In 2011, many sunflower crops in New South Wales and Queensland were severely defoliated by loopers. In some instances the defoliation reached close to one hundred percent of the leaf area. The rapidity of the defoliation caught many agronomists unaware, with crops defoliated between checks. There are currently no thresholds for loopers in sunflower, mainly because loopers are a sporadic pest, and in most instances cause minor levels of defoliation. In response to the deficiency in information on looper thresholds, we have conducted trials in 2012 to develop preliminary thresholds for loopers in sunflowers. The sporadic nature of looper outbreaks makes undertaking threshold work in the field, with loopers impossible. The trials have used artificial defoliation to simulate looper damage. Defoliation rates of 0, 25, 50, 75 and 100% of total leaf area were applied to a sunflower crop at V12, R1, R3, R5 and R9. Yield was affected at the higher level of defoliation (75-100%) at R1-R5. Oil content was significantly reduced only for the 100% defoliation treatment at R3-7. Consumption trials will clarify the defoliation rate of individual larvae over their lifetime, and form the basis of the preliminary threshold.
The management of other key insect pests (Helicoverpa and Rutherglen bug) will be discussed.