How to grow plants without the use of toxic chemicals
Disease - organically treating common diseases of fruit, grass, and flowers
Plants can fend off most disease if they are grown in good soil, getting the right amount of water and light, and grown in a climate which is appropriate. Right plant, right place. If you have a plant with a disease, take a look at what kinds of conditions that particular plant likes, and adjust as best you can the soil, water, light, and temperature to better meet its needs.
To address a current disease problem, first you must identify the disease. If you are having trouble identifying it on your own, take a sample to your local county extension agent or Master Gardener. Here is a link to find your local county extension agent: http://npic.orst.edu/pest/countyext.htm