Yellows, a leafhopper-borne virus disease affecting many kinds of 
plants, is particularly damaging to China aster. Affected plants 
have yellowish leaves, many lateral branches with an upright habit 
of growth, green flowers, and no viable seeds. The disease is 
generally prevalent over the United States, occurring in a slightiy 
different form westward. China asters for commercial cut flowers 
are Rearly always produced under cloth to exclude the leafhopper 
vectors. 
Chrysanthenuns 
Verticillium wilt, stunt, and leaf nematodes, carried in cuttings 
used in propagating chrysanthemums, have forced the business of 
propagation into the hands of specialists, who index and reselect 
plmts free from such diseases for commercial growers. Their suc- 
cess in producing healthy propagation stock has greatly reduced 
losses in commercial greenhouse and shads-house chrysanthemums. 
Such reselection service is not generally available for garden 
varieties, and losses remain heavy for the amateur. Leaf spot 
causes heavy losses in wet seasons unless sprays are applied. In- 
roads of these diseases tend to discourage the amateur and thus 
lower the demand for garden varieties. 
Leaf spot is characterized by yellowish spots on the leaves, be- 
coming brown to black with black dots near the centers. In unpro- 
tected garden chrysanthemums severe defoliation follows in wet 
seasons. Commercial chrysanthemums are sprayed with ferbam when 
necessary, so that losses in these plantings are rarely important. 
The leaf nematode causes leaves to wither and droop, marring the 
appearance and lowering the production of garden chrysanthemums, 
especially in wet seasons. Initial symptoms are yellowish spots 
in the leaves; later these spots enlarge and turn black, often 
being delimited by veins to form wedge-shaped areas. This nematode 
is widely distributed and damaging in gardens, but rare in commercial 
shade chrysanthemums, which are produced from selected disease-free 
plants. 
Stunt, a virus disease, shortens the plants and reduces the size 
of the leaves and blooms. In some varieties stunted plants bloom 
earlier than normal ones, and some bronze=- and pink-flowered sorts 
bear bleached or yellow blooms. The disease is widespread in gar- 
den chrysanthemums, but less prevalent in florists’ varieties be- 
cause of intensive work of reselection of disease-free stock. 
Verticillium wilt is caused by a soil-borne fungus. Affected 
plants show yellowing and browning of leaves progressing from the 
lowermost upward, and sometimes dark streaks in the woody tissues 
of stems. Plants are killed or, in earlier stages of the disease, 
unproductive. In garden chrysanthemums this wilt is common and 
difficult to control. Commercial plantings under glass and under 
