Early Season Fungicide Use on Corn

Foliar fungicide applications on corn at V5/V6 are being marketed to growers in an attempt to increase corn yields.  Fungicides applications on corn have increased dramatically in the past decade, but are typically applied at tassel.  From a logistical standpoint, making an additional fungicide application at V5/V6 works well since the fungicide could be tank mixed with a post-emergence herbicide.  Work done at the University of Missouri showed no yield increase when a fungicide was applied with a post-emergence herbicide versus a post-emergence herbicide alone.  The article can be read by clicking here: http://ipm.missouri.edu/IPCM/2012/5/Considering-Early-Herbicide-and-Fungicide-Combinations-on-Corn-Results-from-a-2011-Study/   Another trial from the mid-West showed that tasseling/silking was the best time to apply fungicide. It was recently mentioned in a article on a Penn State Extension blog:  http://cmegicmlebanon.blogspot.com/2012/05/tank-mixing-fungicide-herbicide-and.html  As is most cases, the response from a pesticide application is going to be determined by the level of disease in the field.   I suggest doing on farm research in a few locations if you are interested in using a fungicide application at V5/V6 that compares no fungicide, fungicide at VT/R1, and fungicide at V5/V6 plus VT/R1.  Remember to randomize and replicate treatments in order to make your experiment successful.

Phillip Sylvester, Extension Agriculture Agent, UD, Kent County

Corn Seedling Blights

A YouTube video from Purdue University describing some of the corn seedling diseases and why they occurred this spring.  While we started dry in early April, the rain and cool temperatures that came at the end of the month was more suited for disease development.  If you suspect seedling diseases in your corn, bring a sample to your County Extension office.

 

University of Delaware Pea Twilight

Wednesday June 6, 2012    

6:00-8:00 p.m.

Carvel Research and Education Center

16483 County Seat Highway

Georgetown, DE 19947

Tour the late pea variety trial and discuss preliminary results from the early pea trial.  Hear about recent work with cover crops and no-till peas.  UD Extension personnel will be on hand to answer questions.
There will be refreshments following the tour. To register, contact Karen Adams at (302) 856-2585 ext. 540 or adams@udel.edu by Monday, June 4. For additional program information, contact Emmalea Ernest at (302) 856-2585 ext. 587 or emmmalea@udel.edu.

Armyworms in Corn

Be sure to scout for true armyworms in field corn.  They can be a destructive insect pest in corn, especially in high numbers.  Be sure to check corn fields next to un-sprayed small grain fields.  Below is from Joanne Whalen, Extension IPM Specialist, UD as written in the Weekly Crop Update:

Field Corn
True armyworms can now be found in corn fields. There have also been reports of yellow striped armyworm in fields which I have not seen before. As small grain dries down, be sure to watch for true armyworms moving out of small grain and into adjacent corn fields. You should also scout corn for true armyworms in fields that were planted into a small grain cover. Remember, worms must be less than 1 inch long to achieve effective control. The treatment threshold for true armyworms in corn is 25% infested plants with larvae less than one-inch long. Large larvae feeding deep in the whorls will be difficult to control.

Yellow Striped Armyworm in Corn.  Photo by P. Sylvester

True Armyworm in Corn Whorl.  Photo by P. Sylvester

True Armyworm Damage.  Photo by P. Sylvester.

Source:
Whalen, Joanne.  2012.  Agronomic Crop Insects-May 25, 2012.  Weekly Crop Update.  Volume 20, Issue 10.  University of Delaware Cooperative Extension.  Online.  http://agdev.anr.udel.edu/weeklycropupdate/?p=4251
Photographs by Phillip Sylvester, Extension Agriculture Agent, UD, Kent County.

Pre-Sidedress Soil Nitrate Test for Corn

Corn growth has picked up the pace with the recent warm temperatures.  Many corn fields have been sidedressed with nitrogen by now, but later planted fields still need to be done. The PSNT has been used for years in Delaware to help growers that used manure know how much nitrogen, if any, needs to be sidedressed. The test is not designed for fields where only starter and commercial fertilizer were used. Below are documents from UD the discussing the PSNT as well as guidelines for recommendations:

 

  

 

Grain Marketing Update

The grain markets have been extremely volatile, especially over the past few weeks.  Below is an update from Carl German, Extension Crops Marketing Specialist, UD:

Will Greece Stay or Go?

Uncertainty in world equity markets, dry conditions in portions of the U.S Corn Belt, needed rain in the Russian wheat region,  strengthening of the dollar, a commodity sell-off driven by non-commercial fund trading, and tight old crop corn and soybean supplies have kept market participants hopping this past week. Most notable is the commodity sell-off that occurred on Tuesday due to the EU situation that has seen the Euro decline in value and the U.S. dollar strengthen. The matter of whether Greece stays a part of the Euro or goes on its own is still pending? Either way the economic problems of the EU will not be going away anytime soon.  

Crop Progress  

U.S. corn planting was reported to be 96 percent complete, 76 percent emerged, with the crop condition rated at 77 percent good to excellent. U.S. soybeans were 76 percent planted and 35 percent emerged. The U.S. winter wheat crop was reported as 79 percent headed, with 58 percent in the good to excellent category, and 3 percent harvested. Spring wheat was reported to be 99 percent planted, 86 percent emerged, with 74 percent in the good to excellent category.

Overall, crop progress and condition ratings are well ahead of the five year average(s). However, the ink was no sooner dry on this week’s report when market analysts began expressing concerns about portions of the corn belt needing rain in order to maintain the current lofty 2012 crop ratings. We have officially entered into a weather market. Decent rains occurring over the weekend would send new crop prices tumbling while insufficient rains would send prices soaring.     

USDA Export Sales Report      05/24

Pre-report estimates called for weekly corn export sales at 35.4 to 78.7 million bushels. Total export sales of only 19 million bushels were reported with 6.1 million bushels scheduled for ‘11-‘12. This was below the 13.1 million bushels needed this week to stay on pace with USDA'S demand projection of 1.7 billion bushels. Weekly shipments of 27.1 million bushels were below the 36.1 million bushels needed this week. This report should be viewed as bearish.

Pre-report estimates for weekly export sales of soybeans ranged from 25.7 to 40.4 million bushels. Total export sales were reported at 35 million bushels with 29.4 million bushels scheduled for ‘11-‘12. This was  

well above the 1.6 million bushels needed this week to stay on pace with USDA’s export demand projection of 1.315 billion bushels. Shipments of 14.7 million bushels were above the 13.3 million bushels needed this week. This report should be viewed as bullish.

Pre-report estimates for weekly wheat export sales ranged from 14.7 to 29.4 million bushels. Total export sales were reported at 30.4 million bushels with 2.7 million bushels slated for ‘11/’12. This was above the 0.9 million bushels needed this week to stay on pace with USDA's demand projection of 1.025 billion bushels. Weekly shipments of 20.9 million bushels were below the 36.9 million bushels needed this week. This report should be viewed as bearish.

Market Strategy

Commodity prices are bidding higher in e-trade with soybeans showing double digit gains. It could be that the markets were becoming oversold or that the advancing dollar stabilized, if only briefly. The Dow is currently higher on the day at 12,523. Nearby crude is down about $20 per barrel since the first of March, now at $90 per barrel for nearby crude.

Commodity prices can be expected to remain extremely volatile over the near term. The weather and crop development are likely to take precedence over outside forces in determining whether opportunities for advancing sales are presented in the near term. Rain was reported earlier in the week to have occurred in the Russian wheat region. Traders will be paying close attention to rain events now occurring across the U.S. Corn Belt. Position squaring can be expected ahead of the three day Memorial Day holiday weekend. Currently, Dec ’12 corn futures are trading at $5.21; Nov ’12 soybeans at $12.71; and July ’12 SRW wheat at $6.71m per bushel. For technical assistance on making grain marketing decisions contact:

Carl L. German, Extension Crops Marketing Specialist, UD

What's Going On In Those Corn Fields

This is the time of year, it seems like a million things are going on, especially in the corn field.  Corn in some parts of the county has been planted for 6-7 weeks while other fields are recently planted.  No matter what stage it's in, this weekend's forecast of 80-90 degrees will encourage rapid corn growth.  Corn is a grass and responds to heat in a way that we can measure and predict leaf development.   Typically, this done using a system called modified growing degree days.  The math is simple:  Find the average daily temperature (high temperature plus low temperature and divide by two) and subtract 50.  If temperatures go over 86, then use 86 and if temperatures fall below 50, use 50.  Yesterday’s high and low were 75 and 63 so (75+63)/2= 69-50= 19 MGGDs.  From emergence to about V10, a new leaf emerges every 85 MGDD’s.   If temperatures continue on the same, a new leaf should emerge every 4-5 days.  From V10 to the final leaf, a new leaf emerges every 50 MGGD’s.  A free MGDDs calculator can be found here:  http://www.weather.com/outdoors/agriculture/growing-degree-days/19943   Like 2011 at this time, we are running about a 100 MGGDs higher than normal. This is an important concept to understand as many of our field activities revolve around growth stages in corn (i.e. postemergence herbicide applications, PSNT, sidedressing nitrogen).  

Postemergence Corn Herbicide Height Restrictions:  

PSNT (UD Recommendations):  http://ag.udel.edu/dstp/forms/Croprecs/soiltestnotes/stn14.pdf

Recommended Soil Nitrate Tests (Recommended Soil Testing Procedures for the Northeastern United States):   http://ag.udel.edu/extension/agnr/pdf/soiltesting%202011/CHAP4.pdf

Kent Conservation District Contact (The conservation will take and process PSNT’s):  http://kentcd.org/

On another note, I have received phone calls from growers with purple corn wanting to know what’s going on.  Like typical extension answers, it could be a number of things.  If it is widespread across the field and the field is planted to the same variety, then is probably “genetic.”  It’s a response to the weather conditions we had last week and not all corn contains the genes for the purple corn so this is why some hybrids stay green.  A good explanation of why purple corn is around this year can be found here:  http://www.agry.purdue.edu/Ext/corn/news/timeless/PurpleCorn.html

Don’t be too quick to write it off as genetic though (remember, it could be a number of things).  Purple corn could also be caused by insect feeding injury to the roots, low phosphorus, soil compactions, dry conditions, and herbicide carryover.   Be sure to take a shovel and dig up a few plants and take a look at the roots.  Compare to taller plants in the same field and see if the roots look healthy.  The next 2 weeks will be a busy time as herbicide applications are made, PSNT’s are taken, and nitrogen side-dressed.

Phillip Sylvester, Extension Agriculture Agent, UD, Kent County

References:

Nielson, Bob.  2012.  Prevalent Purple Plants Perennially Puzzle Producers.  Corny News Network, Purdue University.  Online.

Nielson, Bob.  2002.  Corn Growth & Development, What Goes On From Planting to Harvest.  AGRY-97-07.  Purdue University.  Online.  http://www.agry.purdue.edu/Ext/pubs/AGRY-97-07_v1-1.pdf

VanGessel, Mark and Brad Majek.  2012.  2012 Corn Weed Management Guide for Delaware and New Jersey.  University of Delaware and Rutgers University.  Online.  http://www.rec.udel.edu/weedscience/CornGuideWeb/CornWeedguide.pdf

Noxious Weeds

For the first time in more than 25 years, two weeds may be added to the noxious weeds list in Delaware:

The Delaware Department of Agriculture is proposing action to limit the spread of two weeds that are beginning to harm farm crops in southern Delaware.

The proposal to add Texas panicum and Palmer amaranth to the state’s noxious weed list has the support of the state’s Noxious Weed Committee, which includes three farmers, one from each county. It was drafted in partnership with the University of Delaware and Delaware Cooperative Extension.
The Department will begin educating farmers and landowners about how to properly control the weeds, which are problems in the South but relatively new to Delaware.

“Farmers across Delaware have been reporting increasing trouble with these two weeds,” Secretary of Agriculture Ed Kee said in announcing the proposal. “We want to get out ahead of this before they become a larger problem. Our focus is on education and helping farmers and landowners recognize and target these weeds.”

Texas panicum emerges throughout the growing season and grows rapidly, while Palmer amaranth robs plants of nutrients and moisture and can make harvesting difficult. In addition, Palmer amaranth has developed resistance to different herbicides.

“We want people to be aware of what’s going on and the proper ways to control these weeds,” said Todd Davis, noxious weeds supervisor with the Department’s Plant Industries Section. “Delaware has been relatively fortunate in the last few years, and we want to keep it that way.”

Dr. Mark VanGessel, a professor and extension specialist with the University of Delaware’s Department of Plant and Soil Science, provided advice and technical assistance.
 “These weeds can grow very quickly, so it’s important that farmers and landowners get educated, recognize the problem and work to control them,” VanGessel said. “We have been monitoring the situation very closely in Delaware over the last few years, and now is the time to take preventative action.”

The Department of Agriculture’s Noxious Weed Program assists property owners with management of noxious weeds by providing information on identification, management and weed control.  The Department also loans herbicide application equipment at no charge to farmers and other qualified individuals to help control noxious weeds, which decreases the cost to landowners.

The additions would mark the first addition to the noxious weed list in more than 25 years. Johnsongrass (Sorghum halepense) was added in 1970, Canada thistle (Cirsium arvense) in 1982 and Burcucumber (Sicyos angulatus) and Giant Ragweed (Ambrosia trifida) in 1986. Weeds on the list are not allowed to produce seed or grow more than 24 inches tall.

The proposal was published today in the Delaware Register of Regulations (http://regulations.delaware.gov/register/may2012/index.shtml). Comments and questions from the public are being accepted through May 31, and should be directed to Plant Industries Administrator Faith Kuehn via E-mail or via phone at (302) 698-4587) or Noxious Weed Supervisor Todd Davis via E-mail or via phone at (302) 698-4581.

 For additional information on the weeds, please visit the Virginia Tech Weed Identification Guide:

• Palmer amaranth: http://www.ppws.vt.edu/scott/weed_id/amapa.htm
• Texas panicum: http://www.ppws.vt.edu/scott/weed_id/pante.htm

Source:  Delaware Department of Agriculture Press Release.  Online.  http://dda.delaware.gov/pressrel/2012/shtml/050112_PlantIndustries.shtml

Postemergence Corn Products

It's time for postemergence corn herbicide applications to begin.  Below is more information from Mark VanGessel, Extension Weed Specialist, UD:

Some corn fields need to be sprayed for weeds, but the corn is only 3 to 4 collars. In many ways this is good because the corn leaves will not interfere with herbicide spray pattern and will allow for maximum control. However, that means it may be two to three weeks until the corn canopies over. So relying on glyphosate or Liberty for postemergence weed control, could run into situations of weeds emerging between the postemergence sprays and the time corn canopies over. You should consider a residual herbicide in this scenario. Be sure to read individual labels for information on maximum corn size and recommended adjuvants. The following table of products will help with your selection:

Table of Corn Herbicides

		Control of:
Herbicide1	POST activity2	Broadleaf	Morningglory	Grasses
Atrazine	Yes	Yes	Yes3	No
Callisto	Yes	Yes	No	No
Capreno	Yes	Yes	No	Limited
Halex	Yes	Yes	No	Yes
Impact**	Yes	Yes	No	##
Laudis**	Yes	Yes	No	##
NorthStar	Yes	Yes	No	No
Permit Plus	Yes	Yes	No	No
Resolve	Yes	Yes	No	Yes
Dual	No	Some	No	Yes
Prowl H2O	No	Some	No	Limited
Warrant	No	Some	No	Yes

¹Other herbicides maybe be available, but the list includes those UD Weed Extension has evaluated.
²Refers to control of emerged weeds, provided those species are susceptible to the herbicide
³Level of control depends on rate. For residual control of morningglory, rates should be at least 1.25 lbs ai/A
 ##No local data

Source: 
VanGessel, Mark. 2012. Postemergence Corn Products to Provide Residual Control. Weekly Crop Update. Volume 20, Issue 9. UD Cooperative Extension. Online. http://agdev.anr.udel.edu/weeklycropupdate/?p=4220




 

Bob Mulrooney Retirement

After 38 years with the Cooperative Extension System at the University of Delaware I will be retiring officially at the end of June and this will be my last contribution to Weekly Crop Update. After three years as the assistant county ag agent in Kent County I had the opportunity to go to Newark and take the Extension Plant Pathologist position in the fall of 1977. It has been a wonderful career and I have had the pleasure of working with great colleagues at UD and our clientele in the agronomic crops, vegetable, and ornamentals industries. I will be out of the office beginning May 18. Plant samples will continue to be handled by Nancy Gregory in the Diagnostic Clinic as in the past. If you need help with any plant disease issues contact the county Extension agents first and they can help you, or find someone who can. As for the Nematode Assay Service, I have agreed to help continue this service in retirement. The Nematode Assay Service will continue to be part of the Plant Diagnostic Clinic, which will continue to be the point of contact for those services. There will not be any soil accepted for nematode testing from May 16 until July 1. If you have any questions please contact Nancy Gregory at 302-831-1390, or our website http://ag.udel.edu/plantclinic.

The Nematode Assay Program fees for service (effective July 1) are:
· Routine nematode assay, includes enumeration of plant parasitic nematode larvae- $20
· Routine nematode assay for plant parasitic nematodes for tree fruits and grape – $25 (Counting of individuals is necessary for Xiphinema nematodes often found in these samples which takes more time.)
· Soybean cyst nematode (SCN) egg assay – $10
· Routine nematode assay plus SCN egg assay – $30

Young Corn Plant Problems

With our current warm temperatures and sunny skies, corn continues to grow at a rapid pace.  We saw a wide window of planting this year in Kent County with some growers starting in late March while others still have corn to plant (mid-May).  With a drought thrown into the mix this planting season, some fields exhibited uneven emergence.  Many other issues come with this time of year and trying to figure out what went wrong.  Below are a few links to articles on root development in young plants, a helpful worksheet for replant decisions, and a bit of humor with recipe's for a crappy stand of corn:

http://www.agry.purdue.edu/ext/corn/news/timeless/Roots.html
http://www.agry.purdue.edu/ext/corn/news/timeless/ReplantDecisions.html
http://www.agry.purdue.edu/ext/corn/news/timeless/CrappyStands.html

Source:
Nielson, Bob.  2012.  The Chat and Chew Cafe.  Purdue University.  Online. http://www.agry.purdue.edu/ext/corn/cafe/

Soybean Emergence and Germination Common Issues-YouTube

An informative video with tips on evaluating fields with emerging soybeans discussed by Wisconsin State Soybean and Wheat Extension Specialist, Dr. Shawn Conley.

 

UD Small Fruit Twilight Tour

Tuesday, May 22, 2012

6:00-8:00 p.m.
Carvel Research and Education Center
16483 County Seat Highway
Georgetown, DE 19947

Participants will have the opportunity to tour experimental plots and hear about current research on June-bearing and day-neutral strawberries, blueberries and blackberries.

Strawberry research includes plasticulture variety trials with USDA selections from the Beltsville breeding program; summer planted and overwintered day neutral varieties; spring 2011 planted, overwintered, and crown thinned day neutral varieties for summer 2012 production; use of shade cloth and reflective mulch for temperature reduction in day neutral strawberries; and root inoculant and mustard seed meal treatments for root health and soil disease management in strawberries.

Blueberry research includes a 2011 planted variety trial with southern highbush selections; a mulching material study; and a planting hole treatment study.

Blackberry plots are concentrated on evaluating primocane bearing fall fruiting varieties from the University of Arkansas breeding program.

Also featured will be insect management programs and emerging insect pests of small fruits (spotted wing Drosophila). Extension specialists and associates will be on hand to lead the tour and answer questions.

Strawberry tastings and light refreshments served.

To register, contact Karen Adams at (302) 856-2585, ext. 540 or email adams@udel.edu

For additional program information, contact Gordon Johnson, gcjohn@udel.edu, (302)-856-2585 (302)-856-2585, ext. 590, gcjohn@udel.edu

Small Grain Disease Update

Small grain disease update from Bob Mulrooney, Extension Plant Pathologist, UD:
Stripe rust in wheat has been seen in both DE and MD. The outbreaks at this time are small and for most of the state wheat is past flowering, so the impact of increased rust development at this time should be minimal. Anyone who applied a fungicide such as Tilt, Prosaro, or Caramba at boot stage or heading will have 2-3 weeks of control, depending when it was applied and when stripe rust spores arrived from the south of us. We have not seen stripe rust in our region for several years. There have been population changes in the rust and it may be more aggressive than what we have seen in the past. We would be interested to know if you see it and what varieties get infected and the severity of the infection. Initially it might be found in a small area or several small areas but if the continued rain and cooler temperatures prevail it could spread quickly. If the wheat is past flowering, check fungicide labels for timing. See the next article for more information on stripe rust and effect on yield as well as fungicide choices.

Close-up of stripe rust symptoms showing rust pustules in a line or stripe.

Stripe rust on wheat.

Several more wheat samples were confirmed with Barley yellow dwarf virus. Most of the symptoms are mild but very widespread when it is found in a field. There is little impact on yield as best we know, but there is still much to learn about this virus in this region.

Barley yellow dwarf showing reddening of flag leaf.

Wheat Disease Update
The following was written by Arv Grybauskas, Extension Plant Pathologist, University of Maryland and adapted for Delaware by Bob Mulrooney, Extension Plant Pathologist, University of Delaware

The risk of scab development this season has been very low and most of our wheat will be scab‐free or, at worst, have infection levels well below 10%. Vomitoxin levels should therefore be well below the 2 ppm threshold for acceptance at mills for most of the crop. The last few days, however, indicate that there are a couple of regions in the state that might still develop some scab. Much of the wheat in the hot spots in eastern Sussex County should be past flowering, and therefore past the label growth stage limitation for treatment with fungicides. However, there may be late planted fields or later developing varieties that can be treated. Leaf rust has been present on susceptible varieties since early spring but has been kept in check by unfavorable temperature or moisture conditions. It still has the potential to develop and spread if temperatures warm into the 80s at daytime and drop only to the mid‐60s at night as long as showers continue or dew and RH is high. Treatment of susceptible varieties may be warranted if leaf rust is present and is threatening to reach the flag leaves.
Stripe rust has also made an appearance this season. It was just confirmed in Dorchester and Caroline Counties in Maryland as well as in Delaware on Monday, May 7. These outbreaks are in small pockets (foci) in fields and their appearance is consistent with long‐distance spore transport from either NC or KY on storm fronts that came through about 2 weeks ago. Stripe rust, unlike leaf rust, requires cooler temperatures. In fact, at temperatures above 77°F lesions will stop producing spores and secondary spread is reduced, and at temperatures above 85°F the pathogen dies. The question now is, what is the potential damage and do I need to apply a fungicide? The short answer is, in my opinion, the worst‐case scenario for either rust disease (susceptible variety, and continuous disease favorable conditions through grain‐fill, and a focus of rust is present in the field now) would potentially produce a 10% yield loss. Realistically the weather will probably be less favorable sometime during grain fill so losses are more likely in the 1‐7% range (Table 1). For either rust disease it takes 7‐14 days to go through an infection cycle (infections giving rise to more spores that cause new infections) under ideal conditions. With that in mind, by the end of the grain‐fill period it is possible that the plants will look nasty (100% of the plants with 40 to 65% flag leaf severity) but between hard and soft dough stages this typically only produces 1 to 7% yield losses.

Table 1. Approximate Yield Loss in Relation to Severity of Rust on the Flag Leaf at Various Stages of Growth

Growth Stage	Flag Leaf Area Infected with Rust
	10%	25%	40%	65%	100%
Flowering	10	15	20	30	35
Milk	2	5	8	14	20
Soft dough	1	3	4	7	10
Hard dough	1	1	1	3	5

From: Hunger, B. and K. Jackson. Foliar Fungicides and Wheat Production in Oklahoma.

At this stage the only products that can be considered are triazole fungicides. The products registered for scab management, Prosaro and Caramba, are also effective against leaf and stripe rust. Rust susceptible wheat varieties that are still eligible for a fungicide application (pre‐ or just at flower) that are not at risk of developing scab may be sprayed with Folicur or a properly labeled generic tebuconazole product for rust control. Note that Prosaro, Caramba and Folicur have a 30 day Pre‐Harvest Interval as well as the growth stage restriction. Tilt has a 45 day PHI, and therefore would only be an option on earlier stage wheat where the risk of scab was low.

Source:
Mulrooney, Bob.  2012.  Small Grain Disease Updates – May 11, 2012.  Weekly Crop Update. Volume 20, Issue 8.  University of Delaware Cooperative Extension.  Online.  http://agdev.anr.udel.edu/weeklycropupdate/?p=4169

Postemergence Corn Herbicides

It will soon be time to spray postemergence herbicides in corn.  A two pass herbicide program can provide  better control of weeds than a single pass.  Below are tables on the relative effectiveness of postemergence herbicides for grasses and broadleaves.  Click on either picture to make larger.

Source:
VanGessel, Mark & Brad Majek.  2012.  2012 Corn Weed Management Guide for Delaware and New Jersey.  University of Delaware Cooperative Extension & Rutgers Cooperative Extension.  Online.  http://www.rec.udel.edu/weedscience/CornGuideWeb/CornWeedguide.pdf

Small Grain Insect Pests

Be sure to continue to scout wheat fields for cereal leaf beetle, armyworm, and sawfly damage.  Below is information from Joanne Whalen, Extension IPM Specialist, UD:

We continue to find armyworms and cereal leaf beetles in barley and wheat fields that were not treated, so be sure to check fields as soon as it is dry enough in the day to do a good job scouting. Population levels remain variable throughout the state so scouting fields will be the only way to determine if an economic level is present. Depending on the temperature, cereal leaf beetle larvae will feed for up to 3 weeks. Research from Virginia and North Carolina indicates that the greatest damage can occur between flowering and the soft dough stage so continue to sample carefully for this insect. Although armyworm can attack both wheat and barley, they can quickly cause significant losses in barley. We are also starting to see an increase in sawfly adults laying eggs in wheat fields so hatch may be delayed. Continue to sample for sawflies, especially in areas with a history of problems. Before treatment, be sure to check all labels for the days allowed between last application and harvest.

True Armyworms in a Barley Field.   Photo by P. Sylvester

Be sure to check under weeds during the day when scouting small grains for true armyworms.

Cereal Leaf Beetle.  Photo by P. Sylvester

Source:
Whalen, Joanne.  2012.  Agronomic Crop Insects – May 4, 2012.  Weekly Crop Update.  Volume 20, Issue 7.  University of Delaware Cooperative Extension. Online.  http://agdev.anr.udel.edu/weeklycropupdate/?p=4115

Photographs taken by Phillip Sylvester, Extension Agriculture Agent, UD, Kent County.

Fusarium Head Blight

The picture above is a snapshot from the Fusarium Head Blight Risk Assessment Tool.  Looking at the left side, this assessment was for Monday, May 6th.  The model is showing that some parts of Delaware are showing a medium to high risk for infection, though most parts of the state are in the low risk category.  The model puts Dover at medium risk (45%).  While this may be important for fields that are beginning to flower (Feekes 10.51), many wheat fields are beyond that stage in Kent County.

Below is commentary from the website on a similar situation developing in Maryland:

Several hot spots have developed in the last few days, where the forecasting system predicts a high to moderate risk of scab development in Maryland. Most wheat in the high risk regions in the central to southern part of MD should be past flowering. However, there may be a few late planted fields that have just reached flowering. The hot spots in the northern tier, especially in Cecil county should have wheat at or approaching flowering. The areas with a high risk forecast and wheat at flowering should consider a fungicide application. Stripe rust has also been confirmed in Dorchester and Caroline counties. If cool weather persists and frequent dew or rainy conditions develop during grain-fill, stripe rust can reach levels that will cause some low to moderate yield loss on susceptible varieties. Fungicides can only be applied to wheat up to mid-flower. The products registered for scab management, Prosaro and Caramba, are also effective against leaf and stripe rust. Rust susceptible wheat varieties that are still eligible for a fungicide application (pre- or just at flower) and are not in a scab high risk forecast area may be sprayed with Folicur or a properly labeled generic tebuconazole product for rust control. Note that Prosaro, Caramba and Folicur have a 30 day Pre-Harvest Interval as well as the growth stage restriction. Tilt has a 45 day PHI, and therefore would only be an option on earlier stage wheat where the risk of scab was low.

Written by Arv Grybauskas, Extension Plant Pathologist, University of Maryland.

To visit the Fusarium Head Blight Risk Assessment Tool, visit the top of the page or click here:
http://www.wheatscab.psu.edu/riskTool_2012.html 

2012 Wye REC Strawberry Twilight

Wednesday, May 9, 2012     6:00-8:00 p.m.
Wye Research and Education Center
Farm Operations Complex, 211 Farm Lane, Queenstown, MD
(Directional signs will be posted.)

You’ll hear University of Maryland and USDA small fruit experts discuss the current season’s challenges and the impact that the new fruit pest may have on the industry.
You’ll see: USDA Moveable High Tunnel plots with plasticulture strawberry production; University of MD Strawberry High Tunnel plots with table top production demonstration and bio-fumigation trial; and Outdoor Plasticulture Fertility Trial plots with Chandler strawberries.
Refreshments will be served.

The meeting will be held rain or shine.  Pre-registration is not necessary. For additional program information, contact Mike Newell, mnewell@umd.edu, (410) 827-7388. If you need special assistance to attend this program, please contact Debby Dant ddant@umd.edu, (410) 827-8056, no later than May 2, 2012.

Full Season Soybeans

We are reaching the end of the optimal time period for planting corn.  After May 10, we slowly begin to lose yield potential.  By May 30, it can drop to 80% of optimum yield.  Luckily, this spring has been fairly dry and allowed many growers to get corn planted in a timely manner.  While corn planting is finishing up, full season soybean planting has begun.

Full Season Soybeans Growing in Kent County (2011).  Photo by P. Sylvester

Delaware’s climate allows a wide range of maturities to be planted.   Many of the varieties planted in Delaware fall between late group 3 up to late group 4 maturity range.  Some groups 5’s are still planted in Delaware, though not as common as they once were.  Resistance to Root Knot Nematode can be found in a few group 5 varieties and are worth planting in heavily infested fields.   Maturity group 5 soybeans have a determinate growth habit which is different from the indeterminate growth of group 3 and 4 soybeans.   The main difference is that group 5’s will flower all at once while group 3 & 4 soybeans will continue to grow and flower at the same time.  For this reason, higher yields come from varieties with a maturity in the late group 3 to late group 4 range.   Soybean flowering is related to photoperiod which means flowering is triggered in part by the length of day and night length.  In Delaware, this is why group 00’s will flower when they are 4” high and group 9’s will still be dark green in November or until the frost kills them.

Soybean planting should begin any time after May 1 for optimal yields; though it would be beneficial to wait until soil temperatures reach 60 degrees for a couple of days.  Recently, a study showed that it was critical for soil temperatures 6-24 hours after planting to be above 50 degrees for proper germination.   The article can be found by clicking here:  http://extension.psu.edu/field-crop-news/archives/2012/may-1   Average soil temperatures in Dover range from high 50’s to low 60’s.  A fungicide seed treatment is recommended if planting in colder, wet soils.

Phillip Sylvester, Extension Agriculture Agent, UD, Kent County.

Touching Up No-Till Soybean Fields

Before planting no-till soybeans, it's a good idea to check the field for escapes or weeds that were not controlled with the burndown herbicides.  I have seen a few fields in the county that would benefit from a pre-plant or pre-emergence herbicide application to control the marestail.  Once the soybeans emergene, we lose many of the effective herbicides in our tool kit.  Below is an article from Mark VanGessel, Extension Weeds Specialist, on the subject:

I have had a number of calls about burndowns not being effective for no-till soybeans. Poor control can be attributed to a number of reasons, weeds were too large, gallonage was too low, and wrong products or adjuvants were used. But the question is what to do now. First determine what was not controlled. In most cases it is marestail or horseweed, and it needs to be controlled before you plant because there are not effective postemergence herbicides for it (unless you are using Liberty Link soybeans and use Liberty 280). It’s too late to rely on 2,4-D to control marestail because you need the 1 qt rate to provide effective control. The 1 qt rate of most 2,4-D products require 4 weeks before planting and in too many places sensitive plants have emerged. If you are on an appropriate soil type, Sharpen, with all the required adjuvants, is an option (see the label). Sharpen is not an option for coarse-textured soils because it also needs 4 weeks between application and soybean planting. Liberty or Ignite can be used, but it works best on days with full sun shine and requires excellent coverage (at least 20 g/A and medium droplet size). A chlorimuron-based herbicide is another option, but you need to use rates that will provide good suppression/control. Chlorimuron rates equivalent to 1.5 oz of Classic is needed (see table below). In most situations, the chlorimuron-based products should be used with a burndown herbicide (glyphosate or Gramoxone) and refer to their label for adjuvants.

Herbicide	Rate oz wt/A	Classic Rate	Other
Valor XLT	3.6	1.5	Valor
Envive	4.0	1.5	Valor + Harmony
Canopy	3.5	1.5	Metrbuzin
Canopy EX	1.6	1.5	Express

Source:
VanGessel, Mark.  2012.  Touching Up No-Till Soybean Fields.  Weekly Crop Update.  Volume 20, Issue 7.  University of Delaware Cooperative Extension.  Online.  http://agdev.anr.udel.edu/weeklycropupdate/?p=4117