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June 12, 1998 Vol. 98.7

IN THIS ISSUE:

Production:

HARVESTING WINTER WHEAT

Harvest management in wheat can affect both yield and quality. It is usually suggested to start harvest when grain moisture reaches 14%. This eliminates the need to artificially dry the grain and eliminates a moisture dockage when selling directly from the combine. A wheat kernel is mature at 30% moisture. It will dry at a rate of 2.5% per day from 30 to 20%. From 20 to 14% it will dry at about 1 percentage point per day under good drying conditions but may require 10 days to drop 1 percentage point under poor conditions. Research at Ohio State University indicates that during the time wheat is drying from 30 to 14%, yield will drop by 12 pounds per day and bushel weight by 0.25 pound per day. Therefore, each five days delay in harvest could potentially reduce yield one bushel and test weight 1.25 pounds. Yield losses result from increased lodging, shattering, and bird and rodent feeding. Drying and rewetting from rain and dew causes the reduction in test weight.

Wheat can be harvested, without damage to the kernel or milling quality, once the moisture drops to 20% or lower. Harvesting between 20 and 14% moisture has the following advantages; increased yield and test weight, reduced combine harvest loss, maintaining good germination, and earlier seeding of soybean when double cropping. The disadvantage is the need to artificially dry the grain for proper storage. Compare the cost of drying with the advantages of early harvesting.

Head scab has been found in a few of our variety test plots and in a limited number of fields. Remember that head scab develops when the fungus infects the spikelets during flowering. One or more spikelets per head will turn prematurely straw colored while glumes on healthy spikelets remain green. A pink to orange mold often grows at the base of diseased spikelets. Infected spikelets normally produce shriveled rough kernels, which tend to reduce bushel weight. When harvesting fields with scabby grain the combine should be adjusted to remove as many of the shriveled and pink kernels as possible.

Elwood Hatley,
CCA, Agronomy

Pest Management:

WEED TOURS QUICKLY APPROACHING

Don't forget to register for the 1998 Weed Tours on July 16 at Landisville and July 17 at Rock Springs. We need an approximate head count to anticipate luncheon needs. A registration form is attached in this newsletter. Call Lisa Crytser at 814-865-2543 for additional information.

Bill Curran,
Agronomy, Weed Science



POST STRATEGIES FOR NUTSEDGE

With the variable weather so far this growing season, weeds are escaping pre herbicide treatments. Yellow nutsedge is one weed in particular that is visible throughout the state. Several herbicides are available for post control nutsedge. For additional information on the principles of postemergence applications, see Section 1 of the Penn State Field Crop Weed Control Guide.

Several postemergence herbicides are labeled for control of, or reduced competition from yellow nutsedge; however, only the foliar-applied herbicides that provide more consistent nutsedge control in corn and/or soybeans are included in Table 1. When possible, cultivation in addition to the herbicide treatment accounts for better yellow nutsedge control. Also, remember that yellow nutsedge is not that competitive with corn or soybeans, and that light infestations (i.e., 1 plant/ft 2) may not affect corn or soybean yield.

Unfortunately, there are no postemergence products labeled for nutsedge control in forage crops, so the only viable method in this situation is through the regular mowing or swathing of hay or pasture. The best approach to managing nutsedge in forages is prevention or suppression before crop establishment.

Table 1. Postemergence herbicides for yellow nutsedge control in corn and soybeans.
Herbicide Crop Product/A Control Ratinga Comments
POST
Atrazine 4L/90DF + COC Corn 1.5-2 qt 4L or 1.7-2.2 lb 90DF 8 Apply while nutsedge is 4-8 inches tall and before corn is 12 inches in height. Add 1 qt of crop oil concentrate/A to spray solution. If corn is under stress from prolonged cold, wet weather or other factors, this treatment may cause crop injury. Refer to current atrazine label for use restrictions and additional information. (Restricted-use pesticide and groundwater advisory)
Basagran 4S (bentazon)

or

Laddok S-12 5L (bentazon + atrazine) 		corn, soybeans



corn 		1.5-2 pt

or

2.3 pt 		8



9		 Basagran application should be made when nutsedge is 6-8 inches tall and actively growing. Add 1 q/A of crop oil concentrate to spray solution. Apply in a minimum of 20 gal of water/A and at a minimum pressure of 40 psi. Split-applications are suggested for improved nutsedge control. Make second application 7-10 days after the first, if necessary.

Laddok application should be made to actively growing nutsedge but before corn is 12 inches in height. Add 2 pt/A of crop oil concentrate to spray solution. For best results, cultivate 7-14 days after application. (Restricted-use pesticide and groundwater advisory)
Classic or Skirmish 25DF (chlorimuron) Soybeans 0.5-0.75 oz 8 Apply treatment when nutsedge is 2-4 inches tall and soybeans have at least one trifoliate leaf; both should be actively growing. Always include a proper adjuvant with this product. Use a minimum of 10 gal of water/A at a pressure of 25-40 psi. If the soil pH is less than 7.0 at Classic rates of 0.5 oz/A or greater, do not plant corn for at least 9 months after application. Classic must be applied 60 days before harvest.
Permit 75DF (halosulfuron) Corn 1 -1 1/3 oz 9+ Permit can be applied over-the-top or with drop nozzles from spike through layby (last cultivation) of corn and when nutsedge is 4-12 inches tall and actively growing. A nonionic surfactant or crop oil concentrate must be added to the spray solution. Spray volumes of 10 or more gallons of water/A at a pressure which provides thorough and uniform weed coverage is optimal. Refer to label for any additional information.
Tough 3.75E (pyridate) Corn 2 pt 8 Apply 2 pt product/A when nutsedge is 6-8 inches high. Treatment will burn back top growth but regrowth may occur. Use a spray solution of 20-30 gal of water/A at 30-40 psi. Tank-mixing with atrazine enhances activity.
Roundup Ultra 4S (glyphosate) Roundup Ready corn and soybeans only; burndown/spot treatment 1-2 qt

1-3 qt or 1-2% solution 		9 Apply 1 qt/A (single application) in Roundup Ready corn before 24 inches tall (V6) and 1-2 qt/A (single or split application) in Roundup Ready soybeans before flowering. Apply when nutsedge is >6 inches tall but before nutsedge flowering. Lower spray volumes/A (10 gpa) provide better control. Roundup Ultra does not require the additional adjuvants in the spray tank. Roundup is a nonselective herbicide and will injure or kill any plant it comes into contact with unless it is a Roundup Ready crop.

a10=95-100%,9=85-95%,8=75-85%,7=65-75%,6=55-65%. Ratings based on optimal application timing.

For nonselective maintenance applications or spot treatments, use Roundup Ultra to clean up fields prior to planting or to kill isolated patches of yellow nutsedge (Table 1). Roundup can effectively kill yellow nutsedge prior to seeding late summer forages or before planting double-crop soybeans.



POISONOUS PASTURE WEEDS

Calls and reports concerning livestock death due to poisonous weeds frequently increase during the next few weeks. During the hot and dry months of July and August, the condition of many pastures becomes poor and over-grazed. Cattle may be forced to graze on weeds that they normally would not, or they may eat a weed out of curiosity. Scout your pastures and remove these weeds before they cause livestock health problems. Keep in mind, there are numerous poisonous plants that could invade an area or a pasture. If you suspect a poisonous plant and are unsure of it's identity contact your local Extension agent or another knowledgeable resource. Following are descriptions of some of the more common poisonous weeds:

White Snakeroot (Eupatorium rugosum).
Perennial. Leaves and stems are the dangerous parts of the plant. Has a fibrous root system. Leaves are opposite along stem, oval, toothed margins and with long petioles. Small white flowers in compound terminal clusters are conspicuous in late summer. Found in woods, damp and shady pastures, and occasionally in thickets and clearings. Newly cleared lots may also contain this weed.

Nightshades (Solanum spp.).
Several different nightshade species are close relatives, including eastern black nightshade, bitter nightshade, jimsonweed, groundcherry and horsenettle, and have been known to be poisonous to livestock and pets when parts of the plant are consumed. Plant appearances vary between species, but most all (except jimsonweed) produce small berry-like fruits. Most of the plants in the Nightshade family are considered poisonous; however, the green leaves, stems, and seeds are especially toxic. The green fruit may be quite poisonous while the ripe fruit may be relatively nontoxic. The concentrations of the toxins are higher following dry conditions and often lower following damp, rainy periods. The toxic properties are not removed by drying and are relatively heat stable. Portions of the plant stored with forage will remain poisonous, so producers must be cautious when feeding livestock nightshade-contaminated hay. The toxicity of the green plant material varies from 0.1% to 1% of the animal's body weight.

Wild Black Cherry (Prunus serotina).
Perennial woody tree or shrub. Not necessarily a "pasture weed," but sometimes found in or along fencerows bordering pastures. Damaged or wilted leaves or branches are the dangerous parts of the tree. Leaves are alternate, simple, elliptic-pointed, leathery in texture, and finely toothed on the margins. Flowers are showy, fragrant, and white, hang in drooping clusters, and produce dark-red to black cherry fruits.

Poison Hemlock (Conium maculatum).
Biennial. It looks very similar to wild carrot or wild dill. Leaves are alternate and have a lacy appearance, while the small white flowers are arranged in compound umbles. Stems are smooth and covered with purple blotches. All parts of the plant are poisonous, however, stems are less poisonous than the rest of plant. Generally, it is not palatable to livestock but ingestion of as little as 0.25 to 0.3% of body weight of poison hemlock is lethal. It grows in moist soils of pastures, ditches, roadsides, and disturbed sites.

Common Pokeweed (Phytolacca americana).
Perennial. Pokeweed can grow as tall as 10 feet with alternate oblong leaves, smooth reddish purple stems, and deep purple berries (mature) in clusters. The roots are the most poisonous part of the plant, while the berries are the least poisonous part. Poisoning is rare in animals since the large taproot is generally difficult for animals to forage and ingest. Found in pastures, no-till fields, shady roadsides, wasteplaces, woodlots, and fencerows.

Certain weeds or plants such as pigweed, lambsquarters, and sorghum normally have feed value and can be consumed by livestock, however, during extended dry periods they can accumulate toxic amounts of nitrates.

Dwight Lingenfelter, Agronomy
(some parts from Purdue Pest & Crop Newsletter)



INSECT ALERT

The following insects can be active during this time period. This does not mean they have been seen in the state, but it is the period of time when they can injure crops. Insects that have been reported are shown in bold type and specifics about their management are presented in individual articles. Pictures of each corn insect species, economic thresholds, and scouting guidelines can be seen on the world wide webpage, http://www.fra.cas.psu.edu/ (Note correction from an earlier newsletter).

Corn
1. black cutworm
corn root aphid
2. corn rootworm larvae
3. European corn borer adults and larvae (1st brood) 		flea beetle
garden symphylan
grape colaspis
4. slugs		 sod webworm
5. Stalk borer
thrips
white grub
wireworm
Soybeans
bean leaf beetle
green cloverworm		 potato leafhopper
seed corn maggot		 thrips
Alfalfa
alfalfa blotch
leafminer
Alfalfa weevil larvae 		Clover root curculio
Meadow spittlebug		 6. Potato leafhopper
Spotted alfalfa aphid
Small Grains
corn leaf aphid English grain aphid True armyworm

1) Black cutworm - We should be nearing the end of period for cutworm injury in most areas of the state. Continue to watch corn fields where plants are less than V5 (18 inches tall). I have only received a couple of messages about black cutworm injury.

Economic Threshold Values:
Seed leaf stage-2% of plants cut
Two leaf stage-3% of plants cut
Three leaf stage-5% of plants cut
Four leaf stage-7% of plants cut
Five leaf stage-Seldom a problem at this stage

2) Corn Rootworm Larvae - In most areas of the state corn rootworm hatch has begun, and in southern areas it is proceeding rapidly. See Tables 2 and 4 for degree day information in your area. For western corn rootworm, 380 DD are required to reach 5% hatch and 478 DD are required for northern corn rootworm to reach the same level. Only the most northern counties have not accumulated enough degree days for 5% hatch. For those individuals interested in Furadan 4F application timing, the product should be applied within a week of 5% egg hatch. This allows time for the material to reach the corn's root zone and provide a high level of protection. Other cultivation time treatments should be applied during the same window. A consideration in choosing to use Furadan 4F is its water solubility. When applying the product postemergence for corn rootworm control, it is important that adequate rainfall or irrigation occurs in the field to move the material into the root zone. If our weather continues to stay dry, Furadan 4F applications may have a difficult time reaching the root zone in time to offer adequate protection. A Furadan application applied too late will offer little protection for the corn's root system.

Because corn rootworm hatch was early this year and corn development has been delayed because of a rainy period in mid-May, corn plants will be smaller this year when corn rootworm larvae are actively feeding. This means that untreated corn fields with significant corn rootworm populations have at greater probability of severe injury. We should be entering the period of major root pruning between mid-June and early-July. If injury is significant, plant lodging should become evident at that time. If you did not treat a field and are concerned about the possibility of corn rootworm injury, you should begin checking for larval injury on the roots now. If significant numbers of corn rootworm larvae can be founds, there still may be time to apply a postemergence treatment to prevent severe injury. Both granular and liquid formulations can be used as long as they are incorporated. Because you are close to the point of hatch and larval feeding, you can used reduced rates to cut costs.

3) European corn borer - The adults are flying in many areas of the state and beginning to lay eggs. In southern counties, small larvae are actively feeding in the whorls. Watch early planted corn fields (late April) closely for injury symptoms. The first evidence of injury will be small areas of the mesophyll missing at the lower end of leaves which have not completed expanded out of the whorl. As larvae get larger, the leaves will look shotholed, with some leaves having a row of round 1/4 holes across the leaf. Small to medium size larvae (1/8 to 3/8 inches long) can be found in the whorl by cutting off the tops of plants and unrolling the leaves. See the Fund for Rural America Webpage (http:/www.fra.cas.psu.edu/) for a methods to calculate the economic threshold or the "Field Crop IPM Training and Reference Manual".

4) Slugs - This has not been a big year for slug injury due to the warm dry conditions. However, their have been a couple of recent reports in western Pennsylvania soybean fields grown under no-till conditions. Slugs in these fields are staying in the planter slit and feeding on developing seedlings.

Economic Threshold Values: 50% of leaf area removed per plant and plants are less than V6 (6 leaves with the collar showing outside whorl).

5) Stalk Borer - Southern areas have reached enough degree days for stalk borer larvae to begin moving from grasses in field margins and tunneling into small corn plants. Central and northern counties should be reaching this point within the next week. Farmers who have orchardgrass in fields that will be killed with a postemergence treatment, should watch for stalk borer injury as the orchardgrass begins to die or apply an insecticide with the herbicide as insurance against injury. See the Agronomy Guide for insecticide options and the "Field Crop IPM Training and Reference Manual", for economic thresholds (This manual is available from Dennis Calvin, Dept. of Entomology, 501 ASI, Penn State University, University Park, Pa. for $75.00).

Economic Thresholds Values - See the "Field Crop IPM Training and Reference Manual" for specific thresholds which vary based on plant growth stage and market value of the crop.

V1-4 to 10% of plants showing injury symptoms
V2-5 to 12% of plants showing injury symptoms
V3-6 to 15% of plants showing injury symptoms
V4-6 to 16% of plants showing injury symptoms
V5-7 to 17% of plants showing injury symptoms
V6-14 to 34% of plants showing injury symptoms
V7-Plants are usually safe by this time

6) Potato leafhopper -Reports of potato leafhopper are increasing across the state. So far no fields have been reported above the economic threshold. However, within the next two week period populations should build to levels where some fields will have populations that exceed the economic threshold.

Economic Threshold Values - See the Publication, "A Pest Management Program for Alfalfa in Pennsylvania", for specific thresholds.

Threshold Ranges:
For 0 to 4 inch high alfalfa-0.2 to 1.0 leafhoppers per sweep
For 5 to 8 inch high alfalfa-0.3 to 1.7 leafhoppers per sweep
For 9 to 12 inch high alfalfa-0.8 to 5.0 leafhoppers per sweep

Dennis Calvin,
Entomology


Precision Vision:

FARM MAPPING - WHO NEEDS IT?

Several years ago, I started asking people I met, "How do you know where you are? Geographically speaking, that is." I was surprised at the answers I received. Some people would reference their location to a major landmark, others would reference themselves to a distance and a direction from north, like "we live 10.5 miles northwest of the center of Philipsburg." Still others (usually geographers or engineers) would give a set of coordinates such as "I am at 40 and a half degrees north latitude and about 78 degrees west longitude." Still others, when asked how to get to their work, or home or to the store, might say, "it's over there (pointing vaguely with their finger)." Others, say with utter sincerity and if checked by their performance, use the sun as a positioning and direction instrument. That's ok as long as the sun is shining or it is daytime.

Now, I've met a lot of farmers, when asked where the ground was the wettest, or where a patch of weeds were located in his field, could walk me right to the spot, but when asked how they knew where they were standing in the field, could not give a consistent and precise answer - but they knew exactly how to get to a certain problem location in the field.

The point is this, in today's emerging agricultural production arena, many different people are interfacing in acquiring data from the field (soil characteristics, nutrient levels, yield from grain combines, topography (elevation), and weed/pest outbreaks). These people may not be the farmer that has driven all the farm machinery over those fields for the last 30 years. In evaluating the field data and making decisions about chemical application, manure application, nutrient application, we have to have a common language that can be used to personally discuss the interpretation of the data and make management decisions, and also to program or control the farm machinery to apply those crop inputs we discussed.

We need a system of keeping track of where we are and how to get to the next place, so that both humans and machines can communicate with sufficient accuracy that the chemicals and crop inputs get to the approximate correct location in the field. There are two considerations: 1) a consistent set of locational guidelines and, 2) an understanding of the accuracy of the specific location we think we are talking about when we decide to apply some manure or chemical, or - even the seed population. That is why farm mapping is becoming much more important.

There are two kinds of data, spatial data - such as a location point on the surface of the earth (like in the middle of a corn field where a sink hole is developing), and attribute data (descriptive data) that describes a condition, like "wet, dry, clay, loam, red, green, but - you get the idea." Farm mapping systems can be simple, such as a hand drawn sketch that gives the reader an approximate sense of the location and characteristic of some place in a field. Farm mapping systems can be complex, using computers and geographic information systems (GIS) to store digital maps in the GIS data base. Each of the digital maps, is characterized by a common set of locational (spatial) characteristics, so that the different digital maps can be referenced to each other.

That is the purpose of the GIS - to keep track of each location in all of the digital maps and to make sure that any location in one specific map can be located on each of the other maps. To visualize this, if you had a stack of transparent maps of the same field, and could lay each map on top of the other, a single location in a field would form one single point if you were above the map stack and looked down through the digital map layers. That is called "piercing", so we could electronically choose any point in a field, say where there was a weed problem, and electronically, look down through each layer - the soil, nutrients, yield, weed, pest maps, and data at that location in each map layer could give us an insight as to the probable cause of the problem.

Now we could talk about the geographic data and coordinate systems, like latitude and longitude, and the datums, and geoids that allow us to use a consistent set of distances and coordinates. But, if we are going to get into the precision agriculture age, we need to use computers and spatial (locational) data that is universal in its ability to allow any person, or computer, or agricultural machine to understand where the point of interest is located or "where we are". We need these computer-based farm mapping systems that use GPS-derived locational data and a system of common coordinates so that we can store digital and locational information about the production fields. By using computer-based farm management systems, we can, from year-to-year, always be able to refer to the same place in the field with accuracy. We will talk much more about this "farm mapping" technology in future articles.

David Wagner,
Ag & Bio Engineering, Precision Ag


Agents Corner:


ADAMS COUNTY

Where did all the rain go? That seems to be the most frequent question being asked these days as our growing conditions have dramatically changed from extremely wet to very dry. The dry conditions are affecting emergence for both corn and soybeans. Most fields are showing uneven emergence patterns. If the corn was planted shallow, some seed has never swelled, as there was not adequate moisture in the planting zone. Bean fields are also showing bare spots were the seed has finally germinated but is having trouble emerging. Some no-till fields that were planted early and a little wet, are showing sidewall compaction of the seed trench and the seed trench has not closed. There has been some uneven weed control in the early planted corn due to the excessive moisture. With the later corn, there is a question as to what type of weed control we will have as we have not had rain during the past two weeks. Early planted corn has reached the four leaf stage.

First cutting forages are testing higher in fiber and lower in energy than normal. The earliest regrowth on alfalfa fields is 8-10 inches tall with leafhopper pressure light and below threshold levels. Grass hay yields have been above average with high quality as a result of the good drying conditions.

The first barley was harvested on June 1. If that is not a record for our area, it has to be close. Wheat is maturing and shows promise of 100+ bushel yields.

Rain would be a welcome sight as corn is still being planted and with the early barley harvest, additional soybeans will be planted if there is adequate moisture.

Larry Swartz, Adams County

CENTRE/CLINTON COUNTIES

With no appreciable rainfall since May 12, corn, soybeans and new seedings of alfalfa are showing little growth. Each threat of showers brings hope that much needed rain will arrive soon.

Weed control in corn and soybeans has been less than ideal. Many applied herbicides were not very effective without subsequent rain. Nutsedge and foxtail, in particular, are presenting problems. Likewise, the effectiveness of soil insecticides in corn may be reduced without adequate rain. Some damage from rootworms and slugs has been noted in fields across these counties.

Wheat and barley crops appear to be progressing well, still a week or so ahead of normal. First cutting of alfalfa is complete on most farms, and made for some high quality hay, if cut at the proper stage. Potato leafhoppers are beginning to appear, but there is little alfalfa regrowth for them to feed on.

Gary Dauberman, Centre/Clinton Counties

SCHUYLKILL COUNTY

After the rains stopped it was amazing to observe how farmers and crops both adjust to the shortened planting season. Somehow, within a period of one week, the farmers seemed to make up one of the two weeks lost to the rains. This is nothing short of remarkable especially when an early maturing hay crop complicated the issue. Several county farms seemed to be tackling everything at the same time. There was evidence that the oats had recently been sprayed for weeds, manure was still being hauled, corn was being planted and sprayed and hay harvest was in progress.

Concern was expressed by one ag supply dealer about the long hours being worked by the farmers. He pointed out that accidents happen when tired and not alert. Corners were sometimes being cut and equipment jury-rigged to keep things going. All potential problems that tend to compound themselves. A rainy day would bring a welcome day of rest. One producer pointed out that he was looking forward to harvesting hay because you could not do that in the early morning and he thus could shorten his corn planting season "5 to 9" day. The crops also cooperated to make up for the delay in planting with some corn being reported spiking through the surface in as little as six days and beans even faster.

Maintaining operational timeliness on a year like this one (or any other) is very important to obtaining good yields and profitability. This may mean longer hours, extra help or oversized equipment. One word of caution on the oversized equipment is to be careful not to spend so much on equipment to save the crop on a challenging year that you limit the profitability of the operation in the more typical years. The trick is to maintain an efficient balance between equipment investment and labor/time needs. (Undoubtedly easier said than done.) The shortened planting season is reportedly putting more stress on the supply system than it can handle at times resulting in some items being in temporary short supply. Perhaps some on-farm inventory storage would be insurance against planting delays.

Allan Shoener, Schuylkill County

SUSQUEHANNA/BRADFORD COUNTIES

Field work in the northeast has slowed as recurrent rains and cooler weather have kept many on the bench waiting for small windows of opportunity to get some work done. Corn is still being planted around the area but for the most part this task is over.

I've fielded several calls and visitors asking about yellow corn. I was in several fields as well and it would seem the same symptoms are being described and observed by all of us and I am fairly confident our corn is experiencing cold stress and maybe even frost damage in some cases. Fortunately, we can expect the corn to grow out of this none worse for the wear. Herbicide damage or starter burn might also be real suspects since the symptoms are from hedgerow to hedgerow, but I'm still inclined to believe its simply Canadian air - we've had a whiff or two of it.

Our forages continue to grow well and regrowth from first cut looks great. Our local crop management technician found a potato leafhopper on June 1st in southwest Bradford County during his scouting activities and this is noteworthy only because our earliest recorded finding prior to this year was June 13. Most years we don't find these until the third week of the month. We notified our local ag-product dealers that we found them in the area and that scouting should begin soon.

Mark Madden, Susquehanna/Bradford Counties

Degree Day Accumulations:

1998 DEGREE DAY ACCUMULATIONS

To track corn and insect development, compare the 1998 cumulative degree-days shown in Table 2 to the required values in Tables 3 and 4. Choose a location that is closest to your site when making a comparison.

Table 2. Cumulative Degree Days for Corn and Insects for the Period Ending June 8, 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 437 384 53 1246 688 572 422 338
Crawford Meadville 467 410 57 1326 739 618 461 372
Mercer Mercer 471 412 59 1345 750 627 469 379
Bradford Towanda 464 408 56 1337 742 620 461 370
Lycoming Montoursville 498 437 61 1438 803 676 508 412
Tioga Mansfield 434 381 52 1257 691 574 423 338
Susquehanna Montrose 398 350 47 1182 639 526 382 303
Butler Butler 501 437 64 1431 804 676 510 414
Indiana Indiana 497 433 63 1434 804 676 508 413
Lawrence Lawrence Jct 470 413 57 1323 740 619 462 373
Blair Martinsburg 479 416 62 1403 783 655 491 398
Centre State College 475 415 60 1382 769 643 481 389
Columbia Bloomsburg 506 443 63 1471 822 693 522 424
Clearfield Curwensville 470 411 59 1361 757 633 473 382
Dauphin Elizabethville 527 459 67 1535 862 729 552 451
Bedford Bedford 516 448 67 1508 850 717 541 442
Mifflin Belleville 508 444 64 1477 828 698 526 428
Northumberland Sunbury 528 461 67 1528 858 726 550 448
Lehigh Trexlertown 539 469 70 1580 887 752 571 466
Schuylkill Hegins 506 442 64 1481 828 698 526 427
Westmoreland Greensburg 498 434 65 1444 811 681 513 418
Somerset Somerset 438 377 61 1302 718 595 440 355
Washington Washington 532 461 70 1529 867 733 556 455
Franklin Chambersburg 557 484 74 1629 924 785 598 491
York York 576 500 76 1692 961 818 627 515
Lancaster Ephrata 539 468 71 1588 894 757 575 470
Berks Hamburg 546 475 71 1595 898 761 580 474
Corn degree-days based on a May 1 starting date. Insect degree-days based on a January 1 starting date.


Table 3. 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 4. 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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