ii8 
FLORIDA STATE HORTICULTURAL SOCIETY. 
seed tubers were sooner or later complete¬ 
ly destroyed by the fungus, but the plants 
were fairly well established before the 
destruction of the seed. When the disease 
is once introduced in the field it is apt to 
remain in the soil for a number of years, 
hence it is desirable to practice a syste¬ 
matic rotation of crops. 
Carefully selecting clear smooth seed 
and rejecting from time to time all tubers 
showing any sign of rot, also aids material¬ 
ly in checking the spread of the disease. 
Exposing the seed to the light from four 
to five weeks before planting is an ex¬ 
cellent practice. Ths treatment tends to 
hasten the germination of the tubers after 
planting and enables the plarit to become 
established before the seed tuber is en¬ 
tirely destroyed. 
Bacillus Solanacernm (Smitli.) 
Bacterial Wilt —A very common and 
destructive disease. This disease causes 
the foliage to wilt, and later, the stems and 
branches become discolored and die. In¬ 
fection rnay occur either above or below 
the ground. The disease also produces a 
brown or black rot of the tubers. This 
organism also attacks egg plants and to¬ 
matoes. 
Select clean, smooth seed, rejecting all 
those showing black end vascular bundles. 
Expose the seed to the light four or five 
weeks before planting. 
Corticinm Vagnm Var. Solani (Burt). 
Rhizoctonia —A wide-spread disease. 
It is usually most troublesome on low 
lands but during excessive wet weather it 
also causes more or less loss on the higher 
lands. The young plants suffer most, and 
many of the young shoots are completely 
cut off before they reach the surface of 
the ground. This disease also frequently 
produces injuries which bring about an 
abnormal development of small tubers. It 
is also injurious to the surface of growing 
tubers and freguently produces a rough 
surface known as scab. 
This fungus forms a white felt-like 
fruiting membrane on the green stems 
just above the surface of the ground, often 
covering the stems for a distance of three 
inches. This membrane is composed of a 
network of hyphae which produce many 
short, club-shaped branches (basidae) on 
which small stalks (strigmata) develop. 
At the end of each strigmata a single, 
brown spore (seed) develops. These 
spores fall as soon as they mature. If 
they fall on a moist surface they ger¬ 
minate in a few hours and thus may start 
new areas of infection. It is also pro¬ 
pagated by black scale-like bodies called 
sclerotia. These form freely on the 
stems and tubers below the surface of the 
ground. The sclerotia are composed of 
large, closely packed cells. When dry, 
the sclerotia are hard to detect, but when 
wet, they are dark brown and easily seen. 
Tubers which are more or less covered 
with these bodies ought not to be used for 
seed, since the cells of these sclerotia de¬ 
velop into long, feeding threads, which, 
under favorable conditions, soon invade 
and frequently destroy the young shoots. 
A diseased tuber in a sack of clean ones 
under favorable conditions of heat and 
moisture, may spread the disease to ad¬ 
joining tubers and in time infect the entire 
lot. Carefully selecting clean, smooth 
tubers and exposing them to the light 
from four to five weeks before planting, 
gives excellent results. When the fungus 
is once introduced into a field it remains 
in the soil a number of years. Good 
drainage and careful cultivation aids ma- 
