468 DISEASES OF CULTIVATED PLANTS 



pathologists, have shown that the fungus frequently follows 

 scab on apples, caused by Fusidadium dendriticum, and 

 produces rotting. The Tridwthecium acts as a wound- 

 parasite, and cannot infect an apple through the unbroken 

 skin, but appears at those points where the scab fungus has 

 ruptured the skin, usually as a ring of mould surrounding a 

 scab. By degrees the whole of the scab is covered with a 

 white mould, which gradually changes to a pale pink colour. 

 This colour is due to the presence of numerous conidia. At 

 this stage the skin surrounding an infected scab turns brown. 

 This browning extends in all directions, so that the various 

 scab spots merge into each other, covering large areas, or 

 even the entire surface of the apple. As the spots increase 

 in size they become depressed, due partly to the dissolution 

 of the solid parts of the apple by the fungus, partly to the 

 loss of water due to evaporation through the spots. The 

 flesh beneath the diseased patches also turns brown, and is 

 bitter. 



Conidiophores hyaline, erect, simple, crowded, springing 

 from a weft of creeping vegetative hyphae; conidia ellip'ic- 

 oblong, apex rounded, base narrowed, i -septate, constricted 

 at the septum, springing in small clusters from tip of conidio- 

 phore, obliquely attached, hyaline, pale rose-coloured in the 

 mass, 17-22 x 7-10 /'. 



It is considered as an attendant on apple scab, and in- 

 capable of causing injury as a primary cause. The pre- 

 vention is obvious prevent, by means of spraying and 

 pruning diseased shoots, the appearance of apple scab. If 

 there are signs of the presence of pink rot as harvest time 

 approaches, spray the trees and fruit before picking with 

 copper sulphate at the rate of one pound to 250 gallons 

 of water. 



Craig, J., and Hook, J. M. van, Cornell Univ. Agric. 

 Expt. St a., J udl. No. 207 (1902). 



SCOLECOTRICHUM (Kze. and Scum ) 



Hyphae short, somewhat fasciculate, coloured ; conidia 

 oblong or ovate, lateral and terminal, 1 septate. 



Cucumber and melon rot. According to Prillieux, when 

 the weather is unfavourable for the growth of cucumbers and 

 melons about the commencement of June, brown spots appear j 



