Sevier RN ArT LON CO... ING. 11 


TREATMENT OF INSECTS AND DISEASES 
RED SPIDERS . 
This is the worst insect pest with which carnation growers have to contend. 
There are scores of remedies, particularly sprays, many of which are worthless, 
and some of which are dangerous. By far the best method of control is by fumi- 
gation with naphthalene base compounds. Liquid Fulex is outstanding in this 
field. Control] in the field, in mixed houses, or where only small areas are in- 
volved may be by spray or dust. It is preferable to spray as little as possible, 
for there are very few sprays which will not injure the plants if used frequently. 
Sprays and dusts kill by contact, and must be applied thoroughly. Rotenone 
sprays are generally safe and effective on carnations. Oily sprays should be 
avoided as these are likely to remove the bloom from the foliage. Syringing 
with a fine stream of water under pressure may be practiced when plants are 
small and on bright, warm days, but should never be done whenever any fungus 
or bacterial disease is present. Dusts have met with varying degrees of success, 
and must be used very carefully in hot weather in order to avoid damage. 
APHIDS AND THRIPS 
These are comparatively minor problems, and are easily remedied, although 
thrips will continue to blow in from outside as long as ventilators are open. 
Nicotine in one form or another is the best cure. Nicotine fumigation every 
four or five days until the insects are cleaned up is the most effective means of 
control. Spraying with Paris Green and brown sugar is effective in the case of 
thrips, but this leaves the foliage dirty and sticky for months. 
RHIZOCTONIA STEM ROT (Rhizoctonia solant) 
Foliage becomes dull, losing green color; entire plant wilts suddenly. Stem 
near soil wet and soft; the shredded bark sloughing off from the slightest twist, 
exposing harder tissues beneath. Roots remain intact. Brown knots of fungus 
mold evident about decayed portion of stem and adhering soil. Is caused by 
a common mold fungus which inhabits most soil and soil-contaminated sand. 
It is not carried in cuttings. Ordinarily the mold is a harmless soil fungus, but 
under favorable conditions it becomes a serious disease. It thrives under exces- 
sively moist and warm conditions. Control is a matter of correct watering and 
airing, sanitation, shallow planting, soil sterilization and soil rotation. Acidity, 
alkalinity or fertility of soil within the limits of good plant growth are of no value 
in the control of the disease. Spraying is useless. Steam sterilization, or steril- 
ization with tear gas, helps, but sterilized soil may easily become reinfected if 
plants are brought in from outside. 
FUSARIUM BRANCH ROT (Fusarium dianth) 
Begins with the wilting of a single branch. Leaves are a dull green, then 
yellow and straw colored. The affected branch dries and shrivels. Infection at 
first is localized in the stem or branch near crotches or nodes. Injuries of one 
sort or another caused by careless handling, too rapid growth, topping, picking, 
etc., are essential for infection except where the disease has been carried with the 
cuttings. Upon cutting the branches lengthwise, the conductive tissue under the 
bark is seen to be yellowish or reddish brown extending up and down following 
the sap channel. If the branch is removed before the disease has progressed into 
the stem, the plant may possibly be saved. Later the brown color expands into 
the inne tissue of the stem and into the outer bark from the conductive tissue. 
When the stem is invaded, the branches on the infected side die, and ultimately 
the entire plant succumbs. The inside tissue of an invaded stem is dry and of 
a dull brown color, similar in appearance to dead timber. As the infection is 
usually aerial, soil sterilization is of little value, and there is no known spray 
which will prevent or cure it. Sterilizing benches, flats, soil and sand are sanitary 
