Crown gall
A recent resurgence of galls on apple trees has sparked new interest in an old disease. By Anna Mouton. Plant galls are abnormal growths formed by cell enlargement or proliferation — or both — resulting from infections and other causes.…
Integrated pest management
Effective pest control in perennial crop monocultures demands a diversified approach. By Anna Mouton. Modern agriculture has created areas of crop monocultures that are primarily managed through chemical interventions. Crop-protection specialist Dr Gideon van Zyl of ProCrop discussed the challenges…
The enigma of pear stony pit
What causes pitted pears in South African orchards? Apple stem pitting virus or antestia stink bug? By Anna Mouton. Pear stony pit is a disease of pear trees characterised by deformed fruit. Moderately affected fruit are dimpled or pitted. Severely…
Beware of this tiny beetle
The invasive polyphagous shot-hole borer threatens fruit trees. By Engela Duvenage. Polyphagous shot-hole borers began killing trees in gardens and forests nationwide in the past five years. Prof. Francois Roets of the Department of Conservation Ecology and Entomology at Stellenbosch…
Fruit-fly management in Europe
Climate change is driving biological invasions in temperate European zones. What is being done to protect agriculture? By Engela Duvenage. Warmer weather is increasingly allowing tropical pests and other species to persist throughout winter, and become problems, according to applied…
Systems approach proves its worth
Dr Aruna Manrakhan of Citrus Research International reviews its use in South African citrus and deciduous fruit. By Engela Duvenage. “Prior to 1980, fruit industries relied on single-point disinfestation treatments to mitigate insect pest risks,” said Manrakhan. “The ban or…
Can RIMpro work in South Africa?
Predictive models can help growers to better align their spray programmes with infection risk — but how well do they work in practice? By Engela Duvenage. Predictive models are only as good as the data available for input. In addition,…
Are mancozeb formulations rainfast?
The broad-spectrum fungicide mancozeb is the go-to option for apple-scab control. But what happens to mancozeb when it rains? By Engela Duvenage. “Some mancozeb products on the market claim in their advertising to be more rainfast than others,” says Prof.…
Fifty years of apple-scab research
A summary of historical South African research on apple scab starting in 1970 with the work of Dr Wolf Schwabe. By Anna Mouton. Schwabe conducted extensive research on apple scab while with the Fruit and Fruit Technology Research Institute —…
Apple scab 101
What is it and what can be done about it? By Anna Mouton. Apple scab or black spot is a disease of apples caused by the fungus Venturia inaequalis — unaffectionately known to many growers as fusi — short for…