162 
leguminous crop be used for soil renovation, and (2) that a winter cover crop be 
used in prevent washing. < ►neof the simplest rotations practicable is already widely 
u.-ed. It has three courses: I I Corn, with cowpeas between the rows; (2) oats, 
followed by cowpeas, and (3) cotton. Tins Ls an excellent rotation, and is prob- 
ably better adapted to present conditions in the South than any other. Owing to 
the fact that many fanners feel obliged to plant half their land in cotton each year, 
it is often necessary to add another year in cotton to this, making two years of cotton. 
Where such a rotation is adopted and a liberal application of potash and phosphoric 
acid made to the pea crop, rust in cotton is rarely ever seen, and much less trouble 
is experienced from shedding of the bolls. 
The function of winter cover. crops is mainly to prevent the washing that occurs 
when the soil is Left unprotected, but they also furnish valuable winter pasture. 
Hairy vetch, with wheat or oats; burr clover, with Bermuda grass; crimson clover 
and rape are the most prominent in the list of available plants. They have not yet 
come into use in the South enough to have become parts of any common system of 
rotation. Their value is unquestionable, but there is need for more experiments and 
demonstrations to introduce these crops to the public. 
More extended systems of rotation will come later with the increase in stock rais- 
ing. For the present the simple system first outlined will be a great advance. Some 
modifications of it for special conditions will be mentioned later. 
Next in order for consideration come a number of diseases requiring special atten- 
tion. The cotton wilt, caused by the fungus Neocosmospora vasirifecta, is ;i soil disease 
widely prevalent in sandy and gray land. It occurs in spots of varying size, often 
covering many acres. The fungus is able to live in the soil for many years in the 
absence of cotton, and rotation is consequently not a remedy after land becomes 
infected, though, if practiced in advance, it would undoubtedly do much to prevent 
the disease from gaining a foothold. The cotton wilt must be combated by breeding 
resistant strains. It has been shown that this can be done successfully, and the 
Department of Agriculture has originated varieties that will grow on wilt-infected 
land. This does not entirely settle the question, however, as the wilt problem is 
further complicated in many instances by root knot, caused by the nematode worm 
Heterodera radicicola, which occurs to a considerable extent in sandy soils south of 
Virginia. The nematode worm inhabits the same warm, sandy lands that surfer from 
cotton wilt, and while the two do not always occur together a great deal of wilt- 
infected cotton land also contains nematodes. They increase the injury done by wilt 
and must be considered in every case. The matter is more serious because root knot 
occurs on a number of other farm crops, particularly on cowpeas, and the extensive 
use of cowpeas as a rotation crop has resulted in great injury in many cases by 
increasing the amount of root knot. Cowpeas are particularly liable to this disease, 
and cotton following them on infected fields is liable to suffer more from both wilt 
and root knot. The wilt-resistant cotton developed by the Department of Agricul- 
ture does not resist nematodes and can not be used successfully on such land unless 
a system of rotation is practiced. It is quite certain that the remedy for root knot is 
rotation of crops. The essential point is to starve out the nematodes by growing 
immune crops and to avoid the use of any crop that is subject to attack. 
The subject of root knot is a most important one and is not given proper consider- 
ation by southern farmers and their advisers. In the Gulf States especially root 
knot may be suspected in all sandy soil and all rotations must consider this factor. 
Cowpeas in general must not be grown; the Iron cowpea is practically immune to 
root knot, as are also some new hybrids obtained by the Department of Agriculture, 
and they can be grown in root-knot rotations, but all other varieties must be avoided. 
There are fortunately other good legumes adapted to this section. We may use for 
this purpose the Iron cowpea, velvet bean, beggar weed, and peanuts. 
ROTATIONS SUGGESTED. 
In arranging a rotation for the South economic conditions must be considered and 
the backward state of agriculture kept in mind. The crops grown must be useful 
ones and easily grown and marketed. Corn, the grains, and grasses are the best 
Cleaning crops and also have a money value. The effect of oats on root knot is very 
marked, and a single crop will do much to reduce the root knot in a held. For land 
badly infested with nematodes, which it is desired to clean out, three years in 
immune crops are recommended. An example of a rotation that may be adopted is: 
Corn, with Iron cow peas or peanuts between the rows; oats, followed by velvet beans, 
and beggar weed for hay. Of the leguminous crops available, the velvet bean is 
especially adapted to the extreme South. In Florida and the Gulf States it excels 
all others in vigor of growth and rank foliage. It is practically free from root knot, 
