Han Chhen has farmed at Port Gawler in South Australia for the past 25 years. For ten months of the year the 100-hectare family farm grows broccoli and cauliflower. Brassica planting usually starts in November on the Chhen farm, with potatoes grown over spring. Most of their broccoli and cauliflower crop goes to a major supermarket chain.
Like all brassica growers, diamondback moth can be a major pest issue for Mr Chhen, particularly in warmer months when populations can explode.
After planting, he and his sons monitor crops weekly for diamondback moth and only spray an insecticide once their economic threshold for diamondback moth has been reached. This is critical to their operations as their cauliflower or broccoli will be rejected if they have any damage from diamondback moth as it cannot be sold to the supermarket.
Mr Chhen said at the start of every year they are on the lookout for alternative chemicals that they can use to mix things up to control pests like diamondback moth so as to manage insecticide resistance. As it turns out, Mr Chhen bought the very first drum of Simodis, a novel Group 30 mode of action insecticide, sold in Australia.
“Our CRT (Nutrien Ag Solutions) store told us that Simodis was coming in and I said if it’s a different chemical group then I want to try it,” Mr Chhen said.
“We don’t want to keep using the same chemical groups all the time for diamondback moth and start to get resistance. New products are good, but we still use other modes of action as well because we just don’t want to build up resistance by using only one thing.”
Mr Chhen sprayed Simodis insecticide on his cauliflower crop at 300 mL/ha, five weeks after planting. Three weeks later they sprayed an insecticide from a different group and after another three weeks made a second application of Simodis insecticide at 300 mL/ha. Mr Chhen said he didn’t tank mix Simodis insecticide with any fungicides as he generally doesn’t have disease issues.
“After we sprayed Simodis we checked about a week later and diamondback moth larvae seemed to disappear. It’s always good to have something different to use, to mix up our chemical modes of actions.”
Mr Chhen said cooler than normal temperatures earlier in the year meant the pest pressure from diamondback moth was low. But he is keen to see how Simodis insecticide goes in a season where there is a higher diamondback moth population.
“It was pretty cool in summer really for the time of year, so diamondback moth didn’t have a big explosion. In a warmer year when it’s a bigger problem that will be a good test of Simodis.
“After mid-May we don’t really need to spray for diamondback moth as gets too cold.”
Mr Chhen said Simodis insecticide does cost a little more, but from the few times they have used it he can maybe see a saving in the number of sprays he might have to apply due to the longer residual activity of Simodis.
“The control seemed to last pretty well and the 3-day withholding period is pretty good. If something works then it’s worth it, because maybe you only have to spray two times instead of three times.”
