326 GARDEN FARMING 



yellow before the leaves die. It has been particularly troublesome 

 in the Bermuda-onion growing sections of Texas and in some 

 Northern fields. It is usually most abundant during dry periods, 

 for an abundance of moisture is not congenial to the life or the 

 reproduction of the insect. 



There are no satisfactory methods of controlling this pest. 

 Spraying the plants with kerosene emulsion made with resin whale- 

 oil soap is one of the best applications. Spraying with standard 

 Bordeaux mixture to which 2 ounces of resin whale-oil soap have 

 been added will also be found a good preventive. 



Onion smut (Urocystis cepulce). This is a disease which attacks 

 the young plants, causing the formation of dark spots or lines on 

 the leaves and stem near the surface of the ground. As the onion 

 seedling develops, these spots crack open, exposing a black, pow- 

 dery mass, which is the spores of the fungus. The disease, if very 

 severe, causes the tops to wither and die, and then often spreads 

 to the bulbs. Onion smut is more or less prevalent in different 

 parts of the country, the loss from it being very great in some 

 years. As a preventive, all the refuse upon the onion field should 

 be burned immediately after the crop is harvested, thus destroy- 

 ing most of the spores from which the disease rapidly spreads the 

 following season. Adherence to a strict system of crop rotation, 

 however, is the most practical preventive against the disease. 

 Transplanting is also quite effective, as the smut does not attack 

 sets or well-grown transplants as readily as young seedlings. 



Experiments at the Connecticut and New York State Agricul- 

 tural Experiment stations have demonstrated that treatment with 

 a mixture of equal parts of sulphur and lime, or of sulphide of 

 potassium and lime, increased the yield on land badly infected with 

 smut in a ratio of about 5 to I. The mixture is sown in the drill 

 with the seed. At the Ohio station an effective remedy has been 

 found in the use of a formaldehyde solution, made at the rate of 

 I pound of 40 per cent formaldehyde to 25 to 33 gallons of water, 

 applied to the seed and soil at the time of planting, by means of a 

 drip attachment to the seed drill, using from 125 to 150 gallons 

 of the solution to the acre. 



Heart rot. This is a bacterial trouble which seems to attack all 

 varieties of onions which have been carelessly or roughly handled 



