The Triticum pathotype of Magnaporthe oryzae (MoT) that causes wheat blast has not yet been reported in the U.S., but the closely related M. oryzae 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 (P < 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.

在小麦的致病型稻瘟病菌（MOT），导致小麦爆炸，尚未见报道，在美国，但密切相关的稻瘟病菌在小麦的几个生长地区也发现了黑麦草病型（MoL），它也能够引发稻瘟病。由于由MoL引起的小麦瘟病的流行病学尚不清楚，因此很难预测这种病原菌在何处和什么条件下可能很重要。为了量化有利于MoL感染和小麦胚芽发育的条件，在花期对单独的小麦穗进行喷雾或点接种，并立即对其进行不同的温度组合（温度； 20、25和30°C），相对温度为100％湿度（RH）持续时间（0、3、6、12、24和48小时）。爆炸在所有测试条件下都会发生，发病率（INC）和严重性（SEV）均会随着时间的推移而增加。TEMP对角度变换的INC和SEV（arcINC和arcSEV）的影响显着（P<0.05），在大多数情况下，喷洒尖峰时TEMP效应的强度受RH持续时间的影响。接种后（DAI）12到21天之间，在25和30°C而不是20°C时，高RH和arcINC和arcSEV的小时数之间存在显着的正线性关系。在高RH持续时间下，转化的INC或SEV每小时每小时增加的估计增长率在12至14 DAI时显着高于25°C，而在19至21 DAI时则没有。在25和30°C时，INC和SEV的最高瞬时估计增长率以及最短的估计潜伏期（5至8天）发生在接种后24到48 h。这些结果将有助于不断努力，以更好地了解由MoL和MoT引发的小麦瘟病的流行病学。