Diseases of field crops (1941) Diseases of field crops diseasesoffieldc121smit Year: 1941 Diseases of Field Crops 69 many weeds. The worms are embedded in lliese galls, the largest form being the adult female which lias a white, pearl-shaped, pinhead-sized body. The sugar-beet nematode Heterodera schactii, (p. 35) is very similar to the garden nematode; leaf, bulb, and stem-attacking nematodes of a number of species occur commonly, especially on alfalfa, oats, and wheat, among the field crops. Stem nematode Ditylcnchus dipsaci, on alfalfa, is discussed on page 13. Although a great deal of wo
Diseases of field crops (1941) Diseases of field crops diseasesoffieldc121smit Year: 1941 Diseases of Field Crops 69 many weeds. The worms are embedded in lliese galls, the largest form being the adult female which lias a white, pearl-shaped, pinhead-sized body. The sugar-beet nematode Heterodera schactii, (p. 35) is very similar to the garden nematode; leaf, bulb, and stem-attacking nematodes of a number of species occur commonly, especially on alfalfa, oats, and wheat, among the field crops. Stem nematode Ditylcnchus dipsaci, on alfalfa, is discussed on page 13. Although a great deal of work has been done in many parts of the world in trying to find some way of controlling root-knot nematodes, the only practical method which has thus far been found is to starve out the Fig. 43.—The narcissus stem nematode, with young worms and eggs. Enlarged nearly 150 times.) (From Ext. Cir. 118.) worms by growing some unsusceptible crop or keeping the land clear of all vegetation for one or more years. Drying the soil tends to kill out the worms. Of the crops commonly grown in California, the various grains, including sorghum, milo, and Kafir, as well as wheat, barley, oats, and rye are highly resistant and some of these may be grown as a winter crop followed by summer fallow for one or more seasons. The dryer the soil and the more frequently it is worked during the summer the quicker the worms will be exterminated. Other resistant crops which may be grown are certain varieties of cowpea (consult Division of Agronomy, College of Agriculture, Davis, regarding names and seed), velvet bean, sweet clover (Medicago), and peanuts. All weeds must he kept down whenever the eradication of nematodes is being attempted.
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