Onion white rot

Three or four years is the usual recommended minimum for a crop rotation, but it can certainly be longer. If you know that your soil has a serious, persistent problem, such as potato cyst nematode, onion white rot, or clubroot, you may need a much longer rotation to grow susceptible crops with any success. 

Symptoms Young plants wilt and die leaves and stems of older plants become soft and rotten. Larvae bore into onion bulbs, which then rot Most severe in early to midsummer. May be confused with stem eelworm and onion white rot... 

Torres-Barragan A., Zavaleta-Mejia E., Gonzalez-Chavez C., Ferrera-Cerrato R. The use of arbuscular mycorrhizae to control onion white rot (Sclerotium cepivorum Berk.) under field conditions. Mycorrhiza 1996 6 253-257. 

The following can affect bulb onions leaf blotch, downy mildew, onion white rot, neck rot, onion fly, cutworms, bean seed fly, thrips and bulb and stem nematode. 

Experiments in the mid-1970 s demonstrated excellent control of white rot disease of onions with iprodione. 

Calogreen Calomel Calotab Chlorure mercureux Dimercury dichloride EINECS 233-307-5 Mercurous chloride Mercurous chloride (Hg2Cl2) Mercury chloride (Hg2Q2) Mercury subchloride Mercury(l) chloride. Fungicide. Used for control of clubroot in brassicas and white rot in onions. Antiseptic cathartic diuretic antisyphilitic. Used as a cathartic, local antiseptic and desiccant in veterinary medicine. Sublimes at 400-500 d = 7.15 practically Insoluble in H2O insoluble in alcohol, Et20 incompatible with bromides, iodides, alkali chlorides, sulfates, sulfites, carbonates, hydroxides, lime H2O, acacia, ammonia, golden antimony sulfide. 

Onions (and other albums) should not be grown more often than one year in fom, and ideally one year in six in the same field, because of the risk of nematode, onion fly and white rot disease. 

Cutworms, bean seed fly, onion fly, leek moth and thrips can be a problem in the crop. Rust, foot rot, leaf blotch, white tip and white rot are the main disease problems in leeks. 

White and yellow strains of sweet Spanish onions have recently been irradiated by the Brookhaven group (D5). An 8,000-r. treatment was found to be completely effective in sprout suppression although there was no indication that any of the radiation treatment affected rotting, which proceeded at a normal rate. 

Plant yeUow and wilted. Causes Fusar-ium bulb rot onion maggots lesser bulb flies wireworms. Onions infected with Fusarium bulb rot have soft necks, and entire bulbs may be soft and brown. Destroy infected plants. Prevent problems by planting cultivars, such as Long White Summer Bunching , Northern Oak , Sentinel , and Valiant , that are somewhat resistant. 

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