Powdery mildew fungus on the surface of a leaf of the cultivar Carignane.  (Courtesy J. Schlesselman).

Distortion and stunting of young Carignane leaves affected by powdery mildew. (Courtesy J. Schlesselman)

Blackened tissue on shoots infected with Uncinula necator. (Courtesy R. C. Pearson).

Blotchy ripening of Chancellor berries infected with Uncinula   necator. (Courtesy R. C. Pearson).

Netlike pattern of scar tissue on ripe Thompson Seedless (Sultanina) berries infected with Unicinula necator. (Courtesy J. Schlesselman)

Cleistothecia of Uncinula necator in various stages of maturity.  (Courtesy W. Gärtel)

Conidia of Uncinula necator, formed in chains. (Courtesy W. Gärtel)

Stunted shoot covered with mycellium of Uncinula necator (flag shoot) that grew from an infected bud. (Courtesy R. C. Pearson).