In the United States, 56,200 acres of bell pepper were planted in 2011, with a total production value of just under $685 million [U.S. Department of Agriculture (USDA), 2012b]. However, desirable traits vary from region to region, based on a variety of factors, including the growing conditions in the region (e.g., climate and predominant soil type), major diseases affecting the region, the market for which peppers are grown (e.g., fresh vs. processing), and whether fruit will be harvested green or when reaching their mature color (e.g., red or yellow) (Crosby, 2008). This results in different varieties being preferred by growers in different parts of the country. For example, ‘Revolution’ yielded well in a Pennsylvania trial (Sánchez et al., 2011), but performed poorly in Maine where the growing season is shorter and generally cooler (Hutton and Handley, 2007).
In New York State, the majority of fruit are harvested green. Production was valued at $9.9 million in 2010 (the last year for which data are available) on 1200 acres (including upstate and Long Island), and all are grown for the fresh market (USDA, 2012a). For fresh market, not only total yield but also fruit size, shape, and appearance affect the value of the crop and are important characteristics when New York growers select a bell pepper variety. For the highest grades, USDA standards require that fruit be at least 2.5 inches (for U.S. No. 1 grade) or 3 inches (for U.S. Fancy grade) in diameter, free from damage or injury, and not misshapen (USDA, 2005). In addition, early-yielding plants with fruit that are blocky, larger (4 inches diameter), thick walled, and have four lobes are increasingly desirable for fresh market production in the United States. (Crosby, 2008).
One abiotic disorder that can reduce the value of bell pepper fruit or make it completely unmarketable is skin separation, often called “silvering.” These mottled patches of white or silver on the fruit surface are superficial but can reduce marketability, especially if they cover large areas of the fruit (Kline et al., 2011). One study reported up to 66% of fruit affected by silvering on a single harvest date (Wyenandt and Kline, 2006). Previous work has shown that incidence of silvering can vary by harvest date, field site, and the rate and type of fertilizer applied, but pepper variety appears to be the most important and consistent factor (Kline et al., 2011). Interestingly, fruit silvering tends to be more common on bell pepper varieties with tolerance to the disease phytophthora blight, whereas it is less common on more susceptible varieties (Kline et al., 2011).
Phytophthora blight is a soilborne disease caused by the oomycete Phytophthora capsici (Leonian, 1922). Once phytophthora blight is on a farm, it is essentially impossible to eradicate from the soil and can result in severe yield losses in pepper because of fruit rot and plant death (Granke et al., 2012). This disease may have been introduced to New York State as early as the mid-1930s, when infected watermelon (Citrullus lanatus var. lanatus) fruit shipped from Colorado were observed in New York City markets (Wiant and Tucker, 1940). It is now present on many New York vegetable farms (Dunn et al., 2010), in vegetable production regions across the United States and around the world (Granke et al., 2012). Because of the large host range [including eggplant (Solanum melongena), tomato (Solanum lycopersicum), snap bean (Phaseolus vulgaris), and cucurbits (Cucurbitaceae)] and the increasing prevalence of insensitivity to fungicides (Dunn et al., 2010; Jackson et al., 2012; Keinath, 2007), host resistance is a key component to successful management of phytophthora blight. Many commercial bell pepper varieties with varying levels of tolerance to phytophthora blight are available, including ‘Paladin’ (highly tolerant but not completely immune), ‘Revolution’, and ‘Aristotle’ (both showing intermediate levels of tolerance) (Foster and Hausbeck, 2010; McGrath and Fox, 2009). The genetic basis of this tolerance is not clearly understood, but involves multiple genes (Ortega et al., 1992), with tolerance to different disease symptoms (i.e., stem and root rot, fruit rot, or leaf lesions) being conferred by different genes (Sy et al., 2005).
Like all plant diseases, the severity of phytophthora blight in any year depends on inoculum abundance, the presence of a susceptible crop, and the occurrence of favorable environmental conditions. These conditions include warm air temperatures (Mchau and Coffey, 1995) and periodic flooding or soil saturation events (because of heavy rainfall, overirrigation, or poor soil drainage) (Bowers and Mitchell, 1990). Therefore, predicting disease pressure before the season begins is difficult. If bell pepper varieties with tolerance to phytophthora blight have less desirable traits (e.g., fruit silvering or smaller fruit size), then growers will need to weigh this information against the history of disease severity (and probable inoculum level) in their fields. The objectives of this study are to 1) determine which commercial bell pepper varieties have the best combination of yield, fruit quality traits, and tolerance to phytophthora blight when grown under conditions similar to those on vegetable farms in upstate New York (i.e., relatively heavy soil and moderate temperatures), in the presence and absence of disease pressure, and 2) compare phytophthora-tolerant pepper breeding lines to commercially available varieties.
We thank Holly Lange and Maryann Fink-Brodnicki for technical assistance. Support for Amara R. Dunn was provided by a fellowship from Cornell University College of Agriculture and Life Sciences. The project was funded through a grant from the NY State Department of Agriculture and Markets Specialty Crop Block Grant. Support for Lindsay Wyatt was provided by a Cornell University Presidential Life Sciences Fellowship and USDA National Needs Graduate Fellowship Competitive Grant No. 2008-38420-04755 from the National Institute of Food and Agriculture.
Bowers, J.H. & Mitchell, D.J. 1990 Effect of soil-water matric potential and periodic flooding on mortality of pepper caused by Phytophthora capsici Phytopathology 80 1447 1450
Crosby, K.M. 2008 Pepper, p. 221–248. In: J. Prohens and F. Nunez (eds.). Vegetables II. Springer, New York, NY
de Mendiburu, F. 2012 Statistical procedures for agricultural research. Version 1.1-3. 11 Apr. 2012. <http://tarwi.lamolina.edu.pe/∼fmendiburu>
Dunn, A.R., Milgroom, M.G., Meitz, J.C., McLeod, A., Fry, W.E., McGrath, M.T., Dillard, H.R. & Smart, C.D. 2010 Population structure and resistance to mefenoxam of Phytophthora capsici in New York State Plant Dis. 94 1461 1468
Foster, J.M. & Hausbeck, M.K. 2010 Resistance of pepper to Phytophthora crown, root, and fruit rot is affected by isolate virulence Plant Dis. 94 24 30
Fox, J. & Weisberg, S. 2011 An R companion to applied regression. 2nd ed. Sage Publ., Thousand Oaks, CA
Granke, L.L., Quesada-Ocampo, L., Lamour, K. & Hausbeck, M.K. 2012 Advances in research on Phytophthora capsici on vegetable crops in the United States Plant Dis. 95 1588 1600
Jackson, K.L., Yin, J. & Ji, P. 2012 Sensitivity of Phytophthora capsici on vegetable crops in Georgia to mandipropamid, dimethomorph and cyazofamid Plant Dis. 96 1337 1342
Keinath, A.P. 2007 Sensitivity of populations of Phytophthora capsici from South Carolina to mefenoxam, dimethomorph, zoxamide, and cymoxanil Plant Dis. 91 743 748
Kline, W.L., Wyenandt, C.A., Ward, D.L., Sudal, J.F. & Maxwell, N.L. 2011 Evaluation of six nitrogen fertility programs on marketable yield and development of skin separation in bell pepper fruit HortTechnology 21 323 328
McGrath, M.T. & Fox, G.M. 2009 Evaluation of Phytophthora-resistant bell pepper cultivars with and without a fungicide program, 2008 Plant Dis. Mgt. Rpt. 3 V132
Mchau, G.R.A. & Coffey, M.D. 1995 Evidence for the existence of two subpopulations in Phytophthora capsici and a redescription of the species Mycol. Res. 99 89 102
Ortega, R.G., Español, C.P. & Zueco, J.C. 1992 Genetic relationships among four pepper genotypes resistant to Phytophthora capsici Plant Breed. 108 118 125
R Development Core Team 2012 R: A language and environment for statistical computing. 11 Apr. 2012. <http://www.R-project.org/>
Ristaino, J.B. & Johnston, S.A. 1999 Ecologically based approaches to management of Phytophthora blight on bell pepper Plant Dis. 83 1080 1089
Sánchez, E.S., Butzler, T.M., Bogash, S.M., Elkner, T.E., Oesterling, R.E., Orzolek, M.D. & Stivers, L.J. 2011 Pennsylvania statewide bell pepper cultivar evaluation HortTechnology 21 384 390
Sy, O., Bosland, P.W. & Steiner, R. 2005 Inheritance of Phytophthora stem blight resistance as compared to Phytophthora root rot and Phytophthora foliar blight resistance in Capsicum annuum L J. Amer. Soc. Hort. Sci. 130 75 78
U.S. Department of Agriculture 2005 United States Standards for Grades of Sweet Peppers. 31 Dec. 2012. <http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELPRDC5050318>
U.S. Department of Agriculture 2012a New York Agriculture Statistics Annual Bulletin 2012. 29 Dec. 2012. <http://www.nass.usda.gov/Statistics_by_State/New_York/Publications/Annual_Statistical_Bulletin/2012/2012-bulletin.htm>
U.S. Department of Agriculture 2012b Vegetables Summary 2011. 29 Dec. 2012. <http://usda01.library.cornell.edu/usda/current/VegeSumm/VegeSumm-01-26-2012.pdf>
Wyenandt, C.A. & Kline, W.L. 2006 Evaluation of skin separation (silvering) in fruit of bell pepper cultivars HortScience 41 494 (abstr.)