CMEG Crop Management Extension Group

Field Crop News

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

May 5, 2009    Vol. 09:09

IN THIS ISSUE:

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

The unsettled weather will continue for several more days with the southeastern two-thirds of the Commonwealth more favored for rain. With light winds and rather cloudy skies, drying conditions will be quite poor in the parts of the state where the growing season has begun. Temperatures will stay near to below seasonal levels into early next week, though one mild day is possible (perhaps Friday). The current moist, cool pattern will evolve into a drier and warmer regime next week. While frosts are expected in the northern tier either Sunday and/or Monday mornings, indications show a several day period without rain and steadily increasing temperatures from Monday into Wednesday.

The risk of a cool snap after mid-month is still likely, though it may be preceded by another warm spell (May 16–20). Rainfall will remain above normal until mid-May and then become much less frequent. Odds favor above average temperatures for the June through August period with a notable wet period in the latter half of July or August. The hurricane season should have a late start with fewer storms than recent years, though Florida and the Carolinas appear more vulnerable.

Weather and Pre/Early Post Weed Control Considerations for Corn — Bill Curran and Dwight Lingenfelter, Penn State Weed Science

With a fair amount of corn being planted prior to the current wet spell and some of that not yet receiving a soil applied herbicide, you may be wondering if given the choice whether it is better to wait and kill the weeds postemergence or go ahead and spray as soon as you can. Once you leave the field following a tillage event (or a nonresidual herbicide such as Roundup), weed seeds are germinating and will emerge within 7 to 10 days depending on the weather. The soil residual herbicides must have rainfall to move them into the zone of the geminating seedlings to effectively do their job, so timing the herbicide application just prior to rainfall before weed seedlings emerge can sometimes be challenging. Fortunately, we have a number of options in corn with the arsenal of products available to help manage weeds.

A number of residual herbicides can be applied after planting up until corn and weeds reach a certain size or growth stage. The greatest risk of failure comes with trying to control annual grasses such as foxtail and panicum as they are emerging without including a foliar applied herbicide. With the increasing acres of Roundup Ready (glyphosate) and Liberty Link (Ignite) corn, we have more flexibility in how we manage weeds after emergence. In addition, a number of “conventional corn” products are available to control emerged grasses (e.g., Accent and Accent Q, Basis, Celebrity Plus, Equip, Impact, Laudis, Option, Resolve, Resolve Q, Steadfast (ATZ) and Steadfast Q) and even more are available for broadleaf weed control. In most cases, these POST or foliar-applied herbicides can be tank-mixed with residual products to provide several weeks of control. For most products, do not apply in a liquid fertilizer carrier if corn has emerged or injury may occur. Maximum corn and weed sizes vary for early POST herbicide applications in corn depending on the product. Herbicides such as Balance Pro, Radius, and Princep must be applied before corn emergence. Balance Flexx and Corvus contain a safener and can be applied early POST to corn. Other herbicides such as Bicep II Magnum, Bullet, Dual II Magnum, etc. can be applied to corn up to 5 inches tall. Acetochlor-containing products such as Degree (Xtra), Harness (Xtra), FulTime, Keystone (LA), and SureStart can be applied to corn up to 11 inches tall. Herbicides including Atrazine, Lumax, Lexar, Guardsman Max, and Resolve can be applied to corn up to 12 inches tall (20 inches tall for Resolve Q). And finally, Prowl H2O and Halex GT can be applied to 30 inch tall corn or less. Keep in mind, when tank-mixing with other pesticides follow the most restrictive product label. For a listing of additional herbicides and maximum corn heights and information on maximum weeds sizes for these products pleaser refer to Table 2.2-12 in the Penn State Agronomy Guide and check the most recent herbicide label for specific use guidelines.

Soil Crusting — Sjoerd Duiker, Soil Management

Soil crusting may pose a problem to young seedlings as they try to emerge. Crusting happens due to dispersion of soil particles, reorientation of dispersed particles, drying, and dessication. There are three types of crusts: chemical crusts, biological crusts, and physical crusts. Chemical crusts are the result of encrusted salt on soils in arid or semi-arid regions. Biological crusts are primarily formed by algal growth and occur when ponded water stands and retreats on soils with low permeability. Physical crusts are the result of structural degradation of the surface soil and may be classified as structural or depositional. Physical crusts are most common in Pennsylvania. Structural crusts are formed when surface aggregates disintegrate due to the forces of raindrops of irrigation water. Depositional crusts are formed by transport and deposition of fine particles from eroded surfaces in depositional areas. Both rainfall characteristics and soil properties influence crust formation. Heavy, intense rain has high kinetic energy primarily because of large drop size. Similarly, there are differences between irrigation systems due to drop size distribution reaching the soil surface. Rainfall characteristics vary during the year in Pennsylvania, with higher intensity convectional storms being common in the summer. These storms tend to lead more easily to crust formation. Rainfall characteristics also vary by region, with higher intensity being more common in southeastern PA and decreasing to the north. As a result, crust formation can be expected to be a greater problem in southeastern PA than in northern PA. The most important explanatory factor of differences in crusting, however, is the soil. It seems that most of our soils are susceptible to crusting due to the fact that they have a range of particle sizes in the surface soil. When the soils are weakly aggregated, the impact of drops causes the fines to fill in the pores between the large particles. The result is a very thin layer (only a few millimeters thick) that, upon drying, is cemented into a crust with low permeability and high tensile strength. Water will not or very slowly infiltrate (dry soil under crust), gas exchange between air and soil atmosphere will be inhibited, and seedlings have to exert great strength to push through the crust. What to do about crusting? First, we can protect the soil from the impact of raindrops by keeping it covered. This means no-tillage and no removal of crop residue from the row. Second, the surface soil structure needs to be improved. This can be done by increasing the organic matter content in the very top of the soil, as is achieved by using no-tillage continuously, and by adding organic matter in the form of manure, compost, cover crops and crop residues. What can be done to remediate an existing crust? The crust needs to be broken up, and the best tool to achieve that is probably the rotary hoe. Another tactic is to plant seeds close together, because they will be able to push through a crust by joint force. This tactic could be applied by planting soybeans with a planter at 30" row spacings and narrower spacing in the row instead of with a drill with 7" row spacing and wider spacing in the row. Increasing seeding rates may also help. Seeding depth may also be a factor to consider: deep planting should be avoided in a crust-sensitive soil to allow the seedling to emerge before the crust re-forms. It will also be advisable to avoid very early planting dates so crusts do not have time to form above the seedlings prior to emergence.

Updates on Alfalfa Weevil and Black Cutworm — John Tooker, Penn State Entomology Specialist

Alfalfa weevil continues to be active across Pennsylvania. In the southern half of the Commonwealth, larvae appear to be common and feeding damage can be found easily. We have even heard of some fields in Lebanon County with economically damaging populations that required treatment. Today’s map from the PA-PIPE is predicting larvae to be widely active with third and fourth instars being possible in many counties:

Map

Due to wet weather and associated delays in corn planting, growers might have the opportunity to scout their alfalfa fields for weevils and their damage. Economic thresholds for alfalfa weevil are determined from the size of plants, the value of the hay, the cost of insecticidal treatment, and the number of larvae per 30 stems of alfalfa. See our new alfalfa weevil fact sheet for details on biology, sampling, and economic thresholds. In some parts of PA, alfalfa is getting tall enough for harvest, so keep in mind that harvesting the crop can be a good alternative to chemical treatments, particularly if conditions remain wet and spraying will be challenging. If weevil populations are high and growers choose to cut, it might be wise to consider spraying the stubble to try to prevent weevils from becoming a problem in the second cutting; however, remember that in most years alfalfa weevil is only a problem for the first cutting and weevil larvae are usually out of fields by mid-June. An added benefit of harvesting rather than spraying is conservation of beneficial organisms.

On the trapping front, we continue to capture black cutworm moths in our pheromone traps across the state. Most traps are reporting low numbers of moths, but traps in Berks and Westmoreland Counties detected significant flights of moths on 22 and 28 April, respectively. Flights of moths at the trap in Berks County (south of Kutztown) have been particularly heavy with 20 or more moths recorded twice over the course of just a few days. Cutting behavior by black cutworm caterpillars can be expected 300 degree days after detecting significant flights. To date we have accumulated approximately 130 degree days since the significant flight in Berks County. We will keep you updated as the threat for cutting increases.

Soybean Seed Quality Considerations — Del Voight, Interim Grain Crop Specialist

Only a year ago the quality of the soybean seed germination was a hot topic going into planting season. Reports were coming in of varying germination (70-80%) soybeans all across the soybean growing regions. I talked to the PDA lab last week and found that most of the beans that they tested for sale in Pa were testing at or near the 90% germination level. This is great news particularly with the high price of soybeans and the fact that the grower will receive a good quality product. In our studies over the last few years, established soybean populations struggled from the time they dropped out of the planter to the time they came up. In some cases, a 30% loss from seed drop to emergence was observed, while losses from pop up to mid season were only 4%. If there aren’t any pests, where might these losses come from?

Soybean handling comes into play and while we do not have all the data to support this, handling might be a cause. Dr. Elwood Hatley, retired Extension Specialist, often cautioned growers that each time a seed bag is dropped 2% or more of the germination can suffer. Recall that the soybean seed has two halves that are easily broken. Those halves are the structures of the plant that end up being the cotyledons. When dry they easily separate and germination is lost. So if you go to the dealer and toss the bag on truck(1), get home and toss the bag on a old hay wagon(2), then toss the bag back onto the truck(3), then man handle the bag to load the planter(4); an 8% minimum loss could occur in the soybeans. With that in mind the point is to handle them like you handle eggs from the chicken house.

One final note dealing with the weather, if you have alfalfa to get off, fungicide to get on wheat, corn and beans to plant, manure to spread and the rain finds you behind the game, then I would put less priority on early planting soybeans and get the other activities out of the way. Soybeans have a large window in which to establish without significant yield losses. Be sure to compensate seed populations for germination loss and soil conditions.

Wheat Production Decisions — Del Voight, Interim Grain Crop Specialist

On the wheat front there are some disease management factors at play and you will need to be apprised of the local conditions. Here with is the 2009 Scab tool.

It will tune you into conditions that are ripe for spraying which includes rain during flowering. There are only two products Proline and Caramba; however, Tilt and Propimax have some suppression of Scab.

Also to keep in an unbiased way, use the Kentucky Decision Guide for leaf diseases. Fill out the form and it will assist the producer in making the decision to spray. Remember Septoria is a wet weather disease and powdery mildew is a high humidity low rainfall disease.

The first section is the stage of development. You will need to be looking at GS 8-10. The weather is a big factor. The last section allows for the forecast to be included in that decision. You will need to consult the Ohio Screening program for the sensitivity of the variety to leaf diseases.

Finally it’s treatment time… Product… rate… and costs. Here are some comparisons. Rates may vary so be sure to check the label.

Efficacy of Fungicides for Wheat Disease Control and Their Relative Cost Per Acre
Product Rate/A Powdery Mildew Stagnospora leaf/glume blotch Septoria leaf blotch Tan spot Leaf rust Head scab Cost per acre
*The greater the number of + signs, the greater the relative efficacy
**(+) indicates greater efficacy at higher application rates.
Sources Kansas State, Kentucky State. Adapted by Del Voight for PA use.
Tilt 3.6EC 4 fl oz +++* +++ +++ +++ +++ + 7.78
PropiMax 3.6EC 4 fl oz +++ +++ +++ +++ +++ + 9.21
Quadris 2.08SC 6.2 (to 9.0) fl oz +(+)** +++ +++ ++++ ++++   12.59–21.94
Quilt 200SC 14 fl oz +++ +++ +++ +++ +++   13.125
Stratego 250EC 10 fl oz ++ +++ +++ +++ ++   12.5
Headline 2.09EC 6.0 (to 9.0) fl oz ++ +++ +++ ++++ ++++   11.72–17.57
Proline 480 4.3 to 5.7 fl oz per acre +++ +++ +++ ++ ++ +++ 75% head emergence 9.9–13.13
Caramba   +++ +++ +++ +++ +++ ++ ?

The Kentucky Decision Guide for Multiple Leaf Diseases can be another useful resource. Leaf diseases, like insect pests, weeds, and root diseases, usually occur as mixtures that must be monitored simultaneously and are ideally controlled by a single treatment or no more than two treatments. The Kentucky Decision guide (reproduced in this box, reprinted from R. E. Stuckey and D. E. Hershman, 1988, University of Kentucky, College of Agriculture, Cooperative Extension Service Bulletin PPA-36) illustrates one approach to monitoring and treating a combination of three leaf disease: Septoria tritici leaf blotch, powdery mildew, and leaf rust.

The guide takes into account the following factors:

  1. Disease development from early jointing (Feeks stage 6) through the milk stage (Feekes 11.1), with the greatest emphasis (weight) given to disease on plants between early boot (Feekes 9 or 10) and flowering (Feeks 10.5),
  2. Whether Septoria tritici leaf blotch and powdery mildew have progressed to the youngest one or two leaves or are limited to the older, less important leaves,
  3. The percentage of leaf area affected by leaf rust,
  4. The susceptibility of the variety to one or more of these diseases,
  5. The yield potential of the variety, with greater weight given to higher yield potentials,
  6. The rate of nitrogen applied and hence the density of the crop canopy, with greater weight given to higher rates of nitrogen, and
  7. The temperature and moisture during the past 2 weeks and as forecast for the following week.

References to particular fungicides in the Kentucky Decision Guide are based on those available and registered for use when the guide was proposed. Check the labels and consult your local office of the Cooperative Extension Services for current information on fungicides for use on wheat.

Workers at the University of Kentucky and at the Wageningen Agricultural Research Station, in the Netherlands, compared the Kentucky Decision Guide with the EPIPRE method, developed in the Netherlands, and with regularly scheduled fungicide applications, the traditional approach used in northern Europe. In the Netherlands, yields of winter wheat were highest with the traditional method of intensive fungicide application, second highest with treatment according to the Kentucky Decision Guide, third highest with treatment according to EPIPRE, and lowest with no fungicide. The economic returns, on the other hand, were greatest with treatment according to the Kentucky Decision Guide (in the trials with the second highest yields) and lower with treatment according to EPIPRE, the traditional intensive schedule (in the trials with the highest yields), and no treatment, in descending order. In Kentucky, actual yields and economic returns both were greatest with treatment according to the Kentucky Decision Guide and lower with treatment according to EPIPRE, the traditional intensive schedule, and no treatment, in descending order.

These results indicate the value of fine-tuning existing guides and the need for new and better guides to increase the efficiency of fungicide usage and economic returns. More research is needed in this important area of plant health management.

Should I Be “Mudding in” My Corn? — Jeff Graybill, CCA Lancaster County Extension

The recent wet weather has been a challenge for all farmers. Whether making rylage, planting corn or even applying herbicides, we’re tempted to wade into the field earlier than we otherwise might. When is it too wet? What penalty will I pay later for planting into wet soil?

One guide for too wet soil is when you can easily make a ball with a handful of soil from the top 2 inches. If the ball falls apart/shatters easily between two fingers, then soil is marginal. If the ball can be handled, and behaves more like clay than soil, it is too wet. Also, in conventionally-tilled fields, excessively wet soil will accumulate on depth and/or closing wheels. However, in no-till with good cover we can easily be compacting the seed zone without soil accumulating on equipment.

No-tillers: if the seed trench is not closing well and you are tempted to put additional tension on the closing wheels—even thought the soil is wet and pliable then you are probably causing serious sidewall compaction. Should a wet spring lead into a dry June, normal root penetration and growth will be greatly restricted. My feeling is that a lot of sidewall compaction goes undiagnosed in the form of slowed plant growth (Paint brush roots) and reduced drought tolerance, resulting in reduced standability and yields for serious violators.

What can I do? Correct decisions require one to weigh the options and have good information. What are the negatives of delayed planting? Looking in the Penn State Agronomy Guide, we see some excellent advice and information. “Mudding in” corn can have immediate negative effects on stands and emergence. Late planting delays harvest, slows drydown and we start to lose about a bushel per day after May 10th. However, Table 1.4-8A in the Agronomy Guide shows us that planting and obtaining a stand of 30,000 ppa on May 19th will still return 91% of your expected yield; by May 24th this drops to 86%. Clearly, uniform stands can return very high yields up through most of May. So, when in doubt get off the planter, squeeze some soil, evaluate and examine the seed trench—there is still time to do it correctly. We don’t want to make a bad situation worse.

What about switching to a shorter season hybrid? It will depend upon your situation and the RM of your hybrids. Grain growers would naturally consider this before silage farmers. Here is a quote from the Agronomy Guide. “In most areas, switching to shorter than adapted hybrid maturities should not be considered until at the least the last week of May.”

Haylage Production: Understanding the Process and Potential Benefit of Wide Swathing — Craig Atlemose, Centre County Extension

Some farms are mowing forage in a wide swath (WS) without crimping versus the conventional narrow swath (NS) with crimping. Wide swathing is mowing and laying down a swath of forage that is at least 80% of the mower width. This increases the area that sun and air can get to and speeds up drying. There are no conditioners on these mowers. This allows for faster removal of plant moisture through the stomata in the leaves. The goal under good drying conditions is to mow in mid morning and have it wilted to around 65% moisture and be able to chop it late afternoon for storage as haylage.

In research done by Cornell Cooperative Extension found that during wide swathing 30% of the water in grass stems and 35% of the water in alfalfa stems can be removed by transpiration through the stomata before they close. Sunlight keeps the stomata open and the WS gets three times more sunlight than the forage in a NS. A NS is 5.5 times denser than a WS and it can take up to 100 times longer for the soil surface under it to dry. That slows drying of the forage. The humidity in the NS stayed at 95% throughout the first day after mowing while it dropped in the WS from 90% to 40%. Under good drying conditions, alfalfa dried to 65% moisture in four hours while grass took two hours. BMR Sorghum Sudan grass in a WS was at 65% moisture in three hours while NS took three days to dry to 65% moisture and tested high for butyric acid.

The more exposure to the sun the forage has during wilting reduces drying time and energy losses due to respiration. Forage in a NS has less exposure to sun then in a WS, does not dry as fast and continues respiration using up energy. The energy lost is the most digestible part of the forage sugars and starches. Cornell’s research showed dry matter (DM) energy losses of sugars and starches during wilting to be 17% in NS alfalfa and grass haylage. While WS alfalfa and grass haylage showed a DM energy loss of 5% for sugars and a 4% gain in starches during wilting. In first and second cut alfalfa and second cut grass net energy for lactation (Nel) increased by 3% in WS and decreased by 7% in NS during wilting. The increase in Nel in WS per ton of DM yield accounts for a potential increase of 300 lbs in milk production per ton of DM haylage. In today’s milk market, that increases the haylage value by $30 per ton. On an average dairy farm in NY with 275 acres of haylage yielding 3 tons of DM, that equals an increase of $24,750 to the bottom line per year. Their research also showed significantly better fermentation in WS haylage versus NS.

Contributors: State Specialists: John Tooker, Sjoerd Duiker, Bill Curran, Dwight Lingenfelter, Ron Hoover, Del Voight; Extension Educators: Paul Craig (Dauphin), Kevin Fry (Armstrong), Mena Hautau (Berks), Jeff Graybill (Lancaster), Dave Messersmith (Wayne), John Rowehl (York), Susan Alexander (Jefferson), H. Grant Troup (Lebanon), Mark Madden (Sullivan)

Editor: Mark Madden

Upcoming Events

Real time pest and heat unit activity: http://agsci.psu.edu/news/spotlight/pa-pipe

Calendar of Events: http://www.events.psu.edu/cgi-bin/cal/webevent.cgi?cmd=opencal&cal=cal209&

If you have any questions or would like to suggest a topic, please contact your local Extension Educator.

Readers can subscribe electronically to this newsletter at the Field Crop News Web site.

If you have problems subscribing or wish to cancel your subscription, please contact Lisa Crytser by e-mail at lac8@psu.edu or by phone at 814-865-2543.

Information presented above and where trade names are used, they are supplied with the understanding that no discrimination is intended and no endorsement by Penn State Extension is implied.

This publication is available in alternative media upon request.

The Pennsylvania State University is committed to the policy that all persons shall have equal access to programs, facilities, admission, and employment without regard to personal characteristics not related to ability, performance, or qualifications as determined by University policy or by state or federal authorities. It is the policy of the University to maintain an academic and work environment free of discrimination, including harassment. The Pennsylvania State University prohibits discrimination and harassment against any person because of age, ancestry, color, disability or handicap, national origin, race, religious creed, sex, sexual orientation, or veteran status. Discrimination or harassment against faculty, staff, or students will not be tolerated at The Pennsylvania State University. Direct all inquiries regarding the nondiscrimination policy to the Affirmative Action Director, The Pennsylvania State University, 328 Boucke Building, University Park, PA 16802-5901, Tel 814-865-4700/V, 814-863-1150/TTY.