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This portion of the July 30 to Aug. 5 Crop Observation and Recommendation Network (CORN) report is a summary of crop observations, related information and appropriate recommendations for Ohio Crop Producers and Industry. CORN is produced by the Ohio State University Extension Agronomy Team and State Specialists at Ohio State University and Ohio Agricultural Research and Development Center.

Drought Information
Drought brings on a whole set of management decisions that farmers face for their businesses. A drought resource Web site has been created that may be useful to help with decisions about crops, forages, livestock and marketing at http://corn.osu.edu/drought02

A mailing list with connections to Extension professionals has also been created to help answer any questions related to drought at drought@ag.osu.edu

Impact of Drought
Many corn growers want to know what impact drought stress has had on corn pollination, the stage in corn development most sensitive to stress. When severe drought stress occurs before and during pollination, a delay in silk emergence can occur. Sometimes the length of this delay is such that little or no pollen is available for fertilization when the silks finally appear. When such delays in silking are lengthy, varying degrees of barrenness will result. This year it's very likely that silk emergence will be delayed in many drought-stressed fields.

There are two techniques commonly used to assess the success or failure of pollination. One involves simply waiting until the developing kernels appear as watery blisters. This usually occurs about 1½ weeks after fertilization. However, there is a more rapid means to determine pollination success.

Each potential kernel on the ear has a silk attached to it. Once a pollen grain "lands" on an individual silk, it quickly germinates and produces a pollen tube that grows the length of the silk to fertilize the kernel in 12 to 28 hours. Within 1 to 3 days after a silk is pollinated and fertilization is successful, the silk will detach from the developing kernel. Unfertilized ovules will still have attached silks.

Silks turn brown and dry up after the fertilization process occurs. By carefully unwrapping the husk leaves from an ear and then gently shaking the ear, the silks from fertilized kernels will readily drop off. Keep in mind that silks can remain receptive to pollen up to 10 days after emergence. The proportion of fertilized kernels on an ear can be deduced by the proportion of silks dropping off the ear. Sampling several ears at random throughout a field will provide an indication of pollination.

Will Lodged Corn Recover?
Strong winds and heavy rains associated with severe thunderstorms can lodge or knock corn plants over, especially if the nodal root system is not fully developed. The recent hot, dry weather and soil compaction have inhibited good nodal root formation and predisposed plants to wind injury.

Strong winds can pull corn roots part way out of the soil, a condition referred to as root lodging. The problem is more pronounced when soil is saturated by heavy rains accompanying winds. If root lodging occurs before mid-grain fill, plants usually recover at least partly by "kneeing up." This results in the characteristic gooseneck bend in the lower stalk with brace roots providing above ground support. If this stalk bending takes place before pollination, there may be little effect on yield. When lodging occurs later in the season some yield decrease due to partial loss of root activity and reduced light interception may occur. If root lodging occurs shortly before or during pollen shed and pollination, it may interfere with fertilization. Hybrids differ in their ability to resist root lodging.

Soybean Leaf Beetle
The first generation of bean leaf beetle is active in Ohio soybean fields. Most fields probably do not have a large population, although some, especially if planted early, might have larger numbers. Although defoliation from this beetle alone is usually not severe enough to warrant treatment, feeding from this and other defoliators such as Japanese beetle, grasshoppers and green cloverworm can often reach levels requiring treatment. Growers should scout fields to ensure such levels, usually set around 15 percent defoliation during bloom and pod set, are not being reached. If defoliation reaches this level and insects are present and still actively feeding, treatment is probably warranted. Of special concern this year is that most soybeans are not that large, with smaller than normal canopies. Assuming the insects are feeding normally, the likelihood that economic levels of defoliation are reached sooner is greater.

Another reason to scout for the bean leaf beetle now concerns pod feeding by the second generation that occurs in mid-to-late August and September. That generation can cause greater loss for growers because insects feed directly on the pods and seeds. Research shows good correlation between the first generation and the second generation that will be present later. Thus, large bean leaf beetle populations now suggest greater likelihood for a large second generation, and a greater potential for significant pod injury. Growers can help identify fields during the next few weeks that have a higher potential for pod injury. This will allow them to better manage their time and fields later in August.