CMEG Crop Management Extension Group

Field Crop News

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

July 18, 2007    Vol. 07:20

IN THIS ISSUE:

Register Today!–––2007 Penn State Agronomic Field Diagnostic Clinic – July 24 and 25

The Diagnostic Clinic is next week! Register today to avoid the late fee. The cost is $45 if registered before July 19 and credit card payments are accepted. (This initial deadline has been relaxed a couple days.) Registration fees after the July 19 deadline will be $65. To register call Lisa Crytser at 814–865–2543 or visit our website http://cropsoil.psu.edu/extension/clinic.cfm for additional details. As in the past, the Clinic is a one—day event conducted at the Penn State Agronomy Research Farm near Rock Springs, PA. This year’s Clinic will be held on Tuesday, July 24 and then repeated on Wednesday, July 25, 2007. The topics include cover crop selection and management, no—till planter adjustments and attachments for use in cover crops, an overview of biomass crops for alternative energy use, nitrogen management issues, and secondary pest management topics. As always, various CCA, pesticide applicator, and nutrient management credits will be offered.

For additional information or comments about the Diagnostic Clinic contact Dwight Lingenfelter at (814) 865-2242 or by email, DwightL@psu.edu.

Weather Outlook — Bill Syrett, Weather Observatory Manager

High humidity and moderate warmth are in store for Pennsylvania into Thursday night. Significant cloudiness will preclude widespread hot weather, but with the humidity will come ample opportunities for rain. Although much of the state should see some rain, with patches of heavy rain possible (exceeding 2 inches), there will also be areas that receive little, as is often the case with summertime convection. Much cooler and drier air will move in Friday and stay through the weekend. By midweek next week, temperatures should increase to above normal, and there are indications that hot weather, with limited opportunities for rain will dominate Pennsylvania for much of the following week.

Week One (July 18 — July 24): It will soon become and then stay very sticky and warm across the state on Wednesday and Thursday, as a warm front passes through Pennsylvania late tonight into Wednesday. Thunderstorms should develop in the western counties overnight and move eastward through Wednesday morning. Some storms will produce over an inch of rain with western and north—central counties most likely to see the heaviest rain and the southeast least likely to see thunderstorms overnight into Wednesday morning. Although much of the time from Wednesday morning through Thursday noon should be dry, most areas should see one or two showers during that period. More widespread thunderstorms will develop across northwestern Pennsylvania Thursday afternoon as a cold front approaches, and some will produce hail and high winds, especially across the western counties. The front and its accompanying storms will move southeast and exit the state by late Friday morning. Cooler than normal weather will then extend through the weekend and through the rest of Week One. Widespread precipitation will be unlikely, although scattered afternoon thunderstorms (less than 30% coverage) may develop Sunday through Tuesday.

Week Two (July 25 — July 31): There are indications that the pattern may shift to one favoring hotter and drier conditions for much of Week Two. Near—normal temperatures next Wednesday should be replaced by progressively hotter weather with limited opportunities for much more than isolated, mainly afternoon thunderstorms.

Check out the predicted Growing Degree Days (base 55) for Pennsylvania for the next two weeks at: http://climate.met.psu.edu/data/regional_gdd.php

Market Outlook — Tom Murphy, Extension Educator, Lycoming County

If you’re planning to sell hogs to China right now, you bet right! If it was grain, you’re missing the mark. Corn was down limit Monday with the recent rain and cooler weather in many parts of the western and eastern corn belts. Pollination is now occurring in most parts of the corn belts, so the weather is what it is all about at the moment. Although there are still some very dry and hot areas in the upper Iowa, Nebraska, and Minnesota grain areas, large areas of the western corn belt are getting moderate to heavy rain. Beyond that, news is mixed. Exports are running ahead of projections from USDA although big purchases from China aren’t happening. Industry speculation is that with weather improving for the U.S. corn crop, Chinese buyers are thinking they still have time to wait on expectations of a better price. Ethanol use continues to increase with California the latest state to indicate they will require more ethanol in their fuel in the near future. I saw an oil industry report yesterday indicating the long—term need for biofuels would have to make big strides ahead due to large increases in worldwide energy needs and decreasing oil and gas to fill the gap. Although that might seem somewhat obvious to many, it’s interesting to hear the oil industry becoming stronger advocates of biofuels.

Soybeans were down the limit on Monday as well with news of favorable weather in most of the main U.S. growing areas. The latest USDA report showed expected bean carryover to be off 20 million bushels but this seems to be largely discounted by industry. With corn it’s pollination in July, and with beans it’s August weather, so we wait to see. On the international level, palm oil took a big hit yesterday and that had a big influence on the soy market here. More and more, it is a global market that is very interconnected on many commodities. And as we broaden the move of agriculture into energy production, this linkage is going to be even more important for those marketing grain to understand. Bottom line is to develop a good grain marketing plan, make sure your partner(s) understand it, stay informed of current market forces, and sell when you have a profitable moment. You may not always hit the peak, but you will increase the odds of profiting from your efforts.

Locally in most parts of PA and many of the surrounding states, we continue to be very dry with the crop yield being impacted. Beans are short in most areas of the state, corn is erratic in height and will be pollinating over a longer window in many fields which could affect yield and dry down in the fall. Hay prices will likely continue to rise which will help those with some to sell. If you need forage, you may want to lock in some supply now, as there are expectations of tightening supplies this winter. And if you buy large amounts of propane for ag. use, keep an eye on where the price is at the moment.

Monitor Soybean Fields Now for Weed Escapes — Bill Curran, PSU Weed Specialist

It’s time to scout those soybean fields and assess your weed control success. I have heard a number of recent reports of poor weed control and weed escapes around the state and region. This can occur for a number of reasons including application errors, herbicide resistance or tolerance, or problems with the weather at or following application (i.e. rainfall too soon after spraying, drought conditions, etc.). We identified glyphosate resistant horseweed or marestail in southeastern Pennsylvania a few years ago and I have observed abundant horseweed along field margins, roadsides, and elsewhere this year even in the central part of the state. Hopefully, most of this isn’t resistant, but this is the time of year that resistant or tolerant weeds like horseweed can push up through the soybean canopy and continue to cause problems. Last year we had several reports of lambsquarters surviving post glyphosate applications and glyphosate resistant common and giant ragweed have been identified in states to our west. ALS resistance is a concern in all these species, so simply adding FirstRate, Classic, or other ALS chemistry to the spray mix may not solve the problem. Finally, also assess the success of perennial weed control tactics for pokeweed and other problem perennials to determine whether additional efforts are still necessary.

When resistance isn’t the culprit (which is usually the case), several factors are often present when we see these control failures; 1.) We are spraying annual weeds after they are too big (less than 6 inches tall is best), 2.) Poor spray coverage is occurring because of low spray volume, inappropriate tips and/or low boom height; 3.) Herbicide rates and/or adjuvant selection is incorrect for the product(s) or weeds present. It often requires some detective work to root out the cause of a weed control failure, and the sooner you investigate after application the better, while perhaps there is still time to rescue the situation.

Drought Stress in Corn Moves to the Next Level — Greg Roth, Grain Production Specialist

Drought stress has continued in many areas since last week and many corn crops are showing signs of moderate to severe stress. Many fields are beginning to pollinate, so the drought stress is coming at the worst time for the corn crop. Drought stress symptoms in the crop are becoming more evident. These include delayed silk emergence, yellowing of lower leaves, shortened internodes, uneven height and tasselling and some of the worst areas are beginning to take on the grayish cast of severely stunted corn. Yield losses from severe leaf rolling are estimated to be 3 to 8% per day through the silking stage, and these can be increased if other stress factors, like weeds or nutrient deficiencies, are present.

Generally, it is not advisable to consider harvesting immature drought stunted corn for silage. The forage is lower in energy, generally high in moisture, and low yielding. If the corn has tasseled and leaves cease to unroll at night and the tops start to brown out, the plants are probably not going to recover. As browning of the crop continues, the forage quality will decline as the plants are using stored carbohydrates in the leaves and stalk to sustain themselves. If half the leaves were dead or dying it would be a good candidate for evaluating for silage harvest.

Now is a good time to be planning for feed inventories. For silage growers, it might be advisable to be trying to secure some other acres for silage harvest. Price is always an issue on corn silage and the drought and volatile grain prices will make it more challenging this year. One resource is the Feed Price List maintained by Virginia Ishler in the Department of Dairy and Animal Science: http://www.das.psu.edu/pdf/feedprices.pdf. These are based on local forage and grain prices and anticipated feed value and are a starting point for assessing the value of silage. Others considerations are the harvesting and storage costs and the value of an alternative use of the crop, i.e. grain harvest.

Planning for emergency forages is another issue, as is documenting losses for crop insurance purposes. These will likely be covered in subsequent articles, but are things to be thinking about. More details on managing drought stunted corn are on our webpage at: http://cornandsoybeans.psu.edu/droughtstressmanagement.cfm

Drought stress is not a fun part of crop production, but with some planning and management, some of the economic impacts can be minimized.

Plan now for late summer cover crop establishment — Bill Curran, PSU Weed Specialist

Now is the time to consider what your cover crop needs and options are as we approach late July and early August. Establishing a cover crop after wheat, barley or oat harvest is especially attractive as it allows numerous options for species selection and establishment. Below are some brief comments about some of our more common cover crops that can typically follow a small grain. Seed costs are only estimates and will differ depending on cultivar and source.

Legumes

Crimson clover
Advantages:
Rapid growth and above—average shade tolerance; can be used as a forage (no bloat); good nematode resistance.
Disadvantages:
Poor heat and drought tolerance; no—till planting into residue more difficult due to stemminess; does not consistently overwinter in Central PA.
Management:
Seed at 18 to 20 lb per acre during August. Be sure to inoculate seed. Seed cost averages $1.00 to 1.50/lb.

Hairy vetch
Advantages:
Most cold tolerant and highest yielding of all winter annual legumes with above average drought tolerance; adapted to a wide range of soil types.
Disadvantages:
Requires early fall establishment, and slow to establish generally providing little winter cover; matures in late spring; high P and K requirement for maximum growth; potential weed problem in winter grains; winter hardiness and maturity differ depending on cultivar.
Management:
Seed at 20 to 40 lb per acre (less in companion seedings with oats or rye) from mid August to mid September. Be sure to inoculate seed. Seed cost averages $1.50 to 2.50/lb.

Red clover
Advantages:
Thick, deep taproot; adapted to humid areas; tolerates wet soil conditions and shade; possible forage use if mixed with grasses.
Disadvantages:
Initial growth slow; high P and K requirements for maximum growth; seed can persist creating volunteer problems; pure stand forage causes bloat; vulnerable to several pathogens and insects.
Management:
Seed at 7 to 18 lb per acre in mid to late August. Be sure to inoculate seed. Seed cost averages $1.50 to 3.00/lb.

White clover
Advantages:
Adapted to most temperate zones; good heat, flood, drought and shade tolerance; low—maintenance and tolerates high traffic; good forage use with grasses.
Disadvantages:
Poor growth during hot—dry weather; requires good nutrient management; susceptible to several diseases and insect pests.
Management:
Seed at 6 to 14 lb per acre during August. Be sure to inoculate seed. Seed cost averages $2.00 to 4.50/lb.

Field Pea
Advantages:
Rapid growth in cool weather; used as food or feed; competitive with weeds in mixture with grasses.
Disadvantages:
Austrian winter pea will not overwinter north of Maryland; shallow root system; sensitive to heat and humidity; susceptible to diseases and insect pests.
Management:
Seed at 70 to 220 lb per acre during August. Be sure to inoculate seed. Seed cost averages $0.50 to 1.00/lb.

Grasses

Annual rye grass
Advantages:
Rapid establishment and can also be used as forage.
Disadvantages
Not as winter hardy as cereal rye or wheat; can be a weed problem in winter grains.
Management:
Seed at 15 to 30 lb per acre (less in mixtures) by early October. Seed cost averages $0.50 to 1.00/lb.

Cereal Rye
Advantages:
Most cold tolerant of the commonly used cereal cover crops; later establishment possible; rapid establishment and growth with good winter cover; tolerates poor soil conditions and drought; relatively inexpensive to establish.
Disadvantages:
Must be timely managed in the spring due to rapid aggressive growth.
Management:
Seed at 60 to 180 lb (1 to 3 bu) per acre by mid October. Seed cost averages $7.00 to 12.00/bu.

Spring Oats
Advantages:
Rapid growth in cool weather; ideal for quick fall—cover or nurse crop with legumes; winterkills; relatively inexpensive to establish.
Disadvantages:
Early fall establishment necessary; susceptible to diseases and insect pests; winter kills.
Management:
Seed at 100 lb (3 bu) per acre by September 1. Seed cost averages $3.85 to 5.00/bu.

Sorghum sudangrass
Advantages:
Rapid establishment and competitive crop; drought and heat tolerant; possible forage use.
Disadvantages:
Summer annual cover crop that will not overwinter; poor growth under cool conditions. Management:
Seed at 30 to 50 lb per acre by September 1. Seed cost averages $0.25 to 0.75/lb.

Other

Buckwheat
Advantages:
Grows on a wide variety of soils (infertile, poorly tilled, low pH); rapid growth; quick smother crop and good soil conditioner.
Disadvantages:
Limited growing season; frost sensitive; doesn’t tolerate heat and drought.
Management:
Seed at 50 to 100 lb (1 to 2 bu) per acre by September 1. Seed cost averages $15.00 to 40.00/bu.

Brassicas
Advantages:
Quick establishment in cool weather; withstands light frost but winter kills unless winter hardy variety; deep, thick root systems; drought tolerant; highly digestible forage crop; may help insect and weed management.
Disadvantages:
Low tolerance to wet soils; potential bloat problems (mix with 25% grass); “weed” problem if allowed to set seed; may winter kill.
Management:
Seed at 5 to 12 lb per acre by September 1. Seed costs vary by species and cultivar but average $2.00 to 4:00/lb.

Soybean Insect Defoliation Assessment — Del Voight, Extension Educator, Lebanon County

The full article can be found at http://ohioline.osu.edu/icm-fact/fc-22.html.

Identification & Distribution

A complex of insect pests attack soybean foliage from emergence to harvest. This insect pest complex includes (1) the bean leaf beetle, (2) the Mexican bean beetle, (3) the Japanese beetle, (4) the redheaded flea beetle, (5) grasshoppers, and (6) the green cloverworm.

The bean leaf beetle is a chrysomelid leaf beetle that varies in color from golden brown to green, generally has 4 black spots on the wing covers, and always has a black triangle on the scutellum (area centrally behind the thorax). The larvae develop below ground on the root system. This pest is distributed statewide in Ohio.

The Mexican bean beetle is a coccinelid beetle (i.e. the lady bug family). The adult is a gold color and rather oval shaped beetle having 16 black spots on the wing covers. The larvae have conspicuous spines and when fully grown measure approximately 1/2 inch in length. Although distributed throughout the state, this pest has been predominantly a pest in the southern and east central regions of Ohio.

The Japanese beetle is a scarab beetle. This bright metallic green and bronze beetle measures nearly ½ inch in length. The larvae is a typical grub similar but smaller than the grubs of June beetles. This pest is primarily a problem in areas other than the northwestern regions with the exception of the area bordering Lake Erie.

The redheaded flea beetle is a leaf beetle with developed hind legs and measures almost a ¼ inch in length (thus, larger than most flea beetles. The entire beetle appears initially black, but close inspection will detect a dark red head coloration. This pest is widely distributed but seldom occurs in large numbers.

Grasshoppers affecting soybeans are primarily the differential grasshopper and the redlegged grasshopper. Economic activity of grasshoppers (both adult and nymphal stages) is generally higher in the western and northwestern regions of the state.

The green cloverworm is a migratory moth that enters the state each year from the south. The larvae are green in color having 2 thin white stripes along each side of the body. Full grown larvae may reach 1 to 1 ½ inches in length. This pest may appear anywhere in the state, but heavy infestations are sporadic and uncommon.

Field Symptoms

Insect defoliation assessment is based on the collective foliar damage by the entire pest complex at any one time. If a significant problem exists, generally one species is causing the most of the injury. Thus, it is important that the problem pest be identified and determined whether the casual agent is increasing or decreasing in activity. The following symptoms are characteristic of the individual pests.

Bean leaf beetles chew fairly small but clean cut holes in the foliage. Individual holes are seldom not more than ¼ inch in diameter, unless feeding is extensive. Redheaded flea beetle is very similar to bean leaf beetle injury.

Mexican bean beetles — both adults and larvae — cause a very skeletonized form of injury compared to that of the other defoliating insects.

Japanese beetle adults chew larger holes than the other beetles. In general, Japanese beetle damage is very concentrated in comparison to other insect feeding that is randomly dispersed.

Grasshopper injury is difficult to distinguish from bean leaf beetle or Japanese beetle injury. However, grasshopper injury tends to be more pronounced along the perimeters of fields near grassy alleyways, fence rows, and ditch banks.

Life Cycles

The bean leaf beetle has 2 generations per year and overwinters in the adult stage. Overwintering adults become active during the first warm weather of spring and move to soybeans as the crop emerges. By mid—June adult activity declines as immature egg, larvae, and pupae stages of the 1st generation develops below ground. First generation adults appear in July and defoliation activity resumes. A second generation develops and adults begin to emerge in September. As weather cools and soybeans are no longer available, the 2nd generation adults seek protected overwintering sites.

The Mexican bean beetle has 2 generations per year and overwinters in the adult stage. All stages develop on the foliage and both the larvae and adults may cause significant skeletonized defoliation. Adults of the 1st generation peak around early July and the 2nd generation appears in late August or early September.

The Japanese beetle passes through 1 generation per year and overwinters in the larval stage. Larvae pupate in the late spring and adults generally appear in June or early July. Eggs are laid in the soil which hatches into grubs that develop and remain as the overwintering stage.

The green cloverworm overwinters in the south. One or more generations may occur in Ohio depending on the time of migration and the climate. Peak larval activity may range from July to late August.

Grasshoppers overwinter in the egg stage in the soil. Eggs hatch in the spring and nymphs feed on grassy areas gradually moving into soybeans. As nymphs become adults, populations become more evenly dispersed. In the fall, eggs are deposited in the soil which becomes the overwintering stage.

Sampling and Assessment

During initial emergence of soybean plants, damage assessment is based on the potential for stand loss. To estimate stand loss, check 20 row feet of soybeans in at least 5 locations of the field and determine the percentage of plants cut or destroyed (significant defoliation is tolerable).

IF 20% of plants are cut and stand has gaps of one foot or more, or if at least one seedling per foot of row is destroyed, then rescue treatment is warranted.

After trifoliate leaves have formed, damage assessment is based on estimates of defoliation. To estimate defoliation, the following procedure is recommended:

  1. Pick a trifoliate leaf from the top, middle and low third of 10 randomly selected plants. (It is suggested that one carry a plastic bag for collection of foliage so that damage assessment may be made at one time.)
  2. From each trifoliate discard the most and least damaged leaflets. At this point one should have 30 leaflets upon which the defoliation estimate will be based.
  3. Compare the selected leaflets to the illustration provided in Figure 5 and record the average level of defoliation.

The action thresholds for determining the need for a rescue treatment varies with the stage of soybean development. Recommended action thresholds include the following:

If defoliation exceeds the action threshold at a given stage of soybean development, then a rescue treatment may be warranted if the pest causing the injury is present and vulnerable to treatment.

Sampling foliage and assessment of defoliation should always be accompanied by observations of the defoliating pest complex present. Preferably, the field observer should take a minimum of 30 sweeps with a standard insect sweep net. Soybeans are generally swept parallel to the rows (not across the rows). In the process, the dominant pests present and their predominant stage of development should be noted. Maintenance of sweep catch records will enable comparison from time to time to determine whether pest activity is increasing or decreasing.

Here are some points to keep in mind when using insecticides for beetle control —

For a list of suggested insecticides, rates and restrictions for soybean insect control follow the link to the PSU Agronomy Guide.

Upcoming Events

Ag Progress Days — August 14–16
http://apd.cas.psu.edu/

Contributors: Dept. Crop & Soil Science: Dwight Lingenfelter, Greg Roth, Ron Hoover, Bill Curran, and Marvin Hall. Extension Educators: Andrew Frankenfield (Montgomery), Kevin Fry (Armstrong), Jeff Graybill (Lancaster), Tom Murphy (Lycoming), Del Voight (Lebanon)

Editor: Kevin Fry

Upcoming Events

Real time pest and heat unit activity: http://psu.zedxinc.com/cgi-bin/site.cgi?location=2&user=psu#

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

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