RUST 
SYMPTOMS: Rust attacks plants from the cutting 
stage to the mature plant. The fungus causing 
rust on carnations is not the same one as the 
one causing rust of snapdragons or asters. The 
characteristic reddish-brown pustules develop on 
the leaves and stems. These spores may be 
disseminated by wind rather than water but 
water must be present on the leaves for infection 
to take place. Only a few hours are required 
for infection. Fungus grows inside the tissue and 
two to four weeks later a new crop of spores 
are formed. 
CONTROL: Rust infection will not take place when 
the plants are kept perfectly dry. Secure cuttings 
from rust-free plants only. Under some conditions 
such as leaky greenhouses and for those who 
cannot control the moisture of the hose, a 
spraying with either Dry Parzate or Liquid Par- 
zate plus zinc sulfate should be followed. Use 
dry Parzate at the rate of 1 pound per 100 
gallons and the liquid Parzate at the rate of 2 
quarts of fungicide plus % to 1 pound zinc 
sulfate plus a good spreader in each 100 gal- 
lons. Regular spraying every ten days to two 
weeks should control rust under rather unfavor- 
able greenhouse conditions. Orthocide 406 has 
recently been reported to be very effective in 
the control of rust. 
Alternaria Blight — A lesion has girdled the stem and 
caused the death of the parts above. Black spore 
masses of the pathogen can be seen on surface 
of lesion. 
Yellowish mottling and ringspot patterns produced in 
upper young leaves of plants affected with Alternaria 
Blight. 
BACTERIAL LEAF SPOT 
SYMPTOMS: This disease is troublesome in some areas, especially areas like the Hawaiian Islands where 
carnations are grown out-of-doors and where there are frequent rains. The spots are circular or 
oval-shaped with purplish borders. Lower leaves are affected first and then spreads upward by 
syringing or splashing water. Optimum temperature for its development is 75° F. 
CONTROL: Bordeaux Mixture has proved to be the most effective. 
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