Narcissus 
Fusarium rot is a soft brown rot that starts at the basal plate 
of the nercissus bulb, spreads through the bulb and destroys it in 
the field or in storage. The fungus is cerried in diseased bulbs 
and can persist for years in infested soil, Damage cccurs wherever 
narcissus is grow, but is most severe in warm soils. Losses were 
extremely heavy in the early years of domestic narcissus preduction. 
Changes in verieties and in cultural practices and the development 
of fungicidal dips containing organic mercury compounds have de- 
creased losses but have not eliminated then. 
Roses 
Blackspot occurs wherever roses are grown, causing leaf spots and 
defoliation, and contributing to dieback and winter injury. It is 
the chief disease of garden roses, and limits the use of hybrid tea 
roses in gardens. In all but the driest areas, regular spraying or 
dusting with sulfur-copper or sulfur-ferbam is necessary to hold 
blackspot in check. In wet seasons the most effective fungicides 
and proper timing of applications are important. On greenhouse 
roses, blackspot has nearly disappeared since miticides have come 
into use for control of spicer mites. 
Rose mildew, another fungus disease, appears as a white powdery 
coating on leaves, buds, and canes, with curling and distortion of 
leaves and buds. It is present each year on the susceptible rambler 
roses, and in humid weather it may also damage hybrid teas. In 
greenhouses mildew is troublesome especially in spring and fall when 
temperature fluctuations afford high humidity. Spraying roses in 
greenhouses is often necessary to prevent decrease in production 
and cull blooms. Spotting, staining, and sometimes burning produced 
by mildew fungicides add to the losses assignable to this disease. 
Shace and Ornamental Trees 
Over 1,000 species of native and introduced shade and ornamental 
trees are used in home grounds, on farmsteads, in parks, and along 
streets and highways. No species is immne to diseases, Some di- 
seases kill the trees, some weaken them so that they are unsafe, 
and others kill the tops and reduce growth. Examples of killing 
diseases sre Dutch elm disease, elm phloem necrosis, oak wilt, 
mimosa wilt, and cankerstain of London planetree. There are hun- 
dreds of canker diseases, wood rots, leaf diseases, and root diseases 
of shade and ornamental trees. 
to protect shade trees from many of these diseases, a costly maine 
tenance program of spraying, pruning, and fertilization must be con- 
ducted. No definite information is available on the total cost of 
protecting shade trees from disease and of replacing those killed or 
structurally weakened. A conservative estimate of the average cost. 
Cy W 
