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To Scout Your Soybeans For Bean Leaf Beetle

We are getting a wide variety of reports from across Pennsylvania on the severity of feeding in soybeans by bean leaf beetles.

Extension entomologist John Tooker says that in some fields they are absent or hard to find, while in others they may be causing economic damage. To find out for yourself, get out and walk your fields!

The bean leaf beetle’s color varies. It can be tan or red with spots or without spots — and anywhere in between — but the key is the black triangle at the top of its hard wing covers.

As far as damage goes, we are fortunate that soybeans can tolerate a large amount of defoliation without losing yield. In vegetative stages, they can tolerate upwards of 25% defoliation, so often bean leaf beetle populations do not end up causing economic damage even though their numbers may be high.

Once the reproductive stages start, however, this tolerance drops to 15% defoliation. It is important to remember that these defoliation percentages are averages of plants across entire yields, not just individual plants. Bean leaf beetle can also damage soybeans by feeding directly on pods, which can leave pods vulnerable to excess moisture and infections.

To keep an eye on this pest, inspect fields to estimate the amount of feeding damage across the entire field based on the average amount of feeding per plant. Counting beetles per plant can also be helpful. Economic thresholds for bean leaf beetle in the soybean growth stages relevant for this time of year are as follows:

From bloom to pod fill: 20% of leaf area removed and there are 16 or more beetles per foot of row.

From seed maturation: 5 to 10% of the pods are damaged, the leaves are green, and there are 10 or more beetles per foot of row.

Of course, if damage or beetle populations exceed economic thresholds, growers will need to weigh the benefits of control against the cost of running over the beans with a sprayer. If you need guidance on insecticide selection, consult the Penn State Agronomy Guide at bit.ly/AgronomyPS

To Learn About Alzheimer’s and Dementia

Many families are affected by Alzheimer’s disease and dementia, and many times family members are at a loss for what to do. Those interested in learning more about Alzheimer’s and dementia are encouraged to participate in a workshop offered by Penn State Extension from 10 to 11 a.m. on Wednesday, Aug. 21, at the Farm and Home Center, 1383 Arcadia Road, Lancaster, Pennsylvania.

The “Understanding Alzheimer’s and Dementia” program provides a general overview for people who are facing a diagnosis.

Participants will explore the relationship between Alzheimer’s and dementia, learn what happens in a brain affected by Alzheimer’s, learn about risk factors and the three general stages of the disease, and receive other resources.

There is no cost to attend the course, but space is limited. Registration will be open until Aug. 14 or until full. For more information or to register, call 1-877-345-0691 or register online at bit.ly/Alzheimers2

To Plan Corn Silage Harvest Based On Predicted Moisture

Harvesting corn silage at the optimal dry matter is critical to optimize corn silage quality. Our tactic in the past has been to monitor the moisture of representative fields and then estimate harvest dates by assuming a dry-down rate of approximately 0.5% per day.

Some farms and custom harvesters could benefit from longer range forecasts of harvest timing so they can plan to optimize the harvest from multiple fields or farms. One older rule of thumb in some areas has been to estimate harvest approximately 45 days after silking.

Cornell research has shown that tracking the growing degree days after silking is a better monitoring technique for silage moisture than relying on the old adage of 45 days after silking. Depending on the climatic conditions in the late part of the growing season, silage harvest may occur within 35 days in a hot, droughty year. However, researchers found that tracking accumulated GDD after silking resulted in a more consistent prediction of the date at which the plants reached a 70% moisture content. The researchers recommend monitoring plant moisture at 750 GDD after silking with harvest occurring approximately 800 GDD after silking.

Once the silking date has been determined, you can estimate the sampling and harvest dates using the Cornell GDD calculator at bit.ly/GrowDayCalc

Quote of the Week

“Be not hasty to believe flying reports to the disparagement of any.”

— George Washington

Leon Ressler is a Penn State Extension educator based in Lancaster County.