I have been using Gemstar NPV Virus for the control of Helicoverpa caterpillar in my organically certified corn, broccoli and lettuce crops but have had mixed results because the virus will die too quickly in hot dry conditions. To provide the moisture to keep the virus alive for the three days necessary to produce a complete kill, I decided to add Absorbacide (ultra‐fine diatomaceous earth) at 50 kilograms per hectare . The Absorbacide is a registered organic input and is not only a physical insecticide, it also preferentially holds and retains water within the skeletal remains of the individual diatoms.
The Absorbacide was mixed with water in a 1000 litre agitation tank and the virus added. I have trialled the mix on my Corn crop with surprisingly good results. My agronomist has declared it an exceptional result. It would appear that when the diatomaceous earth settles on the leaf it may appear to look dry but enough moisture is still retained within the diatoms that the virus can stay alive and remain affective, even in very hot and dry conditions.