Viral diseases of soybean can also cause leaf distortion. However, even if soybean plants have been infected by viral diseases, it is too early in the season for the leaf symptoms to be exhibited.

There are still a number of soybean fields to be planted in the area. On average, soybeans planted in early June in central and southern Iowa have yielded about 10% less than those planted in early May. The yield potential does drop more rapidly after early June. Stick with an adapted full season variety through June. A good source of information on soybeans is "Soybean Replant Decisions" (Pm-1851) at http://www.extension.iastate.edu/Publications/PM1851.pdf.

As water recedes from flooded and ponded areas, many are asking the question "how long can crops be under water and survive?" Corn and soybeans can normally only survive complete submersion for 2 to 3 days (80 day air temperature) and most forages can survive for 1 - 2 days. I have seen survival for considerably longer periods of submersion, however. The cooler the air temperature, the longer the plants can survive. Plants NOT totally submerged will survive considerably longer. By the time the water has receded and the field dried out, it will be easy to see whether the crop has survived or not. Some corn has been flattened by the rushing flood waters, but if it survives, should be able to straighten up again. Any corn beyond V6 (6 leaves fully emerged from the whorl) will likely be goose necked, because stalk elongation will have begun. Flooding can lead to greater disease problems on all crops. A light rain in the near future might be beneficial to wash off the mud on plants. If a replant is going to be done and it will be to a crop different from the one originally planted, remember rotational restrictions from any herbicides applied. Several good references on flooding are at .

Feeding of alfalfa weevil should have ended in locations along and south of Highway 30, and feeding should end along Highway 20 by about June 14. Even if feeding should be over by the time first cutting re-growth begins, it is still best to watch to be sure.

High numbers of potato leafhoppers can be found in many hay fields. As re-growth begins, be sure to also use a sweep net to monitor potato leafhopper numbers and treat if numbers exceed the threshold. For more information on managing potato leafhopper, see pages 107 - 110 of the June 21, 1999 Iowa State University Integrated Crop Management Newsletter or .

If potassium deficiency symptoms occur or persist, inspect the root system. I have been in several fields where the mesocotyl (area between the old seed and the main plant) is rotting. The primary (seed, seminal) roots, which develop from the old seed, may be a small portion of the total root system, but it is still highly functional at this time, and if the plant is cut off from the primary roots prematurely, it is forced to rely on the secondary (nodal) root system (the whorls of roots) before it is ready to do so, resulting in potassium deficiency symptoms. Generally, plants will recover and go on to be productive plants.

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