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
Amara R. Dunn, Lindsay E. Wyatt, Michael Mazourek, Stephen Reiners and Christine D. Smart
Nathan Shoaf, Lori Hoagland and Daniel S. Egel
Worldwide vegetable production valued at over $1 billion each year is threatened by phytophthora blight ( Lamour et al., 2012 ). This devastating disease is caused by P. capsici, a soil-borne oomycete pathogen that can infect a wide variety of
Regina P. Bracy, H. Hobbs and D. Dufresne
Field studies were conducted in 1993, 1994, and 1995 to evaluate chemical and biological agents for control of phytophthora blight in bell peppers grown on polyethylene-mulched raised beds. Treatments included Kocide 606 (foliar applied), Ridomil 2E (soil applied), Ridomil 2E (directed spray), Ridomil/Copper 70W (foliar), Ridomil 2E (soil) + Ridomil/Copper 70W (foliar), fluazinam (soil/foliar), and Actinovate bioconcentrate (seedling media applied). The experimental area was inoculated with Phytophthora 2 weeks after transplanting. All plants were rated for disease incidence (number of plants exhibiting visual symptoms) beginning at inoculation and continuing every week for 5–6 weeks. Disease incidence was severe in 1993 and 1995. None of the chemical or biological agents had an effect on total marketable yields or fruit weights during the three years. Disease ratings were highest in the control, Ridomil 2E (soil), and Actinovate plots. Yields did not reflect the severe disease infestation that occurred in some plots, possibly because greatest disease incidence occurred late in the season. Best Phytophthora control was obtained from chemical treatments containing copper compounds (Kocide and Ridomil/Copper 70W).
Juan Carlos Díaz-Pérez
of this study were to evaluate the effects of shade level on incidences of Phytophthora blight and Tomato spotted wilt, fruit mineral nutrient content, bell pepper fruit yield, quality, and postharvest attributes. Materials and Methods The study was
H. Matsunaga, T. Sato and S. Monma
Thirty-one Capsicum accessions collected in Ghana and 20 Capsicum accessions introduced from Sri Lanka were evaluated for resistance to bacterial wilt and to Phytophthora blight. In the evaluation of resistance to bacterial wilt, 12 seedlings per accessions were transplanted to the infected field with Pseudomonas solanacearum. Subsequently, an inoculum suspension was poured into the soil at the base of each plant with root wounding. Disease severity of each plant was evaluated using a symptom index of 0 (no symptoms) to 4 (death) scale at 10 weeks after inoculation. In the evaluation of resistance to Phytophthora blight, 20 seedlings per accession were transplanted into a bed, the soil temperature of which was maintained at 28°C after root-dipping inoculation. Disease severity of each plant was evaluated using a symptom index of 0 (no symptoms) to 2 (death) scale at 2 weeks after inoculation. To bacterial wilt, two Ghanaian accessions and 10 Sri Lankan accessions had no symptoms and nine Ghanaian accessions and six Sri Lankan accessions showed some wilted plants, but their disease indices were less than 1. The accessions were regarded as resistant. To Phytophthora blight, two Ghanaian accessions and four Sri Lankan accessions were regarded as weakly resistant. Remaining accessions were regarded as susceptible. `GJ93/287' collected in Ghana and `Nil miris', `MI 1', `KA 11', introduced from Sri Lanka, were resistant to bacterial wilt and weakly resistant to Phytophthora blight.
W.R. Jester, M. L. Adams and G. J. Holmes
The experiment was conducted at the Cunningham Research Station in Kinston, N.C. (coordinates: N35 18.372; W77 34.937), on Goldsboro loamy sand. Three cultural systems (bare ground + overhead irrigation bare ground + drip irrigation, black plastic + drip irrigation) and seven fungicide treatments were evaluated in a split-plot design with cultural system as the main plot and fungicide treatments as subplots. The cultivar used was `Mickey Lee'. The trial was installed 18 July. Soil moisture was monitored in each of the cultural regimes using soil moisture sensors (Spectrum Technologies, Inc, Plainfield, IL) and rain gauges. The cultural systems using drip irrigation were irrigated to 10 cb starting when soil moisture reached 40 cb. Overhead irrigation was used to maintain at least 2 inches per week total precipitation beginning 12 Aug. Cultural systems and fungicide treatments were replicated 4 times. To prevent gummy stem blight and powdery mildew, Pristine (14.5 oz/acre) and Quintec (6 oz/acre) were alternated with Bravo Weather Stik (2 pt/acre) and Flint (4 oz/acre) on a 7-day interval, beginning 16 Aug. Experimental fungicide treatments were applied using a CO2 backpack sprayer equipped with a 3-nozzle (19-inch spacing) handheld boom with hollow cone nozzles (TXVS-26) delivering 40 gal/acre at 45 psi. Treatments were initiated when the largest fruit were about 6 inches in diameter. All treatments were applied on a 7-day interval with applications on 25 Aug. and 2, 9, 16, and 23 Sept. Plots were inoculated on 12 and 19 Sept. by hand-scattering 0.5 lb of 1-cm cubes of naturally P. capcisi-infected acorn squash fruit per plot. Disease severity was evaluated on 26 Sept. as fruit rot incidence and percent foliar necrosis. Captan was most effective in suppressing fruit rot regardless of cultural regime. Captan and NOA-446510 were both effective in reducing vine collapse across all cultural regimes. Incidence of fruit decay was significantly greater in the bare ground + overhead irrigation (overhead) cultural regime while plasticulture (plastic) and bare ground + drip irrigation (drip) resulted in similar levels of fruit decay and vine collapse. No interaction of cultural regime with treatment was detected. Watermelon stems and foliage are typically very resistant to Phytophthora blight, but significant vine collapse occurred in many plots. P. capsici was consistently isolated from diseased foliage and stems and is considered the primary cause of vine collapse.
Charles S. Krasnow, Andrew A. Wyenandt, Wesley L. Kline, J. Boyd Carey and Mary K. Hausbeck
). Table 4. Mean weight of individual marketable fruit harvested from pepper entries evaluated for resistance to phytophthora root rot in Michigan (MI) and New Jersey (NJ). Discussion Phytophthora blight annually threatens pepper production in the eastern
Lindsay E. Wyatt, Amara R. Dunn, Matthew Falise, Stephen Reiners, Molly Jahn, Christine D. Smart and Michael Mazourek
at the immature green stage, bell peppers at the mature ripe stage are also produced. Red bell peppers have excellent nutritional properties, with carotenoids, flavonoids, and vitamin C ( Greenleaf, 1986 ). Phytophthora blight is a disease of pepper
Phytophthora capsici is a serious soilborne pathogen in chile pepper [Capsicum annuum L.] in New Mexico, and has been shown to spread under high soil moisture conditions and cause losses in a wide array of crops worldwide. This study was conducted to assess whether soil water saturation predisposes chile pepper to infection by P. capsici. Potted chile pepper plants of `Criollo de Morelos 334' (`CM334') and `New Mexico 6-4' (`NM6-4'), resistant and susceptible to P. capsici, respectively, were subjected to soil water saturation conditions (saturated and nonsaturated) for 3 and 6 days at two growth stages (six- to eight-leaf stage and one- to four-flower bud stage) prior to being inoculated or noninoculated with zoospores of P. capsici. Regardless of growth stage, no disease symptoms developed in `CM334' grown either under saturated or nonsaturated soil conditions at any of the two periods (3 or 6 days) of soil water saturation. In `NM6-4', disease symptoms consisting of stem necrosis, defoliation, and wilting were expressed. Plant growth stage at inoculation had a significant effect on disease severity (P < 0.0001). However, the response of `NM6-4' to P. capsici at each growth stage under saturated soil conditions was similar to that under nonsaturated conditions regardless of the period of saturation (P = 0.09). These results indicate that soil water saturation does not exert a significant predispositional effect on infection of chile pepper by P. capsici.
Mohammed B. Tahboub, Soumaila Sanogo, Paul W. Bosland and Leigh Murray
Phytophthora blight, caused by Phytophthora capsici , constitutes a limiting factor to profitable production of many crops worldwide ( Erwin and Ribeiro, 1996 ), including chile pepper ( Sanogo, 2003 , 2004 ; Sanogo and Carpenter, 2006