370 



THE CEREALS IN AMERICA 



after such treatment. One of the reasons for flooding is to prevent the growth ot 

 weeds, but tliose which germinate quickly are enabled to keep even or ahead of the rice 

 and thus escape injury from flooding. In some cases, where the weeds get ahead of 

 the rice, especially those weeds (not grasses) which grow from the tip, the fields are 

 mown, which checks the weeds, while the rice, but little injured, shoots ahead, when 

 the field can be flooded and weeds killed. This is not effective for weeds of the 

 grass family, because the habits of growth are the same: as in the rice. Mowing 

 stubble and burning it soon after rice has been harvested is a rather effective 

 method of killing weeds ; but the exposure of the bare soil to the rays of the sun 

 and the lack of vegetation bring about physical, chemical and biological conditions 

 that are undesirable. Mowing and burning late in the fall, after weeds have gone 

 to seed, is, therefore, more commonly practiced, but is not so effective in destroying 

 weeds, since the moist soil protects many from burning. This late burning is 

 sometimes followed by early spring plowing to induce g3rmination of weeds, when 

 they may be destroyed by cultivation before seeding. This results in late seeding, 



which is objectionable. (514) In the alluvial 

 lands the weeds are pulled by hand two or 

 three times during the growth of the crop. 



519. Fungous Diseases. — The rice 

 plant is sometimes attacked by a smut 

 {Tilletia corona Serib.), occurring on several 

 grasses. It is very similar to the stinking 

 smut on wheat. While not definitely proven, 

 it is believed that the treatment recommended 

 for stinking smut on wheat would be effica- 

 cious. (149) The smut has not been widely 

 reported, but in some instances it has appar- 

 ently done considerable damage. The kernel 

 of the rice is filled with a mass of black 

 spores, as in the case of wheat, but it is not 



usually abnormally large. The cause ot blast or blight, a premature death of the 



plant or only the head, is not fully understood. 



520. Insect Enemies. — The number of insects attacking rice are not many, 

 nor are their injuries extensive or ordinarily serious. The principal one is tlie 

 water weevil {Lissorhopirtis simplex Say). The adult is a small gray beetle, which 

 makes its appearance in April and May and feeds upon the leaves ot the young rice 

 plant. The insects soon breed, and being semiaquatic in habit, the female lays its 

 eggs among the roots of the plant. The eggs hatch in July and August into 

 white, legless grubs, which feed upon the roots of the plant, where the principal 

 damage is done, and which may be detected by the yellowish appearance of the 

 plants, often in clumps. The presence of water seems necessary to the larvae; 

 hence the removal of the water and drying the land at the proper time is recom- 

 mended, although this practice is injurious to the rice. 



The rice grub {CJiahpus irochypygus Burm.) is a scarabaeid beetle, the larva ot 

 which feeds upon the roots of upland rice. Water kills it. 



glumes 

 mature 



Three spikelets of rice ; outer 

 shown at base. A, normal 

 spikelet with healthy grain enclosed ; 

 B, grain affected with rice smut shown 

 at e ; C, grain more completely de- 

 stroyed with rice smut shown at e. 

 (After Anderson.) 



