Cranberry^ Cucumber. 281 



Treatment. The habits of this insect render it of easy de- 

 struction by the use of the arseuites. The bogs should be 

 sprayed as soon as the fruit has set, and later applications be 

 made at intervals of about ten days as frequently as appears to 

 be necessary. Two treatments will probably prove to be suffi- 

 cient in the majority of cases. No danger of poisoning the 

 berries need be feared. 



There are several other insects which feed upon the foliage 

 and the fruit of cranberries ; among them may be mentioned 

 a weevil, the yellow-headed cranberry-worm, and the tip-worm. 

 Proper applications of the arsenites, if made when the insects 

 begin to cause trouble, will practically control the pests. Paris 

 green is on the whole the safest insecticide, but it should be 

 used with an equal volume of lime. Some farmers use tobacco 

 water with satisfactory results. Proper flooding will also mate- 

 rially reduce the number of insects. 



CUCUMBER. 

 FUNGOUS DISEASES. 



Mildew (Erysiphe Cichoracearum, DC.). Description. The 

 cucumber mildew caused by this fungus is found almost en- 

 tirely in greenhouses. All parts of the vines are affected, 

 although upon the fruit the disease is not so serious. The 

 parasite grows merely upon the surface of the plant, producing 

 white, moldy areas, which appear as if they consisted of a 

 white powder scattered thinly upon the affected part (Fig. 52). 

 These may be so abundant that the entire upper surface of a 

 leaf is covered, and the stems are frequently surrounded by the 

 fungus for a considerable distance. These spots may be easily 

 removed by rubbing the leaf, since the only portions of the para- 

 site which enter the cucumber plant are small projecting threads 

 that enter the cells, and from these the nourishment is drawn. 



Treatment. Fungi growing upon the surface of the host- 

 plants may be successfully treated whenever they are seen, and 

 the cucumber mildew is no exception to the rule. It mav be 

 controlled by spraying with a solution of the liver of sulphur, 

 the ammoniacal carbonate of copper, or the Bordeaux mixture. 

 These should be used at about three-fourths their normal 

 strength, as cucumber foliage is tender and the disease is not 



