Downy mildew of Rhubarb
Peronospora jaapiana
The symptoms of this disease are first seen on the upper leaf surfaces. The light-brown patches that develop are angular at first because they are bounded by veins. If the weather continues cool and wet, however, the patches may continue to spread until large areas of the leaf are brown. Eventually these areas will tear, and pieces will fall out so that the leaves have tattered appearance. Severe defoliation can occur. Underneath the leaf the furry growth characteristic of down mildew is produced, and the spores on this furry growth are spread about by the wind to other leaves and to other plants.
Pesticides
Axiom MZ 720
intensity: ★★★
Cupro Isagro 375 WG
intensity: ★★★
Dithane Rainshield Neo Tec
intensity: ★★★
Frenta 750 WG
intensity: ★★★
Isacop
intensity: ★★★
Kocide Blue Xtra
intensity: ★★★
Manzate DF
intensity: ★★★
Neoram 375 WG
intensity: ★★★
Ospray Copper Oxychloride-WP
intensity: ★★★
Penncozeb
intensity: ★★★
Penncozeb 750 DF
intensity: ★★★
Ridomil Gold MZ WG
intensity: ★★★
Rotam Milor 720 WP
intensity: ★★★
Rotam Winner Mancozeb WP
intensity: ★★★
tradewyns Blu-Cop 400DF
intensity: ★★★
Uniguard 500 WP
intensity: ★★★
Unizeb Disperss 750 DF
intensity: ★★★
Zeemil 720 WG Systemic and Protective
intensity: ★★★
Zeemil MZB 720 WP Systemic and Protective
intensity: ★★★
Arysta LifeScience Copper Oxychloride 50 WP Fungicide/Bactericide
intensity: N/A
Arysta LifeScience Copper Oxychloride WP Fungicide/Bactericide
intensity: N/A
Arysta LifeScience Mancozeb 750 WG
intensity: N/A
Blue Shield DF
intensity: N/A
Isagro Neoram 375 WG
intensity: N/A
Liquicop
intensity: N/A
Manco 750 WG
intensity: N/A
Mancoflo
intensity: N/A
Manzeb
intensity: N/A
Maxyl
intensity: N/A
Medley Mz
intensity: N/A
Metal-Man Mz 720
intensity: N/A