By) endes pel ep Comira 
FOLIAGE DISEASES 
There are three foliage diseases: Alternaria Blight and Branch Rot, Rust and Bacterial Leaf Spot: 
ALTERNARIA BLIGHT AND BRANCH ROT 
SYMPTOMS: Alternaria blight and branch rot probably occurs wherever carnations are grown and is 
most serious on plants that have been grown in the field. This is an external disease and the 
symptoms appear on stems, leaves and occasionally on the flowers. Tiny purple spots are the first 
symptoms of the disease on the leaves, and later on the spots enlarge until a light brown, dead 
shrunken place appears in the center. Branches of the plant are usually infected at the nodes 
where they girdle the stem or branch, causing it to die. Brown spots later become black, as spores 
of the fungus appear on the surface. 
The main source of infection occurs in the cutting bench. The fungus apparently does not live over 
in the field. The disease is spread from plant to plant in water during syringing operations or by 
splashing water in the field. The spores land on leaf surfaces, germinate and enter through stomata. 
Infection takes most rapidly about 70° F. and free water must be present for at least 8 to 10 hours. 
CONTROL: Year around inside culture with careful watering is the best preventive measure. For those 
who continue to grow out-of-doors, in addition to sanitation and other good cultural methods a reg- 
ular weekly spraying of Bordeaux Mixture with a good wetting agent should be applied. Dimock 
has reported that Orthocide 406 was very effective in the control of Alternaria Blight. When field 
culture is practiced, it is advisable to rebench as early as possible, 
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 Parzate plus 
zine 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 gallons. Regular spraying every ten days to two weeks should control rust 
under rather unfavorable greenhouse conditions. 
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Alternaria Blight— A lesion has girdled the stem and Yellowish mottling and ringspot patterns produced in 
caused the death of the parts above. Black spore masses upper young leaves of plants affected with Alternaria 
‘0 of the pathogen can be seen on surface of lesion. Blight. 
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