232 Diseases of Greenhouse Crops 



FusARiuM Leaf Spot 

 Caused by Fusarium sp. 



Symptoms, This form of leaf spot usually fol- 

 lows the injury caused by the rust fungus {Uromyces 

 caryophyllinus). The variety Emily Pierson is es- 

 pecially subject to the attacks of this peculiar leaf 

 spot. The spots are large, often occupying the en- 

 tire width of the leaf. The diseased tissue becomes 

 covered with a pinkish mold in the center of which 

 are found minute spore clusters of the Fusarium fun- 

 gus. Little is known of the causal organism. In 

 controlling rust, the leaf spot will also be kept in 

 check. 



'Branch Rot," Dry Stem Rot, or Die Back 

 Caused by Fusarium sp. 



Symptoms, This troublesome carnation disease 

 was first described by Sturgis.* Attacked stems and 

 branches wilt rapidly and the color of the leaves 

 turns to a yellowish green. Dead stems remain firm, 

 although wilted and shriveled. The bark likewise 

 remains firm. The causal fungus seems to gain 

 entrance through cuts or wounds. With cuttings 

 the trouble may start at the base, causing them to 

 dry up and to lose their normal color. The condi- 

 tions which favor the disease are excessive rains 

 in the summer when the plants grow out of doors. 

 This favors a large, bushy, soft growth, with a 



♦Sturgis, W. C, Conn. Agr. Expt. Sta., Rept. 21: 175-181, 1898. 



