CARNATION MANUAL 
ROOT AND STEM ROTS 
There are two root and stem rot diseases: Rhizoctonia stem rot and Fusarium root rot. 
RHIZOCTONIA STEM ROT 
SYMPTOMS: This disease is characterized by a progressive wilting, collapse and browning of the entire 
plant, associated with a soft decay at the soil line. The stem at the soil level is soft and moist and 
the bark is easily rubbed off. It is not sticky, however, and the wood beneath the bark remains firm. 
The roots remain intact. The fungus Rhizoctonia, is almost universally present in soil and it can at- 
tack carnations at any stage from the cutting bench to the mature plant in the bench, High soil 
temperatures and soil moistures both favor the disease, and losses are highest during the summer 
months, Deep planting also contributes to the efficiency of the disease. 
CONTROL: Steam sterilization is the only preventive measure. Inside culture is by far the better over 
out-of-door culture. Dimock reports that in cases where Rhizoc begins to show up in an occasional 
spot in a sterilized bed, immediate drenching of the affected area and the soil for a couple of feet 
beyond the obvious infection with a suspension of Semesan at the rate of 1 pound to 50 gallons 
water or approximately 1 rounded tablespoonful per gallon will hold this disease in check. It might 
be advisable to make a second application at about half the above dosage rate in about ten days. 
Because there is always some danger of a little injury from the chemical, it is not recommended as 
a general prophylactic treatment, but suggested as a means of definitely stopping further advance 
of accidental contamination, Planting high, with the top of the original root ball somewhat above 
the general bench level, has been found quite effective in reducing trouble from Rhizoc. 
FUSARIUM ROOT ROT AND STEM ROT 
SYMPTOMS: Fusarium root rot and stem rot is distinct from Fusarium wilt. When plants are affected with 
root rot the entire plant wilts, the roots rot and slough away to the root base. Some rotting of 
the base of the stem may take place, but there is no extensive vascular discoloration as in Fusarium 
wilt or bacterial wilt. Extensive losses may occur in the cutting bench as diseased cuttings usually 
fail to root, or root poorly. The disease is most serious in young plants and in soil that is kept ex- 
cessively wet. Fortunately for control, the organism does not spread into the upper parts of the 
plant. 
CONTROL: Follow the general sanitation practices such as steam sterilizing, proper use of the hose, and 
the avoidance of wet soil. 
Yellows. Leaves from plant affected with both mosaic Mottling and streaking of leaves in plant affected with 
and streak. mosaic and streak viruses. 
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