0518 NowTime

5/18/2013 7:00 AM

To Monitor Barley, Wheat, <\n>Corn for Freeze Damage

Monday night’s widespread frost could cause injury to wheat and barley. Extension grain specialist Greg Roth reports more than two hours of exposure to 28 F temperatures in the boot stage or 30 F in the heading stage is required to cause injury.

At the Penn State research farm at Rock Springs, we had about four hours at 28 F. Frost injury symptoms may be difficult to diagnose for a few days or a week.

One symptom of minor injury you may see would be heads having difficulty emerging from the boot. In more severe cases white or discolored heads may be evident. In the worst cases, complete head sterility is common.

This Kansas State publication provides some detailed scouting guidelines for diagnosing freeze damage on wheat: http://www.ksre.ksu.edu/bookstore/pubs/C646.pdf .

Often the heads appear normal even though the anthers are dead. Anthers are more sensitive to freeze damage than other plant parts. By carefully examining anthers, you may be able to detect if crops with suspected frost injury are still viable.

After freezing, anthers are white and desiccated instead of their normal light green or yellow color, according the Kansas State publication.

It would be good to evaluate barley fields and even wheat in the week ahead to determine how much damage has occurred for both crop insurance assessment and the potential to salvage damaged crops for forage.

Corn has emerged from early plantings in many areas of the state. Some of the top growth of this corn will likely be burned off by the frost event.

The growing point of the corn is below ground at this time so the plant should recover with the onset of warm weather later in the week, and yield impacts should be minimal.

However, corn that has been defoliated once can be more susceptible to subsequent defoliation stress, so it may be wise to keep an eye on these fields for slug, armyworm or cutworm damage later in the spring.

To Understand Effect of Vertical <\n>Tillage on Soybean Herbicides

As more farmers use vertical tillage to manage crop residues or to mellow the seedbed prior to planting (especially soybeans), questions have arisen about possible impacts of using these types of tillage operations in combination with certain soybean herbicides.

Extension agronomist Bill Curran tells us that PPO herbicides (Group 14) in particular are drawing attention in these discussions.

The soil-applied PPOs include flumioxazin (Valor SX, Valor XLT and Envive), sulfentrazone (the Authority family lineup and Spartan), fomesafen (Prefix, Reflex) and saflufenacil (Sharpen, Verdict, Optill).

In general, if vertical tillage is completed prior to the PPO herbicide application, residual weed control will typically not be negatively affected.

However, if the PPO herbicide was included in a burndown application before the vertical tillage operation, then weed control could be compromised. Flumioxazin and saflufenacil-containing herbicides can be affected the most.

In this case, any tillage after herbicide application disrupts the uniform layer of herbicide potentially causing weed escapes or patchy weed control.

Even though sulfentrazone and fomesafen are labeled for preplant incorporation applications, most vertical tillage implements don’t provide enough mixing action to thoroughly incorporate the herbicide into the soil.

It seems logical that streaking or poor weed control may result from any residual herbicide application that is followed up closely with vertical tillage.

If vertical tillage must be performed as close to planting as possible, then another option to consider would be to spray the burndown herbicides (e.g., glyphosate, paraquat, 2,4-D) first, then conduct the tillage procedure and then apply the PPO herbicide near planting to allow more residual effects of the PPO herbicide longer into the season.

On a side note, keep in mind that vertical tillage equipment is not designed to provide weed control, so don’t be surprised if weeds are still evident after running this tool over the field.

To Understand Status of Honeybees

A new federal report blames a combination of problems for a mysterious and dramatic disappearance of U.S. honeybees since 2006. The intertwined factors cited include a parasitic mite, multiple viruses, bacteria, poor nutrition, genetics, habitat loss and pesticides.

The multiple causes make it harder to do something about what’s called colony collapse disorder, experts say. The disorder has caused as much as one-third of the nation’s bees to just disappear each winter since 2006.

Bees, especially honeybees, are needed to pollinate crops. The federal report, issued Thursday by the USDA and the Environmental Protection Agency, said the biggest culprit is the parasitic mite varroa destructor, calling it “the single most detrimental pest of honeybees.”

The problem has also hit bee colonies in Europe, where regulators are considering a ban on a type of pesticides known as neonicotinoids that some environmental groups blame for the bee collapse.

The U.S. report cites pesticides, but near the bottom of the list of factors. And federal officials and researchers advising them said the science doesn’t justify a ban of the pesticides yet.

Quote of the Week

“Agriculture, manufacturers, commerce and navigation, the four pillars of our prosperity, are then most thriving when left most free to individual enterprise.”

— Thomas Jefferson

Leon Ressler is district director of Penn State Cooperative Extension for Chester, Lancaster and Lebanon counties.

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