Influence of photoperiod on sporulation of and infection by Helminthosporium turcicum on Zea mays

Abstract

The influence of photoperiod on sporulation of and infection by Helminthosporium turcicum Pass. (Trichometasphaeria turcica Luttrell), the causal agent of northern leaf blight of corn (Zea mays L.), was studied in growth chambers simulating normal, field weather conditions. The results were compared to an epidemic of the disease on sweet corn in Kent County, Ontario, in 1972 during a period of unusual weather conditions. An 8-h photoperiod was required to maintain both the diseased plants in a state of survival and the fungus in a state of repeated sporulating cycles on the plants in the growth chambers. The specific climatic component which could be correlated with growth chamber data was the photoperiod. Extremely wide temperature and rainfall variations from their long term means, and a low average exposure to light, contributed to the progress of the disease.

Identification and expression analysis of regulatory genes induced during conidiation in Exserohilum turcicum

“…E. turcicum (teleomorph, Setosphaeria turcica) is a Wlamentous, heterothallic ascomycete that causes northern corn leaf blight (NCLB). Development of E. turcicum and NCLB disease progression are impacted by light and photoperiod (Benedict, 1979;Leach et al, 1977). As in many diseases caused by plant pathogenic fungi, conidiation occupies a central role in the NCLB disease cycle, because the multicellular, pigmented conidia of E. turcicum are the primary inoculum initiating NCLB epidemics and are the principal means of dispersal and survival of the pathogen.…”

“…As in many diseases caused by plant pathogenic fungi, conidiation occupies a central role in the NCLB disease cycle, because the multicellular, pigmented conidia of E. turcicum are the primary inoculum initiating NCLB epidemics and are the principal means of dispersal and survival of the pathogen. Epidemiological studies and Weld observations of E. turcicum-infected maize indicated that the rate of disease progression increased with shorter photoperiods and that repeated infection cycles requiring production of conidia were eVectively prevented by photoperiods longer than 12 h (Benedict, 1979).…”

Epidemiology of sorghum anthracnose (Colletotrichum sublineolum) and leaf blight (Exserohilum turcicum) in Kenya

“…Both anthracnose and leaf blight are polycyclic diseases. Disease epidemics are favoured by high rainfall and relative humidity, moderate temperatures, and the presence of large amounts of inoculum (Berger, 1970;Benedict, 1979;Frederiksen, 1986;Hennessy et al, 1990). However, severe epidemics can occur, even in suboptimal conditions, where highly pathogenic strains infect susceptible host cultivars (Levy, 1991;Pande et al, 1991).…”