Feburary 2006

EVALUATION OF 25 ENTRIES OF RACE 3 BACTERIAL SPOT RESISTANT BELL PEPPERS

By Darrin Parmenter, Extension Agent, Palm Beach County Extension Office

Introduction Bell pepper is one of the primary vegetable crops grown in South Florida, with approximately 90% of Florida's production located south of Orlando . During that season 20.2 million bushels (28-lb) were harvested from 18,300 acres, with an average price per bushel of $10.78.

(Red peppers: Cross-sections of bell peppers that were allowed to ripen until maturity)

Bacterial spot ( Xanthomonas campestris pv. vesicatoria ) is one of the serious diseases affecting bell pepper production in the southeastern United States, especially Florida . Loss in yield due to bacterial spot can be attributed to both defoliation and spotting or rotting of fruit. Currently on the commercial vegetable market there are numerous bell pepper cultivars available to growers that are marketed as having the Bs2 gene, expressing resistance to races 1,2,3 of X.c pv. Vesicatoria . Unfortunately for the growers, there are additional races, such as 4, 5, or 6, that can overcome the resistance to the Bs2 gene.

The purpose of this study was to evaluate new bell pepper varieties for their yield potential, marketable traits, and resistance to bacterial spot in two different growing areas, Delray Beach (southeast Florida) and Immokalee (southwest Florida).

 
(Green peppers: Bushel bins of portion of 1st harvest from Immokalee, FL.)

Materials and Methods Transplants of 24 (Immokalee) and 25 entries ( Delray Beach ) were started from seed at the Everglades Research and Education Center (EREC) in Belle Glade. Entries in each location were situated in a randomized complete block design with three replications for evaluation of mature green peppers. Blocks were 5 ft long, single raised beds on 6 ft centers. Beds were fumigated with methyl bromide/chloropicrin prior to being covered with polyethylene. Each plot consisted of 10 plants planted in double rows, with in-row plant spacing at 8 inches and between-row spacing at 16 inches.

For the Immokalee experiment, seeds were sown on 3 Aug. 2004 and transplanted into the field on 4 Oct. 2004. After transplant, fertilization, pest management, and all other cultural practices were managed by the growers at Collier-Pacific. The first harvest was 57 days after transplant (DAT) on 2 Dec. 2004, with subsequent harvests on 17 Dec. 2004 (72 DAT) and 5 Jan. 2005 (91 DAT). Seeds for the Delray Beach experiment were sown on 3 Oct. 2004 and transplanted into the field on 23 Nov. 2004. The trial was managed by the growers at Thomas Produce after transplant. The first harvest was on 11 Feb. 2005 (80 DAT) with subsequent harvest on 25 Feb. 2005 (94 DAT) and 11 Mar. (108 DAT).

At harvest fruit from each plot were placed in paper bags and transported back to refrigerated storage at the EREC were they were held until yield and quality measurements were made. Tables 1 and 2 list the measurements taken from both locations. Bacterial spot ratings for late-developing infection were performed in Immokalee on 8 Feb. 2005 and in Delray Beach on 23 Feb. 2005. Ratings are defined by Dr. Ken Pernezny as “an estimate of the percentage of symptomatic foliar tissue and leaf surface lost due to disease-induced abscission combined into one number representing loss of phytosynthetically active foliage.”

Conclusions When planted in Immokalee during the late-fall early-winter season, PR99R-16, 8338, and ‘Crusader' were the highest yielding entries. Of these three only PR99R-16 had a bacterial spot rating less than 10%. When planted on the east coast of Florida (Delray Beach) during the winter months, a number of entries performed exceptionally well with the top three producing entries being 5776, 8364, and 7682. In both locations, low resistance to bacterial spot did not necessarily correlate to decreases in yield and horticultural quality. Entries 7682, 8338, and ACX 248 all yielded well at both locations despite having relatively high bacterial spot ratings. Conversely, some entries that had an elevated level of bacterial spot did show below average yields. Further research is needed to determine if a correlation between lower yield and bacterial spot exists for these entries. Both trials are currently being repeated for the 2005-06 season, although Hurricane Wilma delayed both plantings by 6-8 weeks.

Table 1. Summary of yield and fruit characteristics for a bell pepper cultivar evaluation, Collier-Pacific, Immokalee, Fla., 2004-2005.

z Bushel = 28 lb; one acre = 7,260 linear ft of bed with beds spaced on 6 ft centers.

y Mean separation in columns by Duncan 's multiple range test, 5% level, when applicable.

x Length to width ratio. Scale: 1.00 = blocky, length same as width.

^w Evaluated and rated 8 Feb. 2005 visual rating of percent loss of photosynthetic material.

Table 2. Summary of yield and fruit characteristics for a bell pepper cultivar evaluation, Thomas Produce, Delray Beach, Fla., 2004-2005.

z Bushel = 28 lb; one acre = 7,260 linear ft of bed with beds spaced on 6 ft centers.

y Mean separation in columns by Duncan 's multiple range test, 5% level, when applicable.

x Length to width ratio. Scale: 1.00 = blocky, length same as width.

^w Evaluated and rated 25 Feb. 2005 visual rating of percent loss of photosynthetic material.

See Calendar of Events - It's packed with meetings
you may be interested in attending!