Volume 8, Issue 2
March
24, 2000
Reminder…
The Weekly Schedule Begins –
April 7
If
you would like to continue to receive Weekly Crop Update for the rest of the
growing season, please fill out the blue form enclosed with this issue. 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). If
you can access the newsletter via the Internet, there is no charge. 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. If you received an e-mail reminder in 1999, I will still
need to hear from you for 2000. Please
forward any comments or concerns to me at 302-856-7303 or at wootten@udel.edu Thank you.
Vegetables
Vegetable Insects - Joanne Whalen, Extension IPM
Specialist; jwhalen@udel.edu
New
Insecticide Registration: Danitol 2.4 EC insecticide/miticide from Valent recently received a
supplemental label for additional uses for a number of crops grown in our area
including apples, grapes, head and stem brassica, melons, pear, strawberry and
tomato. During the past two seasons, we have tested this pyrethroid insecticide
in our spider mite trials on melons. It will provide a good rotational material
with Agri-Mek. The use rate for mite control on melons is 10 2/3 oz per
acre.
Pea Planting Progress and
Weed Control –
Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu
Pea planting moved along smoothly with good weather until the rains of March 21 and 22. Peas are starting to emerge from the earliest planted fields. It is important to check fields early for emerging weed problems. The only post-emergence herbicide for broadleaf weeds in peas is Basagran. Basagran is more effective when the weeds are small.
Basagran
can be applied 1.5 to 2 pints per acre.
Do not use crop oil or any other additives with Basagran when sprayed on
peas. Check the label for details.
Phosphorus on Peas – Ed Kee, Extension Vegetable Crops Specialist;
kee@udel.edu
Last year we conducted a strip test in a commercial
field of peas to measure response to phosphorus when the soil test was high in
Phosphorus. The plots were over 1,000
feet long and replicated six times. We
compared zero phosphorus versus 78 pounds of P2O5
broadcast before planting. All other nutrients
were the same. Yields and tenderometer
readings were equal, and the phosphorus content in the leaf tissue samples were
exactly the same.
This
trial was planted on April 8, near Lewes, with the variety ‘Early Freezer
680’. Nitrogen was applied at 70 pounds
per acre for each treatment.
With no response in yield, maturity, or tissue content, it suggests that fertilizer applications of phosphorus on peas when the soil test levels are high are not necessary.
Winter Temperature Index For Predicting Stewart’s Wilt in Sweet Corn 1993-2000
- Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu
Corn
flea beetles are the overwintering host and vector of Erwinia stewartii, the bacterium that causes Stewart’s wilt. Winter survival of the flea beetles can be
predicted using a winter temperature index which is calculated by adding the
average temperature for Dec., Jan., and Feb. Flea beetles do not survive well
when the average temperature is below 27oF for any month. If the
temperature is above 33oF, flea beetles may be present in early
plantings of sweet corn. The occurrence of Stewart’s wilt on early-planted
sweet corn usually corresponds with the ability of flea beetles to overwinter.
The following table shows that overwintering is very likely again in Delaware
and the prediction would be for a severe Stewart’s wilt season.
Fortunately
for Delaware growers resistant varieties of sweet corn have been available for
most processing sweet corn. A dependable level of resistance in fresh market
sweet corn has been more elusive. Despite years of favorable flea beetle
overwintering, we continue to have few losses from Stewart’s wilt. Why? Growers
have planted resistant varieties and have effectively used the insecticides
that have been available. Growers need to continue to plant the most resistant
varieties available and scout sweet corn for flea beetles and treating with
insecticides when thresholds are exceeded. The use of seed treatments to
control flea beetles is another avenue that is being carefully examined and
research is currently underway to see if it will be of value to Delaware
growers.
Average monthly temperatures
in oF at Georgetown, DE
REC. 1993-2000.
1999-2000
1998-99 1997-98 1996-97
1995-96 1994-95 1993-94
December
40.3 41.3 39.3 42.0 33.5
43.0 36.5
January
33.9 39.5 42.6
35.0 33.5 39.0 29.5
February
39.7 38.7 40.6
41.5 34.7 33.8 36.0
INDEX
113.9
119.5
122.5
118.5 101.7
115.8
102.0
Severity Index: < 90,
usually absent; 90-100, intermediate; >100, usually severe.
Field Crops
Field Crop Insects - Joanne Whalen, Extension IPM Specialist ; jwhalen@udel.edu
Wheat.
During
the last week in March and the first week in April, begin to watch wheat fields
for the presence of cereal leaf beetle adults.
(Picture by Marty Spellman)
Adults are small beetles, 5 to 6 mm in length. The head and wing covers of the adult beetles are a metallic blue-black and the area behind the head reddish brown. Although we do not spray for adults, they are a good indication that egg laying will soon begin. In recent years, the threshold for cereal leaf beetle has been adjusted to include sampling for eggs, especially in high management wheat fields. The eggs are elliptical, about 1/32 inch
(Picture by Marty Spellman)
long,
orange to yellow in color when first laid changing to a burnt orange prior to
hatching. Generally, eggs are laid singly or in small scattered groups
(end-to-end) on the upper leaf surface and parallel to the leaf veins.
You will find most of the eggs within 22 to 4 ½ inches of the main stem. For high management fields, the threshold is based on the presence of eggs and small larvae. Cereal leaf beetle larvae are brown to black, range in size from 1/32 to 1/4 inch long, and eat streaks of tissue from the upper leaf surface. Since cereal leaf beetle is often unevenly distributed within the field, it is important to carefully sample fields so that you do not over or under estimate a potential problem. Eggs and small larvae should be sampled by examining 10 tillers from 10 evenly spaced locations in the field while avoiding field edges. This will result in 100 tillers (stems) per field being examined. Eggs and larvae may be found on leaves near the ground so careful examination is critical. You can also check stems at random while walking through a major portion of the field and sampling 100 stems. In high management fields with good yield potential and/or where the potential for cereal leaf beetle problems is high, the threshold of 25 or more eggs and/or small larvae per 100 tillers should be used. If you are using this threshold, it is critical that you wait until at least 50 – 60% are in the larval stage (i.e. after 50% egg hatch). If the egg/larvae threshold is not used, the threshold of 0.5 larvae per stem and 10% defoliation can provide enough lead-time to provide good control if fields are scouted on a routine basis. A number of products are labeled for cereal leaf beetle control. Sevin will provide good control although experience in 1996 demonstrated that it could result in aphid explosions by reducing predator populations. Furadan provides good control; however, it can not be applied once grain is heading. Lannate and Warrior provide good control of the entire insect complex present in small grains (cereal leaf beetles, aphids, armyworm and grass sawfly). If you are using the egg threshold, Warrior may be the best option due to its longer residual nature. Warrior is still only labeled on wheat.
![]() |
Winter Wheat – Did This Week’s Heavy Rain Affect Nitrogen Availability? - Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu
Many
are probably wondering what effect this week’s rainfall had on the amount of
nitrogen available to their winter wheat crop.
The answer is not necessarily clear since it can be influenced by many
factors. Factors can include how
recently the nitrogen was applied, how much was applied, whether nitrogen will
be applied in multiple applications, what form the nitrogen was in, how large
the wheat plants were, how much applied nitrogen was taken up by the wheat,
temperature, soil type (top soil and subsoil), and many more. Certainly late-planted wheat growing on
sandy soil that was topdressed very recently will be most at risk if a split
application was not planned.
Is
there anything that can be done other than waiting and watching for nitrogen
deficiency symptoms to appear? A wheat
tissue test can be taken around Feekes growth stage 4 or 5 which is after full
tillering and when the leaf sheaths begin to lengthen (Feekes 4) or when the
leaf sheaths are strongly erect (Feekes 5).
The closer you sample to Feekes 5 the more accurate the test is for
predicting whether the plant has optimum N uptake for maximum economic
yield. If you make arrangements with a
commercial lab ahead of time, turnaround time is minimal and the results can be
faxed to you or you can call in for the results so there will be time to apply
a final nitrogen application if called for by the tissue test.
To
take a tissue test, you need to obtain a good plant tissue sample about the
size of what can be held in one hand.
The process is similar to taking a good soil sample. Unusual areas of the field should be
avoided. A tissue sample is taken by
cutting a handful of wheat at 20 to 30 representative areas across a
field. The top growth should be cut
about ½ inch above the soil line and all soil particles and dead leaf tissue
should be removed. Place the samples in
a large, clean paper bag and mix the total sample after collection. Take about three handfuls of the mixed
sample and place it in a clean paper bag or in the sample bag provided by the
laboratory. Ship samples as quickly as
possible to the lab, do not store longer than 24 hours after collection, and
never package tissue in plastic bags.
For
interpretation when the tissue nitrogen level is determined, use the following
guidelines from Virginia. If the
percent nitrogen is 4.85 or higher, no additional fertilizer is needed. At 4.5 percent, apply 15 lb N/A. At 4.0 percent, apply 35 to 40 lb N/A and at
3.5 percent apply 60 lb N/A. Finally,
at 3.0 percent, a full shot of 80 lb N/A will be needed.
Weeds resistant to ALS-inhibiting herbicides have
been identified in Maryland and there are suspected fields in Delaware. These fields have had a history of repeated
use of the same herbicide (mostly Pursuit).
All ALS-inhibiting herbicides work on the same enzyme in the plant,
these herbicides are very specific to this one enzyme (acetolactate
synthase, hence ALS-inhibiting herbicide). Furthermore, these herbicides have
soil-activity as well as foliar-activity so the weeds are exposed to the
herbicides over a period of time.
Usually weeds resistant to one ALS-inhibiting herbicide are often
resistant to other ALS-inhibiting herbicides even though the second herbicide
has never been used in the field. This
is referred to as “cross-resistant”.
Take home message is do not use herbicides repeatedly with the same mode
(or site) of action in the same field.
Do not make more than two consecutive applications of herbicides with
the same mode of action to the same field unless other effective control
practices are included in the management system.
A list of ALS-inhibiting herbicides follows. Prepackaged mixtures with ALS-inhibiting
herbicides are also given with the specific herbicide in parenthesis. Some prepackaged mixtures contain more than
one ALS-inhibiting herbicide.
Corn
Herbicides |
Soybean
Herbicides |
Others |
Python Accent Beacon Permit Pinnacle |
Classic FirstRate Pinnacle Pursuit Raptor Scepter |
Harmony Extra Matrix |
Premixes: |
Premixes: |
|
Basis (Pinnacle/Matrix) Basis Gold
(Accent/Matrix) Bicep Magnum TR ( Python) BroadstrikeSF+Dual (Python) Celebrity Plus (Accent) Exceed (Beacon and Peak) Hornet (Python) Lightning (Pursuit/Arsenal) NorthStar (Beacon) Scorpion
III (Python) Spirit (Beacon/Peak) |
Backdraft (Scepter) Broadstrike+Dual
SF (Python) Broadstrike+Treflan (Python) Canopy (Classic) Canopy XL (Classic) Detail (Scepter) Extreme (Pursuit) Pursuit Plus (Pursuit) Squadron (Scepter) Steel (Pursuit/Scepter) Synchrony STS (Pinnacle/Classic) Tri-Scept (Scepter) |
|
REMINDER…
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. There is a separate guide
for 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.
Grain
Marketing Highlights - Carl German, Extension Crops Marketing Specialist ; clgerman@udel.edu
Drought
Concerns Become Major Factor in Commodity Markets
Until recently, the futures market has paid little attention to the fact that
most of the U.S. soybean and corn cropping area has been precipitation
deficient since the beginning of July 1999. A substantial amount of snow and
rain normally accumulates over the corn belt
through the fall and winter months. The moisture shortage is probably
due to the ongoing effects of the La Nina weather phenomena. In any event, the
opportunity to substantially correct 'subsoil' moisture conditions has probably
passed. Recent rains and snows have been sufficient only to marginally improve
'topsoil' moisture.
Topsoil moisture conditions may be expected to improve over the month of April
as the planting season approaches.
However, it is unlikely that enough precipitation will be received to amend
subsoil moisture conditions (the jury is still out on the overall effect on the
corn belt of this weeks rains, however, large areas in corn belt states such as
Illinois, Indiana, Iowa, Nebraska, and Ohio are in need of substantial rainfall
in order to alleviate drought concerns). The lack of subsoil moisture will make
timely rains during the growing season much more important than usual. Repeated
news service stories about these conditions will increase the markets focus on
new crop corn and soybean growth and development. The resulting news "over
play" will expand speculative activity in the commodity markets.
Considering comparisons to other drought years('56,'76, and '88) and trend line
yields, the range in the national corn yield estimate is from 103-134 bushels
per acre. Applied to a ball park harvest figure of 70 million acres, gives a
total corn crop of 7.14-9.45 billion bushels.
Demand is estimated at 9.65 billion bushels for the year, so the
situation we are in now indicates a mildly bullish price outlook.
Market Strategy
Local forward cash pricing opportunities for new crop wheat and soybeans
continue to be below the 2000 loan rates ($2.67 for wheat; and $5.36 for
soybeans). No forward cash sales are warranted at this time.
Initial pricing decisions for new crop corn have been completed. Considering the potential for drought in the
corn belt and the fact that drought is normally not mentioned this early in the
marketing year, no further sales are warranted at this time.
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:
March Pesticide Applicator
Training Session & Exam
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.
Poultry Grower Informational
Meeting:
“Your Responsibilities Under Delaware’s Nutrient
Management Law”
Tuesday,
April 4
Gumboro Fire House
Gumboro, DE
7:00 – 9:00 p.m.
Thursday,
April 6
University of Delaware
Research & Education Center
Georgetown, DE
7:00 – 9:00 p.m.
If
you are a poultry grower in Delaware with more than 3,200 broilers or if you
use poultry manure in your farming operation, in the near future, you will be
required to implement an animal waste management plan or a nutrient management
plan. Members of the Nutrient
Management Commission (including poultry growers representing your interests on
the Commission) along with the program administrator and University Cooperative
Extension Personnel will present details of the law and answer your
questions. More important, this is an
opportunity for you to express your views on details of the regulations as they
are being developed.
This
informal program will provide information on and answers to:
Ø
An
introduction to the Delaware Nutrient Management Commission and what it does.
Ø
Review
of the Nutrient Management Law.
Ø
As
a grower, if you need an animal waste management plan or a nutrient management
plan.
Ø
What
will an animal waste management plan and nutrient management plan entail?
Ø
If
you use poultry litter, what will be required of you in the future?
Ø
What
are certified nutrient handlers and what are the requirements for the four
categories:nutrient generator, private nutrient handlers, commercial nutrient
handler and nutrient consultant?
Ø
What
are the rules on manure stockpiles?
There
is no charge or registration for this meeting. If you have questions, please
call Jeanie Johnson at 302-856-7303 or jeanie@udel.edu.
Week
of March 9 to March 22 |
Rainfall: |
0.22 inches :
March 12, 2000 |
0.32 inches :
March 16, 2000 |
0.89 inches :
March 17, 2000 |
3.13 inches :
March 21, 2000 |
0.54 inches :
March 22, 2000 |
Readings taken for the previous 24 hours at 8
a.m. |
Air
Temperature: |
Highs Ranged
from 78 °F on March 9 to 37 ° F on March 18. |
Lows Ranged
from 56 °F on March 9 to 24 °F on March 18. |
Soil
Temperature: |
50.4°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.
I
would like to subscribe to the WEEKLY
CROP UPDATE NEWSLETTER for 2000
Please
send $30 and this form to:
Tracy
Wootten
University
of Delaware Research & Education Center
16483 County Seat Highway,
Georgetown,
Delaware 19947
Please
make checks payable to "University
of Delaware"
Check#
|
|
Name: |
|
Address: |
|
|
|
Telephone: |
|
Fax: |
|
E-Mail: |
|
Do
you want to receive the "Weekly Crop Update" via FAX o YES o NO _______________________________________________________________________________________
Please
send me __ copy (ies) of the 2000
Commercial Vegetable Recommendations Guide. They are $7.00/book.
Check#
|
|
Name: |
|
Address: |
|
|
Please
make checks payable to "University
of Delaware" .
Please
send check and this form to:
Tracy
Wootten
University
of Delaware Research & Education Center
16483 County Seat Highway,
Georgetown,
Delaware 19947
_______________________________________________________________________________________
Please
send me __ copy (ies) of the 2000 Pest
Management Recommendations For Field Crops.
They
are $10.00/book.
Check#
|
|
Name: |
|
Address: |
|
|
Please
make checks payable to "University
of Delaware" .
Please
send check and this form to:
Tracy
Wootten
University
of Delaware Research & Education Center
16483 County Seat Highway,
Georgetown,
Delaware 19947
_______________________________________________________________________________________