402 OHIO EXPERIMENT STATION: BULLETIN 214 
HOLLYHOCK 
Anthracnose (Colletotrichum malvarum (Braun & Casp.) Southw.) An 
illustration has been published in the Journal Mycology (Vol. 6:46-48). It may 
attack any part of the plant, and is a serious trouble where it occurs. 
Leaf Blight (Cercospora Althaeina Sacc.) is another fungus disease of the 
hollyhock. These two diseases of the hollyhock should be amenable to spraying 
with standard fungicides. 
Rust (Puccinia Malvacearum Mont.) On the other hand this recently 
introduced disease of the hollyhock is much less likely to be prevented by 
spraying. The rust fungus forms dense patches, spots or sori, on the under 
side of the leaves. These are commonly about one-sixteenth inch or more in di- 
ameter, of grayish-brown color and projecting below the leaf surface, while a 
minute yellow spot early appears on the upper surface of the leaf. Sub- 
sequently the diseased leaves drop and by the time the plants are blooming the 
the stem below is bare or disfigured by the remains of the diseased leaves. At 
the Station this rust has been prevalent and the complaint is general respecting 
the same-trouble. It would seem wise to gather and burn all the affected 
leaves and likewise the old stems as early as possible. Between anthracnose 
and rust these popular old flowers are having, at present, a difficult time of it. 
HORSE-CHESTNUT 
Leaf-Spot of the horse-chestnut (Phyllosticta paviae Desm. )is quite frequent. 
During 1908 and 1909, tip-burn was associated with leaf-spot; as near as could 
be determined, the tip-burn followed punctures of leaf hoppers or other insects 
and the plants made very restricted growth during the season. It may be 
necessary to take combined spraying applications for leaf-spot and the insect- 
troubles. Bordeaux mixture is recommended for this purpose and has in the 
past given very satisfactory results for leaf-spot. The first application should 
be made when the leaves are about half grown, to be followed by others at 
intervals of three weeks. 
HORSERADISH 
Leaf Blight (Ramularia armoraceae Fckl.) is frequent upon horseradish 
and is also found upon other mustard plants. Ordinarily the severity of attack 
does not call for spray treatment. 
Leaf-Spot (Cercospora armoraceae Sacc.) is less frequent and not serious in 
its effects. 
White Mold ( Cystopus Candidus Pers) which is so common upon shepherd’s 
purse and other low plants of the mustard family, likewise attacks horseradish. 
Owing to the heavy root development of horseradish the temporary parasitic 
attack does not give noticeable injury. 
HYDRANGEA 
Leaf Blight. A leaf blight fungus (Phyllosticta fydrangeae E. & E.) has 
been observed on Hydrangea by Dr. Halsted in New Jersey. This may be 
serious at times upon this ornamental plant. 
Rust. Hydrangea is likewise attacked by the rust fungus. (Melampsora 
Hydrangeae BC.) This may also be at times, quite serious. Remedies for 
neither of these troubles have as yet been worked out. 
