The effects of three nitrogen fertilization treatments on the development of rice blast were studied on eight cultivars under field conditions in Arkansas in 1995 and 1996. The eight cultivars (Kaybonnet, Cypress, Lacassine, Mars, Adair, Alan, Newbonnet, and RT7015) ranged from resistant to susceptible to blast according to previous field observations. The recommended nitrogen levels for the eight cultivars varied from 123 to 168 kg/ha/year. Three treatments, consisting of different rates and timing of nitrogen applications, were tested over 2 years at one location. The first treatment consisted of a single nitrogen (N) application applied to plots at the recommended rate at preflood during the midtillering stage. The second treatment consisted of applying nitrogen as a single preflood application but at 1.5 times the recommended N rate used in treatment one. The third treatment (control) consisted of applying the recommended amount of nitrogen fertilizer used in treatment one, but in a three-way-split application with 56 to 100 kg/ha (depending on the cultivar) of urea applied at preflood followed by the application of 34 kg/ha of N applied approximately 10 and 20 days after the panicle differentiation (PD) growth stage. Inoculated spreader plots were used to initiate rice blast epidemics in the test plots. The results indicate that the disease progress for rice blast, regardless of N treatments, followed a unimodal curve, whereby disease incidence and total lesion area per plant reached a maximum near midseason (PD growth stage) and then gradually declined. This decline in disease was attributed to adult resistance, leaf senescence, and the formation of new (noninfected) leaves. Application of nitrogen above the recommended rate for any given cultivar significantly increased disease incidence and total lesion area per plant on all cultivars except Kaybonnet, a highly resistant cultivar. Furthermore, a differential cultivar response to nitrogen was observed when measuring both disease incidence and total lesion area per plant. Leaf blast was significantly more severe on the susceptible and very susceptible cultivars when N fertilizer was applied as a single application at preflood than in the split application treatment. Nitrogen treatments did not significantly affect the incidence of collar rot or neck blast.

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Objectives Our study aimed to (1) assess health-related quality of life (HRQoL) and mental well-being of healthy and diseased persons in the general population during the early stage of the COVID-19 pandemic and (2) examine the relationship between HRQoL and mental well-being and individual characteristics and government response against COVID-19, as measured by the stringency index. Methods A web-based survey was administered to a cohort of persons from the general population of eight countries: Greece, Italy, the Netherlands, Russia, South Africa, Sweden, the United Kingdom (UK) and the United States of America (US) from April 22 to May 5 and May 26 to June 1, 2020. Country-level stringency indices were adopted from the COVID-19 Government Response Tracker. Primary outcomes were HRQoL, measured using the EQ-5D-5L, and mental well-being, measured using the World Health Organization-5 Well-Being (WHO-5). Findings 21,354 respondents were included in the study. Diseased respondents had lower EQ-5D-5L and WHO-5 scores compared to healthy respondents. Younger respondents had lower WHO-5 scores than older respondents. The stringency index had a stronger association with the EQ-5D-5L and WHO-5 among diseased respondents compared to healthy respondents. Increasing stringency was associated with an increase in EQ-5D-5L scores but a decrease in the WHO-5 index. Conclusion The stringency of government response is inversely related to HRQoL and mental well-being with a small positive relation with HRQoL and strong negative relation with mental well-being. The magnitude of effects differed for healthy and diseased persons and by age but was most favourable for diseased and older persons.

Field experiments were conducted in 1996 and 1997 with a marked strain of Pyricularia grisea to determine if inoculum from infested rice grain could cause primary infections and sustain a rice blast epidemic during the growing season by giving rise to leaf, collar, and neck symptoms. The marked strain, a sulfate nonutilizing (sul) mutant of P. grisea, was grown on autoclaved rice seed for 7 days at 25°C. Infested rice grains were applied to the soil surface at the time of plant emergence (approximately 10 days after planting) at densities of 0, 0.5, 5, 25, and 50 grains per 0.1 m2 in plots planted to the blast susceptible cv. M-201. Leaf blast symptoms were first detected in the plots containing infested grain 35 days after plant emergence in both 1996 and 1997. The sul mutant was isolated from more than 90% of the lesions sampled from rice seedlings 35 to 45 days after plant emergence. Leaf blast increased more rapidly in plots with 25 and 50 infested grains per 0.1 m2 than in plots with less inoculum pressure (0.5 and 25 infested grains per 0.1 m2), although in 1996, leaf blast incidence recorded at midseason in plots containing 0.5 and 5 infested grains per 0.1 m2 was 41 and 55%, respectively. At the end of both seasons, the sul mutant was recovered from over 90% of the leaf, collar, and neck blast lesions except for one sample date in 1996. Rice blast was not detected in the control plots (no infested grain) in 1997 and not until 65 days after planting in 1996. Comparisons of disease progress on leaves between the marked strain and the parental wild-type strain under field conditions indicated that development of disease caused by the sul mutant was similar to disease caused by the wild-type strain.