Hull rot a key target for almond orchards

June 12, 2023 | 5 Min read
Hull rot has largely become the number one disease target in almonds and it’s likely to continue following wet conditions in recent seasons.

Hull rot has largely become the number one disease target in almonds and it’s likely to continue following wet conditions in recent seasons.

Graeme Judd, senior agronomist with EE Muir and Sons, said Monilinia and Rhizopus were the two hull rot pathogens existing in Australian orchards, with Rhizopus the most dominant and more prevalent in wetter seasons.

“We have seen a lot of hull rot the last two years, with mild summers and above average rainfall.

“Hull rot causes dieback up the branches, killing off the spurs that grow next year’s crop, so if let go, it can be a real problem. Control, or at least suppression of hull rot is very important.’’

Mr Judd said pruning and removal of mummy nuts and continuing to monitor orchard hygiene during winter aided the suppression, while fungicide sprays around the hull split stage also were vital to provide four to six weeks of suppression against hull rot.

He said in recent years, Custodia and its latest, high concentrate version, Custodia Forte, had been one of the fungicides of choice for hull rot suppression. Like any fungicide, he said spray coverage is vital for any application.

Adama Australia’s latest version, Custodia Forte, contains almost twice the amount of the active ingredients, tebuconazole (Group 3) and azoxystrobin (Group 11), allowing application rates of about half of that for Custodia and improved cost-effectiveness and convenience, along with reduced handling, packaging and hence, waste.

Adama Australia southern market development manager – horticulture, Daniel Polson, said Custodia Forte could be applied twice for hull rot suppression during the season, with a buffer spray between the applications.

He said the target timing is hull split or just before, depending upon the season.

Custodia Forte also offered a wide disease spectrum, including control of blossom blight and shot-hole, however it was vital to help suppress hull rot from hull split through to the later stages of seasons.

Mr Polson said the tebuconazole in Custodia Forte performed most of the work to suppress the Rhizopus pathogen, while the azoxystrobin provided added support and also helped to control diseases such as rust, which can emerge following favorable weather conditions.

“It has a very good fit, and we are certainly seeing improved hull rot suppression with Custodia Forte. The ideal timing for it is just prior to hull split.’’

He said Custodia Forte also was highly compatible with other common fungicides and insecticides.

“It can be used in various mixes, including insecticides for control of carob moth and carpophilus beetle, although this can probably be applied a little later.’’

Categories Almonds Nuts

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