DISEASES OF CULTIVATED PLANTS 393, 
Unlike the downy mildew, anthracnose may be checked after it appears, though 
best prevented by earlier applications of the fungicide. In the field, Bordeaux 
mixture is to be preferred; in*the greenhouse, copper sulfate solution, one pound 
to 50 gallons, has proved efficient and has checked the anthracnose after one- 
fourth of the plants had been destroyed by it. 
Damping-off is a frequent trouble upon greenhouse cucumbers. It is serious 
often where plantings are made following lettuce attacked by rosette. The 
fungus in that case is the same as lettuce rosette (s2hizoctonia) or lettuce drop 
(Botrytis). There isa strictly damping-off fungus (Pythium De Baryanum 
Hesse) that is sometimes troublesome. The Botrytis named at times attacks 
pruned parts of cucumber plants, also extending its attacks to the blossom end 
of young fruits. - 
The results of Rhizoctonia on greenhouse cucumbers have been curious 
owing to attacks on the smaller root branches or rootlets. The growth of the 
vines is at times checked, 
accompanied by coloring 
of the leaves and reduced 
“fruitfulness. Some grow- 
ers have given the name 
‘Yeaf-curl’’? to this phe- 
nomenon but it is strictly 
the effect of the fungus 
named. It has been found 
necessary in soiltreatments 
where cucumbers follow 
affected lettuce to increase 
the strength of formalin 
drench to 4 or 5 pounds 
per 50 gallons of water. 
{See Soil Diseases). 
Downy Mildew. Downy 
-mildew fungus (fPlasmo- 
para Cubensis (B. & C.) 
Humpbh. ) is late in its at- 
tacks, not having been 
found in Ohio fields earlier 
than August 3rd._ It causes Fig. 48. Cucumber leaf from greenhouse, attacked by Downy 
angular, yellowish spots Mildew. The spots in the leaves caused by the mildew are 
on the leaves, followed by usually outlined by the veinlets of the leaf.—From a photograph 
by T. F. Manns. 
yellowing of the whole leaf 
and death, as by frost. It spreads with extraordinary rapidity, requiring only 
three or four days to become disseminated throughout a large field. Unlike 
anthracnose, it may not be successfully checked after its appearance, and it is 
not safe to leave untreated plots in fields to be sprayed. July 25th to August 1st 
is sufficiently early to begin spraying for mildew, but applications should be 
repeated at intervals of 7 or 9 days. In 1898 an increase of 75 bushels per acre, 
of sprayed over unsprayed cucumbers, was obtained at Creston. (Bulletin 105). 
Cucumber pickle growing finds in this mildew its most serious enemy. If any 
of the crop is to be harvested after August 20-25 spraying with fungicides ap- 
pears necessary. Early planting may permit gathering the crop before this 
date. The downy mildew is also very destructive in the forcinghouse, and is to 
be treated with the same fungicides recommended for anthracnose. (Bulletins 
73, 89 and 105). 
