Volume 12, Issue 17
July 16, 2004
Vegetables
Vegetable Crop Insects -
Blacklight and
Pheromone Trap Catches.
Trap catches have started to
increase, especially corn borers. Since this information can be used to make
treatment decisions on sweet corn, snap beans and peppers, you will need to
check for the most recent trap catches at least twice a week. Trap catches are updated twice a week
(generally Monday and Thursday PM late) on our website (http://www.udel.edu/IPM/traps/latestblt.html)
or on the Crop Pest Hotline (1-800-345-7544
– in state only or 1-302-831-8851 – out of state).
Cucumbers.
Continue to scout for
aphids. A treatment should be applied for aphids if 10 to 20 percent of the
plants are infested with 5 or more aphids per leaf.
Lima Beans.
The earliest planted fields with pin
pods should be scouted for lygus bugs and stinkbugs. Treatment should be
considered if you find 15 adults and/or nymphs per 50 sweeps. Lannate, Capture
or Mustang can be used if both species are present. The higher labeled rates of
Capture (4 oz/A) and Mustang (4.3 oz/A) will be needed if stinkbugs are the
predominant insect present. You should also start scouting the earliest planted
fields for corn earworm. A treatment will be needed if you find one corn
earworm larvae per 6 ft-of-row from late flat pod stage until harvest.
Melons.
Continue to scout all melons for
aphids, cucumber beetles, and spider mites. We continue to see an increase in
the number of fields with spider mite, aphid, and cucumber beetle infestations.
Since beetles found now can often lead to damage to rinds, be sure to watch
fields carefully and treat as soon as you see an increase in the
populations. Be sure to watch for bees
foraging in the area and avoid insecticide applications on blooming
crops.
Peppers.
In areas where corn borer trap catches are above 2 per-night and pepper fruit is
½ inch in size or larger, fields should be sprayed on a 7-day schedule for corn
borer control except in the Harrington, Greenwood and Laurel areas where sprays
are needed on a 5-day schedule. You will also need to consider a treatment for
pepper maggot. If Orthene is used for corn borer control, it will also reduce
damage from pepper maggot. Otherwise, dimethoate should be added to the mix.
You should also watch for beet armyworm (BAW) larvae. Economic damage is
starting to show up and small larvae can be readily found. No threshold is
available, so you need to watch for the first small larvae as well as their
feeding. You will also need to use a product like Spintor, Avaunt, or Intrepid
which provide BAW control.
Potatoes.
Continue to scout fields on a weekly
basis for Colorado potato beetle (CPB) adults and
larvae. We continue to find economic levels of green peach aphids. A control
will be needed if you find 2 aphids per leaf pre-bloom, 4 aphids per bloom –
post bloom and 10 aphids per leaf at 2 weeks from vine kill/harvest. If melon aphids are found, the threshold
should be reduced by ½. If green peach
aphid is the predominant species, Fulfill, Lannate, Monitor, Provado, or Vydate
will provide control. If Fulfill is used, a penetrating surfactant is needed to
achieve good coverage and achieve optimum control.
Snap
Beans.
Continue to scout all
seedling stage beans for leafhopper and thrips
activity. The thrips threshold is 5-6 per leaflet and
the leafhopper threshold is 5 per sweep. If both insects are present, the
threshold for each should be reduced by 1/3. Dimethoate,
Lannate, Asana, Capture, or Warrior will provide
control of both insect pests. At this time, all fresh market and processing
snap beans in the bud to pin stages should be sprayed for corn borer. Acephate should be used at the bud and pin stages on
processing beans. After the pin spray on processing beans, sprays will be
needed on a 5-6 day schedule except in the Harrington,
Sweet Corn.
All fresh market silking
sweet corn should be sprayed on a 3-4 day schedule throughout the state except
in the
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Vegetable Crop Diseases - Bob Mulrooney, Extension Plant
Pathologist, bobmul@udel.edu
Late Blight Advisory.
Disease Severity Value
(DSV) Accumulation as of July 14, 2004 is as follows:
|
Date |
Daily DSV |
Total DSV |
Spray Recommendation |
|
4/25- 5/18 |
4 |
18 |
7-day |
|
5/19 |
4 |
22 |
7-day |
|
5/20 |
2 |
24 |
7-day |
|
5/21 |
2 |
26 |
7-day |
|
5/25 |
5 |
31 |
7-day |
|
5/27 |
3 |
34 |
7-day |
|
5/30 |
8 |
42 |
7-day |
|
5/31 |
1 |
43 |
7-day |
|
6/1 |
1 |
44 |
7-day |
|
6/4 |
17 |
61 |
5-day |
|
6/7 |
2 |
63 |
5-day |
|
6/8 |
1 |
64 |
5-day |
|
6/10-6/13 |
9 |
73 |
7-day |
|
6/14-6/15 |
3 |
76 |
7-day |
|
6/16 |
3 |
79 |
7-day |
|
6/17 |
3 |
82 |
7-day |
|
6/22 |
1 |
83 |
7-day |
|
6/23 |
1 |
84 |
10-day |
|
6/25 |
3 |
87 |
7-day |
|
6/26-30 |
0 |
87 |
10-day |
|
7/1 |
2 |
89 |
10-day |
|
7/4 |
2 |
91 |
10-day |
|
7/7 |
2 |
93 |
10-day |
|
7/11 |
1 |
94 |
10-day |
|
7/12 |
5 |
99 |
7-day |
|
7/13 |
2 |
101 |
7-day |
After
this weeks storms, potatoes that have not been sprayed in the last week will
need a protectant spray as soon as possible. Hopefully applications of Ridomil
or UltraFlourish at planting or later will pay off if potatoes are in
waterlogged soils. Bacterial soft rot decay and pink rot are both threats where
soils stay saturated for any length of time.
Application
rates for protectant fungicides (Dithane, Bravo, etc.) should be at the high
end of the rate with the amount of foliage present. For specific fungicide
recommendations, see pages F132-33, 2004 Delaware Commercial Vegetable
Production Recommendations Book. EB 137.
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Vegetable Crop Diseases –
Downy
Mildew Alert on All Cucurbits: Including Pickles,
Cantaloupes, Pumpkins and Watermelon.
Downy
mildew has been identified on pickling cucumbers and pumpkins in
Downy
mildew (Pseudoperonospora cubensis)
has been identified in many pickling cucumber fields on Delmarva. The downy mildew that infects pickling
cucumbers and other cucurbits is caused by a different species of fungus than
downy mildew on lima bean. Cucurbit
downy mildew cannot survive here and must spread from the southern
There
are several possible fungicide programs to control downy mildew, Phytophthora,
and Rhizoctonia (belly rot). Table 1
identifies the material, the timing, disease target, and relative cost of three
approaches.
Table
1 uses the following rates for each material:
§
Bravo
– 2pts/Acre
§
Acrobat
– 6.4 oz/Acre (Gavel has slightly better downy mildew activity than Acrobat and
is equal in its control of Phytophthora blight.)
§
Copper
– 2 lbs./Acre
§
Ridomil
Gold Bravo – 2 lbs./Acre
§
Amistar
– 5 oz/Acre
Table
1. A comparison of three possible
fungicide programs for pickling cucumbers.
Program Material Timing
Target Cost/A
A Bravo Pre-Flop Downy mildew (DM) $12
Ridomil Gold Bravo 1-inch
pickles
Phytoph. + DM 34
Ridomil Gold Bravo 3-inch
pickles Phytoph. + DM 34
TOTAL $80
B Bravo Pre-Flop DM
$12
Gavel or Acrobat + copper 1-inch pickles Phytoph. + DM 14
Gavel or Acrobat +
copper 3-inch pickles Phytoph. + DM 14
TOTAL $40
C Bravo Pre-Flop DM $12
Ridomil Gold Bravo 1-inch
pickles Phytoph. + DM 34
Ridomil Gold Bravo 3-inch pickles Phytoph. + DM 34
Amistar Pre-Flop to 1 Belly Rot 28
Inch
pickles
(Gavel
could be used instead of Acrobat in the above scenarios).
Which Program to Use: Growers are confronted with several choices, some
outlined above, and there may be good reason to use various combinations other
than those outlined above. For example,
another program would be to use Gavel or Acrobat + copper for the 1-inch stage,
and Ridomil Gold Bravo for the 3-inch stage.
Or, it may be that only two of the applications are needed. The fungicide program decision should be based
on relative efficacy of product, field history, weather conditions, and
observations on the disease pressure present.
The grade and quality of harvested product is also a factor to consider. If there has been Phytophthora in earlier
plantings, or downy mildew in earlier plantings, then more stringent controls
are necessary.
As
for downy mildew and Phytophthora blight, Ridomil Gold Bravo is probably the
best material in terms of efficacy on both diseases (unless a field has had a
history of Ridomil applications).
Chlorothalonil (Bravo or Echo) is a good product when used
preventatively. Acrobat + Copper has also performed well in trials in
Pumpkins.
***Downy mildew is present
in
The
following are fungicide schedule options that are designed to be effective on
most pumpkin diseases, including downy mildew.
The core of the program is chlorothalonil, which is a good preventative
material for downy mildew. This program
will manage most diseases of pumpkin, but it is still necessary to scout for
development of Phytophthora blight.
1st
Fungicide Application : mefenoxam plus chlorothalonil (Flouronil, Ridomil
Gold Bravo)--2 lb 76WP/A. (If you have already applied a fungicide, reapply
chlorothalonil within 7 days of the previous spray).
2nd and 4th, etc.:
Chlorothalonil (such as
Bravo Ultrex 2.7 lb/A or Echo) plus copper (such as Kocide DF 1.5 lb/A) plus
Nova (2.5 oz./A) or Procure (4-8 oz 50WS/A).
3rd and 5th,
etc.: Use one of the following
combinations:
- mefenoxam
plus chlorothalonil (Flouronil, Ridomil Gold Bravo)--2 lb 76WP/A.
-Pristine 12.5-18.5 oz 38W/A,
-Tanos--8
oz 50WDF/A (must be tank mixed with either chlorothalonil, maneb or copper),
-Gavel
2 lb 75 DF/A.
Ridomil
Gold Copper and Acrobat have some efficacy on downy mildew.
Use Acrobat (6.4 oz/A) for Phytophthora blight
later in the season if it is a problem. These fungicides should be
applied at regular intervals.
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Field Crop Insects -
Alfalfa.
Continue to sample all
fields on a weekly basis for potato leafhopper (PLH) adults and nymphs. Sprays
may be needed on multiple cuttings. Remember, controls are most critical on
small plants. The treatment thresholds are 20 per 100 sweeps on alfalfa 3
inches or less in height, 50 per 100 sweeps in 4-6 inch tall alfalfa and 100
per 100 sweeps in 7-11 inch tall alfalfa.
Soybean.
Spider mites continue to be found at
economic levels, especially on beans that were drought stressed. With the rains this week, plants have begun
to actively grow again so it will be a good time to treat fields that had
spider mites before the rains. Although
rainy weather can help reduce populations, we generally do not see populations
crash until we have 3-5 days of rainy weather with warm days and cool evenings
to get diseases started that crash populations. Early treatment is needed to
achieve control – once significant yellowing occurs it will be extremely
difficult to achieve control and multiple treatments will be needed. A treatment is recommended if you find 20-30
mites per leaflet or 10% of plants with 1/3 or more leaf area damaged. At this
point, the only materials available for mite control in soybeans are dimethoate
and Lorsban. If dimethoate is used, the
addition of a penetrating surfactant like LI-700 or Penetrator plus or a
material like
In addition to green cloverworm, we can find
Japanese beetles defoliating soybeans. No controls will be needed until you
find 30% defoliation pre-bloom and 15% during bloom. As a general guideline,
you should also find 10-15 cloverworms or 7 Japanese beetles per foot of
row. Unfortunately, we do not have a
threshold for the number per sweep.
You should also continue
to scout on a weekly basis for soybean aphid. We have found very low levels of
the first soybean aphids in
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Grain Marketing Highlights - Carl German, Extension Crops Marketing Specialist; clgerman@udel.edu
World/U.S. Supply and
Demand Highlights.
The contents of USDA's July 12th crop report are based upon area, yield, and
production forecasts released July 12th for small grains. For other crops, area
estimates reflect the June 30 NASS Acreage report. Survey based area, yield,
and production forecasts reported by NASS will be adopted in the August 12th
crop report.
WHEAT.
Projected U.S. 2004/05 ending stocks of
World wheat production for 04/05 is up slightly from last month and
although use also increases, ending stocks are projected to increase by nearly
6 million tons from last month and about 2 million tons above the previous
year. This is noted as the first year-to-year increase in ending stocks since
the '99/'00 marketing year.
The wheat estimates are termed neutral to bullish as all
CORN.
The '04/'05 outlook for
Reduced export projections of 100 million bushels and an increase of 10
million bushels in the food, seed, and industrial use category leaves an
additional 90 million bushel increase in the ending stocks estimate for U.S.
corn for the '03/'04 marketing year.
Global coarse grain stocks are increased nearly 10 million tons from
last month, due mainly to the 6.35 million ton increase in U.S. ending stocks
for the '04/'05 marketing year. Despite this increase, global stocks are
indicated to be headed for the lowest level since 1976/77.
SOYBEANS.
Ending stocks for '04/'05 marketing year
Market Strategy.
The commodities market is said to be reacting in a 'Buy the rumor - Sell the
fact' fashion today, with the exception of CBT wheat futures whereby the crop
report and trader expectations did not line up. Corn futures were up 1 to 2
cents per bushel for old crop and new crop contracts. Soybean futures were down
hard for old crop soybeans (16 to 28 cents per bushel), while new crop soybeans
were down 6 cents per bushel. Old crop and new crop wheat futures finished the
day higher, up 8 to 9 cents per bushel on the old crop and 6 cents per bushel
for the '05 crop. Farmers that are at least 50% sold on new crop corn and
soybeans are going to need to pay attention to pricing opportunities that may
be available in basis offerings and technical indicators. This report suggests
that we could see further weakness in new crop corn price offerings from their
current levels, some remaining opportunities forthcoming to increase sales
levels for new crop soybeans, and a potential rally in new crop wheat futures.
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Comments on Weed Control - Mark VanGessel,
Extension Weed Specialist; mjv@udel.edu
The
recent rains have put a different wrinkle into decisions for weed control. A lot of weeds have been quite inactive
during the drought and are now starting to grow again. If you are concerned about these plants
becoming a problem and wondering if you should spray, here are two things to
consider. First, how large are the weeds
and does the herbicides labeled have a reasonable chance of controlling the
weeds? Second, at what stage is the crop
(crops in bloom can be an issue for certain herbicides). For soybeans, most of the glyphosate products
are labeled for application through blooming.
Weeds
just beginning to emerge now have a wider window for postemergence control than
weeds that emerged in June or earlier.
Research with soybeans and snap beans has shown that crops planted in
early July or later have an extended period that the weeds are most susceptible
to the herbicides. Mostly, this is due
to the fact weeds emerging now do not attain the same size because they begin
flowering shortly after emerging and additional flushes of weeds will be even
less competitive at this late of a date.
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The Delmarva Cattlemen’s Association and the
Wed. July 28th- Cattlemen’s Picnic in the
Schabinger building following the conclusion of the Beef Breed
Show at the Delaware State Fair (approximately 3:00 p.m.). Drinks, rolls and meat will be provided. All cattlemen welcomed. Attendees are asked to bring a covered dish
and to RSVP to Ron Wright by Sunday July 25th at (302) 398-3219. Many thanks to the Delaware Beef Advisory
Board (providing the meat) and to Tractor Supply (water trough giveaway) and
other local sponsors. Come and hear
about the many benefits of belonging to an association and planned activities!
Tues. August 3rd- Grazing Tour- Bill
Edwards Bison Farm, Dorchester Co. MD-
Bill is a very intense manager of
July 30th
and for more details! A car pool will be
arranged if interest warrants.
Mon. August 12th- Grazing
August 6th and
for more details! A car pool
will be arranged if interest warrants.
Sat. August 28th- Beef and Dairy Beef
Quality Assurance Training-
10:00 a.m.- 2:30 p.m.- lunch
provided, minimal registration fee per operation- location to be
announced. Scott Wright, Pennsylvania
Beef Quality Assurance Coordinator will be joining us to lead this training. Completing Quality Assurance training is
simply part of good management in any livestock industry. The goal of Quality Assurance training is to
assure the consumer that all cattle shipped from a beef/dairy beef production
unit are healthy, wholesome and safe and that their management has met FDA,
USDA and EPA standards. Please consider
joining us for this valuable and important training. Contact the Extension Office at (302)
730-4000 or truehart@udel.edu for more
information.
Sincerely,

Week of July 9
to July 15, 2004
|
|
Rainfall: |
|
0.18
inches: July 11 0.32
inches: July 12 0.43
inches: July 13 0.14
inches: July 14 0.06
inches: July 15 |
|
|
|
Air Temperature: |
|
Highs
Ranged from 88°F on July 10 & 11 to 81°F on July 13. |
|
Lows
Ranged from 70°F on July 12 to 63°F on July 10. |
|
Soil
Temperature: |
|
81°F
average. |
|
(Soil
temperature taken at a 2 inch depth, under sod) |
Web
Address for the U of D Research & Education Center: http://www.rec.udel.edu
Compiled and
Edited By:
Tracy Wootten

Cooperative
Extension Education in Agriculture and Home Economics, University of Delaware,
Delaware State University and the United States Department of Agriculture
cooperating. Distributed in furtherance
of the Acts of Congress of May 8 and June 30, 1914.