As reported on this site yesterday, spring appears to be arriving two to three weeks earlier than normal – despite Tuesday night's frost across much of the Northeast. Alfalfa is 100 to 120 growing degree days ahead of schedule.
Trouble is, so are the weeds, particularly winter annuals. And it may require adjusting weed control programs since the most popular products have little or no residual activity, point out Penn State Extension Weed Scientists Bill Curran and Dwight Lingenfelter.
On March 19 in Lancaster County, Curran and Lingenfelter spotted common chickweed, corn speedwell, and dead nettle all in bloom. Whether they are in winter wheat, barley, a cover crop, or just in a fallow field going into corn or soybean, consider some attempts to control weeds earlier than you might do otherwise in a "normal" year, they advise.
Flowering winter annuals are going to generally be more difficult to control than weeds that are still vegetative. Also, those weeds are using up valuable soil moisture that may become scarce unless April showers are frequent.
The standard corn and soybean burndown herbicides such as glyphosate, paraquat or Gramoxone, and 2,4–D can be applied well ahead of planting. But since they don't have any residual activity, unless you include a residual herbicide you can expect more weeds emerging between now and crop planting.
Many corn and soybean residual herbicides allow application ahead of planting. But on silt loam soils, application more than 15 or 20 days ahead of planting may not persist long enough to avoid a second residual herbicide application, they warn.
The concept of Early Preplant application came into vogue first back in the 1980's in the Corn Belt. In this approach, you apply a residual herbicide 15 to 45 days ahead of planting depending on the product and how it is labeled.
In some instances, farmers split the application using half or two-thirds of the rate in the first application with additional residual herbicide at planting. This approach never really caught on in the Northeast, because it often requires more herbicide than a single application and extra trips over the field.
With the introduction and adoption of Roundup Ready crops, this approach can be more consistent. But it'll still require at least two applications and perhaps even three, depending on crop planting date, according to the weed specialists.
A March 20 Field Crop News table at http://extension.psu.edu/field-crop-news provides some days ahead of planting that common corn and soybean herbicides can be applied according to label.
Bugs ahead of schedule too
The mild winter certainly allowed a few pest species to survive better because their populations are knocked back by cold winters, notes John Tooker, Penn State Extension entomologist. Bean leaf beetle and slugs, in particular, need to be scouted for, he adds.
Cereal leaf beetle adults were already active in the south-central part of Pennsylvania in mid-March. Alfalfa weevil larvae feeding is anticipated.
But many insect pests (e.g., potato leaf hopper, black cutworm) are migratory and come north from southern states. So Mid-Atlantic andNortheast local weather won't influence their arrival much.
Even so, growers will need to rely even more on regular scouting to see what's active, he emphasizes. To direct this scouting effort, check the PA-PIPE (Pennsylvania Pest Information Platform for Extension and Education) system (http://extension.psu.edu/pa-pipe). Follow the link and then choose the Public Map link to see the models that track degree-days and expected development of relevant pest species.