CRAZY-TOP DISORDER OF COTTON 19 
striking contrasts observed between contiguous areas in the same 
fields, with the disease injuries so largely confined to the land that 
had been kept continuously in cotton. Apparently no new or expen- 
sive treatment is required, but only a better recognition of what has 
been urged on other accounts, viz, that it is a bad policy to keep more 
than half of the acreage of the Salt River Valley in cotton. The 
data at hand indicate clearly that the rotation of cotton with alfalfa 
exerts a marked influence on the extent and severity of crazy-top. 
With the disorder becoming more prevalent each year under the 
present system, the need for the adoption of better methods becomes 
more acute. It is not profitable to grow cotton on land that is not 
in condition to produce a good crop. 
The importance of establishing the proper slope or grade of the 
land in order to obtain the most effective results in irrigating crops 
is another matter not fully appreciated by many of the farmers in the 
Salt River Valley. During the years when alfalfa was the principal 
crop, the problem of obtaining penetration of water to the depth of 
the root zone was not considered difficult. The plants themselves 
served to check the flow of water, and their roots provided channels 
and openings for the penetration of the water to the subsoil. After 
cotton had been grown for several years in the valley, some of the 
farmers began to take note of the difficulties experienced in obtaining 
adequate penetration of water in cotton fields during late summer, 
especially in fields with steep slopes, and such indications have been 
confirmed in the investigations of the cultural problems. The com- 
plaint is frequently heard that "three times as many irrigations are 
now required to produce a crop of cotton as were necessary 10 years 
ago," and yet only a few of the farmers have made serious efforts to 
remedy this condition. In many of the fields that are known to be 
growing worse in this respect, the conditions might be improved to a 
large extent by changing the direction of the water flow, by con- 
structing more substantial and more numerous borders and cross 
checks, by providing a greater number of distributing ditches, and 
by contour bordering. 
A regular rotation system with alfalfa is in itself a corrective 
method for obtaining better penetration and storage of water. In 
this connection it seems pertinent to mention that experiments at 
Sacaton have shown that less frequent irrigations were required by 
cotton following alfalfa than where cotton was the preceding crop. 
More water is applied to the land in alfalfa, and a greater penetration 
of the water is obtained, so that more water is stored in the soil and 
the root zone is deepened. These conditions accruing during the 
growth of the alfalfa crop are advantageous to cotton when that crop 
succeeds the alfalfa. When the growers give serious attention to 
cultural methods that promote the deep rooting of the cotton plants 
and thus provide for a supply of soil moisture at all times during 
the fruiting period, the cotton plants respond with greater production 
and do not show the abnormal behavior associated with the crazy-top 
disorder. 
SUMMARY 
A new disorder of cotton plants began to attract attention in the 
Salt River Valley of Arizona in 1919 and became so prevalent in the 
seasons of 1924 and 1925 as to cause serious financial losses to the 
