Volume 12, Issue 1
March 12, 2003
Volume 12, Issue 1
March 12, 2003
The Weekly Schedule Begins –
This
newsletter is designed to provide subscribers with the latest information on
disease and insect problems, weed control information, crop progress reports,
and other timely topics related to agronomic and vegetable crop production in
Email Address Changes
Please
forward email address changes. If your
email address has changed in the last 6 months, please forward the new address
to me at wootten@udel.edu. Thanks!
Avian Influenza Update –
Field
application of poultry litter and complete cleanouts allowed March 11
Today, Michael Scuse, Delaware Secretary of Agriculture, lifted restrictions
on the spreading of poultry litter, and on the complete cleanouts of poultry
houses in
The rescission of regulation 1.0, which refers to the movement, transportation,
or field application of poultry litter, and regulation 2.0, which refers to
poultry house cleanouts, means normal poultry litter removal, storage, and
land application using a nutrient management plan can occur beginning 12:00 AM,
March 11, 2004. The regulations being rescinded were adopted on an
emergency basis on
The rescission is being ordered in cooperation with the Maryland Department of
Agriculture, the Virginia Department of Agriculture and Consumer Services, the
Delmarva Poultry Industry, Inc., and the Delmarva Poultry Industry Emergency
Disease Task Force.
The regulation concerning the transportation of live poultry intrastate or in
or out of
Secretary Scuse said, “Rescinding these regulations is not a call for ‘business
as usual’. The recent and unfortunate avian influenza cases will forever be a
wakeup call for Delmarva’s poultry industry, all poultry industry personnel and
suppliers, and all poultry growers, whether they are commercial growers, back
yard growers, or hobbyists. We must be more vigilant and more careful in
practicing good biosecurity to protect our poultry flocks. I encourage
producers and everyone traveling in the area south of U.S. Rt. 50 to practice
the same strict biosecurity precautions that we have had in effect since
February 6. We don't want to re-infect Delaware flocks nor create more problems
for our neighboring states that have cooperated with us in every way as we have
fought to contain and eradicate avian influenza in Delaware.”
“In addition, I want to thank the agri-business community for their cooperation
in canceling auctions and meetings in the past 5 weeks. At this time, auctions
and meetings not involving live birds can resume. Any person associated
with the poultry industry who must attend these auctions and meetings should
practice strict biosecurity and change clothing and shoes worn in poultry
operations before participating.”
Vegetables
Vegetable Insects -
Seed Corn Maggot (SCM)
in Spring Planted Vegetables.
Although
soil conditions are drier and warmer compared to this same time last year, seed
corn maggot can still be a potential problem in all early planted fields. Seed
corn maggot flies lay eggs in recently plowed and/or manured
fields. Cool wet conditions at planting, the use of manure and/or plowing under
of green cover crops close to planting all favor maggot problems.
(a) Peas and Beans: In recent years,
the use of a hopper box treatment of diazinon 50W has provided excellent SCM
control in peas and early planted beans. At the present time, this is the only
diazinon formulation registered for use on peas and snap beans. It should be
applied at a rate of ½ oz per bushel of seed and graphite added to prevent
bridging in the planter. Unfortunately, we will only have this product
available until July 2004 or at the latest November 2005. Lorsban-SL, only
available as a commercial seed applied treatment, has also provided very good
control. Cruiser 5F (thiamethoxam),
another seed applied material, was labeled in the fall of 2003. It is labeled
for succulent shelled and edible podded beans including lima beans, blackeyed
peas, cowpeas, southern peas, snap beans, and wax beans. The label states early
season seed corn maggot protection at a rate of 0.765 – 1.28 fl oz/100 lbs. of
seed. It is also highly recommended that Cruiser be used with compatible and
registered seed treatment fungicides.
(b) Spinach: The only available SCM control option is a
broadcast application of 2- 3 qts/A of diazinon AG500 applied right before
planting and immediately incorporated 2-3 inches deep. In order to achieve
effective control, diazinon should not be incorporated too deeply and the
ground should only be worked once after application.
(c) Sweet Corn: In addition to the
permethrin (Kernel Guard Supreme and KickStart VP) and the diazinon/lindane(Kernel
Guard, Agrox Premiere and KickStart) hopper box treatments, we now have two new
hopper box treatments available in 2004: Concur
and Latitude. These hopper box treatments should be applied at a rate of
1.5 oz/42 lbs of seed. The insecticide component in both products is
imidacloprid (same active ingredient as Gaucho). In addition to hopper box
treatments, a number of seed applied treatments including Lorsban SL, Gaucho,
Poncho and Cruiser are available for sweet corn. Soil insecticides including
Force, Lorsban, Fortress, Furadan and Counter are also labeled for SCM control
in sweet corn.
Back to Basics:Vegetable Crop Fertility I – Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu
Vegetable
crop fertilization questions seem to be springing up more frequently than in
recent years. I think this is a result
of higher fertilizer prices, new fertilizer products, and a new generation of
farm decision-makers who are facing these choices for the first time. Therefore, I will be addressing these
questions weekly, as well as other timely topics related to general vegetable
production.
Understanding
the acidity of the soil and how liming soils works is the foundation of any
soil fertility program. Many farmers and
others remember Leo Cotnoir, long-time soil fertility specialist with the
The
two main reasons for liming soils are to make soil plant nutrients available
and to prevent aluminum toxicity due to soil acidity. There you have it. A pH test measures the relative acidity or
alkalinity of the soil. On the scale,
seven is neutral; less than seven is acid, greater then seven is basic. In the humid regions with abundant rainfall,
our soils have a natural tendency to be acid.
Maintaining the soil pH at a level between 6.0 and 6.5 on most of our
soils does allow soil plant nutrients to be more abundant in forms that are
absorbed by plants and does reduce aluminum levels to non-toxic amounts
available to plants.
The
major implication here is that if the soil reaction as measured by soil pH is
between 6 and 6.5, more efficient use of fertilizers, manures, and green
manures is obtained. This is expressed
as better crop yield potential and real savings in fertilizer dollars. The lime requirement of a soil depends on
total acidity that must be neutralized to raise pH to the desired level. Most vegetable crops have a target pH of 6.2
or 6.5; only sweet potatoes or scab-susceptible white potato varieties have a
target pH of 5.2. In those cases, the
plant pathogens that cause diseases do not thrive in a low pH environment.
In
addition, lime is the cheapest and most readily available supply of calcium, a
plant nutrient critical for yield and quality for many vegetable crops. Calcium is a major component in the structure
of cells, including cells in the harvested fruit of many vegetable crops, such
as cantaloupes, watermelons, cole crops, cucumbers, and many more. Calcium is considered to be largely immobile
within the plant. That is, it does not
move from one part of a plant to another, but rather is taken up by the roots
and distributed to the developing tissues.
Having adequate amounts of soil calcium readily available is critical
for not only good yields, but good quality as well.
Soil
pH and soil calcium, as determined by soil test are only roughly related. In all cases, calcium increases as soil pH
increases. The amount of soil calcium at
a particular soil pH level, is a function of soil properties, especially soil
texture and cation exchange capacity.
Vegetable Diseases -
Stewart’s
Wilt of Sweet Corn.
Stewart’s Wilt is still one of the most
important diseases of sweet corn on Delmarva. Control of this bacteria (Erwinia stewarti) is based on control of
the corn flea beetle which vectors this bacteria to corn and causes wilt on
susceptible hybrids. Planting resistant fresh market and processing hybrids is
the best control strategy. If susceptible hybrids are grown, control of flea
beetles is extremely important. The Winter Temperature Index is helpful
determining the risk of Stewart’s wilt based on flea beetle survival. As you
can see from the table, most years here are very favorable for flea beetles
surviving overwinter. Predicting severity of Stewart’s wilt based on predicting
populations of beetles carrying the bacteria in reality is very difficult.
However, the last several years have not been favorable for Stewart’s wilt and
it has not been much of a problem here. Sweet corn growers can protect
susceptible and moderately susceptible hybrids by using soil insecticides or
commercially applied seed treatments. Counter and Furadan are the only soil
insecticides labeled for sweet corn that provide effective flea beetle control.
The commercial applied seed treatments, Gaucho, Poncho and Cruiser, will also
provide flea beetle control. Recent
research in
Winter Temperature
Index For Predicting Stewart’s
Wilt in
Average monthly
temperatures in oF at
|
|
2003- 04 |
2002-03 |
2001- 02 |
2000-01 |
1999-00 |
1998-99 |
1997-98 |
1996-97 |
1995-96 |
1994-95 |
|
December |
38.6 |
36.7 |
43.2 |
31.2 |
40.3 |
41.3 |
39.3 |
42.0 |
33.5 |
43.0 |
|
January |
29.5 |
28.9 |
40.0 |
33.8 |
33.9 |
39.5 |
42.6 |
35.0 |
33.5 |
39.0 |
|
February |
35.2 |
33.8 |
39.9 |
38.8 |
39.7 |
38.7 |
40.6 |
41.5 |
34.7 |
33.8 |
|
INDEX |
103.3 |
99.4 |
123.1 |
103.8 |
113.9 |
119.5 |
122.5 |
118.5 |
101.7 |
115.8 |
Average monthly
tempertures in oF at
|
|
2003- 04 |
2002-03 |
2001- 02 |
2000-01 |
1999-00 |
1998-99 |
|