A Survey of Five Stem-Feeding Insect Pests of Wheat in the Northern Great Plains
The wheat stem sawfly, Cephas cinctus Norton, the wheat stem maggot, Meromyza americana Fitch, the Hessian fly, Mayetiola destructor (Say), the wheat jointworm, Tetramesa tritici (Fitch), and the wheat strawworm, Tetramesa grandis (Riley), have long been considered wheat pests in the northern Great Plains. This paper reports results of surveys for these pests conducted over 3 yrs in parts of Montana (10 counties), North Dakota (14 counties), South Dakota (1 county), Nebraska (4 counties) and Wyoming (1 county). Fields were randomly selected and a mean of 191 stems were sampled from each field. The percentage of stems infested with each pest was recorded. The percentage of parasitized wheat stem sawfly larvae also was noted. The wheat stem sawfly, wheat stem maggot, and Hessian fly were the most commonly encountered pests, recorded in nearly every county. Wheat stem sawfly density was twice that of wheat stem maggot (7% vs 3.2%) in infested fields. Wheat stem sawfly densities exceeded 10% in 4 counties: Da...
Estimates of Loss of Yield Caused by the Wheat Stem Maggot to South Dakota Cereal Crops
Populations of Meromyza Americana Fitch were studied in cereal crops in South Dakota east of the Missouri River between 1964 and 1967. Losses caused by this insect were assessed, and attempts were made to develop methods of predicting losses. Losses were highest in spring wheat, followed in descending order by winter wheat, rye, and barley. No estimate of loss exceeded 9%; most estimates in wheat and rye fell between 1 and 3%. Damaged heads tended to occur singly rather than in aggregates. Estimates of populations of gravid females early in the season were not reliable indices to crop losses later in the year.
Research requirements to reduce maintenance costs of civil helicopters
The maintenance problems faced by the operators of civil helicopters that result in high costs are documented. Existing technology that can be applied to reduce maintenance costs and research that should be carried out were identified. Good design practice and application of existing technology were described as having a significant impact on reducing maintenance costs immediately. The research and development that have potential for long range reduction of maintenance costs are presented.