Some Bacterial Diseases oe Plants. 23 
gently and slowly separated, this sticky liquid will string out in fine 
threads an inch and a half or more in length. The juices in the 
healthy, normal stem do not possess this viscid nature to such a 
degree and this phenomenon may be taken as an indication of the 
bacterial wilt. 
Growers seem to think the disease is worse during wet weather 
and just after a heavy rain, especially if the sun comes out very hot. 
If such is the case, it is probably due to the fact that these conditions 
favor the growth of the germs and bring about a more rapid dis¬ 
tribution of the bacteria through the plant. 
The microorganism which causes the disease, Bacillus trachei- 
philus (Smith), lives in the soil, in the decaying leaves and vines 
of the different cucurbits and probably gains entrance into the host 
plant through the root or some injured spot on the runner. Plant 
on new land as far as possible and avoid the use of fields which 
have shown the infection. In all probability, wilt lives in the soil 
for five to ten years and perhaps longer. For this reason no squash 
or other member of that family, which will furnish food for the 
germs, should be grown on sick land during this time. While rota¬ 
tion with other crops is in no sense a cure for the diseased soil, it 
is to be strongly recommended over attempting to grow cantaloupes 
or squash year after year, in spite of the disease. 
Careful observations have shown that when only a few vines 
are affected, the disease is often spread over the whole field by the 
cucumber beetle and squash bug, hence the necessity of destroying 
these insects. While no direct benefit is derived from spraying, so 
far as killing the germs of the wilt is concerned, good often follows 
such treatment, because of the destruction of insects which carry the 
disease from plant to plant. Since no specific remedy can be rec¬ 
ommended and no wilt resistant varieties can be offered, preventa¬ 
tive measures alone are left at our disposal. Where the infection is 
not too general and it is confined to a few hills, further spread can 
often be prevented by digging up the vines and burning them. 
NOTE—It is earnestly desired that the farmers, gardeners and fruit 
growers of the State of Colorado will co-operate with the Experiment Station 
in furthering the study of bacterial plant diseases by reporting all diseases 
of this nature that may come under their notice, and also by sending in 
specimens of suspicious material for examination. Wherever possible, the 
whole plant should be sent, for usually root, stem and leaf are required for 
a satisfactory diagnosis. Address communications relative to suspected 
bacterial plant diseases to, 
BACTERIOLOGIST, 
Agricultural Experiment Station, 
Fort Collins, Colorado. 
