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Soybean Plant Health

Using a Hand Lens

Asian Soybean Rust

Types of hand lenses

One style is not necessarily better than another: choose one you feel comfortable with.

Bring a hand lens with you when scouting fields. A hand lens magnifies small details that will help you distinguish rust from other leaf diseases.

There are many forms of hand lenses: loupes, linen testers, folding pocket lenses, and others. One style is not necessarily better than another. It depends on the style of you feel comfortable using.

Hand lenses come in a range of magnifications. A 5X magnifier shows you the object 5 time larger than life. A 20X magnifier shows you the object 20 times larger than life. The larger the magnification, the smaller the "field area" one sees.

Some scouts equip themselves with a range of magnifiers - lower magnifications (2X to 10X) to scan larger areas, and higher magnification (20X to 50X) to observe disease symptoms and signs in more detail.

How to use a magnifier
For most magnifiers, hold the lens close to your eye and move the leaf closer until it's in focus. For linen testers (bottom photo), place the magnifier on top of the leaf and move your head closer to the lens to view greater detail.

Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: University of Wisconsin-Madison, Departments of Agronomy, Entomology, and Plant Pathology at  www.plantpath.wisc.edu/soyhealth.

11/08