48 BULLETIN 1155, U. S. DEPARTMENT OF AGRICULTURE. 
The California rice industry has grown very rapidly, the acreage 
increasing from 1,400 in 1912*to 162,000 in 1920. New rice land has 
been plentiful and most of the growers have been short-lease tenants. 
The yields on first-year land are much higher than on old land. An 
abundance of new land which produces high yields has induced 
tenant growers to farm carelessly, as they could move to new tracts 
when the land they were farming was fouled. Careless tenants 
have in this way fouled thousands of acres of rice land in California. 
WATER GRASS OR BARNYARD GRASS. 
Barnyard grass (EchinocJiIoa crusgalli) and its several varieties, 
locally known as water grass, have made it practically impossible to 
produce profitably on the same land more than three successive rice 
crops in California. Thousands of acres have been rendered unfit 
for rice culture during the past six years by this grass. When labor 
was cheap it was possible and practicable to keep barnyard grass 
under control by hand pulling, but with high-priced labor and 
decreased efficiency combined with an increase in barnyard grass it 
has not been profitable to keep it under control by this method for 
more than three or four years in succession on the same land. 
There are several different varieties of barnyard grass, some of 
which mature early and others late. The range of maturity is from 
June 25 to October 20. Early red barnyard grass is a native of 
California and was present along the streams and in irrigated sections 
before rice growing began. This variety matures early. Other 
varieties have apparently been introduced with rice seed from other 
rice-growing countries, and these range in maturity from July 20 
to October 20. 
Barnyard grass has been permitted to grow along the canal banks 
of the irrigation systems and the matured seed has been carried by 
the irrigation water to the rice fields. Winter floods, careless thresh- 
ing outfits, unclean seed rice, and birds are all agencies that have 
assisted in the distribution of barnyard grass in the California rice 
fields. Several methods of control have been tried, with varying 
degrees of success. 
HAND PULLING. 
When the rice industry was young and barnyard grass was not so 
abundant as it is at present, it was possible to keep this weed under 
control by persistent hand pulling. Barnyard grass, like rice, 
requires high temperature and moisture to insure good germination. 
Therefore, the rice and grass usually germinate and start growth at 
the same time. The grass, however, after two weeks grows faster 
than the rice, and by June it is usually taller. Some varieties of 
water grass can be distinguished from rice by their dark purplish 
color, but the so-called white water grass is a much lighter green 
than most varieties of rice. 
If water grass is to be controlled by pulling, the plants should be 
removed from the rice fields before they mature seed. Pulling 
should begin about June 25 and continue until the rice crop is mature. 
It is necessary to pull the plants from each field at 10-day intervals. 
