Greenbug Populations Research Articles

Greenbug Resistance in Sorghums1

Resistance to the C biotype of the greenbug, Schizaphis graminum (Rondani), a pest of recent economic importance on sorghum in the United States, was discovered in Sorghum virgatum (Hack.) Stapf. Otherwise, general susceptibility to the greenbug appeared in a wide array of sorghum germ plasm, including representatives from each of the major groups in the genus Sorghum. On the basis of seedling survival, entries were classified as resistant, intermediate, and susceptible. Classifications were confirmed by plant and greenbug reactions following confinement of greenbugs to seedlings. Tolerance appeared to be the major component of resistance, but resistant and susceptible seedlings could be readily separated on the basis of greenbug populations and injury to plants in greenhouse preference trials. Resistance appeared to be conferred by dominant genes at more than one locus. Preliminary observations indicate the type of resistance discovered may be valuable under field conditions.

Nitrogen and Phosphorus Content of Greenbugs Reared on Fertilized Wheat1

The greenbug, Schizaphis graminum (Rondani), is a major pest of wheat in the Central and Southeastern States. Infestations are common in the High Plains of Texas where fertilizer practices vary from no fertilizer on dryland to high rates under irrigation. However, there is little specific work on the effects of plant nutrients on this aphid. Haseman (1946) indicated that the greenbug has a high nitrogen requirement and will not reproduce as well on small grains grown on N-deficient soil, but Arant and Jones (1951) showed populations to vary inversely with the amount of nitrogen applied to oats. Blickenstaff et al. (1954) also found that in oats and rye the greenbug population decreased as the rate of nitrogen was increased. Daniels and Porter (1956) found that high populations were associated with high nitrogen levels in the soil and with increased plant vigor. Daniels (1957) found that the number of greenbugs per gram of plant varied inversely with the amount of nitrogen applied. He found also that plant growth was improved when phosphorus was used in combination with nitrogen.

Greenbug Populations and Their Damage to Winter Wheat as Affected by Fertilizer Applications1

Greenbug Populations and Their Damage to Winter Wheat as Affected by Fertilizer Applications1