VI . General Discussion 345 



of the mycologist in such work depends upon his skill in experimental 

 technique, his experience and his keenness for work. To this must be 

 added a thorough knowledge and sympathy with practice. The physio- 

 logical aspect of the work is of great importance and much has yet to 

 be done with plant hygiene. If possible the worker should commence 

 with simple problems which will give "quick" positive results ensuring 

 the confidence of the grower. The personal qualities of the worker are 

 all-important. He must gain the friendship of the growers, exercise 

 much diplomacy, be impervious to the innuendos of doubting members, 

 be extremely careful and not too hasty to advise, and possess a whole- 

 some lack of conceit. 



Finally I would emphasise the need for some kind of clearing-house 

 for Government officials, research institutes and sub-stations, some 

 body which would gather together the special information and knowledge 

 possessed by each branch and circulate it for the good of all. The great 

 value of such a conference as this is that it brings together all workers. 



Miss D. M. Cayley {John Innes Horticultural Institute). 



There are many abnormal conditions of plants which while not due 

 to the action of any pathogen are yet from the practical point of view 

 to be regarded as diseases. Such for example are the bolting of turnips, 

 lettuce, cabbages and other plants which are a source of considerable 

 financial loss; or the rogueing of peas and potatoes which occasion the 

 expenditure of valuable time and money. In the elucidation of these 

 problems of plant pathology breeding is of primary importance and the 

 facilities for this type of work are in this country extremely meagre. 

 The value of breeding experiments in the securing of strains immune to 

 fungal and bacterial disease needs no emphasis but it is not always 

 realised that its value does not cease when the immune variety has been 

 obtained. Such plants are often low croppers and the further problem 

 is to raise them by breeding to an economic status. 



Dr. J. C. Willis spoke from an experience of twenty years direction 

 of tropical research stations in which the problems of plant disease are 

 ever before one. The crops, such as tea, rubber and coco-nut, are mainly 

 perennial and cannot be handled so easily as the annual crops in English 

 agricultural practice. Further there are no small watertight compart- 

 ments but extensive areas planted solely to tea, coffee and so forth, and 

 diseases therefore have every opportunity of spreading on an epidemic 

 scale. 



The problem of disease control is always an economic one and the 



