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September 4, 1998 Vol. 98.12

IN THIS ISSUE:

Announcements:

AGRONOMY AG-SERVICE SCHOOLS SET

Ever wonder what the long-term outlook, benefits, and potential problems are for herbicide resistant crops? Need to know the latest in Nutrient Management and why phosphorus is now the big concern? Is leafhopper resistant alfalfa worth the extra cost for seed? The Agronomy Ag-Service Schools for 1998 will address these issues and more. Mark your calendar and plan to attend one of these schools.

Date Location
Nov. 3 Meadville
Nov. 4 Somerset
Dec. 8 Williamsport
Dec. 9 Carlisle
Dec. 10 Lancaster
Dec. 11 Reading

Marvin Hall,
Agronomy, Forages

Production:

WINTER GRAIN FERTILITY

As with any crop, the fertility program for winter grains should be based on a regular soil testing program. Ideally the soil levels for pH, phosphorus and potassium should all be in the optimum range on the soil test report before planting. For wheat, the pH should be between 6.0 and 7.0 and for barley it should be between 6.5 and 7.0. If the pH is low, the recommended amount of limestone should be applied and worked into the soil as far ahead of planting as possible. If magnesium is low, a dolomitic type lime should be used.

Both wheat and barley take up large amounts of phosphorus and potassium. If soil tests are in the low range, nutrients must be applied to build the soil up into the optimum range plus replace what is removed in the crop. For soils already in the optimum range the recommendation only considers replacing what is removed. At high soil test levels, there may be adequate nutrients in the soil to supply what the crop removes without any added phosphorous or potassium, in which case the recommendation will be zero. For winter grains, all of the recommended phosphorus and potassium should be broadcast applied prior to planting. A small portion of this requirement can be applied through the drill. To minimize fertilizer injury, do not apply more than 30 pounds per acre of the recommended nitrogen plus potash through the drill. All of the commonly available fertilizer sources of phosphorus and potassium are acceptable for application to winter grains.

Nitrogen requirements for wheat and barley are also substantial. The actual amount of fertilizer nitrogen needed to meet this requirement will depend on the amount of nitrogen supplied by the soil. In Pennsylvania, this is largely influenced by the manure history of the field. Thus, nitrogen recommendations for small grains are mainly based on the manure history of the field as summarized in the following table:

Crop Manure
Every
1-2 yrs.		 Manure
Every
3-4 yrs.		 Manure
None
Recently
  - - - N recommendation (lb/acre) - - -
Wheat 0 - 30 30 - 60 60 - 90
Barley 0 0 - 30 30 - 40

Within a given manure history category, the actual rate selected will depend on the yield potential and the nitrogen history of the field. For higher expected yields use the higher end of the recommendation range. Use the lower end of the recommendation range where the previous manure or nitrogen fertilizer rates were high or where lodging has been a problem in the past. Remember that because of the potential for lodging, do not apply excess nitrogen to small grains.

Only up to 15 lb. per acre of the nitrogen should be applied in the fall at planting time. The balance of the nitrogen should be applied in the spring. If the plants did not tiller well in the fall the nitrogen should be applied by mid-March, otherwise apply it anytime up to growth stage 5, which is the stage just before the stems start to elongate. The commonly available forms of nitrogen fertilizer are all acceptable for the winter grains.

Doug Beegle,
Agronomy, Soils

Pest Management:

FALL IS THE BEST TIME TO TREAT PERENNIAL WEEDS

Even though great progress has been made in our ability to control perennial weeds with the introduction of Roundup-Ready in summer annual crops, fall is still the best time to achieve longer-term control of perennial weeds. In fall, perennials such as hemp dogbane, Canada thistle, quackgrass, and wirestem muhly translocate or move sugars and carbohydrates from their leaves to their roots or underground storage structures. A higher percentage of a systemic herbicide such as Roundup will move with the sugars and carbohydrates to underground structures where they can potentially kill these reproductive organs.

The most common herbicides used for this type of application include Roundup or Touchdown for grasses and broadleaves and 2,4-D or Banvel for broadleaves. A combination of these products may be the best solution for a mixture of different perennial weeds. For most perennials including hemp dogbane, horsenettle, common milkweed, pokeweed, hedge bindweed, multiflora rose, poison ivy, and wild blackberry, make applications from September 1 through October 15 or before a hard frost. In general, applications by October 1 may be more effective. In northern areas of Pennsylvania, consider making the application before October 1. An additional two week application window can exist for Canada thistle and quackgrass, because of their cool-season habit of growth. Most importantly, make sure that the foliage on the weeds appears relatively healthy and capable of absorbing the herbicide spray. Plants that have been damaged by insect feeding, drought, harvest equipment, frost, or autumn leaf senescence are not good candidates for fall applications.

Bill Curran,
Agronomy, Weed Science


Precision Vision:

WHAT ABOUT YIELD MONITORING?

Ag Progress Days is over! I hope that all of you who got a chance to visit APD and the College of Ag Sciences Theme building and enjoyed the new look and the booths. Seems like the summer has flown past and already I noticed some corn just about ready for combining. For most of the farmers, soybean and corn combining is coming up very soon.

Yield monitoring - what about it? During the past year, I have had more questions from farmers on yield monitoring than any other precision farming topic, with GPS guided soil sampling taking second in number of questions. Most of the responses I receive from presentations about precision farming fall into two comments (notice I didn't say criticisms). One is that I am speaking too "high tech" and I need to present more of the basics. The second is that I am speaking too much on the basics and I need to present more of the "meat"and the details of precision farming. In a short column like Precision Vision, I can't get into too much detail. That will be the focus of an Extension Fact sheet coming out this winter, along with a web site and links that will get the web folks to all the sites about precision farming activities.

First some basics. Yield monitoring equipment has been around for over 10 years in some form or other, but has gotten more popular and equipment has advanced during the past five years. There are two versions of yield monitoring equipment available, especially on combines. Many combine manufacturers are adding some form of yield monitoring sensors and a black box in the cab on new machines.

One version of yield monitor provides a direct readout of the grain moisture and an on-the-fly readout of the instantaneous yield in dry bushels per acre as the combine travels across the field. If the proper calibration for moisture and weight is performed on the yield monitor, data can be recorded for each bin or hopper full harvested and the yield monitor data can be downloaded into the farmers computer at the end of the season or at the end of the day. This first version does not have any global positioning system (GPS) attached and in some cases the basic yield monitor does not have the additional electronics to receive a GPS signal. The usefulness of this non-GPS yield monitor provides little more than the electronic equivalent of weigh wagons, but with an on-the-fly readout of grain yield and moisture. This approach does not make any maps of yield. Prices for this first version can range from $600 to $3000. The most elementary $600 version (not including installation labor - about 8 hours) provides basic bin weights as the machine unloads with no moisture sensing.

The second version, a yield monitor equipped to receive GPS signals and with data card recording, can be used to make a map of each harvested field in addition to totaling all of the grain bin and weigh wagon information. The difference in prices reflects the cost of a differential corrected global positioning systems and cabling. For most of Pennsylvania, to obtain the positioning accuracy needed for agricultural mapping, a correction signal transmitted from a satellite needs to be acquired by the GPS. The subscription for this correction signal costs approximately $800 per year. Companies such as Omnistar, Racal and Satloc provide these correction signals. The cost of a GPS and cabling to connect to the yield monitor is approximately $5000. In total, the cost of putting a GPS and combine yield monitor into a combine is about $8,500.

Where does a yield monitor fit into a precision farming program? There are several different thoughts on the value of a yield monitor. Many farmers or custom operators simply use the yield monitor's moisture sensor, without a GPS, to determine if the field is ready to harvest. If the field is too wet, they back out and find another field to harvest. For some reason those farmers like to view the crop yield changes as they drive across the field, even if the data is not being recorded.

The real value of a mapping-type yield monitor is to create a paper map or better yet a digital map of the variability of crop yield across a field. The differences in yield can be used to develop a soil sampling program (using a GPS for locating the sampling locations). The results of the soil sampling may provide an explanation of the cause of yield variation. If GPS-based sampling results are used to generate a number of maps of nutrient variability across the field, then a nutrient application program can be developed to increase the yield for the next year. Variable rate application of nutrients may result in overall reduction of applied chemicals and an increase in crop yield. Where soil samples are mixed together for field nutrient averages, the benefit of reducing the amount of nutrients applied is lost.

Use of digital yield maps and digital soil sampling analysis maps provides a permanent record of the changes in fertility and application of chemicals and nutrients from season to season. This time trace of farming operations provides the farmer with a barometer of profitability.

For those who have access to the internet, there are some interesting websites for farmers who want to read what other farmers are saying about yield mapping and the associated activities. Try the following websites:
http://www.agriculture.com/index.html
http://www.agriculture.com/agtalk/Ag_Groups.html

Websites and telephone numbers of Suppliers of Yield Monitor and GPS Equipment:

David Wagner,
Ag & Bio Engineering, Precision Ag


Agents Corner:


BERKS COUNTY

Rain did finally come the second and third week in August, which was sorely needed for all. But the shale and clay grounds are now showing some signs of stress, as rain is now spotty. It is raining today.

Producers are busy making hay, but with their eye on a rapidly maturing corn silage crop. In the north part of the county (shale ground), corn has been cut for silage. It was so dry in early August, that corn just matured. Several growers have taken their first "green chop" rounds, evaluating moisture levels.

Some acres have been devoted to new seedings. Producers report a shortage of barley seed for fall planting.

It is a good time to evaluate weed control and nitrogen fertilization. There are whole fields that are nitrogen deficient, due to the wet weather periods we had earlier this spring and late summer.

Mena Hautau
Berks County

CRAWFORD/ERIE COUNTIES

When I last reported to you near the end of July, it looked like we were finally going to receive some very badly needed rains as most of northwestern Pennsylvania had pretty much been under drought conditions since the middle of May. Because most of our soils are less than well drained and typically fairly wet and also probably because the "northern tier" climate is generally a little cooler and more humid than much of the rest of the state, our production in a drier season usually fairs pretty well. This year, however, we came uncomfortably close to the typical full-blown effects of a drought season. Fortunately, most areas did receive a couple of significant rains as we moved through the end of July and August. We still could certainly use some soil water recharge, but it looks like, on average, crops are going to be in pretty fair shape. Of course, crops on coarser textured soils have suffered a lot.

Many of our soybean producers were introduced to the two-spotted spider mite and that pest's potential for damage with unchecked population growth. Although some soybeans were only affected around the edges or in spots, many fields received wide-spread damage, required treatment, and are likely to have suffered significant yield loss. Although the spider mites were also infesting corn, most of the damage was seen in the soybeans. Aphid populations were also quite high. Both the aphid and the spider mite populations apparently exploded in some areas as they were accelerated by warm temperatures and unchecked by lack of "cleansing" rains and pathogens. Mexican bean beetles were also a problem in some of the soybeans. In at least one instance, the Mexican bean beetle problem was not discovered as the typical skeletonized leaf, but rather, the larva were found feeding on the soybean roots when the producer was checking nodulation. Although there is wide variation in the soybean crop, pod set is looking pretty good and given ample rainfall, most beans should fill out and produce a decent crop.

In corn, unfortunately for dairy producers hoping for a good silage crop, we have a lot of six and seven foot tall corn. Again, there is also a lot of variation in the corn crop, depending on planting date and the amount of rains received. I would guess that many producers may see yield reductions on the order of 30 percent. Much of the corn is now at the late dough or early dent stage. However, low plant moisture content is suspect and we are urging producers to rely mainly on actual whole plant moisture determinations rather than milk-line or other kernel development indications. Pollination and seed set in the corn actually looks rather good for the dry weather that we had. Although plants are small, some nice full ears have developed in much of our corn. Root worm and corn borer pressure was apparently fairly typical. A lot of corn is showing a fair amount of Northern corn leaf blight along with the general droughty, somewhat stunted, and stressed plant appearance.

Later cuttings of hay were severely limited by the dry weather. Leafhopper pressure was fairly typical and fortunately not quite as severe as last season. Some additional rain will hopefully produce some good last cutting. Many producers are correctly considering applying nitrogen to grass hays to enhance the last cutting. Conditions have been good for late summer seedings and prospects for winter small grain establishment towards the end of September and early October should also be good.

All in all, it looks like we should come through the 1998 season in reasonably good shape. Forages, both hay and corn silage will be somewhat limited. Of course, the extremely low feed and grain prices across the board will be either a curse or a blessing depending on whether the producer is buying or selling. Best wishes to all for a safe, smooth, and productive harvest season.

Joel Hunter
Crawford County

DAUPHIN COUNTY

In my last report I indicated that growing conditions had been excellent, but that we could use some rain soon. We did not get that timely rain in most parts of the county; particularly the upper part of the county. The upper part of the county did not get significant rain until the second week of August. This saved the corn crop from serious yield loss. However, the effect of the dry spell appears to have resulted in incomplete pollination of ears. The lower part of the county got some rain during the "dry spell" and overall is doing a little better.

Corn has begun to brown up with some high moisture corn being harvested this week. Our soybean crop continues to grow well.

On the insect and disease front, the heavy leafhopper populations during third cutting alfalfa appear to have gone. There was at least one farm that had significant damage from fall armyworm.

Jerry Martin
Dauphin County

FAYETTE COUNTY

What a difference several weeks can make. Already (8/30/98) corn silage is being harvested, which is about two weeks ahead of normal for the SW area. April planted corn varieties are mature and drying down rapidly, even with good soil moisture levels. Corn is standing well with very little noticeable pressure from corn borer.

Corn fields that were somewhat waterlogged in June are still looking so, partially due to weed pressure from failed herbicide programs.

Dairymen who got the jump with mid-May hay harvest are still way ahead of the game. Second, Third and now fourth cuttings have been ready in the good weather cycles provided by "Mom" Nature. Some dairymen have reported the silos are full with great legume roughages and are selling corn silage to NW PA farmers.

Those who made late summer seedings of alfalfa have had excellent germination weather with good showers and warm temperatures.

This has been an incredible summer for the SW. Just when topsoil moisture would begin to get scarce, a good rain shower would provide 1/2 or more inches of rain. I can't remember such a growing season since the mid to late 70's. Now if these commodities were worth something, it would really be great. Oh, to dream?

Donald C. Fretts
Fayette County

LYCOMING COUNTY

The weather here is still playing havoc with our crops. We have received several showers over the last two weeks that have brightened the yield picture for corn and soybeans somewhat. It is starting to dry out again though and I have seen several fields in a drought stressed condition already which indicates how marginal our moisture supply is. Corn yields are still predicted to be average on most fields in the area with a few expected to be higher. Not looking for a bin-busting crop in 1998. Much of the corn is early dent or later. Beans look good to excellent in most fields as normally happens in a dry year. I have seen some whitemold showing up. A local PSU research plot is showing good disease control with a commercial product currently on the market (results from the study available this winter). Insect pressure this year in soybeans has been minor compared to last season.

Hay harvested recently has been very good quality but the third cutting has been light due to the lack of rain for much of the period. Same story, those that got the rain got the hay...! Due to the good harvest early, there doesn't appear to be a problem with supply going into the fall and winter months. Pasture is starting to recover in most areas of the region as the temperatures cool off somewhat. Consequently, gains by livestock are increasing.

From the grain marketing side, thinks are looking less then rosy. Prices continue to slide with high yields expected nationwide and poor export markets. Locally the mills have been offering a mixed bag of pricing, but all of it has been dropping. A number of producers still have some of the '98 crop in bins or are currently delivering it to mills at low prices. Hard to believe these are the same commodities that commanded skyhigh prices only two years ago.

Tom Murphy
Lycoming County

YORK COUNTY

Corn and soybeans look good. The latter part of July was dry for us, but we received some rain during the second week of August that helped sure things up. It has been quite hot of late and statements about the corn beginning to dry down fast are being made. Some silage corn has been harvested but I have not gotten any estimates on tonnage so far.

Lots of good comments are being made about the weed control in Roundup Ready soybeans.

John Rowehl
York County

Degree Day Accumulations:

1998 DEGREE DAY ACCUMULATIONS

To track corn and insect development, compare the 1998 cumulative degree-days shown in Table 1 to the required values in Tables 2 and 3. Choose a location that is closest to your site when making a comparison.

Table 1. Cumulative Degree Days for Corn and Insects for the Period Ending August 31, 1998
    Corn Insects
County Location 1998 30-year ave. SCM/SB AW BCW CRW ECB
    50F 50F Diff 40F 48F 50F 53F 55F
Erie Waterford 2260 1843 417 3720 2490 2205 1805 1556
Crawford Meadville 2339 1973 366 3889 2630 2341 1934 1679
Mercer Mercer 2373 1968 406 3901 2633 2343 1934 1678
Bradford Towanda 2281 2012 269 3913 2646 2357 1946 1690
Lycoming Montoursville 2383 2139 245 4100 2794 2499 2080 1817
Tioga Mansfield 2230 1865 365 3733 2495 2210 1808 1559
Susquehanna Montrose 2150 1696 454 3531 2317 2035 1643 1403
Butler Butler 2446 2089 357 4067 2768 2473 2055 1793
Indiana Indiana 2447 2070 377 4051 2749 2452 2034 1773
Lawrence Lawrence Jct 2324 1998 327 3908 2653 2364 1956 1701
Blair Martinsburg 2427 1983 444 3953 2660 2365 1949 1691
Centre State College 2381 1998 383 3945 2660 2367 1954 1696
Columbia Bloomsburg 2410 2165 245 4147 2827 2530 2108 1843
Clearfield Curwensville 2370 1977 393 3913 2638 2346 1935 1678
Dauphin Elizabethville 2476 2225 251 4250 2905 2604 2176 1907
Bedford Bedford 2512 2134 379 4161 2831 2529 2103 1837
Mifflin Belleville 2451 2141 311 4137 2816 2518 2095 1831
Northumberland Sunbury 2460 2243 217 4259 2917 2617 2190 1922
Lehigh Trexlertown 2486 2282 203 4330 2966 2662 2231 1959
Schuylkill Hegins 2429 2149 279 4142 2817 2519 2096 1831
Westmoreland Greensburg 2474 2057 416 4050 2746 2448 2029 1767
Somerset Somerset 2379 1738 641 3677 2420 2130 1725 1478
Washington Washington 2548 2182 366 4224 2890 2588 2160 1892
Franklin Chambersburg 2577 2306 271 4396 3018 2711 2273 1999
York York 2602 2388 214 4512 3109 2798 2355 2077
Lancaster Ephrata 2512 2261 251 4320 2954 2649 2216 1944
Berks Hamburg 2502 2307 195 4364 2995 2690 2257 1984
Corn degree-days based on a May 1 starting date. Insect degree-days based on a January 1 starting date.


Table 2. Cumulative Degree-Days Required for Insects to Reach key Periods for Scouting or Management
  Maturity rating (days)
80 90 100 110 120
50% Silking 1100 1150 1250 1300 1400
Black Layer Formation 1900 2100 2300 2500 2800


Table 3. Cumulative Degree-Days Required for Insects to Reach key Periods for Scouting or Management
  Stalk Borer Alfalfa Weevil Black Cutworm* Corn Rootworm European Corn Borer Seed Corn Maggot
Adlt Emrg 5% Hatch 1st Gen 2nd Gen
SB AW BCW CRW ECB1 ECB2  
Initiation 1400 300 91 1283 380 WCRW** 558 1550 450***
Termination 1700 500 430 2253 478 NCRW** 1228 2045  

*Degree-day accumulation should begin at first moth capture in a black light or pheromone trap.
**These values represent degree day accumulations for optimal timing of Furadan 4F post emergence applications. WCRW-Western Corn Rootworm, NCRW-Northern Corn Rootworm
***This number of degree days represents the number of degree days required from plowdown of green vegetation until it is safe to plant corn or soybeans and avoid seed corn maggot injury.

Dennis Calvin, Entomology

William S. Curran
Associate Professor Weed Science
email: wsc2@psu.edu

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