Volume 8, Issue 1                                                                                                                          March 10, 2000


Issue 2 of Weekly Crop Update – March 24

The Weekly Schedule Begins – April 7,

 

Issue 1 of Weekly Crop Update is a sample of the type of information you will receive each week with a subscription or access via the Internet.  This newsletter is designed to provide subscribers with the latest information on disease and insect problems as they are developing, weed control information, crop progress reports, and other timely topics related to agronomic and vegetable crop production in Delaware.  University of Delaware Extension Specialists and Agents provide information for the newsletter.  Issue 2 will be published on March 24, 2000.  The weekly issues will begin on April 7, 2000 and continue through the month of September.  The Weekly Crop Update can be obtained by mail, fax or from the Internet at http://www.rec.udel.edu/Update00/current.htm .  If you would like to receive Update by mail or fax, the cost of subscription will remain at $30 (same as last year).  Use the enclosed form to subscribe.  If you can access the Internet, there is no charge for the newsletter. Weekly Crop Update is mailed each Friday.  If you choose to receive the newsletter by fax, it will be sent to subscribers on Friday evening.  The newsletter is placed on the Internet by 4:30 p.m. on Fridays.  We also offer to send an e-mail reminder to those of you who wish to receive one each week.  Please forward your e-mail address on the enclosed form or at my e-mail address below.  I would like to ask those of you who plan to access the newsletter from the Internet to notify me of any problems you may encounter during the season.  Please forward any comments or concerns to me at 302-856-7303 or at wootten@udel.edu .

 

 

 

 


Vegetables

 

Vegetable Insects -  Joanne Whalen, Extension IPM Specialist;  jwhalen@udel.edu

 

Seed Corn Maggot.

The first seed corn maggot flies were detected laying eggs last week. In many cases, egg laying will occur before spring tillage of cover crops can be used to help reduce potential problems. Although cool, wet conditions favor maggots, the use of manure or  plowing under of green cover crops close to planting are equally attractive to egg laying adults. In addition to spring planted vegetable crops, early planted field corn and soybeans are also susceptible to seed corn maggot attack. Seed treatments containing diazinon, chloropyrifos and permethrin provide control of moderate populations. A soil insecticide may also be needed if a number of conditions favoring maggots are present including cool, wet soil; manure use;  and green cover crops plowed down close to planting. Diazinon 50W, labeled as a planter box treatment for peas, corn and succulent beans, has provided good maggot control on these crops. It should be used at ½ oz per bushel of seed combined with ½ oz of graphite per bushel of seed to reduce friction between seeds. To reduce the chances of phytotoxicity, seed must also be treated with a fungicide and only treat seed that will be used immediately.  

 

 

Section 18 Requests and 24c Update for Vegetable Herbicides for 2000

 Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu

 

Applications for Section 18 Emergency Exemptions have been made for the herbicides listed below with the EPA, in cooperation with our Delaware Department of Agriculture.  We will notify you of their status as soon as we receive the decision on each of these materials:

 

Herbicide

Crop

Command

Watermelon

Sinbar

Watermelon

Reflex

Snap Beans

           

An application for a Section 18 for Dual on spinach will also be submitted.

 

24c Special Local Needs Labels currently exist in Delaware for:

 

Herbicide

Crop

Dual

Peppers, Cabbage

Command

Pumpkins, Winter  Squash, Summer Squash

 

Please check with your Extension Office, Ag-Chemical Dealer, and/or the label for details on all these materials before using. 

 

 

 

 


Fungicide Update for Vegetables - Bob Mulrooney, Extension Plant Pathologist, bobmul@udel.edu

 

The following are some recently or newly registered fungicides for 2000. Specific use information can be found in the 2000 Commercial Vegetable Production Recommendations E.B. 137.

 

Acrobat MZ 69WP - Labeled on potatoes for the control of Late blight. It is recommended for use once the disease is detected in the region. Use mancozeb as a protectant fungicide until Late blight

appears in the region, and then switch to Acrobat MZ.

 

Armicarb 100 85WP – A broad-spectrum fungicide (formulated product is similar to baking soda) that is labeled for control of a variety of diseases on vegetable crops (Cucurbits, peppers, cabbage,lettuce, potatoes, sweet potatoes and tomatoes). Most of the research associated with this fungicide has been with the control of Powdery mildew on cucurbits.

 

Champ Formula 2 Flowable - A supplemental label is now in place that allows the use of Champ Formula 2 Flowable at the rate of 1 1/3 pt/A on spinach to control Anthracnose, Cercospora leafspot, Downy mildew and White rust. In 1999, growers had to sign a waiver to use the product. The waiver is no longer required in 2000.

 

Flint 50WDG – New fungicide for control of Powdery mildew on cucumbers, muskmelons, pumpkins & winter squash, summer squash

and watermelons.

 

Mancozeb – There are a number of fungicides on the market that contain mancozeb as the active ingredient. These include: Dithane DF Rainshield NT, Dithane F-45, Dithane M-45, Manex II, Manzate 75DF, Manzate 80WP, Penncozeb 75DF and Penncozeb 80W. Any one of these fungicides can be used for disease control when mancozeb is

listed as the recommended fungicide in the 2000 Commercial Vegetable Production Recommendations. However, only Dithane Rainshield NT and Penncozeb are listed in the book. The other

mancozeb fungicides should have been listed in the book, and will be added to the 2001 recommendations book.

 

Quadris 2.01F – In addition to tomatoes, it is now labeled on cucurbits (cucumbers, muskmelons, pumpkins & winter squash, summer squash and watermelons) for control of Anthracnose, Belly

rot, Downy mildew, Gummy stem blight, Leaf spots and Powdery mildew.  It is also labeled on potatoes for control of Early blight and Late blight.

Taken from Plant & Pest Advisory Rutgers Univ. written by Steve Johnston.

 

 

 

 

 

 


Field Crops

 

 

Field Crop Insects - Joanne Whalen, Extension  IPM Specialist ; jwhalen@udel.edu

 

Seed Corn Maggot.

The first seed corn maggot flies were detected laying eggs last week. In many cases, egg laying will occur before spring tillage of cover crops can be used to help reduce potential problems. Although cool, wet conditions favor maggots, the use of manure or  plowing under of green cover crops close to planting are equally attractive to egg laying adults. In addition to spring planted vegetable crops, early planted field corn and soybeans are also susceptible to seed corn maggot attack. Seed treatments containing diazinon, chloropyrifos and permethrin provide control of moderate populations. A soil insecticide may also be needed if a number of conditions favoring maggots are present including  cool, wet soil; manure use;  and green cover crops plowed down close to planting. Diazinon 50W, labeled as a planter box treatment for peas, corn and succulent beans, has provided good maggot control  on these crops. It should be used at ½ oz per bushel of seed combined with ½ oz of graphite per bushel of seed to reduce friction between seeds. To reduce the chances of phytotoxicity, seed must also be treated with a fungicide and only treat seed that will be used immediately.

 

Field Corn.

Since there are no rescue treatments for most soil insects in field corn, understanding the factors that favor soil insect populations can help in making a treatment decision.

 

White Grubs – In general, grubs are favored by a number of factors including planting into double crop soybean stubble, old sod, hay, pasture or set-aside acreage. Although populations going into overwintering were high last fall, frozen soil conditions in January and early February as well as wet soil conditions may help to reduce population levels. The most accurate way to measure the potential for a grub problem is to sample fields for grubs before planting but it should be done before a field is tilled. The most accurate results will be obtained when the soil temperatures at 6-inches deep are at least 45 degrees F. At each site, sample one square foot of soil dug six inches deep. One to two samples should be taken for every 10 acres with no less than 10 samples per field. A treatment is recommended if you find 1-2 grubs per foot in heavy soils or 0.5 – 1 grubs per foot in sandy soils. Soil insecticides need to be placed in-furrow to get effective grub control. Counter, Force or Fortress will provide effective control. The highest labeled rate should be used if populations are heavy.

 

Wireworms – High organic matter content, sod covers, and heavy grass weed pressure the previous season all favor wireworm populations. Fields having a combination of high organic matter and heavy grass weed pressure are the most susceptible to damage. Wireworm larvae spend multiple years in the larval stage and the larvae move up and down in the soil profile following moisture gradients. Therefore, good control is often difficult to achieve. Seed treatments containing lindane or permethrin will control larvae feeding on the seed when population levels are low to moderate. They will not control larvae that have moved to the growing point of a plant and started to feed. If population levels are high, a seed treatment plus a soil insecticide may be needed to prevent larvae from boring into the growing point and killing plants. Similar to grubs, soil insecticides need to be placed in-furrow to get effective control. Counter, Force or Regent applied at the higher end of the labeled rate have provided wireworm control. If Regent is used, fields cannot be planted to leafy vegetables for one month, root crops for five months, or small grains and other rotational crops for 12 months following application.

 

Black Cutworm – This insect is favored by late planting, broadleaf weed growth (especially chickweed) present before planting into soybean stubble, poorly drained fields and reduced tillage. Rescue treatments can be applied for this soil insect if you are able to scout fields twice a week once leaf feeding is detected. If you are unable to scout and you have conditions favoring cutworms, a pyrethroid (Ambush, Asana, Pounce or Warrior) tank mixed with a herbicide applied close to planting has also provided effective control. Force, Lorsban and Fortress are labeled for cutworm control but must be applied as a T-band to be effective.  Pheromone traps placed in the field by mid-March can be used to determine when to look for cut plants as well as areas of the state most likely to experience economic levels. Look for pheromone trap counts (provided in 2000 by UAP) in future reports.

 

 

Wheat.

Aphids – Although we do not have a clear picture of the distribution of Barley Yellow Dwarf Virus (BYDV) in the state, aphid management can play a part in reducing losses from BYDV. Weather conditions were mild last fall through early winter resulting in high aphid populations in some wheat fields, especially in early planted fields. The two most important times to control aphids to help reduce problems from BYDV are the first 30 and 60 days after plant emergence. We know that warm fall and winter weather can favor aphid development. However, last summer’s drought which was detrimental to our crops was also hard on aphids.  In some cases, aphids arrived late to wheat fields. The cold winter weather in January and February reduced winter aphid movement, reproduction, and spread. Additionally, it appears that a large proportion of the aphid population was killed. As a rule of thumb, temperatures below 30 degrees F result in significant aphid mortality. While sampling fields last week for aphids, we found very low levels of aphids. It was also good to see that parasites were already active in fields. With the predicted warm up, fields should be scouted for aphids and beneficial insect activity by mid-March. In late winter to early spring, the treatment threshold of 150 – 200 aphids per foot of row should be used. However, if you have a history of BYDV in your area and localized populations are causing stand reductions, treatment may be needed at 10-15 aphids per foot of row. Information from Kentucky indicates that there is generally no yield impact after Feeke’s growth stage 4 ( stem elongation). Whether you decide to spray or not, remember the BYDV you see this spring is probably a result of what happened in the fall. Warrior, dimethoate, Lannate and Penncap will provide aphid control. Dimethoate will provide poor control if temperatures are below 60 degrees F. Trials in the south indicate that Warrior will provide more residual control. 

 

Hessian Fly – A combination of mild fall conditions, volunteer wheat, and early planted fall cover crops could result in heavier Hessian fly populations this spring.  While scouting fields during the next couple of weeks, do not rule out Hessian fly damage if stands are reduced and you find weakened or dead tillers. Fall infestations affect yield by reducing the number of live tillers per unit area. Spring infested plants have weakened stems, which can lead to stem lodging and poorly filled, smaller grain heads. If 20% or more of the tillers are infested, significant yield loss can occur and you may not get the return from your nitrogen applications. When populations were high in 1998, fields with low tiller counts (from fall infestations) or greater than 50% lodging (from spring infestations) were abandoned before spending more money on inputs. Although no rescue treatments are recommended at this time, you may hear reports from North Carolina regarding Warrior treatments aimed at early fly egg laying. This is not a recommended practice in North Carolina but an attempt to deal with a very serious problem. My colleagues in North Carolina believe insecticidal control will be an “uphill battle” since larvae move deep into the developing tiller. We will also attempt to evaluate this treatment timing in infested fields in Delaware.  

 

 

 

Time To Start Thinking About Small Grain Weed Control -Mark VanGessel, Extension Weed Specialist ; mjv@udel.edu

 

If you are use to spraying your small grains in late March with a herbicide, you may want to check your fields now.  With the warm weather, a lot of the weeds have been growing as well as the wheat.  The temperatures have been warm enough for the weeds to grow, and so the herbicides will be taken up by the plant and control them.  Fields that were no-tilled or chickweed emerged shortly after planting in the fall are fields to check first for spring treatment.  If you have wild garlic or Canada thistle the time of application should be delayed since you need to spray these weeds when they have fully emerged.  Coverage is important for these species.  If weed pressure from winter annuals is great, it may not be possible to get control of the winter annuals and perennials with one application.  In that case two applications maybe required.  You can mix your Harmony Extra with nitrogen.  If spraying Harmony Extra with nitrogen, be sure to pre-mix it in water first.  With nitrogen, there is no need for a surfactant unless wild garlic is over 8 inches tall.  Applying Harmony Extra in nitrogen diluted with water, use a non-ionic surfactant at ½ to 1 pint/100 gallons of solution.  If applying it in water, use non-ionic surfactant at 1 qt/100 gallons.

 

Finally, have you considered resistance management with your small grains?  Most of the small grains get treated only with Harmony Extra, which contains two ALS-inhibiting herbicides (same type of herbicides as Pursuit, Accent, Classic etc).  Many weeds have developed resistance to herbicides that have this mode of action.   Consider how often a field is planted to small grains and how often it gets treated with Harmony Extra.  If this rotation is short, 3 years or less, consider tankmixing another herbicide with Harmony Extra to minimize the risk of developing herbicide resistant weeds.

 

 

Early Burndown In No-Till Fields -Mark VanGessel, Extension Weed Specialist ; mjv@udel.edu

 

Using an early burndown herbicide (Gramoxone Extra, Touchdown, Roundup, or a generic glyphosate product) in no-till fields makes sense in a number of situations.  First, it means less vegetation and the soils warm up sooner, less plant matter to worry with at planting, and the weeds will be smaller and more sensitive to herbicides.  Keep in mind a second spray will be needed at planting.  But do you need a residual herbicide?  Generally not.  In corn you may want to include Princep so that there is a greater chance for rain to incorporate the herbicide.  However, the earlier you spray before planting, the shorter amount of residual you will get in corn.  Generally, using a residual herbicide with your early burndown does not improve control of the weeds that are emerged, since those weeds are small and very sensitive to herbicides.  Most of the residual herbicides being promoted will not provide broad-spectrum residual control so a second application of a burndown herbicide is needed at planting anyway.  In most cases, a residual herbicide with early burndown herbicides is not worth the additional expense.

 

 

 

 

 

New Weed Control Guides Are Available – They Are Free -Mark VanGessel, Extension Weed Specialist ; mjv@udel.edu

 

Available from your county extension office are two weed management guides for assistance in weed control in corn and soybeans.   The first half of each guide deals with soil-applied herbicides and the second half is for postemergence herbicides.  These guides have pre-mixes and what is in the pre-mix, expanded weed control tables, information on application timing, comments for each of the herbicides, and much more.  Contact your county extension office for these free guides. 

 

 

  

 

 

 

 

 

 


Field Crop Diseases  - Bob Mulrooney, Extension Plant Pathologist ; bobmul@udel.edu

 

Soybeans.

Soybean cyst nematodes. It is not too late to soil test for the soybean cyst nematode (SCN). If soybean stubble is present, sample with a soil probe 6-8 inches deep between the plants in the row.  Sample size should be 20-25 cores taken in a zig-zag pattern across the field. Ideally samples should represent no more than 10-20 acres. Sample bags and information sheets are available from the county extension offices. The cost is $10 per sample. New fields and those to be planted with susceptible varieties are the most critical to sample at this time.

 

Keep in mind, that Roundup Ready varieties do not have resistance to race 1 of the soybean cyst nematode (SCN) but carry some resistance.  This makes monitoring SCN populations more important if you are growing continuous soybeans and using Roundup Ready varieties. Periodic sampling can indicate if SCN populations are increasing. Variety trial results are available from the county Extension offices so you can choose the best variety for your situation.  Make use of this information.

 

Without aggressive management such as planting SCN-resistant varieties and rotating with non-host crops, yields can be reduced by 75 percent or more in hot, dry growing seasons.  

 

 

 

 

 

 


Early Planting Beans  - Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu

 

What do I mean by early-planted soybeans?  I am talking about planting group IV and V soybean varieties in late April or the first week of May and group III varieties in early to mid-May.

 

Why plant so early?  Early-planted beans have a higher yield potential than beans planted the usual time of early June.  In fact, beans often yield 5 to 15 bu/A more than traditionally planted beans, depending on the growing season, when beans are planted this early.  Early-planted beans also mature on schedule while June-planted beans and especially the later maturing varieties often do not mature until at or after the first-killing frost in the fall. 

 

Do you need to worry about late spring frosts killing early-planted beans?  In general, this should not be a problem.  In a study that Bob Uniatowski and I conducted, beans planted on April 15 tolerated a frost on May 7 one year that killed corn in a nearby field.  Other agronomists also have noted cold tolerance in young soybean plants.

 

There are several cautions that I should mention.  If you’re still planting corn, it may be more time consuming and costly to switch to soybeans and may delay finishing the rest of your corn acreage.  You should try this first on a limited number of acres to see how it fits into your program.  Vary your planting dates and variety maturity selections to reduce your risk of one dry spell hurting the yields of all your bean acreage.  If you try early-planted beans, consider using beans that have been treated with either Captan and thiram or Apron if the following conditions occur.  The field has a history of Pythium problems, it will be planted no-till and soil conditions are wet and cold, or it will be planted conventional but you expect the field to stay wet and cold for some time.

 

 

Hay and Pasture Fertilization -

Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu

 

With the onset of spring weather, it is time to think about applying nitrogen to boost the spring hay crop or stimulate pastures for early grazing.  For hay fields and pastures that are less than 25 percent clover or alfalfa, you will need to apply at least 50 lb N per acre to get strong vigorous grass growth this spring.  If you are growing a mixed legume: grass hay or pasture and it contains less than 50 percent legume, an addition of 25 lb N per acre will stimulate your grass while not placing your legume at too much of a disadvantage.  If the fields are more than 50 percent legume, no nitrogen fertilization will be needed since the legume will fix atmospheric nitrogen.

 

If you do not have an up-to-date soil test available for your fields, you may want to pull soil samples now so you can determine the phosphorus and potash needs of your hay or pasture crop before your first cutting or grazing.  That way you will know what fertilizer to apply to prepare the crops for the coming summer stresses.

 

 

 

 

 

 


Grain Marketing Highlights - Carl German, Extension Crops Marketing Specialist ; clgerman@udel.edu

 

U.S. Soybean Acres to Increase
USDA is scheduled to release its Prospective Planting Intentions Report on March 31 and speculation has it that we can expect an increase in the acreage estimated to be planted to soybeans during the 2000 cropping season. Private forecasters call for U.S. soybean planted acreage estimates to come in anywhere from 72 to 75 million acres. Acreage has been migrating to soybeans the past few years, partly due to the loan rate for soybeans being relatively high compared to corn and wheat (in the Midwest) and partly due to farmers shifting to a 50/50 corn/soybean cropping rotation. Last year 72.5 million acres were harvested from a planted crop of 73.8 million acres. Ending stocks of 345 million bushels, a yield of 36.5 bushels per acre, and a stocks/useage ratio of 13 % resulted in a season average price for the 1999/2000 marketing year of $4.50 to $5.00 per bushel.

 

The next USDA supply and demand estimate will be released on Friday, March 10th and speculation is that we may see a reduction in the soybean carryout based upon an increase in soybean exports. Any sales decisions for new crop soybeans should be placed on the back burner. The loan rate for soybeans at $5.36 per bushel should be used as a 'free put' for new crop soybeans.

 

 

 

 

 

 


2000 Pest Management Recommendations for Field Crops and the 2000 Commercial Vegetable Recommendations Guide Available at Local Extension Offices

 

 

  

 

 

You may obtain copies of the Pest Management Recommendations for Field Crops and the Commercial Vegetable Recommendation Guide from your local county Extension office or by mail from the Research & Education Center in Georgetown.  The cost of the Pest Management Recommendations for Field Crops is $10.00.  The cost for the Commercial Vegetable Recommendations Guide is $7.00.  Please use the enclosed form and  make checks payable to “University of Delaware” and allow one week for the delivery of the books.

 

 

 

 

 

 


UPCOMING MEETINGS:

 

 

Monday, March 13, 2000

GRAIN MARKETING, Understanding "Put" Options, NCC Extension Office, 910 So. Chapel St. (Rt. 72), 7:00-9:00 pm. The basics of "Put" Options.  For More Information,contact Carl Davis at 302-831-2506 or cpdavis@udel.edu.

 

Tuesday, March 14, 2000

NUTRIENT MANAGEMENT, An Overview from the Program Administrator, Comments from a NCC member of the Nutrient Management Commission, and Techniques for Addressing the new Nutrient Management Guidelines, ChesDel Diner, 7:30-9:30 am. Breakfast on your own (optional).

If you …operate an animal operation in excess of eight animal units (an animal unit = 1,000 pounds of live weight), or …apply nutrients (any type) to lands in excess of 10 acres or waters as components of a commercial venture or lands that you own, lease, or otherwise control, you will be affected.

For more information, contact Carl Davis at 302-831-2506 or cpdavis@udel.edu.

 

 

 

 

March Pesticide Applicator Training Session & Exam

March 13&14, New Castle County Extension Office, Newark, DE  302-831-2506

March 21&22, U of D Research & Education Center, Georgetown, DE 302-856-7303

March 29&30, Kent Country Cooperative Extension Office, Dover, DE  302-697-4000.

 

Day 1: training 8:30 a.m.-4:00 p.m.

Day 2: training 8:30 a.m.-Noon

Day 2: Exam starts at 1:00 p.m.

 

 

 

 

 

 

 

 


Weather Summary

Week of March 1 to March 8

Rainfall:

None

Readings taken for the previous 24 hours at 8 a.m.

Air Temperature:

Highs Ranged from 81 °F on March 8 to 51 ° F on March 3.

Lows Ranged from 49 °F on March 8 to 26 °F on March 4.

Soil Temperature:

48°F average for the week.

(Soil temperature taken at a 2 inch depth)

 

 

 

 

Compiled & Edited By:

Tracy Wootten

Extension Associate - Vegetable Crops

 

 


Cooperative Extension Education in Agriculture and home Economics, University of Delaware, Delaware State College and the United States Department of Agriculture cooperating, John C. Nye, Dean and Director.  Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.  Is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, sex, disability, age or national origin.


 

 

 

 

 

 

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                                    Georgetown, Delaware  19947

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