Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, OH 44691.
Plant Dis. 2020 Oct;104(10):2622-2633. doi: 10.1094/PDIS-12-19-2709-RE. Epub 2020 Aug 17.
The pathotype of (MoT) that causes wheat blast has not yet been reported in the U.S., but the closely related Lolium pathotype (MoL), also capable of inciting blast, is found in several wheat growing regions. Since the epidemiology of MoL-incited wheat blast is unknown, it is difficult to project where and under what conditions this pathogen may be of importance. To quantify conditions favorable for MoL infection and temporal development of wheat blast, separate cohorts of wheat spikes were spray or point inoculated at anthesis and immediately subjected to different combinations of temperature (TEMP; 20, 25, and 30°C) and 100% relative humidity (RH) duration (0, 3, 6, 12, 24, and 48 h). Blast developed under all tested conditions, with both incidence (INC) and severity (SEV) increasing over time. The effects of TEMP on angular-transformed INC and SEV (arcINC and arcSEV) were significant ( < 0.05) in most cases, with the magnitude of the TEMP effect influenced by RH duration when spikes were spray-inoculated. Between 12 and 21 days after inoculation (DAI), there were significant, positive linear relationships between hours of high RH and arcINC and arcSEV at 25 and 30°C, but not at 20°C. The estimated rates of increase in transformed INC or SEV per hour increase in high RH duration were significantly higher at 30°C than at 25°C at 12 to 14 DAI, but not at 19 to 21 DAI. The highest estimated temporal rates of increase in INC and SEV and the shortest estimated incubation periods (5 to 8 days) occurred at 25 and 30°C, with 24 and 48 h of high RH immediately after inoculation. These results will contribute to ongoing efforts to better understand the epidemiology of wheat blast incited by MoL as well as MoT.
（MoT）引起的小麦穗枯病菌在美国尚未有报道，但与之密切相关的Lolium 株系（MoL）也能引起穗枯病，在几个小麦种植区都有发现。由于 MoL 引起的小麦穗枯病的流行病学尚不清楚，因此很难预测该病原体在何处以及在何种条件下可能具有重要性。为了量化有利于 MoL 感染的条件和小麦穗枯病的时间发展，分别在抽穗期对小麦穗进行喷雾或点接种，然后立即将其置于不同的温度（TEMP；20、25 和 30°C）和 100%相对湿度（RH）持续时间（0、3、6、12、24 和 48 h）组合下。在所有测试条件下都发生了穗枯病，发病率（INC）和严重程度（SEV）随时间推移而增加。TEMP 对经角度转换后的 INC 和 SEV（arcINC 和 arcSEV）的影响在大多数情况下均具有显著性（<0.05），而当穗部喷雾接种时，RH 持续时间会影响 TEMP 效应的大小。在接种后 12 至 21 天（DAI），在 25 和 30°C 时，RH 持续时间与 arcINC 和 arcSEV 之间存在显著的正线性关系，但在 20°C 时则不存在。在 12 至 14 DAI 时，每小时 RH 持续时间增加一小时，转化后的 INC 或 SEV 的增长率在 30°C 时显著高于 25°C，但在 19 至 21 DAI 时则不然。INC 和 SEV 的最高估计时间增长率以及最短的估计潜伏期（5 至 8 天）发生在 25 和 30°C，接种后立即有 24 和 48 小时的高 RH。这些结果将有助于正在进行的努力，以更好地了解由 MoL 引起的小麦穗枯病以及 MoT 的流行病学。
