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 dies.
Adding BIOPEST® with an NPV spray increases droplet survival as well as increasing droplet coverage on the leaf surface.
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).
In addition, BIOPEST®, reduces Helicoverpa egg laying as the oil prevents volatiles coming off the plant surface which make it less attractive for feeding.
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 –
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”
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.
SACOA will be conducting further research into the role of BIOPEST® for managing Helicoverpa populations in sorchum over the 2016/2017 summer – evaluating efficacy improvement under ground and aerial application.
The Beatsheet: http://thebeatsheet.com.au/crop s/grains/sorghum/helicoverpa- and-midge-management-in- sorghum/
CRDC Report – UWS 32 – Evaluation of mineral oils for cotton IPM – October 2003
DAF QLD: https://www.daf.qld.gov.au/plant s/field-crops-and- pastures/broadacre-field- crops/integrated-pest- management/a-z-of-predators,- parasites-and-pathogens/assassin- bugs
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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