Influence of fungicides and Phytophthora capsici resistant/tolerant cultivars on bell pepper yield and farm-gate revenues

Abstract: Phytophthora blight, caused by Phytophthora capsici Leonian, is a widespread and destructive disease of bell pepper (Capsicum annuum L.). Bell pepper yield, farm-gate revenues and Phytophthora blight incidence were determined during 2005 and 2006 in a P. capsici-infested field near Shawneetown, Illinois. The study evaluated 12 bell pepper cultivars (one resistant, three tolerant, and eight susceptible to P capsici) with or without a recommended fungicide treatment (mefenoxam at transplant and dimethomorph + copper alternated with manganese ethylenebisdithiocarbamate + copper at 10 day intervals). Bell pepper plants receiving fungicide applications showed less Phytophthora blight incidence throughout the growing season and produced greater yield and farm-gate revenues compared to untreated plants. Additionally, P capsici-resistant 'Paladin' and P capsici-tolerant 'Alliance', 'Aristotle X3R', and 'Revolution' produced greater yields (> 17,800 and 33,800 kg ha^-1 for 2005 and 2006, respectively) and farm-gate revenues [> $12,700 and $27,000 (USA) ha^-1 for 2005 and 2006, respectively] compared to the susceptible cultivars. Therefore, in fields with a high incidence history of Phytophthora blight, 'Paladin' could be a reliable choice for commercial bell pepper production. However, 'Alliance', 'Aristotle X3R', and 'Revolution' may be preferred by growers due to the added benefits of bacterial spot [Xanthomonas campestris pv. vesicatoria (Doidge) Dye] resistance and better fruit quality compared to 'Paladin'. Furthermore, this research indicates that plant resistance and/or tolerance should not be relied upon as the only method of P capsici control and growers should also incorporate fungicides into their management program to provide additional protection.