This beautiful butterfly is no fairy. The larvae of the white cabbage moth and her wicked step-sister, the diamond backed moth, can decimate brassica crops in days. The only way to control the diamond-backed wrigglers is to spray and spray and spray. Every five to seven days for the life of the crop! I’m no buddhist but this is a level of chemical use that scares me (and blows any hope of profitability at the same time).
For this reason, I’m falling out of love with rape. This obscenely-named brassica has long been the darling of dry-land dairy farmers. We’ve come to rely on it for high-quality lush green feed in the height of summer; when little else worthy of our cows’ refined (read “udderly spoilt”) palates will grow without irrigation.
I used to stagger plantings over a dozen hectares of brassicas to provide a constant feed source from January through to early March. Not any more. I’ve planted the oat paddock with Hunter rape and that’s it. Unlike the more hardy Winfred variety, Hunter is safe to graze at any age and when the larvae get a wriggle on, I’ll simply send in the cows and let the caterpillars have the rest. No spraying, no searching under leaves for stealthy marauders and no cow health worries.