Sclerotinia Case Studies

To Spray or Not To Spray

In 2015 FarmLink partnered with Bayer CropScience Technical Advisor Gus MacLennan to conduct a number of commercial scale trials to evaluate the economics of spraying fungicides for sclerotinia protection in differing rainfall zones. Secondary to this, the trials also served to field test a new foliar fungicide due for registration in 2017. Four sites were selected across the Riverina and South-West Slopes to represent differing rainfall zones, they were:

Location Target range2015 actual*Long term average*Barmedman Low-Medium 478mm542mm Lockhart
Low-Medium
481mm525mm Temora Medium 574mm545mm Galong High 650mm679mm *Figures sourced from BOM

Sclerotinia risk, whilst usually greatest in the higher rainfall zones due to their more reliable spring rainfall, is determined by a number of factors such as sowing time, frequency of host crops (canola, legumes etc), flowering length and conditions during spore release. Due to the increase in canola production over the past two decades or more, and with a return to more suitable weather conditions, sclerotinia has a major yield limiting factor in many areas, but the decision to apply a fungicide has not always been an easy one.

Generally a fungicide such as Prosaro® will offer around three weeks protection from sclerotinia depending on rate, crop canopy size, flowering stage and disease cycle. Application is best made to target the petals, leaves and stems of canola plants which is best achieved via ground rig with high water volumes, however aerial application at 30L/ha+ is still very effective.
It is important to note that each of these four case studies had different paddock histories, application methods, varieties, growth stage timings and in some fungicides products (Prosaro® and Aviator® Xpro#).

# - Aviator Xpro is a foliar fungicide containing prothioconazole (triazole) and bixafen (SDHI). A registration submission for sclerotinia control in canola has been made to the APVMA with expected approval and availability for 2017 season.

Aviator Xpro and Prosaro are registered trademarks of Bayer CropScience.