In various parts of the country, mandarin growers are concerned about a leaf-sucking stink bug, which is currently causing their fruit to drop to the ground.
The bug, called leptoglossus membranaceus, is an indigenous pest which has become more common recently. According to citrus researchers, mandarin-producing farms all over South Africa are under threat.
Citrus Research International’s (CRI) manager for research and technical, Tim Grout, says sightings have been reported on farms in Limpopo, Mpumalanga, Northern Cape and the Eastern Cape.
Grout explains leptoglossus membranaceous is a “tip wilter” sort of stink bug.
“They normally suck new leaf shoots and cause them to wilt and droop. Sucking fruit is unusual but it has been recorded before,” he says.
The leaf-sucking stink bug is a cause for major concern because of the potential loss of revenue due to crop damage. “High populations may lead to [between] 10% to 40% of the fruit dropping to the ground,” Grout warns.
Luckily, export programmes are not at risk
Mzansi agricultural group ANB Investments, responsible for popular brands such as ClemGold, BioGold, CitroGold and Indigo Fruit Farming, says they have also sighted tip wilters.
Communications manager Charlene Nieuwoudt explains few instances of tip wilter infections have been reported on their Indigo Fruit farm and partnering grower farms.
“[This was] in the Sunday River Valley and Western Cape, but only on some individual trees in very few orchards,” she says.
Meanwhile in the Burgersfort area in Mpumalanga, Nieuwoudt reports they have had singular swarms travelling together but causing no need to implement corrective sprays.
“It is currently also not causing any disruptions or posing risks in terms of our export programmes,” says Nieuwoudt.
Outbreak not preventable
Citrus growers with mandarins are advised to check whether leptoglossus membranaceous is in their orchards.
“After sucking the fruit, the fruit usually drops to the ground and [those fruits] cannot be marketed,” says Grout.
According to Grout, producers will simply have to bite the bullet on this one as the the outbreak was not preventable. “Growers will need to spray a pesticide that is registered for another citrus pest and that can be used close to harvest.”