it does not impact grain quality or safety. So, the risk of penalties on grain quality are low, and the grain can be safely consumed by people and animals alike.

In contrast, diseases such as the fungal pathogen diplodia ear rot that is already common in South Africa, can also cause significant yield losses. Further negative impacts include losses of grain quality and the fact that degraded grain cannot be fed to people or livestock because of the toxins that diplodia ear rot releases.

“In other words, there are other significant diseases to consider and not only to focus on one. The aim is always to reduce the risk of a single disease event by planting a hybrid package to spread this risk.”