634 INSECTS AFFECTING VEGETATION 



upon the under side of the leaf which appear translucent when held 

 between the observer and the light. These are nothing more than 

 leafcells which have become so gorged with water as to be ruptured. 

 The break down extends to adjoining parts and then tends to pro- 

 duce the spots before described. This is purely a physiological 

 trouble due to excess of water. The remedy is clear. Withhold 

 water until absolutely necessary. 



PEONY. 



Stem-Rot Wilt. The symptoms are a gradual dying of the 

 leaves. Examination shows steins to be rotted near the ground or 

 often very much higher. A strong, insoluble fungicide might be 

 successfully sprayed upon the stems without covering the leaves. 



PHLOX. 



Leaf-Spot. Cultivated phlox is frequently attacked by a leaf- 

 spot fungus (Septoria divaricatae) . This mars the appearance of 

 the leaves but is not often serious. 



Powdery Mildew. There is a powdery mildew fungus also 

 (Erysiphe Cichoracearum) , sometimes found upon cultivated phlox. 

 It develops as a whitish covering over the leaves and other parts. 

 Both should yield to spraying properly done. 



PRIMULA. 



Rot. A rot of Chinese primula due to Botrytis and similar to 

 that on peony has been reported and may be expected with us. 



PRIVET. 



Anthracnose. Privet in hedges is frequently attacked by an- 

 thracnose (Gloeosporium cingulatum) . This shows itself by lesions 

 in the younger stems and results in dying of the portions of the at- 

 tacked branches beyond the lesions. This weakens the hedge and 

 sometimes rasults in secondary consequences. While spraying has 

 not been fully worked out for this disease, it should prove an ef- 

 fective remedy at the proper time. (Ohio E. S. B. 214.) 



PLANT DISEASES AND THEIR CONTROL. 



Rose Mildew. Powdery mildew is one of the most common 

 and injurious diseases of roses, wherever they are grown. In regions 

 where the climate is most suitaible for outdoor rose culture, mildew 

 is also prevalent; but here it is rarely troublesome except in the 

 greenhouse, where it often causes serious injury. A few varieties, the 

 Crimson Rambler and some related forms especially, are badly in- 

 jured outdoors, but much less so when grown away from walls so 

 that they have free air exposure. 



The mildew is usually first noticed as grayish or whitish spots 

 on the young leaves or shoots, these being more or less distorted by 

 the disease. Later as the spots enlarge they have a white, powdery 

 appearance, or on the stems, or thorns more than elsewhere, may 

 have a quite felt-like coating. After a few weeks as the affected 

 parts mature, the mildew appearance is lost and the injured portions 

 show a dark color. 



The young leaves, stems and buds are dwarfed, curled or va- 

 riously deformed by the disease. The foliage is reduced by the de- 

 formation and killing of parts of the leaf surface, and by the drop- 



