Advanced Oxi-Plus (AOP)
Penecillium Spore Bench Test

Penicillium digitatum, the green mold pathogen of citrus, was cultured for 2 weeks at 25C on potato dextrose agar. Spores were collected in water from the surface of the colony, passed through cheese cloth to remove mycelial fragments, and adjusted to about 5,000,000 spores per milliliter. Each test chemical was diluted in a 10 milliliter volume of water at 23C to contain a nine concentration dilution series. The spores in a 0.1 milliliter volume were added to each solution for 10 minutes, then the solution was passed through a glass fiber filter where the spores were trapped. Two more volumes of water, 20 milliliter each, were passed through the spores trapped on the filter to remove the residual of the tested compound. The filter was removed and placed in a test tube with 1 milliliter of sterile water, shaken to remove the spores from the filter, and a 0.1 milliliter droplet of the spore solution was placed on potato dextrose agar. After 18 hours at 23C, the spores were examined with a light microscope to determine if they had germinated. One hundred spores at each compound concentration level were examined. The compound concentration and proportion of germinated spores was used to prepare a Probit regression analysis using SPSS, and the concentrations were 50% and 99% mortality of the spores (with upper and lower 95% confidence limits) estimated using this procedure.

Formaldehyde
50% mortality 1592 ppm (1446, 1742)
99% mortality 3481 ppm (3174, 3897)

AOP
50% mortality 32.5 ppm (29.3, 36.6)
99% mortality 88.3 ppm (77.5, 103.6)

Hydrogen peroxide
50% mortality 676 ppm (610, 745)
99% mortality 1690 ppm (1537, 1893)
Concentrations (mg/L) of sanitizer that inhibit 50% (EC50) or 99% (EC99) of germination of conidia of P. digitatum exposed to them for 10 min at 23 C. Germination was determined after incubation on potato dextrose agar for 18H. Concentrations and 95% confidence intervals (Cl) were estimated using Finney’s Probit analysis.

 

ChemicalEC5095% CLEC5095% CL
Clutaraldehyde12431116-137227742503-3157
Formaldehyde12001023-139225022237-3140
Peroxide676610-74516911537-1893
Chlorine44.331.1-60.3116.691.1-173.7
AOP9.44.9-16.525.317.7-56.1

This testing was conducted by:

Joe SmilanickDavid Sorensen
USDA-ARSFruit Growers Supply
San Joaquin Agriculture Science Center674 E. Meyer
9611 South RiverbendExeter, CA 93221
Parlier CA 93648