. Fig. 26.—Black spot of rose. plants. The same organism—Phytomonas tumefaciens—is responsible. In the rose it sometimes also happens that similar galls appear on the stems aboveground, usually at nodes or points where injuries have occurred. In some cases in greenhouse roses, large, soft, spongy galls develop in abundance in the stems wherever there has been a cut. Care should be taken not to plant rose bushes affected with crown gall. Badly diseased plants should be removed and burned. In the case of bushes which are affected in the canes aboveground, it may be possible to cut off the diseas
. Fig. 26.—Black spot of rose. plants. The same organism—Phytomonas tumefaciens—is responsible. In the rose it sometimes also happens that similar galls appear on the stems aboveground, usually at nodes or points where injuries have occurred. In some cases in greenhouse roses, large, soft, spongy galls develop in abundance in the stems wherever there has been a cut. Care should be taken not to plant rose bushes affected with crown gall. Badly diseased plants should be removed and burned. In the case of bushes which are affected in the canes aboveground, it may be possible to cut off the diseased branches and force out new growth if the galls are not too abundant. All cuts, as well as the tools, should be disinfected with 1-1,000 solution of corrosive sublimate (p. 100). Downy Mildew.—Irregular brown spots are sometimes seen on the younger leaves, with a sparse fungus growth, Peronospora sparsa, on the underside. The leaves are blighted and often fall. This disease is not
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Keywords: ., bo, bookcentury1900, booksubjectflowers, booksubjectplantdiseases
