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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #299754
Title: A latent-period duration model for wheat stem rust

Author
item Hernandez Nopsa, John
item Pfender, William

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2014
Publication Date: 10/31/2014
Citation: Hernandez Nopsa, J.F., Pfender, W.F. 2014. A latent-period duration model for wheat stem rust. Plant Disease. 98(10)1358-1363.

Interpretive Summary: Wheat stem rust (WSR) caused by the pathogen Puccinia graminis subsp. graminis is a highly destructive disease of wheat and other small grains. The discovery of a Pgg race (Ug99) that overcomes durable resistance in wheat raises concerns for global wheat production and food security. Efforts to manage the disease most efficiently would be aided by information that enables understanding and prediction of the speed of epidemic development. This speed is significantly determined by the "latent period", the time needed for an infection to produce the next generation of spores. By collecting data from experiments conducted at various temperatures, we constructed a mathematical model to predict wheat stem rust latent period duration, based on environmental temperature. The model was tested with 4 common wheat cultivars and 4 different races of the pathogen. The upper and lower limits for temperatures conducive to infection development were also determined. This latent period model, when combined with mathematical descriptions of other important stem rust processes, will enable disease managers to forecast the rate of stem rust development in a field.

Technical Abstract: Wheat stem rust caused by Puccinia graminis subsp. graminis (Pgg) is a highly destructive disease of wheat and other small grains. The discovery of a Pgg race (Ug99) that overcomes durable resistance in wheat raises concerns for global wheat production and food security. There is currently no mathematical model that describes the duration of wheat stem rust latent period based on variable temperature or heat units. A study using Pgg race GFCDC in cultivar Stephens was conducted at various temperatures to determine their effect on latent period duration. A mathematical model to predict latent period duration based on temperature was formulated; the model can be applied to data consisting of varying temperature readings measured at any desired time increment. The model was validated in outdoor experiments under natural conditions on wheat cultivars Stephens and McNair, and in a greenhouse with factorial experiments using four wheat cultivars (Stephens, McNair, Scout 66, and Kingbird) and four Pgg races (GCCNC, GCCSC, QFCSC, and GFCDC) at four temperatures (5, 15, 30, and 33.5oC). Field and outdoor experiments showed that latent period durations predicted with the model were within the 99% confidence intervals around observed latent period durations. For experiments conducted on field-grown plants, no significant differences were found between predicted and observed latent period duration. Significant differences among cultivars were found at 15, 5, and 30oC. Temperatures above 30oC were not conducive for sporulation by some races.