F. H. Stewart 
161 
Discovery of the Parasite. 
Aplielenchus fragariae was first described by Ritzema Bos (1891) as causing 
a disease among strawberry plants in Kent; the plants had been sent to him 
by Miss Ormerod. 
Nematoid worms were observed to cause disease in the leaves of Begonia 
by Worthington Smith (1890), in plants which came from Dunstable. In the 
following year Klebahn (1891) found A]ihelenchi in blotched leaves of two 
species of fern {Asplenium diversifolium and bulbiferum) growing in a nursery 
in Bremen, and sent specimens to Ritzema Bos. The latter authority, having 
found the same species in these specimens and in Begonia leaves from England, 
described it under the name of A. olesistus. 
II. DISTRIBUTION OP THE PARASITES, AND THE DISEASES 
CAUSED BY THEM. 
A. fragariae. The disease caused by this species has been named strawberry 
bunch by Cobb (1891) (Blumenkohlkrankheit der Erdbeerpflanze, Ritzema 
Bos, 1891). It is characterised by stunting of growth in the length of the stem, 
and hypertrophy in breadth; the flowers abort, and fruit is not formed. 
Complete failure of the crop consequently results. It has been recorded from 
England, Scotland, Germany, and Norway (Marcinowski, 1908), and is doubt¬ 
less much more widely spread. 
A. olesistus since its discovery in Asplenium and Begonia has been found 
in many species of ferns and flowering plants. It attacks the leaves, causing 
large, sharply defined, brown blotches; the leaves finally wilt and fall off. 
Louis Mangin (1895) recorded the disease “de la Rouille” in Everlasting 
(Helichrysum ) cultivated in the districts of Ollioules, Bandol, and St Nazaire, 
near Toulon. It causes great loss, as affected plants are unsaleable. A similar 
disease has been recorded from chrysanthemums by Atkinson (1891), from 
the United States by Sorauer (1901), Hofer (1901), Osterwalder (1904), and 
Molz (1909) from Switzerland and Germany. Ritzema Bos identified Sorauer 
and Hofer’s nematode as A. olesistus. Sorauer (1902) described a serious 
epidemic in Begonia “Gloire de Lorraine,” in which the plants were unsaleable. 
Osterwalder (1902) found the disease in flowering plants cultivated in the 
open air in Wadenswil and Zurich, in Anemone japonica and Sylvestris, Ranun¬ 
culus montana, Atragena alpina, Eryngium alpinum, Scabiosa sileni folia, 
Spiraea astilboides, Epipactis palustris and others. It also occurs in Coleus 
and Salvia (Hofer, 1901) and in orchids (Marcinowski, 1908). Among ferns 
Pteris ouvardi and cretica have been found affected in addition to Asplenium. 
Material used in the present investigation. 
I received (1) specimens of strawberry plants containing A. fragariae 
from a correspondent in Ayrshire, (2) leaves of Lygodium dicholomum and 
Lomaria ciliata containing A. olesistus from the Royal Botanic Gardens, Kew, 
Parasitology xm 
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