130 TOMATO CULTURE 



last spraying is essential, as those who have sprayed 

 with an arsenical and have reported only partial good 

 results have discontinued within about two weeks of 

 the time of the ripening of the first fruit. 



White fly or aleyrodes. — These minute insects are 

 familiar to most growers who raise tomatoes under 

 glass. They can be held in control by vaporization 

 or fumigation with tobacco or nicotine extracts, or 

 by spraying with kerosene emulsion or the so-called 

 whale-oil (fish-oil) soap. Care is necessary in using 

 the extracts that the smudge does not become too 

 dense and injure the plants. Before applying this 

 remedy on a large scale a preliminary trial should be 

 made following the directions on the packages, and 

 reducing the amount if any ill results follow. Hydro- 

 cyanic acid gas, properly used, is also an excellent 

 remedy for aleyrodes, aphides, "mealy-bug," and 

 other soft-bodied insects which are sometimes troub- 

 lesome on greenhouse tomatoes. 



For a complete account of the methods of making and 

 handling hydrocyanic acid gas, see Professor Johnson's book 

 entitled "Fumigation Methods," published by Orange Judd 

 Company, of New York. Sent postpaid for $1. — [Author. 



