1474 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



tacking the white varieties; it is really au 

 anthracnose of onions. For some time, 

 because of its coincident development 

 with the black neck or dry rot these two 

 troubles have been confused. It is now 

 apparently clear that there is no connec- 

 tion between the two, although this fuu- 

 gus causes dry rotting of sets and bulbs. 

 The smudge fungus is cumulatively worse 

 on old land where onions are grown con- 

 secutively. Apparently also in addition 

 to rotation of crops the formalin drip 

 treatment described under smut gives 

 good results in keeping down this fungus. 

 A. D. Selby, 

 Wooater. Ohio. 

 Onion Smut 

 Vrocystis cepulae Frost 



The disease commonly known as onion 

 smut is exceedingly troublesome on 

 many soils that have been planted con- 

 tinuously to onions for a number of 

 years. When this disease once becomes 

 established in the soil it is very difficult 

 to eradicate. Cases have been observed 

 where land infested with smut was not 

 planted to onions for ten years and 

 where the smut reappeared in destruc- 

 tive quantities the first year that the 

 land was again planted. Onion smut is 

 a disease that can be carried with the 

 seed or by cultivators and implements 

 generally, or the spores may be carried 

 by the wind. This disease first makes 

 its appearance in the form of a swelling 

 or hardening of the leaves, usually just 

 above where they unite with the plant. 

 After a time these places burst open and 

 ■a powdery black dust, the spores of the 

 fungus, emerge and are scattered broad- 

 cast. The disease attacks the entire 

 plant and few, if any, good bulbs will 

 be produced by affected plants. 



Several remedies are offered for onion 

 smut, none of which has proved entirely 

 satisfactory. Soaking the seed for about 

 twenty minutes in a solution consisting 

 of one ounce of formalin in one gallon 

 of water is recommended for destroying 

 the spores that may adhere to the seeds. 

 This process must he done but a short 

 time before planting and the seed dried 

 by means of plaster; however, the soak- 

 ing of the seed will render It difficult 

 to plant evenly. 



Another method is to fit the seed drill 

 with a small tank and allow a small 

 stream of the above solution to flow into 

 the row just behind the seed dropper and 

 before the seed is covered. 



A method frequently used by growers 

 is to provide the seed drills with ferti- 

 lizer attachments and apply a mixture 

 consisting of 100 pounds of sulphur and 

 50 pounds of powdered lime in the rows 

 with the seed. 



On land that is free from smut pre- 

 cautions should be taken to prevent its 

 introduction. The danger of the spores 

 being present with the seed is not great. 

 The introduction is more often made by 

 throwing diseased bulbs or tops in the 

 manure pile and then hauling the manure 

 on to clean land, or by the dragging of 

 infested soil from one field to another 

 with cultivators and other implements. 



Literature 



Duggar. Fungus Diseases of Plants. 



Soft Rot and Storage Rots 



Fwsarium sp. 



This soft rot is produced by the fungus 

 Fusarium, yet under study. It not only 

 causes an early blight but also invades 

 the onion bulbs quite rapidly after stor- 

 age infection. The problems of control 

 are essentially those of storage rots, in- 

 cluding dry rot. 



In onion storage it seems to the writer 

 probable that disinfection of the onions 

 after placing in storage buildings either 

 by sections or otherwise, using the for- 

 maldehyde gas treatment, will give excel- 

 lent and safe results. This needs yet to 

 be worked out. 



Stem Rot 



This disease causes a rotting of the 

 onion at the juncture of the bulb and 

 stem. The rotting continues after the 

 onions are put into storage. The recom- 

 mendations are the same as for anthrac- 

 nose, or black spot. 



OMON PESTS 



Cantaloup Fly. See Cantaloup Pests. 

 Cut Worm. See Beet and Cabhage 

 Pests. 



Ref.t Army Woum. See Beet Pests. 



Onion Macgot 



This small white maggot, which at- 

 tacks onions Is the larva of a fly that 



