CMEG Crop Management Extension Group

Field Crop News

Website Address: http://fcn.agronomy.psu.edu/

April 14, 2009    Vol. 09:06

IN THIS ISSUE:

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

The chilly, dull and damp conditions will prevail across the southern two-thirds of the state into Wednesday afternoon; however drier air will filter into the northern tier. Skies will clear for Thursday and after some morning fog in the southern counties, plenty of sun will raise temperatures above seasonal levels. Friday will be pleasantly warm and dry and this fine weather will linger into Saturday for the southern half of the Commonwealth. A cold front will pass through the state later Saturday (from north to south) accompanied by clouds and widely separated showers. Sunday should be a duller day as showers develop in the western third. Readings will fall below seasonal levels. A complex disturbance forming in the southern Appalachians should bring wet and noticeably cooler weather from Monday into Tuesday. Below average temperatures should persist into mid-week. A longer-lived warm spell is becoming more likely in the period April 24–28, though the month will likely average near or below normal temperatures.

The overall outlook for May is drier than normal with frequent cool spells such that an unusual late frost is possible in the southern or central sections from May 14–22. Odds favor warmer than average temperatures in June and above average rainfall during either July and/or August. Once again, the hurricane season, which starts June 1, is expected produce fewer storms than previous years.

Corn Planting on the Horizon — Greg Roth, Grain Crop Management Specialist

It’s hard to believe, but the season is here. Some corn has already been planted. Planting will accelerate in the next week or so with warm temperatures forecast later in the week. The ideal planting date in Pennsylvania varies depending on location from about the 20th of April until the 15th of May, so it’s difficult to generalize. In any event, now is the time to complete our final preparations. Timely planting is essential to obtain good yields and avoid some of the maturity and drydown issues we encountered last year in some areas of the state. Here are a few thoughts as we begin another season.

Lower-cost Herbicide Program Considerations — Dwight Lingenfelter, Penn State Weed Science

In a quest for less expensive weed control programs during the declining farm economy, here are a few options and points to consider when planning herbicide programs. In most cases, the newer herbicide options can be somewhat more costly than the old standbys that may get lost in the shuffle. Many of these older products and combinations are still useful however they may not always be the cheapest alternative. Some of these programs can stand alone, however many could be used in combination in Roundup Ready or Liberty Link systems. There are many other herbicides and combinations that could be used, below are a few corn and soybean herbicide combinations to consider based on average cost per program.

Considerations in corn:

Considerations in soybean:

Burndown Herbicide Applications — Bill Curran, Penn State Weed Specialist

It’s been a relatively cool spring thus far but the end of this week looks like some nicer weather is coming in. I heard a number of comments this past winter and more recently about the difficulty in killing cereal grain covers and even winter annual weeds in early spring. At a field day at the Landisville research farm (Lancaster County) this past week, we observed purple deadnettle, corn speedwell, and several mustard species starting to flower. Giant and common ragweed and lambsquarters are beginning to emerge in some fields with the foxtails not far behind. It’s a good time to remember that environmental conditions and the size of the weeds or cover crops can greatly affect the activity of burndown herbicides and weed control. In addition, daytime temperatures above 55°F and nights above 32°F with sunny days will help improve herbicide activity and cool cloudy days will reduce their effectiveness. In general, herbicides such as glyphosate and 2,4-D provides the best control when annual weeds are 6 inches tall or less and still in the vegetative stage of growth. Winter annuals that are flowering may require higher rates or different combinations of products. Perennials should be at least 6 to 8 inches tall and preferable more when a systemic herbicide is applied.

Here are a few additional suggestions to help improve burndown herbicide activity:

Cereal Grain Cover Crop Management — Bill Curran, Penn State Weed Specialist

In no-till corn or soybeans, glyphosate is usually the preferred product of choice for burning down cereal rye and other small grain cover crops. In general, rye is quite susceptible to control with glyphosate, although applications during April can be more challenging. Gramoxone can also be effective, but application timing and tank mixing with a triazine herbicide (atrazine in corn and metribuzin in soybean) are important for successful control. Factors to consider in order to achieve effective control include: 1.) herbicide rate—most glyphosate labels recommend increasing the rate of product as the cereal rye matures. This is just as important under cool-cloudy conditions. With Gramoxone Inteon, use the 3 pt rate and remember that it is better on smaller cereals or after they have reached the boot stage—during the period of rapid culm elongation it is less effective. 2.) Include appropriate adjuvants in the spray tank—include 1 to 2 qt/100 gal nonionic surfactant (unless fully loaded formulation) plus 8.5 to 17 lb/100 gal AMS or equivalent with glyphosate. The AMS helps alleviate hard water problems and also can reduce antagonism if tank-mixing with other herbicides such as 2,4-D. Be sure to add the AMS first to the spray tank and agitate before adding the glyphosate. 3.) Use a clean water source that does not contain soil or other sediment that can reduce glyphosate or Gramoxone activity. 4.) Use flat fan nozzle tips that produce a uniform spray pattern and thorough coverage. 5.) Spray in sufficient carrier to achieve good coverage (usually between 10 and 30 GPA). 6.) Make sure the sprayer is accurately calibrated (output, pressure, pattern, speed, etc.) to deliver the appropriate rate uniformly. 7.) Air temperature before, during, and after application can influence control. Cold nights (<40 F) will reduce activity, particularly for glyphosate, and especially when followed by cool (<55 F) cloudy days. 8.) The more time between application and rainfall the better, especially with difficult to control perennials.

PA Black Cutworm Monitoring Program — John Tooker, Penn State Entomology Specialist

Black cutworm is an increasing problem in Pennsylvania, particularly in late-planted corn and corn planted into cover crops. Fortunately, the timing of the risk from the cutting behavior of black cutworm caterpillars can be predicted if one knows when a good number of the adult moths have arrived in the state. Damaging populations of this caterpillar species develop from eggs laid on cool-season grasses and weeds near crop fields. Egg-laying female moths typically migrate into our area starting in April, arriving from the Gulf Coast on storm fronts. Cutting of corn seedlings usually occurs May or June.

To help predict when and where black cutworm might pose a risk, this year we have established a black cutworm monitoring program across Pennsylvania. Manned mostly by county extension educators, we have approximately twenty pheromone traps deployed across the state. These traps are baited with a synthetic version of the sex pheromone produced by female moths, and male moths are attracted to the traps and die. When we capture eight moths over the course of two nights in individual traps, we can then predict that cutting larvae will be active in that area in approximately 300 degree days. We will give regular updates on our trapping success and when we capture enough moths we will provide warnings on when and where black cutworm larvae may be a threat.

In the past week, we have started to capture as many as two moths in an evening in spotty locations, most notably in Berks, Lancaster, Dauphin, and Westmoreland Counties. We will keep you updated as our trapping continues and will let you know when and where risks should develop.

There is also a new fact sheet available describing the pest, its biology and management options.

Watch Out for Slugs in Reduced-tillage Fields — John Tooker, Penn State Entomology Specialist

As our cool spring continues, it is good to be aware of the risk for slug damage in newly planted crops. Slugs, and particularly the gray garden slug, are most active when it is cool and moist, thriving in fields with surface residue and high organic matter. Most slugs have a single generation per year with juveniles hatching over an extended period in spring (March-May) from eggs that overwintered. During mild winters, however, young slugs and adults can survive the cold season. Adult slugs tend to feed on decaying matter in leaf litter and soil, so it is the juvenile slugs that cause the most damage to crop seedlings. Individual slugs can live nine to twelve months.

Because slugs are often a problem following a switch to no-till farming, one management option is moving to a reduced-tillage or conventional tillage program, which will reduce amounts of food and shelter available to slugs. This option is, of course, not feasible for many, so other options must be considered. Dr. Galen Dively, long-time extension entomologist at the University of Maryland, has suggested the following options for farmers who do not wish to alter their tillage practices:

Slugs are a challenge to control and a single tactic may not be successful; therefore, a combination of these tactics provides the best chance for success. Reliance on metaldehyde alone may be tough because it can be expensive.

Check Soil Compaction — Sjoerd Duiker, Penn State Soil Management Specialist

The soil compaction tester, or penetrometer, is the best tool to check for soil compaction. The entire soil profile needs to be at field capacity (24 hours after soaking rain) if you want to use the pressure gauge on the penetrometer. The rule of thumb is that above 200 psi roots are somewhat inhibited and above 300 psi root penetration is severely inhibited. Take 3–4 readings per acre, driving the rod down into the soil at about 1 inch per second. Write down at what depth you exceed 300 psi, and at what depth penetration resistance decreases below 300 psi. The penetrometer rod comes usually with indentations every 3", which you can use to determine depth of readings. The depth of a compacted layer can be judged using these depth readings—and this information can be used to determine how deep to set a tillage tool to alleviate compaction—if necessary. If more than 50% of the readings to a depth of 18" exceed 300 psi, we recommend action. You set the subsoiler or other tillage tool just below the depth of the severely compacted layer. A few notes of caution—the penetrometer is just one tool, and it does not measure cracks and continuous pores in the soil, which roots follow. So the matrix may be firm, but this does not necessarily mean that subsoiling will be beneficial because many macropores may be present (in a soil with high biological activity nature remediates soil compaction). If you have many rocks it the penetrometer is not a useful tool. For more information check Agronomy Facts 63.

Cut Feed Costs by Grazing Your Small Grains — Marvin Hall, Penn State Forage Specialist

Winter cereal crops such as wheat, barley, rye or triticale can usually provide grazing, silage and/or grain options. If these crops are used for spring grazing, certain management practices need to be modified from what is normally done for grain production.

Grazing Management

One acre of properly fertilized and managed small grain pasture should support one animal unit (feeding value of a 1000 lb. dry cow) on a limited grazing basis. Stocking rate and time of grazing will be somewhat determined by the intended use of the crop. If you are planning to take a silage or grain harvest, grazing should only be moderate. Heavy grazing can reduce grain yields.

Spring grazing may be started when they begin to grow. If a grain or silage crop is to be harvested, grazing should be discontinued when the plants start to grow erect just previous to jointing. Small grain plants will be injured by grazing at any time after their growing points are above the ground.

The use of temporary electric fencing should provide a practical way to manage these pastures. Rotational or strip grazing can allow for a higher carrying capacity because of improved forage utilization by reduced wastage and trampling.

Small grain pasture is lush, high in protein, and low in fiber early in the spring. Crude protein levels can range from 15% to 34%, making them an excellent protein supplement for many classes of livestock.

Animal Health Precautions

Grass tetany can occur when small grain forage is grazed in the spring by cows about to calve or those which have recently calved. Animals that are spring-grazing small grains should be supplemented with a mineral mix that contains magnesium. Lactating dairy cows that are grazing small grain pasture should receive an additional 1 ounce of magnesium oxide per cow per day.

There is a risk of nitrate poisoning if animals graze rapidly growing, recently fertilized small grain. Avoid this situation by applying N fertilizer well before the intended grazing period.

Although it is rare, bloat may also be a health risk when animals graze small grains. This most likely can occur when animals are first turned on small grain pasture in early spring and they gorge themselves with the lush forage. Bloat can be prevented by feeding some stored forage just before introducing the animals to the pasture.

Mark Your Calendar

Contributors: County Educators: Kevin Fry (Armstrong), Mena Hautau (Berks), Del Voight (Lebanon), and Mark Madden (Sullivan). Department of Crop and Soil Sciences: Greg Roth, Sjoerd Duiker, Marvin Hall, Dwight Lingenfelter, Doug Beegle, Ron Hoover, and Bill Curran. Department of Entomology: John Tooker: Meteorology: Paul Knight.

Editor: Andrew Frankenfield (Montgomery County)

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