Volume
1, Issue 5
April 25, 2003
Vegetables
Vegetable Insects
-
Asparagus.
Asparagus beetle adults can be found laying eggs on spears. A treatment is recommended if 2% of the spears are infested with eggs. Since adults will also feed on the spears, a treatment is recommended if 5% of the plants are infested with adults. Sevin, Lannate, Ambush, or Pounce will provide control.
Cabbage.
Continue to sample for imported cabbageworm and diamondback larvae in cole crops. A treatment is recommended if you find 5% of the plants infested. The following products will provide excellent worm control: Avaunt, the Bt insecticides, Proclaim and Spintor.
Melons.
Seed corn maggot flies can be found laying eggs in fields, especially where chicken manure or green manures have been recently plowed under. A seed corn maggot control should be considered in all fields planted through the end of May. A broadcast application of diazinon before planting has provided control. The use of Admire or Platinum through the drip or applied to transplants before seeding in the field can also provide suppression of seed corn maggot.
As soon as fields start to bloom, it is important to sample fields on a weekly basis for pea aphids. You should sample for pea aphids by taking 10 sweeps in 10 locations and counting the number of aphids per sweep. A treatment is recommended if you find 50 or more aphids per sweep. Dimethoate or Lannate will provide aphid control. Be sure to check the labels for application restrictions during bloom.
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Thoughts on
Spinach –
Spinach grown for processing has been produced in
Spinach is a cool season crop. Its vegetative growth is optimized in the 60-65 degree F range. Germination is also temperature dependent, see the table below:
|
Degrees Fareneheit |
Days to Germination |
|
41 |
22 |
|
50 |
12 |
|
59 |
7 |
|
77 |
5 |
|
86 |
NO GERMINATION |
The rate of germination increases with temperature, although if soil temperatures reach 86o F, germination does not occur. This fact may explain occasional erratic stands in August plantings, that is, the seed just doesn’t germinate when exposed to high temperatures.
Spinach goes into its reproductive stage in response to day length and temperature. As day length approaches 12-15 hours, depending on variety, seed stalk formation takes place, known as “bolting.” This is accelerated as temperatures get warmer. Bolting is accentuated if the spinach has been exposed to low temperatures, and then long days with high temperatures. This climatic condition can occur with our cool springs followed by a hot month of June. Producers have done a great job of being ahead of the curve, harvesting before bolting begins.
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Onions for
Processing on Delmarva? –
Several small, trial plantings of onions for processing were planted last fall and this spring with growers and at the UD Research & Education Center. Currently, eastern processors ship raw product from the western states for freezing or other processing. Due to climatic advantages, western growers can usually obtain higher tonnage and excellent quality. Increased sunlight, controlled irrigation, and lower humidity all combine to set the stage for better germination, better growth rates, and less disease. As a result, yields per acre and the solids content of the onion are generally higher for onions grown in the west. The critical economic question is can eastern yields and quality be competitive with the higher yields of the west. While freight is another expense associated with bringing western onions to the east, experience to date has indicated that eastern yields have not been competitive despite freight advantages.
An onion bulb is essentially a group of concentric swollen leaf bases. At bulb initiation, basal sheaths begin thickening. New leaves being produced gradually produce smaller and smaller blades until only bladeless sheaths are produced. Bulb enlargement is the result of the thickening of those sheaths which become the bulb scales. The outer sheaths lose moisture as they mature, making the paper thin skin we are familiar with. The inner leaf bases thicken. The ultimate yield of onion is determined by the number of leaves that form prior to bulbing.
In 1923, Garner and Allard of the USDA, discovered that bulbing is a long day, photoperiod response. Long days are required for bulbing to occur. If the photoperiod is shorter than the critical photoperiod, bulbing will not occur. Cultivars differ in minimum length of day required to induce bulbing. Some require as few as 10-12 hours and some up to 16 hours. Long day onions planted under short days will never bulb; short day onions planted under long days will produce very small bulbs. Onions planted on Delmarva would require long day onions, to trigger bulbing for growth in the summer. Onions started from seed require longer photoperiods than those started from sets or transplants.
This explains, in part, the yield differential between
regions. Our cool springs delay
germination and growth, thus limiting the number of leaf sheaths formed prior
to bulbing. Thus the size of the bulb
may be naturally limited by climatic conditions. Newer, better adapted varieties may reduce
this limitation, thus the trials that are on going.
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Vegetable Diseases
-
Potatoes.
The threat of late blight for Delaware growers is almost
non-existent again due to the absence of late blight in the seed growing areas
where our seed is grown. Except for a few scattered spots in
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Field Crop Insects
-
Field Corn.
Black cutworm catches have significantly increased in the
Frederica, Leipsic, Lewes,
As corn emerges, you should also watch for bird damage. You can distinguish bird damage from cutworm damage by the pattern in the field: generally longer strips of damaged plants, plants pulled out of the ground, and/or plants cut high that are compressed at the base of the stems. Although birds can cut plants off at the soil surface, they tend to pull plants out of the ground. In addition, if you look closely you will see " bird prints" near the missing plants or holes were birds have pulled plants out of the ground so do not confuse it with cutworm damage.
We can also find numerous slug eggs under last year's crop residues. Although we have no new products to control slugs, the use of trash cleaners and starter fertilizers can help corn to emerge quickly and grow ahead of the damage. Metaldehyde baits ( e.g.Deadline MPs and TrailsEnd LG) or the use of liquid nitrogen at the spike to one leaf stage also helps to reduce slug activity buying time to enable the crop to outgrow the problem.
Small Grains.
Cereal leaf beetle adults, eggs and larvae can be found in
barley and wheat fields in
2003 Black Cutworm Pheromone Trap Counts

Found on page 10.
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Field Crop
Diseases -
Wheat. Powdery mildew
was seen this week on wheat in
control
measure.
The following article was reprinted from Kentucky Pest News written by Dr. Don Hershman, and accurately reflects conditions here. Only the fungicide prices may vary.
HEADLINE FUNGICIDE ADDED TO WHEAT DISEASE CONTROL ARSENAL
In September 2002, BASF Corporation received an EPA Section
3 registration for the foliar fungicide, Headline. This is important news for
Headline is a valuable addition to the wheat fungicide
arsenal because, like Quadris, it may be applied until the crop begins to
flower, post head emergence. In contrast, Tilt (propiconazole), and Stratego,
which contains propiconazole, must be applied to the crop before 50% crop flag
leaf emergence. This is an important distinction since research and experience
with fungicides in
Headline, Quadris, Stratego, and Tilt are all excellent fungicides. I came to this conclusion after reviewing published research reports from seven different states for 1999-2002. The bottom line is this: assuming proper timing, rate, and method of application, there is very little practical difference in disease control achieved between the different products (see Table 1). Quadris, and to a lesser extent Headline and Stratego, have somewhat less activity against powdery mildew compared to Tilt, and the opposite is true for leaf rust (i.e., Tilt has somewhat reduced activity compared with Headline, Quadris, and Stratego). Nonetheless, I have not seen any data which indicates that any one fungicide is "head and shoulders" above the others as long as sufficient rates of active ingredient are applied at the proper time, and sufficient disease pressure exists.
|
Table 1. Relative Disease Control Spectrum for Various
Wheat Fungicides: |
|||
|
Product |
Powdery mildew |
Leaf/glume blotch |
Leaf rust |
|
Headline |
++(+) |
+++ |
++++ |
|
Quadris |
+(+) |
+++ |
++++ |
|
Stratego |
++(+) |
+++ |
++++ |
|
Tilt |
+++ |
+++ |
+++ |
|
Very good control = ++; excellent = +++; superior = ++++;
(+) = Control at higher use rates. |
|||
Cost is a big factor in making wheat foliar fungicide selection decisions. Recently, we called various ag dealerships in different parts of the state and conducted a limited price comparison survey for the different foliar fungicides available for use on wheat. The results are as follows:
|
Product |
Ave. retail price/gal |
Price range |
Cost per rate applied* |
|
Headline |
$209 |
$200-$229 |
6.0 fl. oz. = $9.80 / 9.0 fl. oz. = $14.70 |
|
Quadris |
$271 |
$250-$289 |
6.2 fl. oz. = $13.12 / 8.2 fl. oz. = $17.36 / 10.8 fl. oz
= $22.90 |
|
Stratego |
$140 |
$137-$143 |
10.0 fl. oz = $10.98 |
|
Tilt |
$341 |
$295-$380 |
4.0 fl oz = $10.66 |
|
*Based on average retail price at different use rates.
Does not include cost of additives or application. |
|||
As can be seen in the above table, the price- competitiveness of Headline and Quadris, compared with the industry standard, Tilt, is dependent on the rate applied. Because of the newness of these fungicides, I do not yet feel qualified to recommend a specific use rate for either fungicide. This, obviously, is an important decision with great potential for economic impact. Thus, I suggest you consult your company sales rep for specific use rate recommendations for both Quadris and Headline.
Anytime you decide to spray a foliar fungicide, it is always
a good idea to leave a small amount of wheat unsprayed for comparison purposes.
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Rootworm – Resistant Bt Corn Hybrids and Buyer Acceptance - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu
EPA approval without global approval (especially by the
European Union) of the new rootworm-resistant Bt corn technology brings to mind
the Starlink GMO issues of corn segregation or identity-preservation and of
buyer acceptance of corn known to be mixed with the new technology. Dr. R. L. (Bob) Nielsen with the Agronomy
Department at
URL: http://www.kingcorn.org/news/articles.03/GMO_Segregation-0423.html
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Additional Comments on Rescue Inoculation of Alfalfa - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu
The
lack of a problem with spring seeding dates may have to do with the cooler
storage temperatures for the seed between inoculation by the seed supplier and
the planting date. For late-summer and
fall seeding dates, the seed likely experienced some months of high ambient
temperatures as well as be nearly at the end of the life expectancy of the
Bradyrhizobia. That combination likely
leads to more failures.
The
approach of N fertilization is likely to work best in fields with some history
of alfalfa. The surface few inches of
our soils can become very hot during our summer weather and after a few years
the Bradyrhizobia population in the surface soil may be too low to adequately
nodulate alfalfa. In part, that is why
we recommend always using inoculated seed.
When a failure occurs, the addition of N helps the alfalfa develop a
deeper and more extensive root system that will likely nodulate as the N supply
decreases again. Alfalfa seeded in a
field that never has been planted to alfalfa can be nodulated in this fashion
if the bacteria have been blown in from nearby fields or otherwise transported
to the field. Some strains of
Bradyrhizobia can also form effective or ineffective nodules on alfalfa. If partially effective, the field will appear
to recover, but may never be very productive.
I would suggest that unless there is a history of alfalfa in a field
where a failure has occurred, the best option is to try one of the methods
discussed in last week’s Weekly Crop Update.
This will ensure that an effective strain of Bradyrhizobia nodulates
alfalfa in these questionable fields.
My thanks again to
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Thinking of Early Planted
Soybeans - 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, early planted soybeans often yield 5
to 15 bu/A more than traditional early-June planted beans, depending on the
growing season. Early-planted beans
mature on schedule while June-planted beans, especially those varieties from
maturity group V, often do not mature until 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. Since
many growers still will be planting corn, it may be more time consuming and
costly to switch to soybeans and will cause too much of a delay in finishing the
rest of the corn acreage. 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 bean yields. 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 Phythium 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.
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Grain Marketing Highlights -
Comments Sought on Trade Adjustment
USDA has invited public comments on proposed regulations for
the Trade Adjustment Assistance For Farmers program. Under the program, USDA is
to provide funds to eligible producers of raw agricultural commodities when the
Secretary of Agriculture determines that increased imports have contributed to
a specific price decline over five preceding marketing years. The request for
public comments was published in the Federal Register on April 24th and can be
viewed on the web at http://www.fas.usda.gov/info/fr/notices.html.
The Trade Act of 2002 established the program and the
procedures for producers to petition for 'certification of eligibility' to
apply for adjustment assistance payments. Comments on the proposed rules must
be received on or before
Comments should be mailed or delivered to Jean-Louis Pajot,
Import Policies and Programs Division, Foreign Agricultural Service,
USDA Announces New Sign-Up for CRP
Agricultural Secretary, Ann Veneman has announced sign-up is
to begin May 5th for the Conservation Reserve Program (CRP). A general CRP
sign-up is slated for May 5-May 30th. Producers will be able to register at
local USDA Farm Service Agencies. The 2002 Farm Bill authorized USDA to
maintain CRP enrollment up to 39.2 million acres.
In addition to the general sign-up, there is a continuous
sign-up program that remains in effect. USDA has reserved two million acres for
the continuous sign-up program, which represents the most environmentally
desirable and sensitive land. Current participants with contracts expiring this
fall, can make new contract offers. Start dates for those contracts can be for
either
General Market Comments
Corn planting in the
Old crop soybeans have declined about 20 cents per bushel
from their recent highs along with a general weakening of the basis both locally
and nationally. Soybean harvest is 75% complete in
Export sales for corn, soybeans, and wheat for last week
were within the range of pre-report estimates, although not viewed as price
motivating.
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Think of All the Angles When Using Clopyralid
(Stinger) -
Stinger (clopyralid) and products containing Stinger such as
Confront have precautions about use of compost and residues in the plant
materials. If grass clippings or plant
materials treated with clopyralid are used as a mulch in landscaping or a
garden, sensitive plants can be killed.
There are a number of instances when a lawn treated with Confront was
cut and the clippings used as a mulch around tomatoes and the tomatoes
died. As a result, Dow AgroSciences has
precautions on the label about not using hay or straw from treated areas, or
manure from animals that have been grazed or fed forage from clopyralid treated
areas for composting or mulching. There
is also a precaution to not transfer livestock from treated grazing areas to
sensitive broadleaf crop areas without allowing 7 days of grazing on an
untreated pasture, because the urine may contain enough clopyralid to cause
injury to sensitive plants. The small
amount of clopyralid in the treated pasture or hay is not harmful to livestock,
but it is at a high enough concentration to injure sensitive plants. As a result, fields cut for hay and sold
should not be treated with clopyralid since that hay or the manure of the
animals could be used for compost.
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Soil-applied Herbicides Need To Be Moved Into
the Soil -
Herbicides applied to the soil surface require rainfall or
irrigation or mechanical incorporation to move them into the soil where the
plants will absorb them. The amount of
water needed to “activate” these herbicides depends on the water solubility of
the herbicide and moisture content of the soil.
Even with good soil moisture like we have, it still will require some
rain or irrigation to move the herbicide into the soil. Most soil-applied herbicides require 0.5 to
0.75 inches to be moved in the soil if the soil is “dry” (less water if the
soil is moist). Princep requires 0.75 to
1.0 inches of water to become “activated”.
If you have irrigation and your corn herbicides have been applied but
you have not received at least 0.5 inches of water, you should consider
applying that amount with your system.
Mechanical incorporation with a field cultivator, set no more than 3 to
4 inches deep, will physically move the herbicide into the root zone. A field cultivator set any deeper will cause
the herbicides to become too diluted. A
field cultivator will mix the soil to half the depth it is set (set to 4 inches
– soil mixes to 2 inches). This is one
situation where spending a little money now could save money later. For instance, if your residual grass herbicide
is not moved into the soil and grass control is poor, you are looking at a
postemergence application of Option, Steadfast, or Accent-containing
pre-mix. Control of crabgrass with
postemergence herbicides is only fair.
Spending the money to irrigate and activate the herbicides could save a
high herbicide bill later.
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|
2003 Black Cutworm Pheromone Trap Counts Trapping date: |
|||
|
Bridgeville |
7 |
Magnolia |
3 |
|
Delmar |
5 |
|
8 |
|
Ellendale |
0 |
|
16 |
|
Felton |
5 |
Millsboro |
1 |
|
Frederica |
8 |
|
7 |
|
|
6 |
Sandtown |
4 |
|
|
6 |
|
0 |
|
Harrington |
6 |
Selbyville |
3 |
|
Kenton |
1 |
|
8 |
|
|
7 |
Townsend |
3 |
|
Leipsic |
27 |
|
1 |
|
Lewes |
13 |
|
|
|
|
2 |
|
|
|
Little Creek |
4 |
|
|
NOTE:
(1)
Moth catches of 9
to 15 moths per 7-day period =mod. to high potential for outbreaks.
(2) You can expect to see cutting activity around 300 degree-days, base of 50 degree F from peak moth activity
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|
http://www.rec.udel.edu/TopLevel/Weather.htm |
Weeks of April 17 to
|
|
Rainfall: |
|
0.09 inches: April 18 |
|
|
|
Air Temperature: |
|
Highs Ranged from 71°F on April
22 to 46°F on April 18. |
|
Lows Ranged from 53°F on April
22 to 38°F on April 20. |
|
Soil Temperature: |
|
55°F average for the week. |
|
(Soil temperature taken at
a 2 inch depth, under sod) |
Web Address for the U of D
Compiled and Edited
By:
Extension Associate -
Vegetable Crops

Cooperative Extension Education in Agriculture and Home
Economics, University of Delaware, Delaware State University and the United
States Department of Agriculture cooperating, Robin Morgan, Director. Distributed in furtherance
of the Acts of Congress of May 8 and