CMEG Crop Management Extension Group

Field Crop News

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

June 27, 2006    Vol. 06:10

IN THIS ISSUE:

Dates to Remember

Agronomic Weed and Plant Disease Management Research Tour — July 11. See article below for additional information.

2006 Penn State Agronomic Field Diagnostic Clinic — July 18 and 20. Visit our website at http://cropsoil.psu.edu/extension/clinic.htm for more information.

For Additional CMEG Activities, Please Visit the Calendar of Events: http://www.events.psu.edu/cgi-bin/cal/webevent.cgi?cmd=opencal&cal=cal209&

Register Now for the Rock Springs Agronomy Weed and Plant Disease Tour — July 11, 2006

Attend the Annual Agronomic Weed and Plant Disease Management Research Tour at Penn State — July 11, 2006 at the PSU Agronomy Research Farm, Rock Springs, PA (Meet at the Agronomy Farm, Rock Springs, Rt. 45 west of State College). A number of experiments will be showcased and available for viewing including new corn, soybean, pumpkin, and snapbean herbicides plus the latest information on herbicide resistance, and cover cropping and weed management research. Also hear an update on the latest crop disease developments including soybean rust and white mold from this year’s wheat disease research. Pest Management CCA CEU’s will be available.

Agenda:
8:30 — 9:00 am — Registration
9:00 am —12:00 noon — Tour
12:00 noon — 1:00 pm — Catered lunch

Registration for this event will be $15.00 and includes lunch and a tour book. Please pre-register by Friday, July 7 with Lisa Crytser by phone (814-865-2543), fax (814-863-7043), email lac8@psu.edu, so we can accommodate luncheon needs.

Weather Outlook — Paul Knight, PA State Climatologist

After a very moist period, the tropical showers will finally diminish and end in the eastern half of Pennsylvania on Wednesday, but not until after another couple of inches of rainfall earlier in the day. Partial sunshine in the west will lead to scattered afternoon thunderstorms. Thursday will bring somewhat less humid conditions along with only scattered thundershowers, mainly in the afternoon and in the northern half of the state. Much of Friday and Saturday will be dry and turning warmer on Saturday. A surge of humid air will trigger thunderstorms from late day Saturday into the morning Sunday, though showers may persist in southern sections. A few more storms are likely on Monday as less humid air arrives. At this point, the Fourth of July looks dry and seasonably warm. In the period from Thursday through next Tuesday, most sections will receive between 0.30 and 1.00 inches of rain.

Soybean Development and Management Issues — Greg Roth, Grain Crop Management Specialist

Our soybean crop has been struggling a bit with numerous issues associated with alternating dry, wet, cool and hot conditions. Development has been lagging in some fields but is recovering well with recent rains. Crusting, seed depth issues, seed corn maggot, and seedling blights have been contributing to some less than ideal emergence and some replanting. We are monitoring emergence rates at the research farm and across the state to assess the potential for cutting back on seeding rate recommendations. Our preliminary data is showing a 65—80% range on emergence rates that suggest reducing seeding rates might not be a good general recommendation unless you have a history of good emergence. Insect pests appear to continue to be an issue with soybeans as leafhoppers and grasshoppers are being reported in many areas. Leafhoppers could be a problem in fields adjacent to harvested alfalfa. Thresholds and treatment options for both these pests can be found in the Agronomy Guide http://agguide.agronomy.psu.edu/PDF03/table2-4-20.pdf As the days shorten following the summer solstice, soybeans will soon begin to flower. Monitoring growth stages will soon become important for timing any fungicide applications planned during the reproductive stages. A flower at any node represents R1; a flower immediately below the node with a completely unrolled leaf signifies the crop has reached R2. For more details on staging soybeans review our previous article on this topic at http://fcn.agronomy.psu.edu/2004/FCN0408.html#determination.

Weed Competition in Soybean — Bill Curran, Weed Management Specialist

With the recent wet weather, unsprayed soybean fields are becoming more visible across the landscape. In general, soybeans are fairly resilient compared with corn to weed competition and can tolerate early season weeds for a few weeks. However, no—till soybeans that did not receive a burndown application are at greatest risk (we recommend always starting clean (with tillage or herbicide) to ensure the greatest yield potential). Assuming you start clean, in general it is important to remove weeds by 5 to 7 weeks after soybean planting. We conducted an experiment at Rock Springs in 2003 looking at weed competition in no—till soybeans. In this trial, we included glyphosate applied at planting time (0 weeks), and at one, two, three, and four weeks after planting. In addition, we included a no herbicide treatment, a sequential application which would be a more recommended practice (0 weeks followed by (fb) 5 weeks after planting) and a glyphosate plus residual herbicide applied 1 week after planting. In this study, soybeans were planted on May 22 in 7 inch rows. Weed severity in this study was intense with common ragweed being the dominant species. A single application of glyphosate produced a minimum of a 27% yield loss and up to 52% when applied at soybean planting time with nothing following in crop (Table 1). The glyphosate plus residual treatment was not very effective in this study because the residual herbicide did not effectively control the ragweed. In the end, weed density and severity will be the determining factor on how herbicide application timing impacts yield. So, even when starting clean, control weeds by 5 weeks after planting in moderately infested fields and by 7 weeks after planting with lighter infestations. Also, remember that small seedling weeds are easier to control and that higher herbicide rates and/or combinations of herbicides may be necessary for larger weeds. Later applications can also help select for resistant weeds.

What Is Your Soil Erosion Grade? — Dave Messersmith, Extension Educator, Wayne County and Sjoerd Duiker, Soil Management Specialist

Recent heavy rains across the Commonwealth give us an opportunity to look for signs of soil erosion in our fields and evaluate our soil conservation practices.

Some common signs of water erosion are:
1. Small rills and channels on the soil surface.
2. Soil deposited in low areas of fields.
3. Sediment in nearby streams and ponds.
4. Pedestals of soil supporting small stones and pieces of plant debris (erosion washed away the surrounding soil).

Use Table 1 to evaluate erosion in fields from recent rain events. Give yourself a grade from ‘best’ to ‘poor’ based on your field observations.

Sufficient amounts of crop residue left on the soil surface can almost eliminate erosion on many fields and greatly reduce erosion on other fields. Residue (and crop canopy) reduces soil detachment by absorbing the impact of falling raindrops. Also, residue may form small dams which slow runoff and create puddles of water that can absorb raindrop energy, thus reducing both detachment and transport of soil particles. You may wonder how much residue cover is enough. It is generally accepted that 30% residue cover immediately after planting is offers significant protection from water erosion. However, it is now becoming clear that more crop residue cover throughout the year is desirable. Farmers, extensionists and researchers are experimenting with different methods to manage heavy cover crops to guarantee higher amounts of mulch for erosion control and other purposes.

Crop—residue management through no—till is one of the best and most cost—effective ways to reduce soil erosion. Conservation tillage and residue management may reduce machinery expenses and save soil, labor, fuel and money. Crop residues uniformly distributed over the soil surface will significantly reduce soil losses over an entire field. Concentrated flow can still be a problem, even in long—term no—till. Where this is the case, the source of concentrated flow needs to be detected and addressed. This may mean a grassed waterway, terrace or diversion may need to be installed.

The Beauties and Horrors of No—Till — Sjoerd Duiker, Soil Management Specialist

Two weeks ago I finished the crop residue survey in Centre County that showed a dramatic increase in no—till in the County compared to the 2004 survey. The survey also enabled me to observe successes and failures with the different tillage systems that I promised to show this week.

First, let me show a few pictures of tillage and its effects. Here is a picture http://fcn.agronomy.psu.edu/images/duiker0609image1.jpg of a bare field that shows us the clay knobs where we can expect poor stands and low crop yield. Tilled fields can also show poor stands http://fcn.agronomy.psu.edu/images/duiker0609image2.jpg and uneven emergence http://fcn.agronomy.psu.edu/images/duiker0609image3.jpg. It is also not uncommon to see stand gaps in conventionally tilled fields http://fcn.agronomy.psu.edu/images/duiker0609image4.jpg. But enough about tillage ....

Many imperfections in no-till are due to management, because we saw some beautiful no-till corn stands in different residue conditions, such as in soybean stubble and poultry litter http://fcn.agronomy.psu.edu/images/duiker0609image5.jpg, and an old sod http://fcn.agronomy.psu.edu/images/duiker0609image6.jpg. However, many problems also were observed, such as corn planted without proper burndown weed control http://fcn.agronomy.psu.edu/images/duiker0609image7.jpg or incompletely killed alfalfa http://fcn.agronomy.psu.edu/images/duiker0609image8.jpg. Unfortunately, poor weed control seemed to be more the rule than the exception in no-till soybeans http://fcn.agronomy.psu.edu/images/duiker0609image9.jpg. Of course, these situations are completely unnecessary with due attention to accepted weed control practices.

We also saw the results of poor residue distribution, such as no corn in soybean residue piles http://fcn.agronomy.psu.edu/images/duiker0609image10.jpg, or swaths of corn stalks intermixed with bare swaths http://fcn.agronomy.psu.edu/images/duiker0609image11.jpg. These problems should have been addressed at harvest of the previous crop by having a residue spreader on the combine. We also saw zero residue cover in no—till corn after corn silage (no picture shown here).

Planting issues were very common, such as hair-pinning (no picture shown), as well as the lack of planter penetration, which was quite common in corn planted into a sod http://fcn.agronomy.psu.edu/images/duiker0609image12.jpg or just in any no-till where you don’t pay attention to these things http://fcn.agronomy.psu.edu/images/duiker0609image13.jpg. Some of these poor stands may also be due to a combination of factors, such as an attack by insects or diseases in combination with the previously mentioned factors.

There are more tribulations to show, but the bottom line is that we saw success and failure both with no—till or tillage side—by—side. This suggests that the devil is in the details of management and that success with no—till is definitely achievable. We encourage all producers therefore to take advantage of no—till training opportunities that are offered throughout the Commonwealth.

POST Herbicide Application Restrictions for Corn — Dwight Lingenfelter, Crop & Soil Sciences

With the weird weather patterns that have been occurring during the past few weeks, corn fields are at varying heights and post herbicides are still being applied to certain stands. When applying post herbicides keep in mind application restrictions for both corn height (or growth stage) and weed size. Remember that post applications of atrazine or atrazine containing products (e.g., Steadfast ATZ, Basis Gold, Liberty ATZ, Buctril+atrazine) are limited to corn that is no more than 12 inches tall. Other products such as Accent, Distinct, Exceed, Hornet, NorthStar, and Steadfast, can be applied over-the-top to corn that is up to 20 inches tall. Callisto, Clarity, glyphosate (on RR corn hybrids only), Permit, Yukon, and a few others allow for broadcast application over taller corn (e.g., 30 inches or so depending on the product). However, as the corn gets larger, it may be necessary to use drop nozzles for better spray coverage under the corn canopy and for reducing potential crop injury from certain herbicides. Even with the use of drop nozzles, some products restrict application to corn that is no more than 30 to 36 inches tall. Also, post herbicides are most effective on small annual weeds (less than 6 inches tall) and on perennials during the bud to bloom stage. For a listing of post corn herbicides and details on their application restrictions see Table 2.2-14 in the Penn State Agronomy Guide or online at http://agguide.agronomy.psu.edu/pm/sec2/table2-2-14.cfm

Effects of Wet Weather on the Wheat Crop — Erick DeWolf, Field Crop Plant Pathologist

Growth stage reports from around the state indicate that PA wheat crop has matured; however, the recent rains have delayed harvest in most parts of the state. These periods of wet weather have promoted the development of a condition called sooty mold in many fields. Symptoms of sooty mold include gray or black mold growth on the surface of a mature wheat spike, leaves and straw. This discoloration of the chaff and leaves is becoming pronounced in many fields. I have seen some fields with small sections of wheat that as died prematurely as a result of take—all become completely black.

Sooty mold is caused by fungi that make their living by decomposing dead plant tissue, and the condition is very common condition in wheats grown east of the Mississippi. However, in most cases sooty mold does not result in significant reductions of grain yield or quality, but it will make harvest a dirty operation. In some situations these sooty molds can cause a condition called black point characterized by a brown discoloration of the embryo end of the kernels. I do not expect a serious problem with black point but it is something to be watching for given or present weather pattern.

Perhaps the biggest threat of this wet weather is the potential direct effects of frequent rain on grain quality. When the grain is wet it may begin to undergo enzyme activities that convert the starch into the sugars needed for germination. This process often results in lower test weight and reductions in other aspects of grain quality. Clearly, little can be done to change the situation at this point. Just be ready to harvest as soon as conditions allow to minimize any additional weathering of the grain and straw.

Contributors: University Park Faculty/Staff: Marvin Hall, Erick DeWolf, Sjoerd Duiker, Greg Roth, Bill Curran, Paul Knight and Dwight Lingenfelter. Extension Educators: Kevin Fry (Armstrong), Andrew Frankenfield (Montgomery), Dave Messersmith (Wayne), Mena Hautau (Berks), Paul Craig (Dauphin) and Dwane Miller (Schuylkill).

Editor:Dave Messersmith, Penn State Extension, Wayne County

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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