Colorimetric and chromatographic methods were used to assess capsaicinoid levels in a pungent Caribbean-grown pepper collection comprising 28 accessions of Capsicum chinense and one each of C. annuum and C. frutescens. Two colorimetric methods, one commonly used and attributed to Bajaj (1980) and a modification of the Bajaj method were also compared for congruity and ease of use. Capsaicin content of the cultivars ranged from 37.6 to 497.0 mg/100 g in ripe fruits and 27.8 to 404.5 mg/100 g in green fruit, as determined by Bajaj's method. The corresponding Scoville units of pungency varied from 15,000 to 300,000 for ripe fruit and 7,500 to 270,000 for green fruit. Levels of capsaicin assessed by the modified Bajaj method varied from 15.0 to 402.4 mg/100 g and 13.7 to 356.4 mg/100 g in ripe and green fruit, respectively. On the basis of capsaicin levels assessed by each colorimetric method, the pepper cultivars were differentiated into seven distinct pungency groups. For each method, similar groupings of cultivars were observed for ripe and green fruit and groups of the same numerical designation were mainly comprised of common assessions. These results indicate that the two colorimetric methods generally agree. In contrast, the modified colorimetric method was more efficient than Bajaj's procedure, which required pretreatment of pepper extracts to remove the extracting solvent by evaporation and interfering chromogenic pigments by column chromatography. Phase separation of capsaicin and interfering pigments in pepper extracts by use of dilute acid was the only pretreatment required in the modified Bajaj method before colorimetry. High performance liquid chromatography performed on fruit extracts of the cultivars revealed the presence of the capsaicinoids capsaicin, homocapsaicin, dihydrocapsaicin, nordihydrocapsaicin, and homodihydrocapsaicin. Capsaicin and homocapsaicin were detected in greater abundance than dihydrocapsaicin and nordihydrocapsaicin in fruit of all cultivars. Homodihydrocapsaicin was the least abundant of the capsaicinoids and was generally absent in ripe fruit.

Tomato (Lycopersicon esculentum), pepper (Capsicum annuum), corn (Zea mays), French bean (Phaseolus vulgaris), soybean (Glycine max), winged bean (Psophocarpus tetragonolobus), lima bean (Phaseolus lunatus), field pea (Pisum sativum), moth bean (Phaseolus aconitifolins), and heliconia (Heliconia bihai) were evaluated as alternative hosts of Xanthomonas campestris, the causal agent of a leaf blight of onion (Allium cepa). On legumes, bacterial growth occurred in planta, and visible disease symptoms developed. From 19 commercial onion genotypes screened for leaf blight resistance, two cultivars, H-942 and H-508, were generally free of symptoms and had restricted bacterial growth in planta. These are the first known reports on alternative hosts of the bacterium and on resistance in onion to leaf blight.

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Changes in prevalence\ aggressiveness and sensitivity to copper and zinc bactericides of Xanthomonas campestris pv[ vesicatoria races from bell pepper and tomato in Bar! bados since 0878Ð89 were determined[ A total of 05 races were identi_ed and 00 of them\ including races P9\ P9T0\ P9T1\ P0T0\ P0T1\ P1T1\ P2T1\ P3T0\ P3T1\ P4T1 and P5T1\ were previously unreported on bell pepper and tomato in Barbados[ Of the 00 races\ P1T1\ P3T0\ P4T1 and P5T1 were detected on pepper only and T1 only was con_ned to tomato[ Races P0T0 and P5T1\ each amounting to 05) of strains from pepper\ replaced race P0\ which contributed 3)\ as the most prevalent strains on this plant genotype[ On tomato\ races P0T0 and P0T1\ in amounts of 25[0 and 10[9)\ respectively\ of the patho! gen collection\ replaced race T0\ which represented 04[7)\ as the predominant strains[ Shifts from frequent association of race P0 to races P0T1 and P5T1 and from race T0 to races P0T0 and P0T1 with the greatest amounts of pepper and tomato crop damage\ respec! tively\ also occurred[ The previously zinc!sensitive and copper!resistant pathogen population became resistant to zinc and reverted by 39) to copper sensitivity[ ZusammenfassungXanthomonas campestris pv[ vesicatoria von Paprika und Toma! ten in Barbados vera Ãndert dessen Rassenstruktur\ Virulenz sowie Emp_ndlichkeit gegenu Ãber chemischen Beka Ãmpfungsmitteln Festgestellt wurde eine Vera Ãnderung von Vorkommen\ Aggressivita Ãt sowie Emp_ndlichkeit zu Kupfer! und Zink!Bakteriziden bei Xanthomonas campestris pv[ ve! sicatoria!Rassen von Paprika und Tomaten in Barbados seit 0878Ð89[ Insgesamt wurden 05 Rassen identi_ziert\ davon waren 00\ die Rassen P9\ P9T0\ P9T1\ P0T0\ P0T1\ P1T1\ P2T1\ P3T0\ P3T0\ P3T1\ P4T1 und P5T1\ vorher U[ S[ Copyright Clearance Center Code Statement] 9820Ð0674:88:3697Ð9286 , 03[99:9 von Paprika und Tomaten nachgewiesen[ Die Rassen P0T0 und P5T1\ jeweils 05) der isolierten Sta Ãmme von Paprika\ ersetzten die Rasse P0\ die nur 3) der isolierten Sta Ãmme ausmachte\ als die am ha Ãu_gsten vorkommen! den Rassen in Paprika[ An Tomaten ersetzten die Rassen P0T0 und P0T1\ die 25\0 bzw[ 10\9) der isolierten Sta Ãmme ausmachten\ die Rasse T0\ die nur 04\7) der isolierten Sta Ãmme darstellte[ Diese Vera Ãnderungen im Ras! senspektrum wurden auch mit erho à hten Scha Ãdigungen der Wirtsp~anzen gekopppelt[ Die Pathogenpopulation war vorher Zink emp_ndlich und Kupfer resistent\ nach der Vera Ãnderung wurde sie Zink resistent und zu 39) Kupfer emp_ndlich[

Fourteen race-1 and race-2 isolates of Verticillium dahliae frotn North America, Europe and Australia were screened against the near isogenic pair of tomato cultivars Roma and Roma VF. The foliar symptoms, extent of stunting and vascular colonization were assessed. Race-1 isolates were significantly more pathogenic on Roma which lacks the Ve resistance gene. Race-2 isolates from N. America were more pathogenic than those from Australia. All isolates tested colonized both cultivars to some extent although the level of colonization by race-1 isolates was significantly higher in Roma than in Roma VF. All race-I, and the majority of race-2, isolates caused stunting of Roma. No isolates stunted Roma VF. Zusammenfassung Pathogenitat von Rasse-! und Rasse-2 Verticiltium dahliae-lsoiiten aus unterschiedlichen geographischen Regionen Untersucht wurden 14 Rasse-1 und Rasse-2 Verticillium dahliae-Isolate, die aus Nordamerika, Europa und Australien stammten, gegen das nahisogenetische Tomatensortenpaar Roma und Roma VF. Bewertet wurden die Blattsymptome, der Grad der Verkurzung und die Kolonisation des GefaCsystems. Rasse-1-Isolate hatten eme deutlich hohere Pathogenitat gegen die Sorte Rotna, die das Resistenzgen Ve nicht enthaJt. Die Rasse-2-Isolate aus Nordamerika hatten eine hohere Pathogenitat als die aus Australien. Aile geprliften Isolate waren in der Lage beide Sorten zu kolonisieren, jedoch war der Grad der Kolonisation durch die Rasse-1-Isolate bei der Sorte Roma deutlich hoher als bei der Sorte Rotna VF. Wachstumsverktirzung in der Sorte Roma ^vurde durch alle Rasse-1-und die Mehrheit der Rasse-2-Isolate verursacht. Das Wachstum der Sorte Roma VF wurde durch kein Isolat verringert, U.S. Copynght Clear™,, Corner Code Staiemem; 0931 "1 785/88/2304-0297$02,50/0