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' The principal objects were to see what work was actually being 
done in certain areas on these crops, and to get into personal 
touch with the men in charge of this work so as to facilitate future 
relations. The chief value of this will be that I shall be better 
able to apply or to refer applications from overseas correspondents 
of the Bureau to the most likely American source of assistance in 
special inquiries. Want of time prevented me from fully carrying 
out my programme in this direction, What I saw convinced me 
that America is far ahead of other countries in the general applica- 
tion of modern methods of plant breeding and the use of fungicides 
for the reduction of the wastage due to disease. Maize, wheat, 
cotton, beans, sugarcane, tobacco, and fruit were the principal 
crops seen in which these methods were being applied with the 
greatest success. 
The very great attention directed to this matter in the United 
States is the result not only of the magnitude of their agricultural 
industry, but also of the generally great severity of the diseases of 
their crops. On the whole, the diseases of plants that have an 
economic value are distinctly worse in the United States than in 
Europe, though not worse than in some of the overseas parts of 
the British Empire. The reason for this appears to be that there 
are two factors concerned in intensifying diseases in countries that 
are newly opened up to settled agriculture. (1) the crops grown 
are largely exotic, and hence become exposed to the attack of 
indigenous parasites against which they have not developed 
powers of resistance; (2) with the introduction of new plants of 
economic value, exotic parasites are brought in, and some of these 
develop into serious pests of pre-existing plants in their new home. 
In Europe both these factors doubtless operated in the past, and 
the latter was responsible for the enormous ravages of introduced 
vine diseases in the last century. But the process has been very 
gradual in Europe as compared with America, and the centuries- 
long history of the operation of these two factors in Europe has 
been condensed into the last century, or even half-century, in the 
United States, especially in the centre and west of the country. 
The same phenomenon is marked in many of the British overseas 
possessions, and is likely to become increasingly evident in some 
‘in the future. 
It is impossible to exaggerate the value to a working mycologist 
of a tour in the United States at the present time. In the last 
‘ten years the study of the diseases of plants in that country has 
progressed until it now easily leads the rest of the world. Since 
the War, American phytopathologists have redoubled their 
energies, and the next ten years will, I believe, see an accelerated 
progress. The most noticeable feature at the moment is the 
concentration of numbers of workers on certain fundamental 
problems, such as the etiology of the mosaic group of diseases, 
biological specialization in parasitic fungi, and the factors 
_ ‘determining resistance or susceptibility to disease. Innumerable 
new points of view and critical attacks on many existing concep- 
