DISEASES OF CULTIVATED PLANTS 409 
threads of the mildew fungus. The melons which are unripened upon the vines 
when attacked by mildew are practically worthless and for this reason large 
losses are usually incurred. The treatment is by Bordeaux mixture, as for 
cucumbers. 
Muskmelon Leaf Blight is a disease more or less peculiar to the muskmelon, 
although the fungus (4dlernaria sp.) which causes it has also been found upon 
cucumber leaves. The leaf blight causes rather large dead areas in the leaves 
which are usually distinguished i 
from those of downy mildew by 
their larger size and the tendency 
of the central portion to break 
out. The prevention of musk- 
melon leaf blight is by no means 
an easy matter, requiring of 
itself great thoroughness and care- 
fulness in the application of the 
Bordeaux mixture and also re- 
quiring that the downy mildew 
shall be watched during the same 
period. For this reason earlier 
sprayings, if made before Aug- 
ust 1st, should be repeated. at 
fortnightly intervals, while those 
after August 1st should be at 
weekly or ten-day intervals. 
Melon growers have succeeded Fig. 58. Muskmelon leaf attacked by leaf blight. The 
by following these lines, while dead spots are caused by aspecies of Alternaria. From 
Bulletin 73. 
others who were less thorough 
were less successful, or failed entirely. The treatment is recommended with 
confidence. (Bulletins 73 and 105). 
Root-Rot. (Rhizoctonia) The root diseases accompanied by rotting of the 
rootlets and induced by the sterile fungus of lettuce rosette is also found on 
greenhouse muskmelons. This is liable to be the case where these follow dis- 
eased crops of lettuce. The prevention is the same as that for the cucumbers, 
viz., thorough soil treatment. 
Muskmelon Wilts are the same in general character as those described for the 
cucumber. Not only the bacterial wilt disease but the wilt due to fusarium has 
developed upon muskmelons in this state. The symptoms are the same as for 
cucumbers, namely: sudden wilting as from lack of water, followed by dying. 
The prevention treatment is the same as before recommended. 
MUSTARDS 
Black-Rot. Mustard plants of all species are liable to be attacked by black- 
rot and if permitted to grow as weeds in fields devoted to cabbage growing and 
will carry the black-rot trouble through the rotations in spite of the grower’s 
other efforts. Let no mustard weeds survive in such rotations. 
Club-Root. Mustard plants generally are attacked by the club-root fungus 
(Plasmodiophora Brassicae Wor.) when this is present in the soil. For this 
reason the weeds of several species may be infested upon lands that have never 
been brought under cultivation. Due attention should be given to mustard plants 
in new lands when designed for cabbage. 
