Wormald. — Further Studies of the ‘ Brown Rot 1 Fungi . /. 315 
range from 10 x 8 /x to 26 x 16 /x and 22 x 18 j u, the average being 16-8 x 12*5 /ot. 
These ‘summer conidia ’ on the fruit were thus greater than those conidia 
produced on the dead shoots and cankers in winter, as will be seen by com- 
paring the dimensions here given with those of the ‘ winter conidia k 1 
These results confirm those of observations previously recorded, 2 which 
go to show that the conidia of Sclerotinia cinerea produced in winter, on 
shoots, cankers, and mummied fruit, are invariably distinctly smaller than 
those which develop on recently infected fruit, leaves, and flowers in 
summer. 
(c) Inoculation of Apple Flowers. 
This experiment was carried out on two trees (variety James Grieve) 
in the fruit plantation. Inflorescences were selected which bore flowers 
recently opened, and two flowers were inoculated on each inflorescence. On 
one tree five inflorescences were inoculated with the Shoot-Wilt Monilia and 
five with the Apple Blossom-Wilt fungus (. Monilia cinerea f. mail) ; on the 
second tree three inflorescences were inoculated with the former and three 
with the latter. Thus each fungus was used to inoculate sixteen flowers on 
eight inflorescences. The inoculations were made by placing conidia from 
pure cultures on the stigmas. 3 
Of the flowers inoculated with the Apple Blossom-Wilt fungus all were 
killed. On one inflorescence the two inoculated flowers fell off without 
infection extending into the axis ; in the rest, however, the mycelium grew 
into the spurs and killed all the flowers and leaves on those spurs, the wilt- 
ing of the leaves being noticeable in from fourteen to seventeen days from 
the day the flowers were inoculated, a condition typical of the Apple 
Blossom-Wilt disease. 4 
Of the flowers inoculated with the Shoot-Wilt Monilia the preliminary 
symptoms of infection were observed in an early browning of the styles and 
a premature withering of the stamens and calyx lobes as seen by comparing 
the inoculated flowers with normal flowers of the same age. All the 
inoculated flowers, with the exception of two, fell before setting into fruit, 
and in no case did the fungus enter the axis of the inflorescence, the other 
flowers and the leaves showing no signs of infection. In this respect the 
Shoot-Wilt Monilia is biologically similar to isolations of Sclerotinia cinerea 
obtained from Monilia fructifications found on plums and cherries, and also 
to an isolation started from an ascospore when the ascigerous stage was 
found on mummied plums. 5 
1 See p. 308. 2 Ann. Bot., xxxiv, p. 161. 
3 For further details of the method adopted in inoculating flowers with Monilia conidia, see 
Ann. Bot., xxxiii, no. .131, pp. 388 and 390. 
4 Vide A Blossom-Wilt and Canker of Apple Trees. Ann. Appl. Biol., iii. 159, 1917. 
5 Vide On the Occurrence in Britain of the Ascigerous Stage of a Brown Rot Fungus. Ann. 
Bot., xxxv, No. 137, pp. 125-35, Jan. 1921. 
