Rutgers bell pepper Phytophthora blight trial, 2021

Screen bell pepper cultivars and breeding lines for resistance to Phytophthora capsici under natural field infection, alongside their published bacterial leaf spot race resistance.

Production system. field.

Analysis. Plots were rated visually every 7 to 10 days and plants killed by Phytophthora counted, giving the percentage dead by the end of production. Infection was natural, not inoculated.

Plants killed by Phytophthora, counted in naturally infected plots. Plots are visually assessed every 7 to 10 days through the season and plants killed by Phytophthora blight are counted, giving a percentage of the plot dead by the end of production. Two things follow from how it is done. Infection is natural rather than inoculated, so the figure measures the season as much as the cultivar; and it counts dead plants rather than diseased tissue, so it cannot be compared with a severity percentage. Standard: Rutgers NJAES bell pepper Phytophthora blight trial protocol.

This trial grew 16 entries. AMSeed publishes results for 5 of them. 11 of the remainder are simply not recorded here yet: the source publishes them and we have not transcribed them, which is unfinished work rather than a judgement about the entries. The point of stating the total is that the trial is represented as what it actually was rather than as the slice we happen to cover.

The report states plainly that Phytophthora blight pressure was very low during this season, and the results bear that out: a cultivar carrying no Phytophthora resistance at all still finished with 81 percent of its plants healthy. A low mortality figure here is therefore weak evidence of resistance, because the disease was barely present to resist. That is a limitation of the season rather than of the trial, and it is the reason these figures should not be read as a ranking.