Thursday, 11 August 2016

Weekly Update (August 10, 2016; Wk 15) - Swede midge

Swede midge (Contarinia nasturtii) - The Swede midge bioclimate model was run for Melfort for 2015 and 2016 (April 1 – August 7). For 2015, model output indicated that the 2015 growing season would have resulted in two generations by the first week in August (first graph below).  For 2016, model output indicated that there has been potential for four generations in the 2016 growing season (second graph below). The extra generations in 2016 are explained by timing of rainfall. Adult emergence is delayed until a) the required number of degree-days are achieved and b) after at least 10 mm of rain has occurred (over a 7 day period). In 2015, low rainfall during April and May resulted in delayed emergence with first adults emerging in early June. A dry period in late June/early July was predicted to delay adult emergence until mid-July.  In 2016 May rainfall was predicted to result in adult emergence occurring during the second week of May and subsequent emergence in mid-June, mid-July and early August.