California Pepper Commission


Prince Powdery Mildew in Pepper (2014)

REVISED 2/24/13
Biocontrol of Powdery Mildew in Pepper Using AQ10 and Sulfur
James P. Prince
College of Natural Sciences
CSU Chico
Chico, CA 95929

Update on progress:

We have obtained a rally-resistant strain of powdery mildew and, after some difficulty, have successfully inoculated a genotype of susceptible pepper plants to establish a working culture of the fungus. Preliminary control experiments show no damage from AQ10 or sulfur alone. Effect of AQ10 or sulfur on PM has not yet been assessed. Plants are being grown to finish all experiments (see grid, below). Target date for completion: June 2014.

Plans to finish up project:

Sporodex is no longer available. The grid of experiments has been changed to include AQ10 (Ampelomyces quisqualis) and sulfur in different combinations (see below).

Materials and Methods

Inoculations with L. taurica. Plants are being inoculated with aqueous spore suspensions of the Rally-resistant strain of L. taurica prepared according to Suliman et al. (1999).

Biocontrol agents and applications. AQ10 (Ampelomyces quisqualis) will be obtained from Ecogen Corp. (Langhorne, PA). Each will be prepared according to its manufacturer's instructions and sprayed onto plants at weekly intervals for 3 weeks.

Experimental design. The following seven treatments will be laid out in the greenhouse at Fresno State in a randomized block design (with 5 plants for each treatment block, replicated four times):

(No PM control)
(AQ 10 alone)
(sulfur alone)
(PM + AQ10, "before")
(PM + AQ10, "after")
(PM + sulfur, "before")
(PM + sulfur, "after")
Powdery mildew---++++
applied before PM
applied after PM
applied before PM
applied after PM

Disease scoring and statistical analysis. The proportion of leaves infected per plant and the sporulation intensity per leaf (Lefebvre et al., (2003) will be scored twice a week starting 3 days post-inoculation. Results will be analyzed by ANOVA.


Cerkausaska, R. 2004. Pepper diseases: powdery mildew. AVRDC Publication 04-580.

Curtis et al. 2004. Management of powdery mildew, Leveillula taurica, in greenhouse peppers.

Falk, S.P., Gadoury, D.M., Pearson, R.C., and Seem. R.C. 1995a. Partial control of grape powdery mildew by the mycoparasite Ampelomyces quisqualis. Plant Dis. 79:483-490.

Falk, S.P., Gadoury, D.M., Cortesi, P., Pearson, R.C., and Seem, R.C. 1995b. Parasitism of Uncinula necator cleistothecia by the mycoparasite Ampelomyces quisqualis. Phytopathology 85:794-800.

Koike, S.T., Davis, R.M., Subbarao, K.V., and Falk, B.W. 2010. UC IPM Pest Management Guidelines: Peppers. UC ANR Publication 3460.

Konstantinou-Doltsinis, S., Markellou, E., et al. 2007. Control of powdery mildew of grape in Greece using Sporodex L and Milsana. J. Plant Diseases And Protection 114:256-262.

Lefebvfre, V., Daubeze-A.-M., Rouppe van der Voort, J., Peleman, J., Bardin, M., and Palloix, A. 2003. QTLs for resistance to powdery mildew in pepper under natural and artificial conditions. Theor. Appl. Genet. 107:661-666.

Smith, R., Koike, S, Davis, M., Subbarao, K., and Laemmlen, F. 1999. Several fungicides control powdery mildew in pepper. California Agriculture 53(6):40-43.

Suliman, M.E., Bardin, M., Daubeze, A.M., Mohamed, Y.F., and Nicot, P.C. 1999. Aggressiveness of Leveillula taurica on pepper. Capsicum/Eggplant Newsletter 18:83-86.

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