Australia

Downy mildew of Onions

Peronospora destructor

Onion downy mildew commonly starts in spots in the field and subsequently spreads to surrounding areas.

Elongated (3-30 cm long), pale-yellow lesions appear on the inner and outer side of leaves, covered by greyish-violet down, leaf tips shrivel. Drying up of leaves occurs, beginning with the older and outer leaves and progressing to young leaves, until the entire plant may be killed.

On seed stalks, similar lesions occur, especially on the upper part. These generally affect only one side of the stalk, often causing twisted or lopsided stalk growth. Lesions weaken the stalk and it breaks due to the weight of the seed umbel. Secondary infection by Alternaria porri or A. alternata and Stemphylium botryosum, frequently hastens death of leaf and stalk tissue.

Bulbs are systemically affected. After a period of storage, the outer fleshy scale becomes amber, wrinkled and watery

Pesticides
Acrobat
intensity: ★★★
Acrobat MZ 690
intensity: ★★★
Acrobat SC
intensity: ★★★
Acrobat WDG
intensity: ★★★
Amistar 250 SC
intensity: ★★★
Antracol
intensity: ★★★
Aprisco 900 WG
intensity: ★★★
Axiom MZ 720
intensity: ★★★
Bravo
intensity: ★★★
Bravo Weather Stik
intensity: ★★★
Cavalry Weatherguard
intensity: ★★★
Cherokee 900
intensity: ★★★
Conan 500
intensity: ★★★
Conan 720 SC
intensity: ★★★
Cupro Isagro 375 WG
intensity: ★★★
Dithane Rainshield Neo Tec
intensity: ★★★
FMC Chlorothalonil 720
intensity: ★★★
FMC Chlorothalonil Bond 720
intensity: ★★★
Frenta 750 WG
intensity: ★★★
Galben M
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: ★★★
Ridomil Gold Plus
intensity: ★★★
Rotam Aprisco
intensity: ★★★
Rotam Milor 720 WP
intensity: ★★★
Rotam Winner Mancozeb WP
intensity: ★★★
Sphinx
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
Barmac Copper Oxychloride
intensity: N/A
Barmac Zineb
intensity: N/A
Barrack 720
intensity: N/A
Barrack Betterstick
intensity: N/A
Blue Shield DF
intensity: N/A
Chlornil 720 SC
intensity: N/A
Chloronil Pro
intensity: N/A
Chlorothalonil
intensity: N/A
Clash Dry 900 WG
intensity: N/A
Clash Storm Guard 720 SC
intensity: N/A
Echo 720
intensity: N/A
Isagro Neoram 375 WG
intensity: N/A
Liquicop
intensity: N/A
Manco 750 WG
intensity: N/A
Mancoflo
intensity: N/A
Mankocide DF
intensity: N/A
Manzeb
intensity: N/A
Maxyl
intensity: N/A
Metal-Man Mz 720
intensity: N/A
Pacific Echo 500 SC
intensity: N/A