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June 4, 1999 Vol. 99.5

IN THIS ISSUE:

Mark Your Calendar

Production

Pest Management

Agents Corner

Degree Day Accumulations

Production:

WINTER GRAIN UPDATE

In general, winter small grains look good. The combination of dry and warm weather that we are presently experiencing has both negative and positive affects. The optimum temperature for grain production in soft red winter wheat is 75 to 80 degrees. As these temperatures move into the mid to high 80's and low 90's potential yield is reduced by lowering the rate of grain fill and the duration or length of the grain fill period (hasten maturity). On the positive side the warm dry weather slows down or stops most of the major diseases. Mildew, in most cases, has stopped because of higher temperatures and low humidity. Septoria has slowed also because of lack of splash action from raindrops to move the organism up the plant. The reduction of these diseases tends to improve yield and grain quality (bushel weight).

I have noticed more visual virus symptoms on winter small grains then normal. In most years virus symptoms are contained in the lower portion of the canopy. I am seeing symptoms up to the mid portion of the canopy (flag - 3 to flag - 4 leaves) this year. I am not sure how this will affect yield. Also, I am starting to see red leaf on spring oat. This is caused by Barley Yellow Dwarf Virus. The best control of virus, in all small grains, is to choose disease tolerant varieties.

The other major disease that affects winter grain yields and quality is head scab. This disease requires frequent rain during flowering. Most of our winter grains have flowered or are in the final stages of flowering. Since rain showers have been sparse during this period, head scab should not be a major threat this year.

Elwood Hatley, CCA
Agronomy, Small Grains



GENERALLY WARM DRY CONDITIONS INFLUENCE CORN GROWTH

The warm dry conditions this spring have favored early planting and rapid crop development. Early planted corn was in the V5 stage in our central PA trials and V6 in southeast PA by June 1, well ahead of normal. According to PDA statistics, our corn was 93 percent planted on May 30, 14 points ahead of the 5 year average.

The warm dry soil conditions have resulted in good corn emergence and appear to have limited the response to starter fertilizers. I see differences in the way some fields are developing and this may be due to early season hybrid vigor or due to soil quality differences. Soil compaction effects are often more dramatic under dry conditions because the soil penetration resistance increases under dry conditions. If these conditions persist, this could result in shortened, purpled plants and reduced yields. Often, though, early season growth differences disappear if adequate precipitation occurs and other factors become more important in determining yield.

The warm soil temperatures will also help to enhance root development at deeper depths. While corn roots will not grow to seek moisture, those that proliferate the most are the ones with the most ideal growing conditions. When adequate moisture and warm temperatures occur deeper in the soil, then root growth is enhanced in these deeper zones. Thus the net effect in warm, dry springs is to have corn crops with more roots deeper in the soil. This should be a plus in no-till fields that often have shallower root systems associated with cooler soils.

Water use by a young corn crop is not great during early season development, averaging only about 0.1 inch or less per day so dry conditions early in the season have little effect on yield. Water use will increase rapidly though as we progress through June as more leaf area develops and could reach 0.25 inches per day by mid July.

The early planting and rapid development of the crop should be very beneficial for our shorter season areas where the season is often cut short by frost. I would also expect that the warm temperatures should hasten rootworm larva emergence and improve the activity of rootworm insecticides.

In conclusion, our corn crop is off to a good start across the state. Crop development so far should provide some insurance against drought and frost. The season is far from over however and yields will be highly dependent on July and August precipitation.

Greg Roth, Agronomy
Corn and Sorghum Management

Pest Management:

REGISTER NOW FOR THE 27TH ANNUAL WEED CONTROL RESEARCH TOUR AT PENN STATE

The Penn State Weed Tour at Rock Springs is quickly approaching. (There will be no weed tour at the southeast research farm in Landisville this year.) The following summarizes the important information about this year's weed tour. If you would like to join us for the tour, please call fax, email, or mail in the registration form that is attached. Send no money with this registration, you will be charged for registration and lunch at the event.

Tour Agenda

July 13, 1999; 8:30 a.m. - 3:00 p.m. - Penn State Agronomy Farm, Rock Springs, PA
(Meet at the Agronomy Farm, Rock Springs, Rt. 45 west of State College; see attached map to location.)

CORN

SOYBEAN



12TH ANNUAL LIVING MULCH RESEARCH AND DEMONSTRATION TOUR - JULY 13, 1999

Sponsored by: The Pennsylvania State University; Department of Agronomy, Weed Science

We have a combination of research and demonstration plots that should be of interest to anyone who wants to know more about the use of birdsfoot trefoil/crownvetch as a living mulch. We have plots showing the establishment of both crownvetch and birdsfoot trefoil in corn and a bunch of different herbicide treatments for suppression of well-established BFT/crownvetch. For anyone just getting started with the use of a living mulch, this is your chance to see how far we've come in the last 25 years.

I would very much like for those of you who represent commercial companies and applicators to see how good the weed control is in IR/IT and Roundup Ready corn without wiping out the cover crop.es of success unless you're making that decision while watching a large storm front move in from the west.

12:00    Meeting Place and Lunch - Agronomy Research Farm, Rock Springs, PA. (Welcome by Dr. Nate Hartwig)

1:00 - 3:30   Agronomy Research Farm - This tour will follow a weed tour conducted in the morning.

Road Map

Map to PSU Agronomy Farm at Rock Springs, PA

Registration Form.


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 our webpage at: http://www.fra.cas.psu.edu/. Also, insect and insect injury images for all crops are being added to the new Agronomy Guide website. Other websites of interest include the University of Maryland's Pest Report in (http://pest.umd.edu/ipm/AgIPM/CropAndIPMReport/CropIPMReport.html). Information on insect trap data and other IPM information can be found under http://www.udel.edu/IPM/. This website contains black cutworm data from a network of 50+ pheromone traps operated by Terra Inc., Bridgeville, DE (Galen Dively). The data is for Delaware, but may provide an alert to future black cutworm injury in Pennsylvania. A website of the Maryland Department of Agriculture operated by Dick Bean has information from a network of blacklight and pheromone traps. You can access the data at ftp://ftp.mda.state.md.us/plantpro/blt/weekly/ or call 800-492-2106. Again, the information is not for Pennsylvania but can provide an alert to pending insect problems.

Corn
billbug
1st gen. European corn borer
flea beetle
sod webworm
true armyworm 		black cutworm
garden symphylan
stalk borer
white grub		 corn rootworm larvae
grape colaspis slugs
thrips
wireworm
Soybeans
bean leaf beetle
thrips		 green cloverworm potato leafhopper
Alfalfa
alfalfa weevil
spittlebug		 clover root curculio potato leafhopper
Small Grains
cereal leaf beetle true armyworm

Alfalfa weevil

Degree day accumulations indicate that the alfalfa weevil populations should be in or entering the pupal stage (cocoon) in most areas of the state. Once at least 50% of the population has entered this stage, a field is no longer at risk of injury by the pest. Check the degree day information in this newsletter for your site. If more than 500DD have been completed, then you should be beyond the period of significant injury by weevil. Only in the cooler, more northern areas should crop consultants and farmers continue to watch for weevil injury. If populations were high just prior to cutting, then check the field to make sure that late instar larvae are not feeding on developing shoots preventing rapid regrowth.

Economic threshold: 2 larvae or more per crown after cutting and less than 50% pupation (cocoons).

Black cutworm

Black cutworm larvae are entering the last three instars when they do most of their cutting. The next couple of weeks should be the key period of major cutting activity. Watch fields that are at moderate to high risk over this time period. High risk fields include corn fields that follow soybeans, those planted in areas along rivers or streams, those with significant infestations of winter annual weeds such as common chickweed, or those planted after a small grain.

Economic thresholds:
seed leaf emerged - 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 of economic importance after this stage.

Cereal leaf beetle

One oat field in southwestern Pennsylvania was reported by Gary Sheppard to have a potential infestation of cereal leaf beetle. This pest typically is not commonly a major problem, but a few fields in the southern and southwestern regions of the state have had economic infestation over the last few years. The most important damage by this pest is feeding on the flag leaf. If an infestation is feeding on the flag leaf, it usually causes enough injury to justify treatment. It is the flag leaf that provides much of the photosynthate for grain development.

Economic threshold: An average of one adult or larva per stem or flag leaf is found and damage is evident. If parasites are present and larvae are still small, the population will usually be controlled by the natural enemy.

Corn Rootworm Larvae

Within the next week, we will have accumulated enough degree days for egg hatch to begin. The pest requires about 384 DD to reach 5% egg hatch. Currently, 271 DD have been accumulated at Waterford in Erie County, 321 DD have been reached at Montoursville in Lycoming County and 407 DD have been reached in York County. Post-emergence applications of Furadan 4F should be timed to a period of 1 week before to 1 week after 5% egg hatch is reached at optimal effectiveness. This allows time for the material to move into the root zone for protection against feeding larvae.

First Generation European Corn Borer

The overwintering adults are beginning to emerge in Central Pennsylvania. These moths should begin laying eggs within the next week. The peak egg laying period is around 558 DD, which will be around mid-June. We have currently accumulated 239 DD in Centre County. At Ephrata in Lancaster County, 288 DD have been accumulated. These early flying moths will seek out non-corn hosts, because they will not lay eggs in corn until the plants reach a minimum of five leaves (V5). Some may lay in winter wheat, on apples, on potatoes and a number of weed species.

Potato leafhopper

So far, I have received no reports of potato leafhopper infestations in Pennsylvania. Watch the weather patterns over the next couple of weeks. Adults can migrate into the state on weather fronts where a low pressure system is up against a high pressure system that leads to major storm fronts. Most PLH arrive in the state on systems that arise in the Gulf of Mexico and move into the mid-west and then eastward in the Northeast. Some leafhoppers can move up the Atlantic coast and into the eastern parts of Pennsylvania. Usually the mountains block their movement westward. Start scouting fields when the regrowth is two to four inches high. If the current weather patterns continue, this may be a light leafhopper year for the second cutting.

Sod webworm

One field in York County was reported by John Rowehl as injured by sod webworm larvae. Injury by this pest is similar to that of the black cutworm (i.e. the insect cuts the plant off), but differs in that the larvae put the cut plant black into a silken tunnel. This silken tunnel is usually covered with soil particles or other residue. The larvae lives in this tunnel during the day as protection against predators and comes out at night to feed. The larvae will crawl up onto the plant and cause some leaf feeding and under dry conditions will go underground and cut off the plant. If an infestation was in the field, it can cause problems regardless of tillage system (no-till or conventional).

Larvae of the pest reach a maximum size of 3/4 inch long. They are a whitish to grayish color with pairs of black dots on each body segment. They tend to have a few long hairs on each segment. The head is a dark brown color.

Economic threshold: None have been established, so use the black cutworm thresholds.

White grubs

White grub larvae are in the late instars in central Pennsylvania. It is during this time that most of the field injury occurs. Watch corn fields that were planted into an old sod or pasture closely for injury symptoms. Injury symptoms of this pest are a general lack of vigor and wilting. In some cases, the plant will have a purplish coloration due to a restricted root system that cannot reach phosphorous in the soil. In severe cases, the plants will dry up and die.

Economic threshold: 1 or more per square foot of soil at the soil-root interface prior to planting. After planting there is no effective method to rescue an infested field. In severe cases, the field may need to be replanted.

Dennis Calvin, Entomology

Agents Corner:


CENTRE/CLINTON COUNTIES

Once again this growing season, the focus has been on the weather. During May, Centre County received about 1 1/2 inches of rain--barely enough to keep the crops growing. The corn crop--most of which was planted by the first week of May--ranges from just sprouted to about 8 inches tall. It appears to be on "hold," waiting for rain.

The soybean crop is much the same. Fortunately, the May rains helped the beans germinate, but they are not showing much growth. Weed control has been a problem in some fields, especially with perennials like burdock, curly dock and thistle.

Barley is headed and looking good. Wheat is also heading. The oat crop does not look to be on track for any kind of record. At the moment, disease problems in the small grains appear to be minimal.

First cutting of hay is mostly complete, and some good quality forage was made--thanks in part to the dry conditions. The crop was shorter than usual and regrowth has been slow.

Gary Dauberman
Centre/Clinton Counties

FAYETTE COUNTY

Corn and soybean planting proceeded very rapidly this year in SW Pennsylvania with most planting concluded by May 22, which is probably a record. Also during the week of May 17 hay harvest began and much was accomplished by Memorial Day. We are probably 50% or more harvested as of this date, June 2. To date alfalfa weevil has had minimal impact on alfalfa fields.

Corn stands look good but due to the dry weather in May, pre-emergence corn herbicides have enjoyed only moderate success. Winter small grains, barley and wheat, are looking well with limited disease and insect problems. Spring seeded oats is short and is beginning to head. Oats grain yield should be okay since significant rainfall occurred on May 22 and 23.

I was in Indiana and Ohio over the Memorial Day weekend, and there still are some soybeans to be planted. Corn size ranged from 6-7 inches tall to just emerging. From just a visual observation, it seems that there are more bean fields than corn as has been forecast. Also, it also would appear that many bean fields are no-till and Roundup ready. There are a lot of very trashy no-till bean fields awaiting treatment.

I was somewhat amazed that in NW Ohio I observed blocks of hundreds of acres of cropland not planted and no evidence that they would be planted. On Memorial Day and June 1, northeast Indiana and northern Ohio received 1 - 3 inches of rain, as did much of the corn belt. Futures dropped significantly on June 1.

Don Fretts
Fayette County

MIFFLIN/JUNIATA COUNTIES

The weather this spring has allowed field work to be accomplished at almost a record pace. Most of the corn and soybeans have been planted, with emergence of both crops taking only about 7 - 8 days. Plant stands on both of these crops look excellent. Insects appear to have taken a long winter holiday and have not shown up to cause us much damage yet.

Possible problems that may be on the horizon include weed escapes from herbicides not being "rained in" to the soil surface and moderate germination problems in some drier soils.

First cutting forage harvesting is rapidly winding up with the Memorial Day weekend being great hay weather. Yields seem to be normal to slightly above normal. Some alfalfa weevil damage was reported on a very limited number of acres. No reports of leafhoppers as of yet.

One of the most dramatic results of the weather for the last 6 - 8 months is the lack of wets spots in fields and pastures. Many fields that normally lay wet until mid to late June were planted in mid-May.

Greg Hostetter
Mifflin/Juniata Counties

MONTGOMERY COUNTY

Field work and crop growth are progressing smoothly in Montgomery County. Most of the corn is up, almost all the beans are in the ground, and the wheat has "headed-out". Much of the hay that was cut prior to the Memorial Day weekend has been baled, but there's still a bit of cutting and baling to be done and the weather is great for that.

From a young plant's stand point the weather has been lousy. It's dry down here. Montgomery County is at least three inches below its average rainfall for April and May. The rain that has fallen has only wet the surface inch or two of soil and below that it is very dry. The soils are close to, if not already at, wilting point. There is a gray cast to many of the small grains and forage crops.

A chance of showers has been prognosticated for the next three days. Although it would be nice to have an inch or two of soaking rain, a good shower wouldn't hurt.

Lou Saporito
Montgomery County

YORK COUNTY

So far everything seems to be going fairly smoothly this spring. It is getting a bit dry now but conditions were good earlier for planting. From what I have seen corn and soybean stands are in good shape. We saw some disease in wheat earlier bit the weather warmed up soon after that and I don't think disease made much progress. It was dry during pollination so scab should not be a problem. We had a few alfalfa weevil showing up but that was just as haying began. Now if only crop prices were better.....

John Rowehl
York County

Degree Day Accumulations:

1999 DEGREE DAY ACCUMULATIONS

To track corn and insect development, compare the 1999 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 May 30, 1999
    Corn Insects
County Location 1998 30-year ave. SCM/SB AW BCW CRW ECB
    50F 50F Diff 40F 48F 50F 53F 55F
Erie Waterford 312 273 39 961 484 389 271 209
Crawford Meadville 328 290 38 1031 524 424 299 231
Mercer Mercer 329 292 37 1049 534 433 306 237
Bradford Towanda 324 286 38 1029 511 411 286 219
Lycoming Montoursville 342 305 37 1120 560 455 321 248
Tioga Mansfield 310 271 39 961 477 382 264 202
Susquehanna Montrose 291 249 42 891 438 347 238 181
Butler Butler 344 308 36 1124 573 468 334 260
Indiana Indiana 341 305 35 1125 571 466 332 258
Lawrence Lawrence Jct 330 291 39 1029 523 423 298 231
Blair Martinsburg 332 296 36 1096 555 451 321 249
Centre State College 330 293 36 1074 541 438 309 239
Columbia Bloomsburg 346 310 37 1148 574 467 331 256
Clearfield Curwensville 328 291 36 1058 534 432 305 235
Dauphin Elizabethville 356 321 35 1205 606 495 354 275
Bedford Bedford 349 316 34 1188 605 494 355 278
Mifflin Belleville 346 311 35 1156 583 476 339 263
Northumberland Sunbury 358 321 36 1199 603 492 351 272
Lehigh Trexlertown 363 327 37 1242 622 508 363 283
Schuylkill Hegins 346 310 36 1157 579 471 335 259
Westmoreland Greensburg 341 306 35 1136 579 473 339 264
Somerset Somerset 311 271 39 1011 514 416 294 228
Washington Washington 358 324 34 1211 624 511 370 291
Franklin Chambersburg 370 338 32 1290 658 539 390 307
York York 381 349 33 1345 686 561 407 320
Lancaster Ephrata 362 327 35 1250 629 513 368 288
Berks Hamburg 367 331 36 1257 632 516 370 288
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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