Aphid control measures differ, depending on whether you’re dealing with Mealy Cabbage Aphid or the Green Peach Aphid
Too often, I receive calls from growers confused by poor aphid control, highlighting why it is vital to correctly identify the species before deciding on aphid control measures.
Once again the hotter, drier conditions at this time of year seem to bring increased aphid pressure particularly in brassicas.
Mealy Cabbage Aphids
Small, compact colonies of Mealy Cabbage Aphids are very easily identified particularly on canola, and area easily taken out with Pirimor (pirimicarb). Apply as a fine spray quality when temperatures are above 16 degrees to get the best control. Pyrethroids such as lambda-cyhalothrin and deltamethrin tend to be highly variable in their control, as is chlorpyrifos.
Green Peach Aphid
The Green Peach Aphid is harder to spot, and also harder to control. Most are resistant to Pirimicarb and pyrethroids, so neonicotenoid containing products such as thiamethoxam, acetamiprid and imidacloprid are usually required.
Problem is, if there are any flowers in the crops and Bees are present you should avoid these at all costs. Secondly control in my trials is 40% at best – probably due to the difficulty of achieving good coverage underneath the pods.
Sulfoxaflor has also been examined in our trials which is highly selective and safe to beneficial insects, but has rarely given above 50% control for me, even at 4.5 Bar pressure with a 015 angled nozzle. The last trial I did just last week was below 25% control in fact! Flonicamid has not been extensively trialled yet but is worth trying.
Thankfully, unless Green Peach aphids are present in particularly high numbers they are rarely worth spraying, especially if they build up towards the end of pod fill. Mealy Cabbage Aphids on less than 5% of plants can be economically damaging – just do NOT mix pirimicarb with triazole fungicides if bees are active in the crop.
Finally, remember that Ladybird larvae, Ground Beetles, Rove Beetles, Parasitoid Wasps and Spiders all predate aphids, so the more selective the product you can use, the better.
Farming for the future requires a change of approach. Monoculture, soil degradation and climate change and soil degradation are threats to the future of how we feed the planet. Agventure Ltd set up the Center of Excellence for Crop Rotation to help farmers diversify cropping systems and introduce techniques which have a long-term outlook to improve soil health. The Center of Excellence for Crop Rotation works extensively with Crop Nutrition Laboratory Services Ltd (CropNuts).
Till next time,
David Jones is the Broad Acre Specialist at Crop Nutrition Laboratory Services Ltd. (CROPNUTS). David has a keen interest in soils and no till farming systems where he has undertaken work looking into weed levels and changes in soil structure, and has extensive experience in field trials and in the development of precision farming techniques. In his spare time he enjoys playing rugby.