|Version 3||Date January 2020||Reference 64|
As sorghum crops move from flowering to grain fill, infestations of Helicoverpa are common with the most damage occurring when eggs are laid on heads before flowering. The preferred option for Helicoverpa management in sorghum is nucleopolyhedrovirus (NPV), a disease of Helicoverpa available under commercially produced formulations (eg. ViVUS Max® or Gemstar®)
The optimal timing for an NPV spray is 3 days after 50% of heads have completed flowering (brown anthers to the base of the head). This delay is necessary not only to target the right size of Helicoverpa, but also for Microplitis larvae (Helicoverpa parasites) to complete their life cycle before their host die.
Adding BIOPEST® with an NPV spray increases droplet survival as well as increasing droplet coverage on the leaf surface.
In addition, BIOPEST®, reduces Helicoverpa egg laying as the oil prevents volatiles coming off the plant surface which make it less attractive for feeding.SACOA has conducted significant research into the effect of BIOPEST® on VMD (volume median diameter), drift reduction, leaf surface coverage and droplet survival. Research conducted in cotton proved a significant reduction in drift and increase in leaf coverage with the addition of BIOPEST® even at relatively low rates (see Charts 1 and 2).
|Image 1: NPV infected, and killed Helicoverpa larva. (Source: The Beatsheet).|
|Image 2: Assassin bug feeding on Helicoverpa. (Source: DAF QLD).|
Aerial applications commonly consist of a total volume of 30- 40L/Ha, but can be as low as 10L/ Ha including 0.5-1L/Ha BIOPEST® and the recommended rate of NPV. For ground rigs 100L/Ha as a banded application with 0.5-1L/Ha BIOPEST® is commonly used. Recent aerial application trials, indicate the addition of BIOPEST® can increase coverage by the equivalent of 10L/Ha of water (see Chart 3).
This work supports the recommendations contained on the ViVUS Max® label –“Broadacre crops: Ground Rig: Apply in a minimum of 100 litres of water per hectare. Aerial – High Volume: Apply in a minimum of 30 litres of water per hectare. This application method is particularly susceptible to droplet evaporation, especially during hot and dry conditions (temperature greater than 30˚C and humidity less than 40%). Droplet evaporation will reduce coverage, which can have a detrimental impact on performance.
During hot and dry conditions avoid using this application method – wait until conditions favour good coverage or apply in ULV (see below).
Alternatively, if application in water by air during hot and dry conditions cannot be avoided, increase application volume and/or use an anti-evaporation additive to improve coverage. BIOPEST® is also an effective mix partner with dilute spraying by ground or air as it will reduce droplet evaporation, increase droplet survival and increase coverage on target pests.”
Aerial – Ultra-Low Volume (ULV): Use an approved carrier such as BIOPEST® Oil and apply in a minimum volume of 3 litres per hectare. When applying ViVUS Max in ULV, do not tank mix with other pesticides or fertilisers (refer to Compatibility).”
The addition of BIOPEST® to the spray mixture also allows the suppression of aphids present at low numbers and delays a build- up of large colonies. As BIOPEST® is soft on beneficials, such as Predatory shield bugs and Assassin bugs, their population will not be disrupted and they will continue to assist in the control of Helicoverpa
|Graph 1: Droplet size changes with the addition of BIOPEST®, treatment differences are between treatments. Nozzle Type 11003 @ 300kPa, 1299-16 @ 400kPa. Means followed by the same letter are not significantly different. (Source: UWS 3C CRDC Final Report 2003).|
|Graph 2: Change in % driftable droplets with BIOPEST®, treatment differences are between treatments. Nozzle Type 11003 @ 300kPa, 1299-16 @ 400kPa. Means followed by the same letter are not significantly different. (Source: UWS 3C CRDC Final Report 2003).|
|Graph 3: Increase in canola leaf surface coverage with the addition of BIOPEST®. (Source: Agvivo demonstration trial June 2014).|
Disclaimer and Copyright
This document should act as a guide only and no purchase or usage decisions should be made based on the information provided without obtaining independent, expert advice. SACOA and contributors do not necessarily recommend or endorse any products or manufacturers referred to. SACOA Pty Ltd will not be liable for any loss, damage, cost or expense incurred or arising by reason of any person using or relying on the information contained in this document. More information is available from SACOA via sacoa.com.au or 08 9386 7666, or by contacting your local reseller.
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