Rose diseases : their causes and control. Page: 2
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2 FARMERS BULLETIN 1547
CONDITIONS OF GROWTH
There are comparatively few localities in the United States in
which some type of rose can not be grown out of doors. The tender
varieties, however, such as hybrid teas, are more restricted as to
favorable localities. Plants grown successfully in one locality under
certain conditions of climate and soil may fail completely under
the different climatic and soil conditions of another locality. Therefore,
if roses are to be grown out of doors, varieties should be chosen
which are adapted to the climate and the soil.3
After a suitable variety has been selected and planted, it must be
provided with the proper food in the form of fertilizers; it needs
water, light, and air in the right quantities. An overabundant or
an insufficient amount of these factors may result in a poor root
system, tender or discolored foliage, buds which fail to Ilature, or
imperfect, weak-stemmed blossoms. In the greenhouse all these factors
may be more carefully controlled, but sudden changes may
cause more serious injury than in the case of out-of-door plants,
which are somewhat hardened to weather changes. For this reason
special attention should be given in the greenhouse to the temperature
and moisture of the air and soil, the application of fertilizers,
the proper ventilation, and the lighting, in order to obtain the most
favorable conditions for growth, particularly during forcing.
ORGANISMS CAUSING DISEASE
The second group of diseases is caused for the most part by
fungous organisms. Because of the fact that they obtain their food
from the tissues of the rose plant they are called parasites. They
are simple forms of plant life and reproduce by means of small
bodies known as spores. One disease described in this bulletincrown
gall-is caused by a bacterium? a very simple form of plant
life which, like the fungi, lives as a parasite upon the rose. It
belongs to that group of organisms which cause many diseases
The diseases described in this bulletin are those which appear most
commonly in the home garden, in the nursery, or in the greenhouse.
The methods of control recommended for each disease are those
which have proved to be best adapted for general use.4
Powdery mildew, caused by Sphacrotheca pannosa Lev. var.
rosae Wor., is one of the most common diseases of roses and is very
rarely absent from any rose garden or greenhouse during the growing
season. Nearly all types of roses are susceptible, including wild
roses, hybrid perpetuals, hybrid teas, and climbing roses, particularly
the Crimson Rambler and Dorothy Perkins.
aInformation on the selection of varieties and methods of cultivation and pruning is
given in Farmers' Bulletin 750, Roses for the Iome.
4Information on the use of sprays other than those mentioned in this bulletin may be
obtained from the Bureau of Plant Industry, United States Department of Agriculture,
Washington, D. C.
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Waterman, Alma M. (Alma May), b. 1893. & Weiss, Freeman. Rose diseases : their causes and control., book, 1941; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc3430/m1/4/: accessed February 21, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.