PLANT DISEASES. 
83 
Conclusion. 
The work described in the foregoing pages, carried on under 
widely different conditions of soil and climate, seems to clearly 
indicate that treating the seed and soil previous to planting with 
various chemicals and with hot water is of no value whatever so 
far as the prevention of rust is concerned. This accords with our 
knowledge of the life-history of the rust fungi attacking cereals, 
and bears out the generally accepted belief of those who have 
studied the matter. Many of the soil and seed treatments were 
positively injurious, diminishing the crop to a far greater extent than 
all the diseases observed combined. 
The spraying treatments did, in some cases at least, diminish 
the amount of rust, and seemingly increased the yield of straw and 
grain. A slight increase of yield in an experiment of this kind, 
however, must be looked upon with a good deal of suspicion, as 
there are many things that might influence the matter one way or 
another. On the whole there seems no good reason for believing 
that spraying, even with the most improved methods with which 
we are now familiar, would be practical or profitable on a large 
scale. At Garrett Park, where this kind of work was done 
with the greatest care, and where every precaution was taken to 
make the various preparations cover the foliage, rust was just as 
abundant on the sprayed as on the unsprayed wheat. A critical 
study of the plants in the field afforded what seems a satisfactory 
explanation of the foregoing fact. On examining the leaves 
immediately after they had been sprayed in the most careful 
manner it was found that fully one-half of the surface was 
wholly free from any signs of the liquid put on. ’ 
The shape of the leaf, its position on the stem, manner of 
growth, and waxy covering all conspire to render it exceedingly 
difficult to wet, and unless thoroughly wetted or covered by the 
fungicide there is little hope of preventing the reproductive 
bodies of the rust fungi from gaining an entrance. 
Finally, it may be said that while improved machinery and 
fungicides and improved methods may make it possible to profit- 
ably spray our cereals, with our present means this cannot be 
done. The work, however, should not be abandoned ; on the 
contrary, it should be continued until the matter is definitely 
settled one way or the other. At the same time the far more 
promising work of breeding rust-resisting varieties should be taken 
up and carried forward along such lines as offer the most promis- 
ing results. 
The following, taken from “ Farmers’ Bulletin, No. 7, U.S 
Department of Agriculture,” illustrates the kind of practical 
information communicated to American fruitgrowers 
Treatment of Apple Scab. 
For this disease, either modified eau celeste or ammoniacal 
copper carbonate, preferably the former, may be used. At least 
