Not only are pesticides failing to do the work they were designed to do (many insects such as the cabbage root fly and the red spider mite are now resistant to them) but they actually increase disease. Before apple scab was sprayed for, mildew was a little known disease – it is now a major disease because the balance of nature has been upset. Chemical sprays change the internal composition of plants. This makes them more liable to pest and disease attack and wipes out soil organisms, which provide disease controlling anti-biotics and build up plant resistance. Organic foliar sprays work on strengthening the plant at a cellular level making them healthy and therefore more able to resist disease.