DISEASES AND PESTS 153 



be killed by spray the following year, when they 

 appear in the open to moult. Care should be taken 

 to have the dip well emulsified, otherwise it will 

 burn the tissues of the plant. Apart from destroying 

 the scale, it is a desirable treatment for all offshoots, 

 as it removes bacteria which might later cause fer- 

 mentation or decay, and gives the young plant the 

 best possible start in life. 



For older palms which are infected, the best 

 treatment is a thorough spray with the same liquid, 

 repeated several times, if necessary, at intervals of 

 a month. Various other treatments have been used, 

 but none of them gives much promise of value; some 

 of them, such as carbon bisulphid, kill the palm much 

 more quickly than the scale. 



Date palms in moist regions are sometimes 

 thickly covered with a fungus, Graphiola phoenicis, 

 which injures the leaf seriously by killing parenchy- 

 matous cells, displacing the bundles of schlerenchyma 

 and rupturing the epidermis and hypoderm. Frank* 

 describes it as follows: "The fruit bodies appear as 

 scattered, hard, dark swellings about 1.5 mm. across, 

 and are sometimes surrounded by a clearer border 

 showing the part of the leaf tissue containing the 

 mycelium of the fungus." It is common on the 

 coast of Southern California, but as it can not tolerate 

 an arid climate it is unknown in the date-growing 

 regions of the interior. On date palms in Egypt 

 and the West Indies, however, it has been the most 

 serious disease; and it appeared at Baghdad a few 



*Die Pilzparasitaren Krankheiten der Pflanzcn, p. 127. 

 Breslau, 1896. For a more technical description see Tubeuf and 

 Smith, Diseases of Plants, p. 325. 



