3^68 Investigation of Rotting of Oranges 



This brown area preceding the Penicilliu m on the orange also occurs 

 on orange gelatine cultures. 



Another change that is undergone by the skin during attack is, 

 that in a sound unaffected orange it is impossible to strip off the cuticle, 

 which can only be removed by cutting the underlying tissues, but 

 when the fungus gets in the cuticle can easily be removed from any 

 of the coloured areas with forceps without any cutting whatsoever. 

 When the attack has become very bad the whole of the cuticle of the 

 orange can be stripped off. 



No trace of the fungus piercing the cuticle could be found, although 

 hanging drop cultures of cuticle and fungus were taken. 



When the attack is very bad the part of the skin below the cuticle 

 becomes a soft sticky mass, which sooner or later pours out a yellow 

 oily liquid on to the soft surface of the skin together with a large amount 

 of water. 



When the orange became soft and pulpy it was noticed that large 

 numbers of small flies appeared on the orange and remained so long 

 as the orange kept its normal shape, but when it completely collapsed 

 the numbers decreased. 



It was found impossible to infect a sound orange by leaving it in 

 a vessel with a badly diseased one even in contact with it, but the 

 pouring out of moisture by the diseased one caused the sound one 

 to become covered with moisture and in this w^ay many more spores 

 would adhere to it than would otherwise have taken place and in this 

 way would have a greater chance of finding any slight puncture in 

 the cuticle. 



Leaving a sound orange standing in a shallow dish of water the 

 wet portion becomes soft and discoloured and then the cuticle can 

 easily be removed and the tissues attacked mth Penicillium when 

 removed from the water, but the dry portions out of the water were 

 never attacked unless a previous puncture of the cuticle had taken place. 



From these few simple experiments it would appear that the most 

 promising way of sending oranges is that they be kept as dry as possible 

 and in picking and packing care being taken to prevent the cuticle 

 becoming damaged in any way. 



Experiments were tried with various chemicals. Solutions of 

 2 per cent, copper sulphate and 5 per cent, formalin were used on 

 the cut surface of the orange skin and were found to be more or less 

 effective, for if spores were sown on the cut areas the fungicide appeared 

 to check their growth. 



