Insecticidal Soap Spray
An organic insecticidal soap spray can be purchased from any garden center or made up for any spare clean spray bottle. You can simply drop a bar of castile soap into water overnight. If you have unscented, liquid castile soap, you add a tablespoon of liquid soap to a quart of water. You can also add 1-2 tablespoons of oil to help coat leaves more effectively.
Spray the leaves lightly on both sides. Spray again after rain. It is a good idea to try the spray out on a couple of leaves to make sure you aren't doing any harm and have your proportions correct.
Mix 1 tablespoon potassium bicarbonate and ½ teaspoon liquid castile soap (not detergent) in 1 gallon of water. Spray liberally to all affected areas. Apply once a week for three to four weeks.
This solution acts both as a treatment of existing powdery mildew infections and as a preventative measure.
Serenade Disease Control
Serenade can be used to combat powdery mildew.
Neem oil can be used to treat flea and cucumber beetles, as well as powdery mildew.
BT Bacillus can be used to treat tomato hornworms.
Apply to established gardens at the start of the season and also in July.
An organic liquid fertilizer ( a fish or seaweed emulsion) can be applied directly to the foliage of plants and the plant leaves will absorb nutrients immediately. Follow the instructions for mixing with water then water each plant directly. This type of fertilizer can be used every time you water your plants.
Granular All-Purpose Fertilizer
Distribute this throughout your entire plot as directed on product label, avoiding direct contact with foliage. You can then lightly scratch the granules into the surface for better absorption. This is a slow acting remedy that should be applied every 4 weeks.