A very easy spray to make. Simply fill a bucket with nettle, add water and let it sit for a few days until it just starts to ferment. In warmer weather 2 or 3 days should be enough. You want to use it when it just starts fermenting, before it gets mouldy or slimy. Strain the water out into your sprayer and away you go. The best nettle to use is the european stinging nettle Urtica Dioica, if you don't have any growing wild we can supply it here.Nettle contains a lot of silica and is particularly good for grapevines and other sun- loving leafy plants. In biodynamics it's believed that the silica helps plants to process sunlight. It's a great overall tonic for any plant (and for humans too!).
Seaweed is a fantastic tonic for plants, containing an absolute wealth of trace elements and minerals. All the different seaweeds are beneficial, however in my experience big chunky bull kelp gives great results. You will need to wash it down first with a garden hose to get rid of the salt, for example by spreading it on a lawn or driveway. Put it in a bucket- chop it up if it's easier, soak it in water for a few days and strain into your sprayer. Seaweed spray will last quite a long time, but if it starts to go green and slimy, make a fresh batch. Seaweed will feed your plants and also build up their resistance to disease. Great for tomatoes.
Animal manure, particularly horse manure can be made into sprays to use as foliar feed. Horse is the best but cow, sheep and chicken manure all work well. With chicken manure you need to dilute it as it's very strong and acidic. Fill the bottom quarter of a bucket with manure- one tenth if it's chicken manure- add water, let it sit for a couple of days and use as a foliar feed. You can also use it to water around the base of plants.
BT is a bacterium that naturally occurs in the soil. It can be purchased from garden shops and is used as a biological control, primarily for the cabbage white butterfly that attacks brassicas and corn. Although not advertised as such it also works on coddling moth in apples and pears. It comes as a brownish powder that you mix with water, and is most effective in spring when the moths start to appear. It attacks the larvae as they try to make their way to the fruit (or vegetable). BT is approved by Biogro
These are used as fungicides, typically on fruit trees and wine grapes. There are various iterations of these sprays, such as powder or liquid form, lime sulphur, Bordeaux mixture. They are approved for use in organic growing however should be used sparingly as both copper and sulphur will build up in the soil over time. With very heavy use they can become toxic, for example copper toxicity in commercial vineyards. Use them if you need to, but don't over- use them.