Sulfur is the oldest known organic pesticide, used by the Greeks against wheat rusts. Sulfur cooked in water with lime or calcium hydroxide, lime sulfur is particularly useful as a dormant spray -- applied only to dormant woody shrubs or trees, not foliage. Chemical companies and agricultural extension services generally warn farmers and gardeners against making their own lime sulfur, because it is caustic and can burn. In recent memory, however, farmers always made their own, using formulas and procedures supplied by extension staff. This recipe makes lime sulfur in concentrated liquid form -- probably more than you need -- so collaborate with your neighbors.
Find an outdoor area where it will be safe to build a smelly open-air cooking fire; lime sulfur smells like rotten eggs, which close neighbors may find objectionable. Place three blocks on each side of the fire area. Place the metal barrel or pan on top to make sure that the blocks will securely support it during cooking.
Set aside the barrel and build a hot fire with kindling and firewood. Your wood supply needs to keep the fire going for more than 1 hour. Place the barrel on the blocks and pour the water into the barrel. Put the lid on and bring the water to a boil.
Put on all safety gear. Mix the sulfur powder, lime and wood ashes in the 5-gallon container. Slowly pour the dry ingredients into the boiling water, mixing carefully. Keep the brew boiling for at least 1 hour after all ingredients have dissolved.
Check to see if the mixture is “cooked.” The concentrate should be clear amber or red-brown, with yellow sediment and some yellow surface scum. Keep boiling if needed. When it’s done, allow the concentrate to cool completely. Leave the lid on to keep dust, lint and insects out.
Filter the lime sulfur while decanting it into bottles. Cut a plastic bottle in half to use as a scoop. Put pantyhose over the small end of the funnel as a sieve, then place the funnel in the first bottle. Filter the liquid to eliminate impurities. Cap the bottle when it’s full. Continue with the rest of the bottles.
Use lime sulfur spray for different purposes. For fruit trees and grapes, its primary use is as winter dormant spray to control leaf curl, mites, scale and rust. The usual rate of application is 50 milliliters per liter of water, or about 7 ounces per gallon.
Things You Will Need
- Safety goggles or glasses
- Heavy leather work gloves
- Protective clothing and boots
- Dust mask
- 6 to 8 concrete blocks
- 10- to 15-gallon steel drum or steel pan, with lid
- Long, thick stick for stirring
- Good firewood
- 5 gallons plus 1 quart water
- 11 pounds sulfur powder
- 1.1 pounds lime
- 1.1 pounds wood ashes
- 5-gallon container
- Old pantyhose
- Plastic PET bottles with lids
- Always wear long sleeves and pants, protective boots, safety goggles and dust mask, to protect against lung damage and caustic burns.
- Don’t use sulfur spray within one month of using dormant oil spray or you may kill your trees. Also avoid using sulfur sprays if temperatures are above 80 degrees Fahrenheit.
- Some plants don’t tolerate sulfur sprays, including all cucurbits, currants, gooseberries, raspberries and apricot trees.