Compost Tea: A basic product used to build soil structure, add to the organic matter content of the soil and helps hold valuable nutrients in the soil. This tea is made from the leachate of compost and may be the best foliar feeding tool of all. It is not only an effective foliar fertilizer, it has powerful insect ñ and disease ñ control properties. The humic materials and microorganisms in compost tea are effective on many pests. German researchers studied the effects of compost tea, but gardeners have known its beneficial properties for years. Common fungal problems like black.