CMEG Crop Management Extension Group

Field Crop News

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

April 17, 2007    Vol. 07:07

IN THIS ISSUE:

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

Winter’s last hurrah will very slowly loosen its grip on Pennsylvania as plenty of clouds, cool winds and occasional light showers (mixed with wet flakes in the mountains) continue through Thursday. Drier air will filter into the region on Friday, but clouds will still be in the majority over the hilly terrain. The weekend will feature partly to mostly sunny skies and after chilly mornings (with sub—freezing readings in the western and northern valleys), each afternoon will be warmer with readings returning to the 60’s on Sunday and maybe on Saturday too. A cold front of Pacific origin will promote clouds and scattered showers or even a thunderstorm on Monday. It will stay rather warm during the first few days of next week with a likelihood of heavy showers late in that week. During the period April 18–24, expect temperatures to rebound to above seasonal levels by early next week. Precipitation, which should accumulate an inch per week, will likely average between 0.10–0.35” in the next seven days with the most expected in the western counties. There are growing indications of a spell of abnormally warm weather in the Northeast during this coming summer.

Delayed Planting Effects — Author, John Rowehl, Extension Educator, Cumberland County

As I write this article, during the third week in April, many farmers are concerned about being behind schedule in getting normal fieldwork done due to the unfavorable weather this spring. There are a few things I can think of that may need to be considered, so I'll give some thoughts on how that might affect cropping management.

One of my prime concerns is what can happen to soils that are driven on with heavy equipment or worked when they are not dry enough. Keep in mind the long—term effects from soil compaction that waiting an extra day or two might avoid.

I would guess that there may be some corn fields that will be no—tilled this spring, which might not normally have been, in order to speed up planting. Check that the coulters and disks on the planter are in good shape and have not worn down too much. They may have been doing OK in tilled ground but may not place the seed properly with no—till planting. Don’t forget that it will take a little longer for that soil to warm up with mulch on the surface. Make sure that the ground is not so wet that the seed furrow is not closing properly. If the weather does turn around and things begin to dry up, there are benefits of no—till in keeping the residue on the surface and retaining moisture.

If delays do occur it will be very important to make sure you use a burn down herbicide and that you are using enough product and carrier to get a good kill of what may be larger weeds.

If you decide to no—till plant soybeans make sure the field is level enough that you will get even planting depth, particularly if using a drill, so a grain header can do a good job at harvest. If soybean planting runs very late (into June) plant populations should be adjusted upward.

If the weather continues to be cool and rainy, it will definitely be a year to use seed treatments. I don’t know if freshly applied manure will attract seed corn maggots more than if it were spread a month ago but I would still recommend protection with seed treatment. Keep an eye out for slugs later on if this weather pattern continues, especially in fields with residue cover.

The optimum time to seed oats (late March to early April in warmer regions of PA) has unfortunately already passed. Based on an Iowa study, oat yields in fields seeded from early to mid May could be down thirty to fifty percent due to late planting. Late planted oats are also more susceptible to barley yellow dwarf virus and crown rust.

White Grubs in Field Crops — Ron Hammond, Ohio State Field Crop Entomologist

White grubs are a potential problem in no—till field crops in the spring. A decisive factor for the need for control is determining what type of grub you have. Annual white grubs (including Japanese beetles and masked chafers) are usually not major problems. When they occur, the damage is usually patchy. Annual grubs have but one generation per year. Their grubs or larvae feed in the fall, and then go deeper in the soil to overwinter. In the spring, the move back up, feed just a little if at all, and then pupate, without normally causing significant damage. However, true grubs (May or June beetles) have multiple year generations. Their grubs, which also go deeper in the winter coming back up each spring, will feed extensively on the roots of the plants if their populations are high, possibly causing significant problems. True grubs are often more of a problem when corn follows sod or set—aside. There is no rescue treatment for grubs in field crops, and there is no threshold. If grubs are present, especially true grubs, a preventive treatment is perhaps warranted. To tell the difference between the grubs, you need to examine the hairs at the tail end. This web site, obtained from The Ohio State University turf program, shows pictures of this: http://ohioline.osu.edu/hyg-fact/2000/2510.html. For control on corn, most soil insecticides are usually labeled for grubs, as are seed treatments. Whether seed treatments will provide acceptable control is currently being determined. However, they would be better than nothing. For soybean, only seed treatments are labeled. http://www.ohioline.osu.edu/hyg-fact/2000/2510.html. For fields with true grubs, rotation will not be of much value because of their multi—year generations.

Is Brown Root Rot a Problem in Pennsylvania Alfalfa Fields? — Marvin Hall, PSU Forage Specialist

Brown Root Rot has been in found in alfalfa fields throughout New York, Vermont and New Hampshire. PSU Cooperative Extension in collaboration with Cornell University has undertaken a project to see if it is present in Pennsylvania and if so to what extent. We should know by mid—summer but until then maybe you could keep your eyes open for the symptoms.

This rot affects both the root and crown but not the above ground part of the alfalfa plant. It causes lesions on the roots that are initially reddish—brown but become light—brown with an almost black border (Fig. 1) http://fcn.agronomy.psu.edu/images/hall0706image1.jpg. When conditions are conducive, the rot area becomes covered with large fungal fruiting structures (Fig. 2) http://fcn.agronomy.psu.edu/images/hall0706image2.jpg. Lesions that do not immediately kill the plant allow secondary organisms to invade further weakening or killing the plant.

Boom Sprayer Setup & Calibration — Andrew Frankenfield, Extension Educator, Montgomery County

Wet weather got you down and you’re still working in the shop — or even worse the flower beds — instead of working in the fields? Well if you didn—t touch your sprayer since last year, now is a good time to give it some attention. Chemicals and fertilizer are too costly to over apply or if they are applied at a lower than desired rates, they are not as effective.

The 2007–2008 Agronomy Guide has an excellent step by step method of boom sprayer setup and calibration on page 163–164 or on the web at: http://agguide.agronomy.psu.edu/pm/sec1/sec110h.cfm. It is in your best interest to utilize this information to calibrate your sprayer.

Something to consider when you are spraying with materials heavier than water, such as UAN, you need to multiply the desired GPA of solution by the water rate conversion factor. Since all tips are calibrated using water as the carrier, the flow or rate changes depending on the weight of the solution. For example, the conversion factor for 28%N is 1.13. If you want to apply 20 gpa of 28%N, take 20 x 1.13 = 22.6. Then look up your tip capabilities to see what speed and pressure you need to be operating at to achieve that rate based on spraying water. For example, a FloodJet TK–VS5 operated at 6 mph at 30 psi is rated at 22 gpa, that is just about right to achieve 20 gpa of 28%N.

http://www.teejet.com/MS/TeeJet/support2.asp?ID=90

Take advantage of this wet weather to be sure your sprayer is ready to go when the time comes to get in the field; you’ll want to be able to cover some ground in a hurry when things heat up.

Tuning Up Your Mower—Conditioner — Paul Craig, Extension Educator, Dauphin County

Weather and soil conditions have held back field operations this spring. Soon rye and first cutting will compete for limited time. While the fields remain too wet some equipment maintenance can be done to get ready for forage harvest.

Agricultural engineers note that disk mower knives must be regularly checked for dullness and wear. Disk mowers will cut even when knives are extremely dull, resulting in a “ragged” cut. Agronomists point out that this raggedness often leads to plant health problems later in the production cycle. Take time now to check your mower knives.

On the outer layer of plant leaves and stems is a “waxy” layer that prevents internal plant moisture from being lost from the plant during the growing process. The plant has stomata on the leaf surface that regulate this process when the plant is growing. Upon harvest, this “waxy” layer works to limit the rapid dry down of the crop. Mowers have incorporated conditioning systems to crack, split or scratch this layer.

One type of conditioning system uses intermeshing rolls to bend and crush plant stems. With all machines, the proper set up of these rolls is critical for optimum performance. The gap or clearance between intermeshing rolls is important. Too great of a clearance and the stems pass through without any crushing. Too small and leaves will be removed, in addition to excessive roller wear and plugging.

Roll clearance for effective alfalfa conditioning needs to be set and maintained at 0.060 (1/16) to 0.090 (1/32) inches to achieve effective conditioning. Check your operating manual for additional references and the procedure to make this adjustment.

The following procedure can be used to measure your roll clearance gap. First, ensure safety by shutting off your tractor engine and disconnecting the PTO. Next, lower the cutting platform to ensure the rolls are at operating conditions.

Procedure:

  1. Cut 3 pieces of aluminum foil 18 inches in length.
  2. Form three separate rolls by wrapping a foil strip around a rod or dowel that is 3/8th inch in diameter. Then slide the roll off the rod taking care not to crush the foil roll.
  3. Place one foil roll in the center and the two other rolls about one foot from each end of the conditioning rolls. Place the foil rolls perpendicular to the roll.
  4. Make sure cutting platform is lowered and turn the conditioning rolls over by hand until the foil rolls come completely through.
  5. The rolls will crush the foil and minimum roll clearance can be determined with a caliper. Take several measurements along each foil roll and determine an average. Take the measurement where the smallest clearance occurs.

Reference: Kevin J. Shinners, Professor of Agricultural Engineering, University of Wisconsin

2007 Alfalfa Weevil Update — Paul Craig, Extension Educator, Dauphin County

Reports and observations this spring around the Capital Region of PA have been noted for the lack of activity of alfalfa weevil. Since 1999 when severe outbreaks started, most alfalfa producers and crop scouts have been paying close attention to the potential for problems. The widespread populations in 2000 through 2004 appeared to drop off significantly in recent springs but localized outbreaks still occur. To date parts of southern PA are quickly approaching the growing degree day total when larva will hatch. The appearance of Colts Foot flowers, along roadsides, is an indicator used by many observers to indicate when larval hatch starts. As weather conditions improve these major pests of first cutting alfalfa will begin to rapidly develop and cause significant feeding damage to alfalfa leaves on many stands. The larvae cause injury by removing leaf tissue at the top of the plant and then work down the stem to other leaves. The injury gives plants a silvery cast when viewed from a distance. Close up the leaves are characterized as “skeletonized”. The feeding reduces forage quality and quantity.

Alfalfa weevil larvae are pale yellow to light green in color. All larvae have a black head. Larger larva have a white stripe down the middle of their back. Their size ranges from 1/16th inch when hatching from eggs to 5/16th inch when close to pupation.

Before control materials are applied growers should scout their fields to determine if population levels justify treatment. A quick look at a field can determine if weevil larva are present. Look for holes in the upper most leaves on the alfalfa. Closer examination in the leaf buds will reveal the presence of the larva.

If the presence of the larva is confirmed then collect 30 stems of alfalfa and place in a bucket. Be careful when you collect the stems so as not to dislodge any larva before placing the stems in the collection bucket. The best way to collect the most larvae is to grasp the tip of the plant with one hand and break the base of the stem with the other hand. Carefully pull apart the leaf buds to look for small larva. The larger larva can be knocked off the stems by beating the stems against the sides of the bucket.

There are many threshold levels published to determine if control materials will be beneficial. All levels are a factor of plant height, potential value of hay, cost of control materials, and the count of larva per 30 stems. For example: hay value $100/ton, plant height 16 inches, $7 to 10 cost of material application; threshold level would be 33 weevils per 30 stems. For additional information refer to publication entitled “A Pest Management Program for Alfalfa” from your local Extension office.

Wanted: York County Soil & Nutrient Management Educator

Penn State Cooperative Extension, Capital Region, is accepting applications for an individual to provide programming in the broad areas of nutrient management education, soil quality and soil health, basic physical and chemical properties of soils, and agronomic application of organic residuals. A master’s degree is required with preference given to degrees in agronomy, soil science or related field and eligibility to be a certified crop advisor. Deadline for applying is May 11, 2007. Visit PSU website http://psu.jobs under Cooperative Extension for details. For application email (bss1@psu.edu) or call (814) 863-3452. Penn State is committed to affirmative action, equal opportunity and the diversity of its workforce.

Stay On—Track with a To—Do List — Dave Messersmith, Extension Educator, Wayne County

When the weather “breaks” there is little doubt we’ll all be scrambling to do field work. One tool that will keep you on track is a To—Do list, which is simply a method of keeping track of jobs that need to be done. Here are some tips on creating an effective one:

  1. Your To—Do list should be kept in a small notebook that fits in your pocket and can be carried with you at all times.
  2. Brainstorm and make a list of all jobs that need to be done (usually on a daily or weekly basis). Update your list with new jobs as they arise.
  3. If one of your jobs feels too big to start, break it down into several smaller pieces.
  4. Rank each job on your list in order of importance. I mark my most important items with an asterisk so I can see them at a glance.
  5. Work on your highest priority jobs first, staying on task until the job is completed.
  6. Throughout the day check off jobs as they are finished.
  7. Use any unfinished jobs on your old To—Do list as a basis for your next list, but be sure last weeks job is still important and relevant before putting it on your new list.

Adapted from “Time Management: Making the Most of a Limited Resource” Dale Johnson and James Hanson, Univ. of Maryland. http://www.smallfarmsuccess.info/management/print_671.cfm

Keeping Tabs on Cover Crops — Sjoerd Duiker, PSU Soil Management Specialist

The wet and cold weather brought field activities to a shrieking halt in most of the state. Although little growth is taking place due to the cold weather cover crops can easily sneak up on us, resulting in a situation we are not prepared for. Rye is the main cover crop of concern, because it grows fast and tall in the spring. Sprayers better be ready to go once field conditions permit to enable burndown of rye cover crops before they get taller than 2 feet. The reason for early burndown is not so much that rye cannot be killed — it dies easily with a full rate of glyphosate — but because the large amount of residue may be hard to plant through if it is not managed properly. If tall rye falls down in multiple directions it can be very hard to cut with coulters or disk openers on the no—till planter. The result can be hairpinning problems and uneven seed depth placement. Heavy rye can also result in difficulty closing the seed slot, and slugs just love to follow the seed slot, munching away on little corn seedlings.

Another reason for timely burndown is nitrogen tie—up. Once the rye cover crop reaches a C:N ratio of 30, bacteria will tie up soil nitrogen to decompose the rye after it is burned down. In no—till we typically worry less about this because the residue is not brought in intimate contact with the soil, but it may still be an issue. Boot stage (head can be felt in stem) is the critical stage when the C:N ratio starts exceeding 30. The living rye can also consume large amounts of soil moisture — this is a concern on shallow soils that could suffer from early drought. Once dead, however, the rye mulch cover conserves moisture. Killing cover crops early is not always recommended. The more growth the cover crops get, the more they contribute to soil improvement and nutrient uptake. Leguminous cover crops should be given time to grow in the spring to fix nitrogen for the following crop. Research in Maryland showed that hairy vetch accumulated about 2 lbs N/A per day from March into May. The hairy vetch I have seen so far in Pennsylvania is very small and can be expected to contribute little N to the following crop if killed now. It will be beneficial to wait a while before burning down the vetch. A biomass sample and N analysis can provide guidance as to how much N it contains. The amount of N in the above—ground biomass can be expected to be available to the following corn crop. An in—season nitrogen test such as the PSNT or chlorophyll meter test can help determine whether side—dressing nitrogen is still needed or not. Crimson clover also fixes most of its N in the spring, but it does so earlier than hairy vetch. However, its contribution to the N need of following corn is expected to be lower than that of hairy vetch. Red clover has typically been established a full year in advance (frost seeded into small grain) and may already have put on much growth in the fall. Giving it more time to grow this spring just results in more N. Remember that glyphosate is not 100% effective to terminate legume cover crops — banvel is more effective, and a mix of banvel and 2,4–D LVE is a sure bet. Remember also that ‘plow down’ of cover crops does not increase the N—benefit compared with leaving the dead mulch at the soil surface (where it does more good!).

Contributors: Dept. Crop & Soil Science: Doug Beegle, Marvin Hall, Sjoerd Duiker, Dwight Lingenfelter, Ron Hoover, Paul Knight. Extension Educators: Mena Hautau (Berks), Kevin Fry (Armstrong), Andrew Frankenfield (Montgomery), John Rowehl (Cumberland), Paul Craig (Dauphin), Mark Madden (Sullivan), Joel Hunter (Crawford), Dave Messersmith (Wayne).

Editor:Dave Messersmith (Wayne County)

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