Abstract: In some embodiments of the apparatus detects the concentration of a substance selected from the group consisting of hydrogen peroxide, peroxyacetic acid, chlorinated compounds and other aqueous oxidizer compounds. The light source may be a laser, or light emitting diode. The source may be part of a transmitter and the detector may be part all of a receiver. The apparatus may further include a data logger cooperating with the light detector. The enzyme coated strip may be a strip coated with catalase and the the strip may be an inert paper. In some cases the enzyme coated strip changes color as a function of the concentration of the substance. The apparatus may further including fiber-optic cable cooperating with said light detector to detect transmitted light from the enzyme coated strip and a fiber-optic cable and/or a fiber optic cable cooperating with said source to direct light on the enzyme coated strip.

Abstract: A method for nonselective killing of weeds which includes providing a quantity of sodium carbonate peroxyhydrate; providing a quantity of a surfactant; mixing the surfactant and the sodium carbonate peroxyhydrate with water; providing foaming apparatus for generating a foam; generating a foam from the mixture of surfactant and sodium carbonate peroxyhydrate; and applying the foam to plants to be killed. In some forms of the present invention the ratio of sodium carbonate peroxyhydrate to water is at least one half of 1 pound per gallon of water. In still other forms of the invention the ratio of sodium carbonate peroxyhydrate to water will be less than 3 pounds per gallon of water. In still other forms of the invention the ratio of sodium carbonate peroxyhydrate to water will be about 1 pound per gallon of water.