We got pulled up by the Soil Association inspector last month for using diluted Ecover soap to deal with aphids. We were told we could only use ‘Savona’ branded soap. Looked it up – they stopped selling it in the UK years ago. Called up the Soil Association again – then told to use ‘Safers’ branded soap. I think this comes from Canada and can’t find a seller for it in the UK.
Would love to know what youz folks are using and where you get it from so I can fill in this annual plan form for our certification officer and have something in the armoury for when mealy aphid invades our brassicas in spring before the ladybirds appear.
I wound up using pyrethrum for dealing with aphids where crop covers were impractical or failed to stop them, it proved far more effective than soft soap ever did, I gave up on Savona a long time before it was removed.
It’s pretty nasty stuff though and will kill everything including bees, so can’t be used if anything is flowering including weeds and ideally should be applied late in the day.
I’ve also found it leaves a residue on sprayed leaves in lettuces and if applied while sunny can burn pak choi and salad crops (in the tunnel with the doors closed to keep bees out), so I’d usually spray it on, leave for a short while to do its job (it kills aphids and flea beetles in minutes) and then irrigate to wash it off.
A little goes a long way, I bought 500mL years ago, and it’s still over half full.
I think Majestik is still available too, it is made from a dextrose sugery type substance and works well at blocking spiracles!! Also mycotal is a biopesticide sold for whitefly which can also help control aphid when temp and humidity are high enough. Vertilec was more effective on aphid but i think is now unavailable. It can be used with the adjuvant ‘additt’. These all require derogation but, certainly mycotal, are less toxic than either savona or pyrethrum.
I grow limnanthes/poached egg amoung our spring greens and early kale, they bring the hoverfly in a treat tho perhaps not early enough? Elliot Coleman suggests that high N levels in protected soils coming out of Winter can drive up pest pressure as growth is very sappy (p185 Winter Harvest Handbook). He reccomends irrigating well before the soil starts to warm up to counter the lack of N leaching that occurs with minimal watering and low crop uptake through Winter. It’s a tricky balence though as you don’t want to wash all the fertility away or unessecarily increase moisture/humidity at that time. I tend to do a couple of good morning soaks mid Feb if I’ve got plenty of rainwater spare and there’s a spell of dry breezy weather. As the soil warms up more N is released assuming you have high organic matter. I wouldn’t do it on a clay soil mind!