Posts Tagged ‘18:16’

WCU Volume 18, Issue 16 – July 2, 2010

Friday, July 2nd, 2010

PDF Version of WCU 18:16 – July 2, 2010

In this issue:

Vegetable Crop Insects
Vegetable Disease Update
Potato Disease Advisory #12 – July 1, 2010
Vegetable Double Cropping

Agronomic Crops
Agronomic Crop Insects
Soybean Disease Update
Grain Marketing Highlights

Two Grass Species To Be Aware Of

Soybean Cyst Nematode Workshop – August 3


Two Grass Species To Be Aware Of

Friday, July 2nd, 2010

Mark VanGessel, Extension Weed Specialist;

There are two grass species that are on the increase and they do not respond the same as other species. The first is Texas panicum (description: Texas panicum is very aggressive and can cause significant yield loss. It is difficult to control with most soil-applied herbicides because the seed is larger than other grasses and it is capable of emerging from relatively deep in the soil. Second of all, it has a very long germination period and is capable of germinating late into the summer. It seems to just keep emerging and grows very rapidly. There are options to control it postemergence (glyphosate, Accent, Laudis, Impact, Poast, Select, etc), but since Texas panicum grows rapidly, it needs to be treated early (earlier than many other grass species).

The other species that seems to be increasing is goosegrass (description: There are two issues to be aware of with goosegrass. First is that goosegrass also germinates late into the summer. Also, it is not controlled with Select (clethodim). We have not tried all the various postemergence grass herbicides, but have had good success with Poast (sethoxydim). It is generally not a problem controlling goosegrass in corn or soybeans, but it can be a problem in vegetables where postemergence grass herbicides are used more often. This is one situation where proper selection of postemergence grass herbicide is important.

Grain Marketing Hightlights

Friday, July 2nd, 2010

Carl German, Extension Crops Marketing Specialist;

June 30 Planted Acreage and Quarterly Grain Stocks Summary

U.S. corn and soybean acreages are up 2 percent from levels a year ago. However, corn planted acreage was reported to be 930,000 acres less than that reported in the March 31 Planting Intentions Report. Soybean planted acreage, reported at 78.87 million acres are about 670,000 acres more than farmers reported on March 31. Since many analysts were expecting an acreage increase for corn, this report is being viewed as friendly to bullish for corn prices, bullish for wheat, and somewhat bearish for soybeans. U.S wheat planted acreage at 54.31 million acres is about 500,000 acres more than reported in March, however, it is just shy of being 5 million acres less than last year.

Quarterly Stocks
U.S. corn stocks were reported at 4.310 billion bushels. Although slightly higher than last year, the number came in lower than the low end of trade expectations. This too is bullish for corn prices. U.S. soybean stocks were reported to be 25 million bushel less than last year and also lower than the low end of trade expectations. This will help to offset any bearishness in the soybean market stemming from the acreage report. U. S. all wheat quarterly stocks were reported to be above the high end of trade expectations and 316 million bushels more than last year at this time. This will offset any bullishness stemming from the acreage report, although this information has been known for some time and wheat prices are more likely to move in sync with the direction of corn.

Market Strategy
We are seeing a positive move in commodity prices in this morning’s trade (6/30/10). The move is likely to be partly due to the report, setting a psychological tone for a rally and partly due to commodity markets being considered oversold. Speculation has it that the tone has also been set for USDA’s July 9 Supply and Demand report where ending stocks for corn and soybeans could be projected to be less than previously expected. The Dow and the dollar are also supportive in this morning’s trade. Currently, Dec ‘10 corn futures are trading at $3.70/ bu., up 26 cents; Nov ‘10 soybean futures are trading at $9.09, down 2 cents; and July SRW wheat futures are trading at $4.64/ bu., up 22 cents from yesterday’s close. 

Acreage (million acres)

  6/30/10 Average High Low USDA 3/31/10 USDA Final 2009
Corn 87.87 89.23 90.15 88.1 88.8 86.5
Soybeans 78.87 78.18 78.9 76.53 78.1 77.5
All Wheat 54.31 53.83 54.09 53.5 53.8 59.13

 Quarterly Stocks (billion bushels)

  6/1/10 Average High Low 3/1/10 6/1/09
Corn 4.31 4.598 4.784 4.459 7.694 4.261
Soybeans 0.571 0.594 0.62 0.58 1.27 0.596
All Wheat 0.973 0.94 0.95 0.929 1.352 0.657

Soybean Disease Update – July 2, 2010

Friday, July 2nd, 2010

Bob Mulrooney, Extension Plant Pathologist;

Soybean Cyst Nematode
SCN was diagnosed this week on soybeans. If you see stunting and yellowing, carefully dig up the affected plants with a shovel or trowel and gently shake the soil from the roots. White or yellow females will be seen attached to the infected roots if present. They are small, much smaller than the nitrogen fixing nodules, but can be seen with the naked eye. A 10x hand lens makes the task much easier to see the lemon shaped females. If it is not clear what the problem is or cysts cannot be seen a soil sample of the affected area can be taken and checked for SCN or other nematodes. Test bags and more information are available at the county Extension offices and forms and info at the Plant Diagnostic Lab site at . We will be having a Soybean Cyst Nematode Workshop on August 3. See the meeting announcements for more information and registration forms.


Septoria Brown Spot
Septoria brown spot has not been as prevalent as last year but it has been seen in a few fields so far. It is one of the earliest fungal diseases that we see and can be found on the unifoliate leaves and the lower trifoliate leaves when it is present. Badly infected unifoliate leaves will usually fall from the plant and we will not see this disease again until the soybeans canopy and conditions would be favorable for infection. Most seasons this disease is not yield limiting.


Septoria brown spot on unifoliate leaves of soybean

Agronomic Crop Insects – July 2, 2010

Friday, July 2nd, 2010

Joanne Whalen, Extension IPM Specialist;

We have seen an increase in potato leafhopper populations this past week so be sure to sample fields for adults and nymphs. 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.

We can find a number of defoliators in full season soybean fields including grasshoppers, green cloverworm, Japanese beetles, oriental beetles and bean leaf beetles. In some fields, the main defoliator is the green cloverworm. Larvae are light green with three pairs of white stripes running the length of the body. In addition to the three pairs of legs near the head, they have three pairs of fleshy legs near the middle of the body, and one additional pair at the end of the body. Larvae wiggle vigorously when disturbed. Smaller larvae may drop from the leaf when disturbed. Young larvae skeletonize the underside of the leaf. Older larvae chew irregular shaped holes in the leaves and can eat all of the leaf except large veins. Although populations of green cloverworm generally increase in number from July through September, if the weather turns dry, we often see an earlier increase in numbers. Fungal pathogens often crash populations; however, under dry weather conditions this will not occur. As a reminder, double crop soybeans can not tolerate as much defoliation as full season beans so be sure to watch newly emerged fields carefully, especially for grasshoppers.

Some consultants are also seeing an increase in leafhopper populations in seedling stage soybeans. As a general guideline, a control may be needed for leafhoppers if you see plant damage and you find 4 leafhoppers per sweep in stressed fields and 8 per sweep in non-stressed fields.

Economic levels of spider mites can be found in all three counties in both full season and double crop fields and in many cases infestations are field wide. As we learned in past years, drought will seriously stress plant growth, favor mite development and create plant growth conditions that make it difficult to achieve effective control. Early detection and multiple applications are often needed under drought stress conditions. Under high population pressure, a single treatment may not be adequate to kill all the life stages. Mite eggs may not be affected by the initial knockdown and thus hatch after a few days. As indicated in past newsletters, dimethoate, Lorsban (chlorpyrifos), bifenthrin and Hero are labeled on soybeans for spider mite control in Delaware. (Be sure to read all labels before spraying for restrictions and rates).

Hero and Generic Bifenthrin (e.g. Sniper) – The bifenthrin component in Hero is the material that will provide spider mite suppression. Please refer to the label for use rates and restrictions – you will need the high rate for spider mite management. It should also be noted that both labels state: “do not make applications less than 30 days apart”.
Hero –
Sniper (generic bifenthrin) —

Dimethoate – This material must be absorbed and translocated by the leaf tissues to provide residual action; otherwise, it undergoes rapid photodecomposition from sunlight. This leaf absorption process is greatly reduced in drought-stressed plants that have “shut-down” physiologically. Another important factor that plays a role in the performance of dimethoate is the pH of the water used as the carrier. Many pesticides, especially dimethoate, are subject to breakdown by alkaline hydrolysis ( In alkaline water (high pH), there is a break in certain bonds in the dimethoate molecule, causing two or more new molecules to form. This increases the decomposition rate of the insecticide and can result in poorer than expected field performance. Dimethoate degradation is also accelerated by the mineral content of the water, especially the presence of iron. If a high pH situation exists, you can lower the alkalinity of the water in the spray tank by adding an acid-based buffer. An important consideration is to select a buffering product that lowers the pH to the acid range without causing phytotoxicity. Also, the buffer must be added to the spray tank first, before the addition of dimethoate. (; ( )

Lorsban (chlorpyrifos) – In past years, Lorsban has provided good contact control of motile mites when applied in enough water to get good coverage. However, since Lorsban is not a systemic product, a second spray 3 to 5 days later may be needed to kill newly hatched mites. The label states that: (1) When large numbers of eggs are present, scout the treated area in 3-5 days and if newly hatched nymphs are present, make a follow up application with a non-chlorpyrifos product and (2) do not make a second application of Lorsban 4E or other product containing chlorpyrifos within 14 days of the first application. So before applying be sure to read the label for restrictions, maximum number of applications, etc. ( )

Vegetable Double Cropping

Friday, July 2nd, 2010

Gordon Johnson, Extension Vegetable & Fruit Specialist;

I have been asked several times in the last two weeks about double cropping vegetables. The following are some considerations in double cropping.

Crop residue management is critical in order to get a good seed bed for the double crop vegetable. Make efforts to spread and incorporate residue evenly. Heavy areas of incorporated straw or vine will lead to crop variability. Incorporation of high carbon materials such as small grain straw can lead temporary nitrogen deficiencies. Therefore, extra nitrogen fertilizer will be needed to speed decomposition of heavy straw residue. In contrast, green materials such as pea vines will not cause nitrogen tie-up and will rapidly decompose. It is advised to allow some time (minimum 5-7 days) for residue decomposition before planting the next crop.

Allelopathic responses (toxic reactions) in the double crop planting have been found in certain cases when planting has occurred immediately after incorporation of residues. One example has been with pea vines. Fresh pea residues have been shown to release pisatin, a chemical which can inhibit the germination and seedling growth of some seeds. Allowing residue to dry before incorporation, moldboard plowing fresh residue so it is out of the germination area, or waiting for a period of time to allow incorporated residue to decompose and the pisatin to break down before replanting (7 or more days) would reduce the risk of this allelopathic reaction affecting following double-cropped vegetables.

Pay close attention to herbicide plant back restrictions for vegetable double crops. Low rates (0.5-0.75 lbs) of atrazine are often used in sweet corn and this normally does not affect subsequent plantings. However, higher rates can damage the double crop planting. Mesotrione (Callisto, component of Lexar and Lumax) which is used in sweet corn has significant replant restrictions to many vegetables as do topramezone (Impact) and tembotrione (Laudis), also labeled for sweet corn. Command, Reflex, and Pursuit are examples of other common herbicides with significant plant back restrictions. Check the Delaware Commercial Vegetable Production Recommendations book and the specific herbicide labels for appropriate waiting periods and crops rotational restrictions.

Potato Disease Advisory #12 – July 1, 2010

Friday, July 2nd, 2010

Bob Mulrooney, Extension Plant Pathologist;

Disease Severity Value (DSV) Accumulation as of June 30, 2010 is as follows:
Location: Art and Keith Wicks Farm, Rt 9, Little Creek, Kent County.
Green row: May 6

Date Daily DSV Total DSV Spray Recs Accumulated
P- days*
6/11-6/12 1 37 7-days 292
6/13-6/14 2 39 7-days 305
6/15-6/16 0 39 7- days 315
6/16-6/17 2 41 7-days 325
6/18-6/20 0 41 7-10 days 354
6/21 0 41 10 days 360
6/22-6/23 1 42 10-days 371
6/24-6/25 0 42 10-days 381
6/26-6/27 0 42 10-days 391
6/28–6/30 0 42 10-days 408


There have been new reports of late blight on tomatoes from central and northern PA, Long Island NY and CT last week. These have been home gardens for the most part. The weather has not been favorable for late blight recently. There have been no reports from eastern shore VA, NJ or DE to date.

For specific fungicide recommendations, see the 2010 Delaware Commercial Vegetable Production Recommendations Book.

Vegetable Disease Update – July 2, 2010

Friday, July 2nd, 2010

Bob Mulrooney, Extension Plant Pathologist;

Cucurbit Downy Mildew
We are at minimal risk at the present but keep up to date by checking the ipm PIPE website regularly for updates. Downy mildew was found in New York state for the first time on cucumber in Erie and Niagara counties close to the Ontario, Canada infection site. The northern march of downy has been slowed. We have had some weather patterns coming north but the clear skies and plenty of UV radiation have probably been keeping viable spore number low. We are checking our sentinel plots weekly for downy mildew here in DE.

Bacterial Wilt
Bacterial wilt on slicing cucumbers was diagnosed this week. Symptoms on this planting were random wilting of several runners on 20% of the plants. Sticky strands of bacterial ooze can be seen when the cut ends of the wilted runners are touched together then slowly drawn apart. Striped and spotted cucumber beetles carry the bacteria on their mouthparts and inoculate them when they feed on the succulent stems early in the season. Bacterial wilt is not seed borne and does not persist in the soil more than 2-3 months. It is thought that the bacteria acquire the bacteria from infected weed or volunteer cucurbit hosts. Cucumber beetle control is the primary control method.

Strands of bacterial ooze from touching cut ends of infected runner and pulling them apart slowly

Potato and Tomato Late Blight Webinar for Home Gardeners
Rutgers, Penn State and Cornell University vegetable plant pathologists will be holding a Webinar on Potato and Tomato Late Blight for home gardeners on July 13, 2010 at 6:30 PM. You are encouraged to participate in this timely topic. The linked announcement has all the information to enroll. It will be a good review for commercial producers as well.

Pythium Blight or Cottony Leak on Snap Beans
Pythium blight or cottony leak on snap beans was diagnosed early this week. This disease likes the hot, humid conditions that we had before this recent break in the weather. When we go back to the humid weather again with scattered showers and irrigation this disease can be a threat. Look for the cottony white growth in the lower canopy and on pods close to the ground. There is a 24c registration for Ridomil Gold Copper (2 lbs/A) for prevention of Pythium blight in DE, MD and VA. Several applications may be necessary if favorable weather persists.

Cucurbit Powdery Mildew
Powdery mildew on cucurbits has been reported in New Jersey. Delaware growers should be scouting and begin applying fungicides for powdery mildew once 1 old leaf in 45 has been found with powdery mildew. See the article titled Powdery Mildew on Cucurbits in WCU 18:15 for suggested fungicides.

Vegetable Crop Insects – July 2, 2010

Friday, July 2nd, 2010

Joanne Whalen, Extension IPM Specialist;

Continue to scout all melons for aphids, cucumber beetles, and spider mites. As a general guideline, a treatment should be considered when you find 20-30% of the plants infested with 1-2 mites per leaf. Be sure to check all labels for rates, precautions and restrictions, especially as they apply to pollinators.

As soon as the first flowers can be found, be sure to consider a corn borer treatment. Depending on local corn borer trap catches, sprays should be applied on a 7 to 10-day schedule once pepper fruit is ¼ – ½ inch in diameter. Be sure to check local moth catches in your area by calling the Crop Pest Hotline (in state: 1-800-345-7544; out of state: 302-831-8851) or visiting our website at ( You will also need to consider a treatment for pepper maggot. Be sure to watch carefully for beet armyworm larvae since they can quickly defoliate plants.

Continue to scout fields for Colorado potato beetle (CPB), aphids and leafhoppers. Controls will be needed for green peach aphids if you find 2 aphids per leaf during bloom and 4 aphids per leaf post bloom. This threshold increases to 10 per leaf at 2 weeks from vine death/kill. If melon aphids are found, the threshold should be reduced by half.

Snap Beans
Continue to scout for leafhopper and thrips activity in seedling stage beans. As a general guideline, once corn borer catches reach 2 per night, fresh market and processing snap beans in the bud to pin stages should be sprayed for corn borer. Sprays will be needed at the bud and pin stages on processing beans. As earworm trap catches increase, an earworm spray may also be needed at the pin stage. Additional sprays may be needed after the pin spray on processing beans. Since trap catches can change quickly, be sure to check our website for the most recent trap catches and information on how to use this data to make a treatment decision in processing snap beans after bloom ( and Once pins are present on fresh market snap beans and corn borer trap catches are above 2 per night, a 7 to 10-day schedule should be maintained for corn borer control.

Sweet Corn
Continue to sample seedling stage fields for cutworms and flea beetles. You should also sample all fields from the whorl through pre-tassel stage for corn borers and corn earworms. The first silk sprays will be needed for corn earworm as soon as ear shanks are visible. Be sure to check both blacklight and pheromone trap catches for silk spray schedules since the spray schedules can quickly change. Trap catches are generally updated on Tuesday and Friday mornings ( and You can also call the Crop Pest Hotline (in state: 1-800-345-7544; out of state: 302-831-8851). W have found the first fall armyworm in whorl stage sweet corn. A treatment should be considered when 12-15% of the plants are infested. Since fall armyworm feeds deep in the whorls, sprays should be directed into the whorls and multiple applications are often needed to achieve control.

Soybean Cyst Nematode Workshop

Thursday, May 6th, 2010

Tuesday, August 3, 2010  8:30 a.m.- 1:30 p.m.
Delmarva Poultry Industry Building
(former UD office building)
16684 County Seat Hwy.
Georgetown, DE 19947

Soybean cyst nematode (SCN) is a widespread and serious pest of soybeans on Delmarva. First discovered in the fall of 1979 it has been causing increased problems for growers in recent years. This workshop will cover some basics about the biology of SCN and it management and the results of the recent Delaware Soybean Board sponsored survey of SCN in Delaware. The workshop will also include visiting a small research plot to see SCN first hand and discuss symptoms, diagnosing SCN from root samples with a hand lens, and proper soil testing procedures. The workshop is suggested for agricultural professionals on Delmarva who advise soybean growers and growers who want to know more about this important pest.

Pesticide recertification credits and CCA credits in pest management will be offered for attendees.

The cost of the program is $10 per person with lunch included. The registration deadline is Friday, July 23. A registration form is available here: