CMEG Crop Management Extension Group

Field Crop News

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

September 19, 2006    Vol. 06:21

IN THIS ISSUE:

Weather Outlook — Paul Knight

Wednesday will be breezy and quite cool with abundant clouds in the northwest (along with scattered showers), but expect considerable sunshine east of the Appalachians. A very chilly morning is likely on Thursday with some 30’s in the western valleys. Sunshine will be plentiful on Thursday with light winds. As warmer air returns on Friday, so will clouds and a band of showers — especially in the west and central sections during the afternoon and evening. Saturday will feature varying amounts of clouds and sunshine as warm air occupies much of the state. Several showers or a few thunderstorms are expected in western counties. The air will become humid during the weekend. A disturbance will push a cold front through the state later Sunday with some gusty showers or thunderstorms. Monday will turn blustery, drier and cooler. Rather cool, breezy conditions are likely from Tuesday through the end of next week. No threats expected from the Tropics.

John Rowehl, Extension Educator — Cumberland County

Starting out with a bin free of old, insect infested grain is essential for storage preparation, particularly if no other protection will be applied to the grain. Sweeping down the walls of the bin and getting old grain out of the cracks and crevices is essential to prevent problems later.

Malathion, Storcide II™  or Tempo Ultra SC™ and several pyrethrin products can be used to apply a surface treatment to the inside of bins and provide a residual.  Check the label for Storcide II; there are restrictions on application method. Chloropicrin is no longer labeled to fumigate underneath false floors and in air ducts. Phostoxin is the only product that can be used.

Once the bin has been cleaned, it is important to put clean, insect free grain in the bin. The first step is making sure your equipment has been cleaned out before you begin harvesting. You could add insects to the bins that have been living in your combine.

Make sure your combine is adjusted to prevent breakage of grain. Whole grain is more difficult for molds and insects to infect and makes aeration of the bin more efficient. If possible, grain should be run through a cleaner before entering the bin. Sanitation and surface treatments should be sufficient to control insects for a six to nine month period.

If you are not able to clean out the bin or don’t fumigate under floor areas, or if you think the storage period may be longer, application of a residual insecticide to the grain as it goes into storage will help keep insects controlled. Actellic 5E is labeled for this use on corn. A dust formulation of Malathion (check the label) may still be available for this. If you do not treat the entire bin this way, you can treat the last load going in with a protectant or mix in a BT product into the top four to six inches of grain in the bin to control Indian meal moth.

During winter months, cool temperatures keep insect activity in check but as spring approaches and grain temperatures rise above 40–50°, insects become active.

If insect populations develop in your bin, your only option is to fumigate. Aluminum or magnesium phosphide is labeled for grain fumigation. You must be a certified applicator to use these products. Remember, fumigation only kills insects that are present and does not provide long-term residual protection. As soon as the fumigation is complete, insects can begin re-infesting grain.

A handy reference is the University of Tennessee 2006 Insects in Farm Stored Grain.

Start Planning Your Horseweed/Marestail Management This Fall — Bill Curran, Weed Science

We are seeing an explosion of horseweed or marestail in some parts of the state. This time of year, the seeds are moving with the wind in hopes of landing at an opportune location where they can germinate and begin the next generation. Horseweed was a common site throughout Southeast PA in soybean fields this summer, but also along roadsides and other non-crop areas. We don’t know how much of this population is glyphosate resistant, but rest assured that PA is now on the radar screen containing numerous fields of glyphosate resistant horseweed.

The biggest problem of resistance has occurred in no-till Roundup Ready soybeans where glyphosate is used exclusively as the weed control tool. Even with two well-timed glyphosate applications, resistant horseweed may/will not be effectively controlled. While the majority of horseweed usually emerges in the fall, it can also emerge in spring and early summer. Horseweed is more easily controlled when small in late fall or early spring.  As it matures and bolts in the spring and early summer, herbicides become less effective at killing this weed. In addition to glyphosate resistance, populations in Ohio and Indiana are also resistant to the ALS inhibitors (Classic FirstRate, etc.). At this point in time, the most economical treatments for control include 2, 4-D ester at 1 to 2 pints/acre, probably in combination with glyphosate or possibly Gramoxone. Even 2, 4-D ester should be applied to small plants (less than 2 inch rosettes) to ensure effective control. Delaware, Maryland, and New Jersey weed scientists are also recommending dicamba (Banvel or Clarity at 6 to 8 oz/acre) at least 30 days in front of soybean planting (see recommendations below). A primary goal for horseweed management in soybeans should be effective control of emerged plants prior to planting.  Here are some important principles for horseweed control outlined by Ohio State weed scientists:

  1. 2,4-D ester should be included in herbicide treatments if at all possible.
  2. Herbicides should be applied when horseweed plants are no more than 4 to 6 inches tall. Horseweed seedlings or rosettes (April) are easiest to kill.
  3. Herbicides applied in the fall will control emerged horseweed, but may not adequately control spring emerging plants. Residual herbicides, Canopy, Valor, or Sencor, applied in the fall can control horseweed through soybean planting.
  4. Spring applications, prior to May, should include a residual herbicide to control later-emerging plants.

University of Delaware, Maryland, and Rutgers recommendations focus on not using glyphosate in the burndown and recommend Gramoxone combinations. Timing is important. The early pre-plant programs may require an additional application of Gramoxone at planting due to later emerging weeds or horseweed that was not completely controlled. The less than 7 day programs should not be used in consecutive years because of concerns for resistance and split applications are preferred over the single more risky application.

  1. Spring application more than 30 days before planting — Apply Gramoxone Inteon at 2 pt/acre plus dicamba (Banvel or Clarity at 6 to 8 oz/acre) or 2, 4-D ester at 1 qt/acre + NIS (the Clarity label requires a minimum of 1″ of rainfall followed by 14 days before soybean planting.  Important — We have not extensively investigated the use of dicamba in front of soybeans for PA, so use caution).
  2. Less than 30 days, but more than 7 days before planting – Apply Gramoxone Inteon at 3 pt/acre + 1 pt 2,4-D ester  + NIS.
  3. Less than 7 days before planting — A.) Apply Gramoxone Inteon at 3.8 pt/acre + NIS, 3 to 5 days before planting followed by Gramoxone Inteon at 2 pt/acre + NIS at planting or B.) Apply Gramoxone Inteon at 3.8 pt/acre + Canopy or Synchrony XP at 1.5 to 2.5 oz/acre + NIS.

Mark VanGessel at Delaware has demonstrated some promising results with fall seeded cover crops such as cereal rye. The Delaware research suggests that horseweed is not very competitive when other plants such as cereal rye are growing in the field. A fall seeded cover crop may not only hold nutrients and provide winter cover and other important benefits, but could also help reduce horseweed establishment and success.

Herbicides for Grassy Weed Control in Small Grains — Dwight Lingenfelter and Bill Curran

Winter annual grasses, such as downy brome, cheat, annual bluegrass, and annual ryegrass, should be controlled as soon as an inch of new growth has occurred. The wheat herbicides available for control of grasses, Axial, Osprey, Maverick, Olympus, Finesse, and Hoelon, are most effective when applied in the fall, and effective spring activity is dependent upon the weeds being small. Be sure to include the necessary adjuvants in the spray mixture and follow label guidelines to minimize risk of crop injury and yield loss. Labels for many products specify the number of tillers or leaves that wheat or barley should have before treatment is allowed. Be cautious of crop rotation intervals, certain herbicides such as Olympus and Maverick have long recrop intervals.

Axial is labeled for use on wheat and barley and will provide control of annual ryegrass when applied up to the 5-leaf stage of the weed. The Axial use rate is 8.2 fl oz/A plus 9.6 fl oz of Adigor adjuvant.  Tank mix to broaden the weed control spectrum. The maximum rotational restriction for any crop is 120 days after an Axial application. Osprey is labeled for use in wheat and in our region it will be primarily targeted for control of annual ryegrass, including Hoelon (ACCase)-resistant biotypes and annual bluegrass. Osprey also provides suppression of brome species and common chickweed, henbit, and pigweed. The Osprey use rate is 4.75 oz/A plus necessary adjuvants.  Applications should be made when weeds are young and actively growing at the 1-leaf to 2-tiller stage. To broaden weed control spectrum, Osprey may be tank-mixed with other herbicides including, Harmony Extra, Harmony GT, MCPA, Buctril, and Stinger. Soybeans can be planted 90 days after application, corn after 12 months and alfalfa after 10 months. Refer to the label for other use restrictions.

Hoelon has been labeled for use in wheat and barley to control annual ryegrass and other weedy grasses, but is not effective on downy brome or cheat. Hoelon may be applied (1.33-2.67 pt/A) pre or post in wheat, but only pre in barley. Maverick (0.67 oz/A) provides control of downy brome, chess, and cheat when applied in the fall. If Maverick is applied in the spring, it provides only suppression to these species. Be cautious of recrop restrictions if using these products. Soybeans may be planted between 5 and 12 months after Maverick application depending on soil pH; for other crops the Maverick label is more restrictive. Finesse (0.3-0.5 oz/A) will provide at least suppression of annual ryegrass, downy brome, cheat, and annual bluegrass in wheat and barley. Control of these species may be achieved depending on rate and timing. Only STS soybeans can be planted 6 months following a Finesse application; many other crops are at least 18 months. Olympus (0.6-0.9 oz/A) provides control of downy brome, cheat and chess when applied in the fall. Olympus provides suppression of downy brome when applied in the spring. Olympus also provides control of some common broadleaf weed species. Be cautious of rotational intervals when using Olympus, 4 months for STS soybeans, and at least 18 months for corn.

Effect of herbicides on selected weedy grasses in wheat*
Herbicide Control Suppression
*Axial, Finesse, and Hoelon can be applied to barley.
Axial
  • annual ryegrass
  • foxtail spp.
  • barnyardgrass
  • volunteer oat
Finesse
  • annual bluegrass (fall)
  • annual ryegrass (fall)
  • downy brome (fall)
  • cheat (fall)
[control of these species can be obtained depending on rate and timing.]
Hoelon
  • annual ryegrass
  • crabgrass
  • foxtail spp.
Maverick
  • downy brome (fall)
  • cheat (fall)
  • chess (fall)
  • downy brome (spring)
  • cheat (spring)
  • chess (spring)
  • quackgrass
  • annual ryegrass
Olympus
  • downy brome (fall)
  • cheat
  • chess
  • downy brome (spring)
  • quackgrass
Osprey
  • annual ryegrass
  • annual bluegrass
  • downy brome
  • chess

Soil Compaction During Harvest Season — Sjoerd Duiker, Soil Management Specialist

Farmers are busy harvesting corn silage and grain and are getting ready to harvest soybeans and the last cutting of alfalfa or grass. Open fields will offer the opportunity to empty that manure storage. With the buzz of activity comes the potential to increase soil compaction. The key to soil compaction avoidance is to stay out of the field when it is too wet. However, that is easier said than done and often feed quality governs field traffic instead of soil moisture content.

Surface compaction is caused by high contact pressures. Road tires inflated to 100 psi and iron wheels cause very high contact pressures. Using flotation tires or tracks or wider iron wheels helps reduce surface compaction by increasing the foot print of farm equipment. Flotation tires or tracks will not reduce subsoil compaction, although they help to reduce surface compaction and sinkage.

The key to subsoil compaction avoidance is to reduce axle load. This can be done by reducing the load or increasing the number of axles. Traffic patterns can help avoid spreading compaction over the full width of the field. It is recommended to use lanes for transport to and from the field instead of zigzagging across the field. We have said for many years that most (80% of) compaction is caused in the first pass. This may be true, but new information suggests that each additional pass of a vehicle causes more extreme and deeper compaction. Therefore, the reduction of the number of passes is important. Keeping concentrated traffic in a part of the field will help to limit remedial action to that part of the field only.

Alfalfa Stand Evaluation — Paul H. Craig, Dauphin County

All hay producers recognize the fact that as an alfalfa stand ages, it eventually thins out. There are many factors that cause stand thinning. These include diseases, insect and weed pressure, poor fertility and poor harvest management. The big question is not why the stand is failing but rather is the existing stand thick enough to keep for another season?

How thick a stand is directly affects both the yield and quality of the cutting; however economics of existing forage supplies and costs of reseeding compound the decision on individual farms. Unfortunately, at some point, a decision must be made. The current evaluation tool is based on work done at The University of Wisconsin by Dr. Dan Undersander and evaluated in Pennsylvania by Dr. Marvin Hall at Penn State.

These forage agronomists recommend looking at alfalfa stands in the fall for the best method for stand assessment.  They note that a second appraisal is helpful in the spring after the stand breaks dormancy. Fall evaluations help to identify troubled stands that may be prone to winter injury. This can allow for tillage or fall applied herbicides for optimum rotation affects. Spring evaluations reveal winter injury damage.

Wisconsin research notes that stem counts are more accurate for estimating yield potentials than crown counts. A stand may have density of 5 to 8 crowns but individual crowns may have few, poorly growing shoots. Research indicates that total stem counts per square foot is a better method. Their conclusions are that stands with more than 55 stems per square foot will have maximum yields; stands with fewer than 40 stems per square foot were not profitable and needed to be replaced; and densities between 40 and 55 will need additional considerations.

In addition to counting stems, agronomists recommend evaluating the condition of crowns and roots stand at the same time. By considering the crown and root health, an estimate of the long range yield potential can be part of the final decision. Healthy crowns and roots are large, symmetrical or balanced in shape, have many roots and shoots, are resistant to bark peeling and have creamy bright internal coloration. Crowns and roots with few roots, a soft feel and/or darken spots are damaged and prone to decline. Healthy stands have less than 30% injured crowns.

To evaluate your alfalfa stands this fall, make a simple 12 inch × 12 inch frame of wire or small PVC pipe. Select 3 or 4 areas of the field, toss the frame and then count alfalfa stems in this area. An alfalfa height of about 6 inches helps.  Keep track of your results and then average the counts across the field. The most reliable estimate will result from multiple tosses. Then dig a few crowns and look for signs of weak crowns.

Stands with stem densities of greater than 55 per square foot can still be high yielding with some crown damage. However, many stands with densities in the lower 40’s/square foot may also have a high yield potential if those stems are growing on healthy vigor crowns. There is no magical number to make this decision error free. Nevertheless, taking the time to walk (or 4-wheel) over your stands this fall may help you identify potentially poorer stands in time to modify cropping plans for 2007.

Grain Marketing — John Berry, Lehigh County

Things I would consider as harvest season begins:

Green June Beetles — Paul Craig and Del Voight

Recently I was contacted by a dairy farm who noticed a roadside area literally covered with extremely large grubs. When I arrived I observed an area approximately 75 feet long where these grubs had crawled out from nearby turf. There were few places where you could not put your foot down without stepping on one or even two of these large grubs that were crawling on their backs. Later I was informed that these were the third in-star larva of the Green June Beetle (GJB). See figures 1 and 2.

The GJB grubs rarely feeds on grass roots, but their extensive burrowing activities disrupt the root-soil contact. The grub is stout, has short legs, and crawls on its back. This distinguishes it from other white grubs which have longer legs and typically curl up into a C-shape when disturbed. Grubs typically feed at night on organic matter. These large grubs are often found under hay bales left in the field, near manure piles, and in thick organic turf. GJB have one generation per year. The green and gold adults fly in the daytime and are a familiar sight in June and July. Eggs hatch in August.

Grubs pupate in cells in the soil during late April and May and remain in the pupal stage for 2 or 3 weeks. Newly emerged adults remain in the soil for an additional week or two. In most years, green June beetles leave the soil beginning in late May and continue through early August. Peak flights usually occur from June through July.

Female beetles fly over the grass surface early in the morning and settle into the grass just after daybreak. Male beetles fly during mid to late morning. The female beetle constructs a walnut-sized ball of soil in which she lays 10 to 30 eggs. Eggs are nearly round, about 1/16 inch in diameter. Each female may lay as many as 75 eggs during a 2-week period. Eggs hatch in about 2 weeks. Newly hatched grubs are about 3/8 inch long. Young grubs begin to tunnel through the soil in search of food (organic matter). They typically come to the surface to feed.

Grubs are capable of pruning the roots of plants, particularly when the grubs occur in high numbers. Grazing cattle easily pull the plants growing in the loosened soil out of the ground. Weeds quickly colonize the bare patches created where a plant dies or is pulled out. Birds and skunks dig grubs out of turf and pastures, often causing even greater damage in the process.

In most years, the best time for grub control is late August through October, before the GJB grubs have caused extensive damage. The only product labeled for use in mixed hay and pasture stands is Sevin used at 1.5 qts./acre applied with 25 gal/acre or more of carrier. Mow or closely graze pastures before spraying. It is important that the grubs come in contact with the insecticide. Make applications late in the day since grubs move to the surface during the evening. Applying the insecticide a few hours before a moderate rain may increase the efficacy of the application. Heavy infestations may require a second application 10 days to 2 weeks after the first application.

Treatments during winter or early spring will be too late to prevent most green June beetle grub damage and will probably give a lower percentage of control. Grubs are larger by this time and are harder to kill. Also, when temperatures are cool, control efficacy declines because grubs are less likely to come to the surface and come in contact with the insecticide.

Contributors: State Specialists:  Marvin Hall, Erick DeWolf, Sjoerd Duiker, Greg Roth, Bill Curran, Dwight Lingenfelter.  Extension Educators:  Paul Craig (Dauphin), Del Voight (Lebanon) Kevin Fry (Armstrong), Andrew Frankenfield (Montgomery), Mena Hautau (Berks), Susan Alexander (Jefferson), John Rowehl (Cumberland), John Berry (Lehigh) and Dave Messersmith (Wayne).

Editor: Paul H. Craig

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