White root rot caused by Rosellinia necatrix afflicts everything from apples to avocadoes. By Anna Mouton. Rosellinia necatrix is a soil-borne fungus that attacks the roots of more than 350 plant species, notably pome- and stone-fruit, grapevines, avocadoes, citrus, and…
The name Phytophthora literally means plant destroyer — fitting for a genus that abounds in disease-causing species. By Anna Mouton. Phytophthora infestans thrust the genus into notoriety by launching the Irish Potato Famine of 1845–1849, estimated to have killed 1…
Bacterial pathogens cause financial losses to fruit growers worldwide —South Africa is no exception. By Anna Mouton. The genera Pseudomonas and Xanthomonas contain disease-causing species that attack many different plants. But whereas all Xanthomonas species are associated with plants,…
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.…
What we’ve learnt about cankers in apple trees. By Grethe Bestbier. Canker development in newly established apple trees has been increasing in the Western Cape, with stem cankers responsible for losses of 30% and 70% respectively in two affected orchards.…
What is in the producer’s toolbox? By Anna Mouton Frank van de Geijn is a senior consultant and post-harvest researcher at Wageningen University and Research. He is with the Agrotechnology and Food Sciences Group which focusses on all questions relating…
Real-time information and forecasting of pest and disease development. By Engela Duvenage. Information gathered daily on farms can be fed into effective modelling programmes to take precision farming to a next level. Modelling can help producers time disease and pest…
We examine the science behind the numbers. By Anna Mouton. Growers know the dosage rates for chemicals because the numbers are provided with the products. But how do scientists evaluate deposition parameters when they are researching ways to optimise spray…
Stink bugs or stem-pitting virus? By Anna Mouton. A new research project funded by Hortgro aims to establish the cause of dimpled and deformed pears seen in Western Cape orchards. The project is led by Dr Rachelle Bester and Prof.…
Conflicting views on a century-old disease. By Anna Mouton. Pear stony pit is a disease of pear trees that shows up as deformed fruit. The fruit are dimpled or pitted. Severely affected fruit may have a distorted shape and become…