452 DISEASES OF ECONOMIC PLANTS 



The number of these diseases is so large that separate 

 discussion cannot be given to them. The grower should 

 recognize, however, the special weakness of this type of 

 plant and compensate for it by special care as to hygienic 

 surroundings, clean-culture methods, and liberal use of pro- 

 tective sprays when acervuli, pycnidia, or molds indicate the 

 presence of a fungus. 



ASTER, CHINA 



Wilt, stem rot, fusariose' (Fusarium sp.). — The wilt, 

 mentioned as early as 1896 by Galloway, has since been 

 reported from Massachusetts and Colorado, and is probably 

 the most important disease of the China aster. The time 

 of transplanting the beds and blossoming time are most 

 susceptible periods, though the wilt is present to some ex- 

 tent at other times. 



The most conspicuous symptom is the sudden death of 

 the plants, with all portions of the stem except the wood 

 rotted at the ground line. Close observation earlier shows 

 the leaves upon one side of the plant, particularly the lower 

 leaves, yellowed and wilted, and the youngest leaves to 

 be smaller than normal. The wilting effect may some- 

 times be found first on one side only of one of the lower 

 leaves. Plants attacked early may die, or in milder cases 

 may survive to produce a few small blooms. If the 

 symptoms first show at blooming time, their sequence is 

 the same. 



The roots in early stages appear healthy, but the stem 

 near the ground, in longitudinal section, shows darkening 

 of the outer wood, local at first upon the affected side, but 



' Smith, R. E., Mass. Agr. Exp. Sta. Bui. 79, February, 1902. 



