222 
Methods of Preventing and GhecMng 
For instance : — 
a. On the effect as regards rust of manuring. 
b. The effect of appl3'ing lime, ferrous sulphate, and salt to the soil. 
c. The effect of applying to the rusted crops, by means of the Straw- 
son izer and otherwise, solutions of sulphate of iron, sulphate ot 
copper, &c. 
d. EfHcacy of Lurning all straw, weeds, and other plants in the infected 
field, and of using other disinfected agencies with the view of 
destroying spores. 
e. The relative values of different varieties of wheat. 
/. The effect as regards rust of different times and modes of sowing. 
ff. Investigations regarding plants that act as intermediary hosts,' and 
regarding all plants that are affected by rust in the different 
colonies. 
For the fungus causing scab on apples (Fusicladium dendri- 
tlcum) no remedies are yet used in England. In the United 
States and Canada most satisfactory results have been obtained 
from spraying the trees with carbonate of copper and ammonia 
— three ounces of carbonate of copper and one quart of ammo- 
nia to 28 gallons of water — also by using " eau celeste," 
which is made by dissolving in hot water 2 lb. of sulphate of 
copper and 2^ lb. of carbonate of soda in separate vessels. These 
are then mixed together, pints of ammonia are added, and 
the whole diluted with 32 gallons of water. It is stated that 
this latter mixture gave the best results, and the conclusion 
arrived at from a series of experiments in localities where 
scab prevailed was that either of the copper mixtures added 
from 25 to 50 per cent, to the value of the crop, at a cost of 
not more than 2s. to 2s. 3(Z. for an average-sized tree. The 
greater number of the fruit-growers in Great Britain do not know 
the origin of scab upon apple and pear leaves and fruit, and 
have no idea that any special treatment will stay it or prevent 
its appearance, and they would probably smile at the suggestion 
that solutions of sulphate of copper would effect these desirable 
results. These affections have not as yet been very serious in 
this country, but as they will probably increase, like other 
fungoid diseases, attention will be fixed upon them, and there 
will be loud outcries for remedial measures. 
Many other instances could be adduced of the increase of 
insects and fungi destructive to crops in this and other lands, 
but enough lias been put forward to show how great and 
alarming it has been. At the same time the knowledge of 
economic entomology and mycology has naturally advanced, and 
there are now numerous skilled workers in many countries 
' As the barberry-tree {Berheris ritJgaris) in Great Britain. 
