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© 2005 Plant Management Network.
Accepted for publication 14 February 2005. Published 16 February 2005.

Impact of Scholar (A New Post-harvest Fungicide) on the California Pomegranate Industry

Eric C. Tedford, Syngenta Crop Protection, 2261 Lava Ridge Court, Roseville, CA 95661; James E. Adaskaveg, Department of Plant Pathology, University of California, Riverside 92521; and Alex J. Ott, California Grape and Tree Fruit League, Suite 120, 1540 E. Shaw Avenue, Fresno 92710

Corresponding author: E. C. Tedford.

Tedford, E. C., Adaskaveg, J. E., and Ott, A. J. 2005. Impact of Scholar (a new post-harvest fungicide) on the California pomegranate industry. Online. Plant Health Progress doi:10.1094/PHP-2005-0216-01-PS.

Gray mold, caused by Botrytis cinerea, is a fungal disease that can be a serious threat to the pomegranate industry. In the 1999 and 2000 growing seasons, gray mold destroyed approximately 30% of California’s harvested pomegranates (5). California pomegranate packers had difficulties storing fruit for two to three weeks, let alone the goal of two to three months of storage that they needed to reach holiday markets from November to January around the world. Costs associated with repackaging, box losses, and price discounts, as well as crop rejections by retailers, almost destroyed California’s pomegranate industry.

Fig. 1. (A) Healthy pomegranate fruit showing the crown with the blossom parts. (B) Fruit with gray mold decay starting from the crown of the fruit.


The pathogen B. cinerea infects the stamens and pistils of pomegranate flowers during and after the bloom period. Although some fruit infections will develop in the field, most infections remain latent (Fig. 1A) until the fruit mature and become more susceptible. With postharvest washing to clean and surface-sanitize the fruit, the flower parts in the crown become wet. The pathogen is re-activated and initiates fruit decay from the blossom infections. Pomegranate storage conditions in packinghouses at 41 to 45°F (5 to 7°C) and relative humidity levels of around 95% are favorable for gray mold development, and thus fruit decay in storage can proceed quickly (Fig. 1B).

In 2001, Scholar, a new postharvest fungicide containing the active ingredient fludioxonil, received a Section 18 emergency exemption registration from the United States Department of Agriculture (USDA) for use on pomegranate in California (1). With this, a postharvest treatment was registered on this crop for the first time (2). Emergency registrations were again granted in 2002, 2003, and 2004. The fungicide is currently under full review, and a full Section 3 registration is expected in 2005. Fludioxonil has a broad spectrum of activity that includes gray mold and other postharvest fungal diseases and is classified by the United States Environmental Protection Agency (US-EPA) as a "reduced risk" fungicide. With no planned preharvest registrations due to its rapid degradation in ultraviolet light and with only one postharvest application labeled for use, the fungicide should be effective as a postharvest fungicide for many years without resistant populations of B. cinerea or other fungi developing.

Postharvest application methods and equipment had to be developed because the infected flower parts of the pomegranate fruit that are protected by the sepals (crown) are not easily accessible by conventional postharvest application methods, such as high- and low-volume sprays. Fruit dips in fungicide solutions where the fruit crowns are immersed with the treatment and excess solution is allowed to drain were found to be the most effective (2). With these treatments, fruit losses due to gray mold were reduced substantially (Fig. 2). Thus, in 2003, 5% of the harvested crop was lost as compared to the previous average of 30% lost in 1999 to 2002 when postharvest treatments were either not available (1999 and 2000) or were not widely used because most packinghouses had not installed treatment equipment (2001 and 2002) (Adaskaveg, personal communication; Table 1). As a direct result, the crop yield (boxes per acre) in 2003 increased by 66.9% and the gross revenue increased by 61.8% as compared to the average yield and average revenue from 1999 to 2002, respectively.


Fig. 2. (A) Untreated pomegranate fruit and (B) fruit treated with Scholar for management of gray mold decay caused by Botrytis cinerea.


Table 1. Economic data for the California pomegranate industry for seasons without (1999-2002) and with (2003) common usage of Scholar for management of gray mold.x

Year Yieldy


Packing and

1999 322 7,071 3,315 3,756 3,410 346
2000 279 5,842 3,350 2,492 2,955 -463
2001 298 5,843 3,517 2,326 2,989 -663
2002 357 7,001 3,600 3,401 3,288 113
2003 524 10,417 3,960 6,457 3,616 2,841

 x Source: grower/processor surveys. Data only available for 1999 to 2003.

 y Pack-out yield of fruit for fresh market. With no postharvest fungicide treatment, 30% of the pack-out yield was lost due to gray mold from 1999 to 2002. With the use of Scholar, 5% of the pack-out yield was lost due to gray mold in 2003.

 z Costs include expenses for re-packing, re-cooling, palletizing, lost boxes, charges for packing even though the fruit is culled, lost revenue due to rejections by buyers, and fungicide treatments.

Profitability to the California pomegranate industry was also regained through an extended storage life of the Scholar-treated fruit. Thus, fruit can now be stored for up to five months as compared to approximately one month before use of the fungicide. This now vastly extends the marketing potential of this fruit of passion. Thus, Scholar has not only reduced the threat of gray mold for the pomegranate industry, but it also revolutionized the industry with the prospects of new marketing opportunities. At the same time, pomegranates are now getting a high visibility to the public through a number of human health benefits due to pharmacological and therapeutic properties of some of the fruit constituents in preventing cancer (3,4). An estimated 9,000 acres of pomegranates are currently grown in California with more plantings planned by some of the large producers.

Literature Cited

1. Adaskaveg, J. E. 2001. Pomegranate postharvest fungicide update. Central Valley Postharvest News 10:4-6.

2. Adaskaveg, J. E., and Förster, H. 2002. Management of gray mold of pomegranates caused by Botrytis cinerea using two reduced-risk fungicides, fludioxonil and fenhexamid. Phytopathology 93:S130.

3. Kim, N. D., Mehta, R. Yu, W., Neeman, I., Livney, T., Amichay, A., Poirier, D., Nicholls, P., Kirby, A., Jiang, W., Mansel, R., Ramachandran, C., Rabi, T., Kaplan, B., and Lansky, E. 2002. Chemopreventive and adjuvant therapeutic potential of pomegranate (Punica granatum) for human breast cancer. Breast Cancer Res. Treat. 71:203-217.

4. Lansky, E., Shubert, S., and Neeman, I. 2000. Pharmacological and therapeutic properties of pomegranate. Production, processing and marketing of pomegranate in the Mediterranean region: Advances in research and technology. Proceedings of the symposium jointly organized by CIHEAM and Escuela Politecnica Superior de Orihuela of the Universidad Miguel Hernandez (EPSO-UMH), Orihuela, Spain, 15-17 October 1998. Options-Méditerranéennes. Serie-A, Séminaires Mediterranéen 42:231-235.

5. Ott, A. 2001-2004. Emergency exemption petition for the post-harvest use of fludioxonil (Scholar Fungicide®) on pomegranates in the Southern San Joaquin Valley of California. Issued by the California Department of Pesticide Regulation and the United States Environmental Protection Agency.