Volume 6, Issue 16                                                                                           July 10, 1998


Vegetables

Vegetable Insects - Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Carrot.

Carrot weevils are now active and sprays should be applied on a 7-10 day schedule. Three applications of Asana or Baythroid should provide effective control.

Peppers.

Maintain a 7 to 10 day spray schedule for corn borer control. Pepper maggot sprays will also need to be sprayed throughout the month of July.

Snap Beans.

Processing snap beans should be sprayed at the bud and pin stages with Orthene for corn borer control. At this time, moth catches are relatively low so a third application with Lannate will be needed within 5 to 7 days from harvest. As moth catches increase, you may need 2 to 4 applications between the pin spray and harvest. In addition, as corn earworm catches increase you will need to combine Asana with Orthene at the pin spray. Be sure to check the Crop Pest Hotline (in state: 1-800-345-7544; out of state: 1-302-831-8851; www.udel.edu/IPM) for the most recent nightly trap catches in your area.

Sweet Corn.

At this time, fresh market silking sweet corn should be sprayed on a 5-6 day schedule in Kent and New Castle counties except in the Milford area where sprays are needed on a 3-4 day schedule. In Sussex County, sprays are needed on a 3-4 day schedule except in the Georgetown areas where sprays are needed on a 5 day schedule. Although moth catches have been relatively low, we generally start to see an increase in populations by mid-July. Be sure to check the Crop Pest Hotline (in state: 1-800-345-7544; out of state: 1-302-831-8851; www.udel.edu/IPM) for the most recent nightly trap catches in your area. Fall armyworm infestations continue to increase in whorl stage corn. Treatments should be applied if 15% of the whorls are infested with live larvae. In most cases, 2 applications of Larvin (30 oz/acre) or Warrior(3.84 oz/a) will be needed to provide control.  *

 

News from the Midwest & Ontario - Ed Kee, Extension Vegetable Crops Specialist ; kee@udel.edu

The pea crop for the Midwestern States of Illinois, Wisconsin, and Minnesota is predicted to meet or exceed earlier projections. Although rain has caused some fields to be by-passed in Illinois, harvest has proceeded fairly well in the other two states. Pea harvest will finish about July 21 to July 24. Ontario had an excellent pea crop and are finishing harvest. Sweet corn fields in the Midwest look excellent, almost "too good" in the words of one Midwest processor. It will be interesting to see how yields and inventory impact next year’s price and contracted acreage here on Delmarva.

 

Morningglories in Lima Beans - Ed Kee, Extension Vegetable Crops Specialist ; kee@udel.edu

Unfortunately, there are no real good herbicide answers for this dilemma. Preemergence treatments using Pursuit offer fair to average control, but usually escapes occur, especially when high populations of morningglories have been present. Multiple cultivations are an essential part of a morningglory control program. Basagran is the only labeled post-emergent broadleaf weed material for lima beans, and it offers poor control of morningglories.

Morningglories not only compete with lima beans during the growing season, but also complicate harvest with trash and vines. In addition, morningglory seed in the processed product is a major contaminant, significantly reducing the value of processed beans, or adding costly re-sorting operations. While new electronic sorting technologies have helped greatly in the factory, the first step is keeping morningglories under control.

Several herbicides are being evaluated for this problem, but it is too early to even know if the results are consistent enough with good crop safety to justify the manufacturer’s investment in a small market crop. We have been disappointed in this area several times over the years.

After being involved with lima beans for 25 years, one observation has been consistently heard from fieldmen. The cleanest fields at harvest are those that have been cultivated twice, sometimes even three times. Although this is often difficult, it does help.  *

 

Vegetable Diseases - Bob Mulrooney, Extension Plant Patholgist ; bobmul@udel.edu

Update on the section 18 for powdery mildew control on cucurbits.

There may be some confusion as to the proper rate for Nova to control powdery mildew on cucurbits. The section 18 emergency exemption was for the 2.5 oz./A rate of Nova. There is a recommendation for 4 oz. that was for another region of the country, not here. The rate for Nova to control powdery mildew is 2.5 oz. of product per acre.

Late Blight Update

DSV accumulations as of July 6 , 1998 are as follows:

Location/Emergence Date

DSV's July 2

DSV's July 6

Recommendations

Baldwin - 4/20

130

134

10-day, mid rate

Jackewicz - 4/20

124

128

       10-day, mid rate
Zimmerman - 4/23

69

69

10-day, mid rate

Baker - 5/1

130

130

7-day, mid rate

What a difference a week makes! The present weather pattern has not been favorable for late blight. But, this is the time to be on the lookout for infections that could have occurred when conditions were very favorable. Disease pressure has lightened for the time being. Keep up the preventative sprays at the appropriate spray interval. The Late Blight Report is also posted electronically at the UD Extension IPM website: http://www.udel.edu/IPM   *

 

Vegetable Diseases - Kate Everts, Extension Plant Pathologist, University of Maryland and University of Delaware ; everts@udel.edu

MELCAST for Fungicide Application on Watermelons.

Do not use MELCAST if there is a disease outbreak in your field, it is a preventative program. Below are the EFI values from weather stations located on the Eastern Shore July 1 - July 8. Any questions please call Phil Shields at (410) 742-8788 or e-mail: ps136@umail.umd.edu

EFI Values

Location

7/1/98

7/2/98

7/3/98

7/4/98

7/5/98

7/6/98

7/7/98

7/8/98

U of M, LESREC
Salisbury,MD

0

2

2

3

2

3

3

1

Wootten Farms, Galestown,MD

0

0

1

2

1

1

1

1

Mark Collins, Laurel, DE

0

0

2

2

3

1

2

1

U of D, REC Georgetown, DE

0

0

 

2

2

2

1

 
Vincent Farms Laurel, DE

0

0

2

3

2

2

2

1

Watermelon Fields should be sprayed with a fungicide when 30 EFI values have been accumulated by the weather station nearest your fields. Add 2 points for every overhead irrigation. After a fungicide spray, reset your counter to 0 and start over. If a spray has NOT been applied in 14 days, apply a fungicide and reset the counter to zero. The first and last day above can be partial days so use the larger EFI value of this report and other reports for any specific day.  *


Field Crops

Field Crop Insects - Joanne Whalen, Extension IPM Specialist ; jwhalen@udel.edu

Field Corn.

Corn earworm and fall armyworm larvae can be found in the whorls of later planted field corn. Feeding damage will appear as large ragged holes with larvae being found deep in the whorls. No controls should be applied unless you find 75 to 80% of the plants infested with one or more worms per plant. Treatment is not recommended for silage corn. In many cases, damage will be confined to localized areas in a field so controls are often not justified. In addition, 2 applications are often needed to provide effective control in whorl stage corn. If you decide to treat for these insects, high gallonage (30 to 50 gallons of water per acre) is needed to move insecticides into the whorl. If fall armyworm is the predominant species, Lannate or Warrior will provide the best control.

Soybeans.

In addition to grasshoppers and potato leafhoppers, green cloverworm populations are starting to increase in soybeans. Small larvae produce "window-pane" feeding holes in the leaves. As larvae increase in size, the damage will appear as large holes between the veins. In general, no controls are needed prebloom unless you find 15 larvae per foot of row and 30 % defoliation. A pyrethroid will provide effective control.

As soybeans begin to flower, be sure to watch carefully for mites feeding on the undersides of the leaves. Damage will first appear at the base of leaves appearing as white stippling on the top surface of leaves. Since we do not have any good miticides available for mite control in soybeans, early detection and application of control materials is critical. If dimethoate is used, high storage temperatures (greater than 95 degrees F) can reduce the effectiveness and it is very susceptible to degradation if the pH and/or iron content of the spray water are high. Buffering agents can be added to the mix to adjust for high pH and iron content. The buffering agent should be added to the spray tank before dimethoate is added. *

 

Hot Dry Weather Forecast Improves Pricing Opportunities - Carl German, Extension Crops Marketing Specialist ; clgerman@udel.edu

Grain and soycomplex futures are taking a run to higher ground this week across the board, on bullishly construed weather outlooks. The market is adding a risk premium to prices amid fears of hot dry conditions moving into the western midwest. The National Weather Service 6-10 day forecast is calling for above normal temperatures in the western corn belt. This news coupled with a slight decline in crop ratings sent prices higher. Just how much higher remains to be seen. One thing for sure, the time window for corn pollination to occur this season will be extended due the variability in crop development. This will give more time for any weather uncertainty to have a positive effect upon commodity price movement. Those producers needing to advance 1998 crop sales should stand ready to make those sales on this upward price swing.

National Agricultural Summary Through July 5

Corn.

Eight percent of the Nation's corn has progressed to the silking stage. Development was most advanced in the Southeast, although only slightly ahead of normal. In the heart of the corn belt, a small percentage of the crop has entered the silking stage. In the southern perimeter of the corn belt, nearly one-fourth of the crop has progressed to the silking stage.

Soybeans.

Nearly all of the crop has emerged, with progress lagging in some areas due to planting delays. Soybeans blooming advanced to 17 percent, several days ahead of last year and the 5-year average. Progress was most advanced in the lower Mississippi Valley, where over half of the crop was blooming. In the western Gulf Coast and Mississippi Delta, hot dry weather caused rapid drying and poor pod filling.

Winter Wheat.

Harvest progress advance to 69 percent complete, more than a week ahead of the normal pace.

Technical Assistance: Anyone needing further information on which to base crop sales decisions should contact Carl German at 302-831-1317 or email at clgerman@udel.edu v

 

Some Thoughts on Planting Double-Crop Soybeans? Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu Derby Walker, Extension Agent; derby@udel.edu

At this time of year, we frequently run into periods when missing storms means our fields become very dry or when we catch storms the fields may be wet for several days. Especially in dry periods, you may agonize over whether to continue planting double-crop beans or not. For full-season, single-cropped beans, the yield loss from a few days delay in planting is not very large so you can easily afford to wait for more favorable moisture conditions. In double-cropped beans, the decision is more complex. We’ll share our thoughts on this and let you add them to your decision making equation.

There are three likely soil moisture conditions to be considered. These are excessive moisture, adequate moisture, and inadequate moisture.

In the case of excessive moisture, the decision should be easy. Usually at this time of year, only a day or two of drying conditions are needed for the soil to return to field capacity or below. While the soil is too wet, you should not plant, work the soil, or do any other operation that might lead to compaction. Compaction can severely impact yields especially if drought conditions occur later in the season during the reproductive growth stages.

For adequate soil moisture levels, the decision is always to plant as many acres as possible since delays in planting double-cropped soybeans result in large decreases in yield potential.

Finally, the hardest decision on whether to continue planting occurs when there’s too little soil moisture to get a consistent stand or any stand at all. The question is whether to plant and hope it rains before the beans loose their ability to germinate or to wait and plant after it rains enough to adequately wet the soil.

Let’s consider it from an economic point-of-view. The seed you’re planting cost probably from 15 to 30 dollars per unit and often beans are planted at about one unit per acre. Adding seed cost to the expense of the planting operation brings the total to between 25 and 42 dollars an acre. At $7/bu beans, you need 4 to 6 bu/A to cover this cost. If you go ahead and plant and there is enough moisture and the beans come up, you’re automatically ahead of the game. If there isn’t, you probably have 10 to 20 days, depending on temperature and weather and soil conditions, for rain to occur before the beans are damaged so that they won’t germinate. If rain falls during this period, you could be several days to a week ahead depending on how wet the fields get, how fast they dry out after the rain, and how many acres you are planting double-crop. At this time of year, storms can drop several inches of rain in a short period. Also for growers planting a large number of double-crop acres, the delay in planting can easily reduce yields by more than the 4 to 6 bu/A needed to recover replanting costs.

What about planting depth in these situations? In conditions where crusting is a potential problem, plant no deeper than necessary (about an inch deep or slightly less) to get them into moisture. In ideal moisture situations, a planting depth of 1 to 1.5 inches is best. When planting into sandy soil under moisture stress, plant beans 1.5 to 2.0 inches deep if that places them in contact with moist soil. When planting to wait for rain in sandy soils too dry to allow germination, plant 1 to 1.5 inches deep. On heavier textured soils where crusting and emergence problems occur, use the shallower planting depths.

In summary, if you have only a few acres to plant, the economics indicate that if it is definitely too dry to plant wait until a rain to plant. If you are planting many acres and it will take many days to plant, the economics suggest that you should continue planting. Also, keep in mind that in situations where you’re on the border-line of soil moisture, you should use the smallest sized seed available. Small seed take less moisture to germinate and often will emerge in situations where larger-seeded seed lots fail to germinate.

 

Strategies for Irrigating Soybeans - Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu, Bob Uniatowski, Extension Associate-Field Crops; bobuni@udel.edu

With double-cropped soybeans going in the ground and full-season beans either closing the canopy or about to begin blooming, it’s time to consider how to irrigate beans. Full-season beans yield best if not irrigated early unless severely impacted by drought, require irrigation to activate soil-applied herbicides, or require additional moisture for germination and emergence. But, about this time of year when the beans begin to bloom, it is time to begin irrigation of full-season beans. The beans are probably using about 1/4 inch of water per day and this will rapidly increase to about 1/3 of an inch per day. Irrigation should raise the soil moisture to near field capacity throughout the rooting depth and then replace the amount of soil moisture loss to evapotranspiration until about the R7 growth stage (physiological maturity designated by at least one pod on the main stem turning to the mature pod color).

For double-crop soybeans, irrigation should begin immediately after planting and continue until the R7 growth stage. In most situations, the soil is quite dry when double-cropped beans are planted so be sure to apply adequate water early in their growth to rewet the deeper soil layers. This will provide the beans with an extra cushion if you experience a long period of very dry, hot weather.

Some of the above information was obtained in studies funded, in part, by the Delaware Soybean Board. The authors would like to express their appreciation for the support from the Board.

 

Manganese Deficiency on Soybeans - Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu

This is an ideal time to scout your full-season, early-planted soybean fields for signs of manganese deficiency. On soybeans, manganese deficiency shows as stunted plants with dark green veins and light green to yellow to white between the veins. The symptoms can be confused with other problems and especially with soybean cyst nematode injury. A soil test for nutrients and nematodes can help confirm the cause of the symptoms.

If the soil pH is much above 6.0 and the native soil manganese level is low, the symptoms are probably caused by manganese deficiency. Research from North Carolina and Virginia has shown that foliar application of manganese can effectively eliminate the problem and improve yields. The best way is to apply two applications of manganese from 0.25 to 0.5 lb actual manganese per acre. The first application should go on around the fifth leaf stage of growth and the second about the time the plants begin to bloom. If only one application can be applied, apply from 0.5 to 1.0 lb actual manganese per acre as soon as adequate foliage is present or about canopy closure on drilled beans.

There are differences in formulations of manganese and, if mixing it with postemergence herbicide applications, be sure to read the herbicide label and follow the directions to prevent antagonism and other potential problems including foliar burn. *


Annual Grain Crop Field Day

Tuesday, July 21, 1998

9:15 a.m. – 1 p.m. (Lunch at Noon)

Location: Marl Pit Road (R.d. 429, approximately 2 mile east of the intersection with Del. Rt. 71/U.S. 301 (Armstrong’s Corner). Look for the University of Delaware signs on the left.

Come join your neighboring farmers, agribusiness respresentatives, and the Extension Staff as we view and discuss this year’s field trials to include: small grain variety trials, full-season and double-crop Roundup Ready and non-Roundup Ready soybean variety trials, Bt corn hybrid and date-of-planting trials, a corn phosphorus fertility study, and two Roundup Ready soybean weed management trials. In addition, we plan a brief in-field insect identification and management training session.

We expect t have the 1998 wheat and barley variety trial results for distribution and discussion. During lunch, the Extension Specialists will present disease, insect and weed situation updates including comments on Hessian fly in small grains.

Credit toward Delaware pesticide license recertification will be awarded.

A boxed lunch will be available for $5 by reservation only. Please call by Thursday, July 16, to insure that we have a lunch reserved for you.

The meeting is free and everyone interested in attending is welcome. To reserve a boxed lunch, for more information, or for special consideration in accessing this meeting, please contact the New Castle County Extension Office at 302-831-2506.


Weather Summary

Week of July 3 to July 9

Rainfall:
0.20 inches: July 5
0.90 inches: July 9
Readings taken for the previous 24 hours at 8 a.m.
Air Temperature:
Highs Ranged from 89 F on July 5 to 84 F on July 6 & 7.
Lows Ranged from 81 F on July 5 to 66 F on July 4.
Soil Temperature:
77.5 F average for the week.
(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

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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