10 



to furnish a green maniire for the succeeding regular crop of the rota- 

 tion. For example, in the fiye-course rotation, given above, an inter- 

 crop of winter rye might follow the oats and be turned under the 

 succeeding spring for the potato crop. If for any reason it should 

 seem desirable to follow one corn crop with another, an inter-crop of 

 rye or crimson clover between the two corn crops would prove a de- 

 cided gain to the soil by saving plant food and renewing the supply 

 of humus. 



11. Plant Diseases. We may have good seed of an approved vari- 

 ety as well as a fertile, well drained and properly cultivated soil and 

 yet fail to secure the best crops if they are attacked by parasitical 

 diseases. The more common of these diseases are popularly called 

 rust, smut, scab, blast or blight. These so-called diseases are minute 

 microscopic parasitic plants that attach themselves to the wheat, oats 

 or corn, feed upon their juices and grow within their tissues. For 

 some time the "host" plant (corn, oats or wheat) may seem perfectly 

 healthy although the micelium or threadlike growths of the parasite 

 may be found inside, on examination, with a compound microscope of 

 high power. Sooner or later the parasite breaks through the epider- 

 mis or bark of the host plant and exposes its fruit or seed (spores) to 

 view. Each species of parasite has its own peculiar way of showing it- 

 self on the host plant. One appears as rust on wheat, oats, rye and 

 corn; another as loose smut of wheat, the entire head of wheat being 

 changed to a mass of black powder; another as loose smut of oats mucli 

 like the last; another as bunt or stinking smut of wheat, which devel- 

 ops within the wheat grain, causing it to grow thick and short and fill- 

 ing it with a brownish-black mass of spores that have a very unpleasant 

 odor; another as wheat scab, which causes the wheat head, or some part 

 of it, to turn lighter in color, giving it the appearance of premature 

 ripeness; another as smut of corn, with which you are familiar; another 

 as potato scab, which attacks the surface of the potato tuber, marring 

 the appearance, injuring the quality and reducing the size of the 

 potatoes. The germs of the smuts of wheat and oats and of potato 

 scab attach themselves to the seed or potato cuttings and make their 

 attacks underground. To prevent this it is only necessary to have 

 both seed and soil free from the germs. In case the seed is affected 

 it may be treated as follows: For stinking smut of wheat and loose 

 smut of oats immerse the seed five minutes in water heated to 135 de- 

 grees Fahrenheit. 



For potato scab soak the seed tubers or cuttings two hours in a 

 formalin solution, using one-half ounce of formalin to a gallon of 

 water. 



