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HERB, a computer-based expert system for soybean weed management developed at North Carolina State University, was evaluated for managing weeds under Georgia conditions. The project was initiated in two phases: a) training Cooperative Extension county agents followed by evaluation in six Georgia counties and b) revision, licensing, and distribution across the state. Field evaluations indicated that HERB was not highly accurate for predicting final yield loss because of weed species senescence and environmental extremes later in the growing season. HERB generally provided a reasonable prediction for a positive economic return due to treatment approximately 60% of the time. Accuracy was directly dependent upon the accuracy of weed-free yield estimates and extremes in growing conditions. HERB should not be the sole source of weed management information but may be useful to producers and county agents where mixed or low populations of weeds exist. The program was distributed statewide in 1993 after revision, duplication, and training was completed.

Improved resolution made possible by aberration correction has greatly increased the demands on the performance of all parts of high-end electron microscopes. In order to meet these demands, we have designed and built an entirely new scanning transmission electron microscope (STEM). The microscope includes a flexible illumination system that allows the properties of its probe to be changed on-the-fly, a third-generation aberration corrector which corrects all geometric aberrations up to fifth order, an ultra-responsive yet stable five-axis sample stage, and a flexible configuration of optimized detectors. The microscope features many innovations, such as a modular column assembled from building blocks that can be stacked in almost any order, in situ storage and cleaning facilities for up to five samples, computer-controlled loading of samples into the column, and self-diagnosing electronics. The microscope construction is described, and examples of its capabilities are shown.