Independent field research is set to continue into the wider effectiveness of key fungicides against various disease complexes in macadamias.
Tebuconazole and azoxystrobin are well known fungicides and their combination in the product, Custodia Forte –which is a higher concentrate version of the original Custodia, has been welcomed against husk spot.
The higher concentrate, low odour formulation is applied at about half of the recommended application rates of the former Custodia, says Jim O’Connor, market development manager with Adama Australia in Queensland.
He said husk spot costs the industry around $10 million a year. It infects the fibrous husk around the macadamia shell, causing nuts to drop-off prematurely, and spreads from old husks to new green ones.
Independent research over a number of years already has confirmed the efficacy of Custodia Forte for husk spot, and now the fungicide will feature in further research in the Bundaberg area in Queensland and the Northern Rivers region in New South Wales.
Mr O’Connor said the latest independent research would investigate the potential effectiveness of Custodia Forte for disease complexes in macadamia, including prior to flowering.
The research also will evaluate the use of in-field sensing systems to determine the development of disease and infection risk. This analysis will produce valuable information for growers to ensure more timely applications of fungicides like Custodia Forte in the future.
Mr O’Connor said the technologies would further the understanding of the impact of fungicides on disease and determining the optimum timing of applications.
For husk spot prevention, Custodia Forte is applied from match head stage, with a maximum of two applications per season spaced 14 to 28 days apart, separated by another fungicide treatment with a different mode of action.
It is also compatible for tank mixing and has a harvest withholding period of 15 days.
Mr O’Connor said specific fungicide programs for husk spot in macadamias should be determined by the particular disease levels, prevailing conditions and orchard hygiene, which in more recent times has been enhanced by cultural methods, including tree shaking.
“Mechanically shaking of trees and adoption of other cultural controls to improve orchard hygiene is increasingly playing a key role in conjunction with new fungicide tools to reduce the risk of husk spot infection in macadamias.
“The industry has continued to evolve and become more sophisticated, and this has resulted in greater understanding and fine-tuning around husk spot disease control in order to maximise yields and quality,’’ he said.
