Common diseases of soybean are caused by viruses, bacteria, fungi and nematodes. Some diseases are spread by insect vectors and nematodes while others are spread by wind, splashing rain, or movement in soil. The best way to determine if disease control would be profitable is to first identify the diseases that are capable of causing  conomic yield losses. Symptoms of disease include plant damage caused by a pathogen and the reaction of plants to infection. Signs are the visible evidence of the pathogen. Some diseases have characteristic symptoms and signs that are identifiable in the field.

There are a number of questions that must be answered before establishing a site-specific crop management (SSCM) program. Many of these questions are economic, some are agronomic and environmental, and others are technology-related. This publication is intended to discuss variable-rate devices that are available, while providing an understanding of which technologies might best fit a cropping system and production management strategy.

Plant growth regulators (PGRs) are chemicals that are designed to affect plant growth and/or development (Figure 1). They are applied for specific purposes to elicit specific plant responses. Although there is much scientific information on using PGRs in the greenhouse, it is not an exact science.