PEACH SCAB AND ITS CONTROL. 
13 
Fig. 5. — Cladosporium carpophilum: a, Con- 
idiophores and conidia from fruit lesions; 
b, conidiophores and conidia from twig 
lesions; c, conidiophore from leaf lesion; 
d, and e, fragments of mycelium from 
Lima-bean agar culture,showing develop- 
ment ofchlamydospores. Camera-lucida 
drawing. (Magnified 485 times.) 
the more exposed cells thicken and darken and the individual cells may 
assume the characters of chlamydospores (fig. 5, d and e). On old cul- 
tures on steamed peach twigs or certain agar preparations, small, irreg- 
ularly rounded to distinctly elongated, olivaceous, sclerotioid masses, 
usually less than one-third of a milli- 
meter in diameter, may be found. The 
outer cells of these bodies are thick 
walled and olivaceous and frequently 
bear conidiophores. The inner cells are 
thin walled and colorless, with an 
abundant content of oily material. 
Conidiophores. — T h e conidiophores 
(fig. 5, a, I, and c) are short, erect, 
more or less flexuous, one to several 
septate, rarely branched, olivaceous 
hyphse, distinctly enlarged at the base 
and often tapering irregularly toward 
the apex. Their dimensions vary with conditions, though in nature 
they are fairly uniform during the early stages of sporulation. The 
conidia are produced acrogenously, beginning usually when the spo- 
rophores are about 30 to 35 n long. The conidiophores elongate 
apically as conidia are developed, the places of attachment of de- 
tached spores being marked ordinarily by small wartlike processes 
or by geniculations on the sporophores. The extent of this type of 
elongation, which is quite variable, determines the ultimate length of 
the conidiophores. On the overwintered twig lesions the conidiophores 
borne from the subcuticular stromateoid fungal masses occur typically 
in tufts (fig. 4), and tend to be somewhat shorter and thicker than 
those occurring elsewhere in nature. On the fruit they grow much 
longer, often attaining a length of 90 to 100 /jl. On leaf infections 
and twig lesions of the current year they tend to be somewhat more 
erect and less flexuous than on fruit or overwintered twigs. In cul- 
ture there is much greater variation, the sporophores ranging from 
undifferentiated hyphse to abnormally long, slender filaments. Meas- 
urements of conidiophores are summarized in Table II. 
Table II. — Measurements of conidiophores of Cladosporium carpophilum. 
Source. 
Number 
measured. 
Average measure- 
ments (microns). 
Source. 
Number 
measured. 
Average measure- 
ments (microns). 
Length. 
Breadth 
at middle. 
Length. 
Breadth 
at middle. 
Fruit 
10 
10 
10 
20 
10 
63.5 
65.0 
73.0 
42.1 
42.7 
4.6 
4.2 
4.2 
5.5 
5.0 
Twig of current 
10 
10 
10 
10 
48.5 
57.9 
60.8 
57.0 
Do 
4.7 
Do 
Leaf 
4.6 
Overwintered twig. 
Do 
4.6 
Do 
Do. . 
4.5 
Conidiophores in early stage of sporulation; consequently, relatively short. 
