Effects of impacting rain drops on the growth and development of powdery mildew fungi

Abstract

The effects of rain on different stages of powdery mildew development were investigated quantitatively for Erysiphe graminis on barley, Erysiphe pisi on pea and Sphaerotheca pannosa on rose. Water drops 4 mm in diameter released from a height of 2 5 m onto target leaves reduced the numbers of conidia on the impacted surfaces and inhibited subsequent mildew development, the effects declining as the interval between inoculation and impaction increased. Simulated rainfall applied after inoculation reduced the numbers of conidia on leaves and inhibited mildew development, the effect declining as the interval between inoculation and treatment lengthened. Simulated rainfall applied to infected plants reduced their capacity to inoculate other plants, the effect declining as the interval between treatment and use as inoculum lengthened. Controlled exposure of infected peas and roses to natural rain reduced the numbers of conidia on leaves and inhibited subsequent mildew development, especially on upper leaf surfaces.

Dynamics in concentrations of Blumeria graminis f. sp tritici conidia and its relationship to local weather conditions and disease index in wheat

“…Sivapalan (1993) demonstrated that rain can cause physical damage to mildews, and the correlation between rainfall and strawberry powdery mildew conidia was negative and significant (Blanco et al 2004). However, in our study, only 4 rainy days occurred in the 2007-2008 season when spores were trapped.…”

Las cenicillas en cultivos agrícolas de Sinaloa: Situación actual sobre su identificación y líneas futuras de investigación

“…Although mildew is common and causes considerable damage in cool areas; they are even more common and severe in areas with warm, dry climates, because in these conditions the wind easily detaches and spreads the conidia (RomeroCova, 1988); also, it has been established that mildew presents itself in the succulent tissue of the host in cool, shady areas (Yarwood, 1973). The lives of conidia are brief and they are favored by high relative humidity, but not by rain and inmersion in water (Sivapalan, 1993a;Sivapalan, 1993b). In general, the mycelium is epiphitic, except in genuses Leveillula, Phyllactinia, Pleochaeta where the mycelium is hemi-endophytic, and occasionally in species of Cystotheca; in this case, hyphae penetrate the leaves through the stomata and form mycelia inside, although the mycelia of the species of Leveillula are more abundant inside the leaf of the host (Braun et al, 2002).…”

“…In con clima cálido y seco, porque en estas condiciones el viento fácilmente desprende y disemina los conidios (Romero-Cova, 1988); además se ha establecido que, las cenicillas se presentan en tejido suculento del hospedante en ambientes sombreados y frescos (Yarwood, 1973). La vida de los conidios es corta y les favorecen altos niveles de humedad relativa, pero no son favorecidos por lluvia e inmersión en agua (Sivapalan, 1993a;Sivapalan, 1993b). En general, el micelio es epifítico excepto en los géne-ros Leveillula, Phyllactinia, Pleochaeta el micelio es hemiendofítico y ocasionalmente en especies de Cystotheca; en este caso, las hifas penetran las hojas a través de los estomas y forman micelio en el interior, sin embargo, el micelio de las especies de Leveillula es más abundante en el interior de la hoja del hospedante (Braun et al, 2002).…”

Modelling and forecasting epidemics of apple powdery mildew (Podosphaera leucotricha)

“…It is well known that production, viability and dispersal of powdery mildew conidia are affected by weather variables (e.g. surface wetness, wind speed) and host leaf age ( Ward & Manners, 1974; Butt, 1978; Butt & Jeger, 1986; Sivapalan, 1993a; Sivapalan, 1994; Xu et al ., 1995a ). However, to simplify the model, Podem TM does not take these effects into account.…”