Holes in leaves suggest damage by foliage-feeding insects or hail, although hail damage looks more like a tear than a spot where the foliage was removed. Generally poor growth suggests poor growing conditions. Problems of this type often involve limited root activity or an insufficient supply of one or more of the inputs that roots supply to the plant. Absence of normal pod or seed development late in the season is often an indication that growing conditions were poor earlier in the year. Roots are not nearly as easy to see as the upper parts of the plant, but they can provide very useful information.
Stunted roots are often the result of chemicals or nematodes.
Small cysts on smaller roots are typically caused by soybean cyst nematodes, while galls on the roots are usually a sign of one of the root-knot nematodes. Limited or unhealthy nodules may be caused by lack of adequate rhizobia, low pH, molybdenum deficiency, or insect injury. The condition may also be caused by factors such as nematodes or inadequate fertility that limit root activity, or by something that limits the overall supply of photosynthate available to the roots. The later a problem is noticed after it first develops, the more difficult it is to diagnose the cause, partly because soybeans have a relatively great ability to compensate for problems. The better the growing conditions and general plant vigor at flowering, the more pods are set.