Bacterial spot, an important disease of bell and chili peppers grown in Oklahoma, is caused by Xanthomonas euvesicatoria. We evaluated isolates from 1995 to 2015 (n = 72) for avirulence alleles and race by assessing hypersensitive responses (HRs) on differentials with resistance genes Bs1, Bs2, Bs3, or Bs4. Most isolates (96%) expressed AvrBs2 (races 1, 3, 7, 8), and only three were virulent on Bs2 (race 6). Chili cultivars, grown locally for capsaicin production, were susceptible to all races. Copper-based spray programs were evaluated on bell pepper hybrids with and without Bs2 resistance from 2008 to 2010 and on bell and jalapeño hybrids with Bs2 or Bs1-2-3 from 2017 to 2018. Bs2 and Bs1-2-3 hybrids generally had lower disease and higher yields (≤21 t/ha) than susceptible entries. Copper reduced disease by 20 to 40% and increased yield by an average of 4 t/ha, but yield responses were not always significant (P = 0.05). In August 2018, disease increased to >50% on Bs2 hybrids but remained low on the Bs1-2-3 hybrid. Despite the breakdown of Bs2 resistance, yields of the Bs2 hybrids were not reduced. Avirulence alleles and race of isolates from susceptible, Bs2, and Bs1-2-3 hybrids at the end of the 2018 trial depended on source plant genetics. AvrBs2 was expressed in 86% of isolates from a susceptible hybrid but not in any isolates from the Bs2 and Bs1-2-3 hybrids. HR resistances effectively protected yield, but their deployment may not be sustainable without cultural practices such as crop rotation that limit pathogen survival and transmission to subsequent crops.

细菌斑点是俄克拉何马州种植的一种重要的柿子椒和辣椒病，是由黄单胞菌引起的。我们通过评估针对具有抗性基因Bs1，Bs2，Bs3或Bs4的差异的超敏反应（HRs），对1995年至2015年的分离株（n = 72）的无毒等位基因和种族进行了评估。大多数分离株（96％）表达了AvrBs2（种族1、3、7、8），而只有3个在Bs2上具有毒性（种族6）。在当地种植辣椒素生产的辣椒品种易受所有种族的影响。在有和没有Bs2的甜椒杂交种上评估了基于铜的喷雾程序在2008年至2010年期间对Bs2或Bs1-2-3和Bs2或Bs1-2-3的钟型和jalapeño杂种具有抗性。与易感病种相比，Bs2和Bs1-2-3杂种通常具有较低的病害和较高的产量（≤21 t / ha）。铜减少了20％至40％的病害，平均单产提高了4 t / ha，但单产并不总是很显着（P = 0.05）。在2018年八月，疾病增加到上> 50％BS2杂交，但是，仍然很低Bs1-2-3混合。尽管Bs2抗性被击穿，但Bs2杂种的产量并未降低。无毒等位基因和易感Bs2分离株的种族和Bs1-2-3杂种在2018年试验结束时取决于来源植物遗传学。AvrBs2在易感杂种的86％分离物中表达，但在Bs2和Bs1-2-3杂种的任何分离物中均未表达。HR抗性有效地保护了产量，但如果没有诸如轮作这样的文化习俗限制病原体的生存和向后续农作物的传播，抗药性的部署可能无法持续。