Volume 8, Issue 1 March
10, 2000
Volume 8, Issue 1 March
10, 2000
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
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
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.
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.
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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Delaware 19947
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