Volume 14, Issue 16                                                                                 July 14, 2006

Soybean Rust Update



Georgia officials reported a confirmation of soybean rust on July 10th from a soybean sentinel plot in Decatur County. Decatur County borders Gadsden County, Florida, were rust was found earlier this year. This is the third report of soybean rust on this year's soybeans. Soybean rust was found on kudzu in two sites in Iberia Parish, Louisiana on July 7th and 12th. There still have been no reports of soybean rust on commercial soybeans in the South. The forecast is for limited transport of spores in the South.


Locally the soybean sentinel plots are at the R3 growth stage for the Group III variety and V8 to R1 for the Group V. Scouting continues and the only disease present currently in the plots is Septoria brown spot. Other diseases have started to show up in commercial soybeans. Frogeye leafspot was seen by a consultant this week as well as downy mildew in addition to brown spot which has been very prevalent.


Bob Mulrooney





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


Lima Beans

As soon as pin pods are present, be sure to watch carefully for plant bug and stinkbug adults and nymphs. Stinkbug populations may be heavier this year as a result of heavier populations in 2005 and mild winter conditions. Treatment should be considered if you find 15 adults and/or nymphs per 50 sweeps. Capture (bifenthrin), Mustang MAX, Proaxis and Warrior (lamdacyhalothrin) are labeled for both insects. The higher labeled rates will be needed if stinkbugs are the predominant insect present. You should also start scouting the earliest planted fields for corn earworm. As a general guideline, a treatment will be needed if you find one corn earworm larvae per 6 ft-of-row. Be sure to read all labels for restrictions and days from last application to harvest.



In addition to aphids and spider mites feeding on leaves, you should also begin to watch for cucumber beetles and beet armyworm feeding on rinds. No thresholds are available for rind feeding; however, controls should be applied before significant damage has occurred. The only effective material labeled for beet armyworm control on melons is Spintor. Be sure to read all labels for days from last application to harvest.



In areas where corn borers are being caught in local traps and pepper fruit is ¼ inch or more in diameter, fields should be sprayed on a 7-day schedule for corn borer control. Be sure to check local moth catches in your area at http://ag.udel.edu/extension/IPM/traps/latestblt.html. You will also need to consider a treatment for pepper maggot. Now that beet armyworm has been detected, be sure to scout for this insect on a weekly basis. No threshold is available, so you need to watch for the first small larvae as well as their feeding signs. You can often find small beet armyworm larvae feeding in groups on young leaves and fine webbing is produced by smaller larvae near these feeding sites. It is important to spray as soon as you see small holes and before you see this webbing since defoliation can rapidly occur. Spintor, Avaunt, or Intrepid will be needed for BAW control. Be sure to read all labels for days from last application to harvest.


Snap Beans

In areas where corn borers are being caught, processing snap beans in the bud and pin stages should be sprayed for corn borer. 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 information to make a treatment decision in processing snap beans (http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/snapbeanecbthresh.html). Once pins are present on fresh market snap beans and corn borer trap catches are above 2 per night, a 7-10 day schedule should be maintained for corn borer control


Sweet Corn

The first sprays should be applied for corn earworm as soon as ear shanks are visible. In general sprays are needed on a 4 day schedule except in the Concord and Seaford areas where sprays are needed on 3 day schedule. However, be sure to check trap catches for the current spray schedule since trap catches quickly change. Trap catches are generally updated on Tuesday and Friday mornings. (http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/silkspraythresh.html). You can also call the Crop Pest Hotline for current trap catches (in state: (800) 345-7544; out of state: (302) 831-8851).



Downy Mildew and Phytophthora Fruit Rot on Processing Cucumbers Bob Mulrooney; Extension Plant Pathologist; bobmul@udel.edu

and Kate Everts; Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu


Downy mildew was identified on Tuesday June 11 on processing cucumbers near Milford, DE.  Fortunately the epidemic is in the early stages.  Our hats are off to the growers, scouts, and consultants for their diligence in scouting. Early detection, along with sound fungicide choices will help keep this disease in check, especially if the weather cooperates as well.  A fungicide program that worked well on Delmarva and in other locations in the past year is Previcur Flex 1.2 pt plus Bravo 2 pt alternated with Tanos 8 oz plus Mancozeb 2 lb.  The fungicides should be applied on a 5 to 10 day interval depending on the weather.  Other materials that have performed well in trials are Ranman or Gavel plus Curzate.  Remember to observe pre-harvest intervals (PHI) and to alternate products that have different modes of action (different classes). 











M2 + 22







Previcur Flex









11 + 27




Keep up with disease development by checking the NC State Downy Mildew Forecast website at http://www.ces.ncsu.edu/depts/pp/cucurbit/. The site should be updated on Thursday July 13th. Downy mildew was found several days ago down on the eastern shore of Virginia as well.


The other disease consideration is control of Phytophthora fruit rot, which will continue to be a problem with the hot weather, especially if we keep getting thundershowers. Phytophthora fruit rot is still the most important disease problem in many fields.


If you are concerned about Phytophthora fruit rot as well as downy mildew Ranman at 2.75 oz/A for fruit rot control and applied when fruit form should provide very good downy mildew control for 7-10 days as well, if it is applied preventatively. Previcur Flex is not labeled for Phytophthora fruit rot. If you made an application of Ranman, Gavel, or Tanos for Phytophthora fruit rot and downy mildew is present and conditions are severe for downy mildew consider switching to Previcur Flex for the next application. We can see no need to combine Previcur Flex and Ranman for control of both diseases. Ranman, Gavel, and Tanos are labeled for suppression of Phytophthora fruit rot.



Downy Mildew on Watermelon, Pumpkin, Squash and Muskmelon Kate Everts; Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu


Although downy mildew has been confirmed on cucumber in Delaware, it has not been seen on watermelon, squash, pumpkin or muskmelon.  We know that different pathotypes of the downy mildew organism may affect one cucurbit but not another.  However, we don’t know what pathotype we are currently dealing with.  In 2004 and 2005, downy mildew became established in July on cucumber but many other crops were not affected until much later in the growing season.  However the potential for severe epidemics remains.  A good strategy on watermelon and summer squash is to apply a protectant such as mancozeb, and to apply maneb on pumpkin and winter squash.  Continue to scout the crops intensively.  When downy mildew is observed within the crop or reported on watermelon, squash or pumpkin in the region, fungicides targeted specifically for downy mildew should be applied.   These products include Ranman, Previcur Flex, Curzate and Tanos.  Gavel also has good activity and is a good choice for watermelon or summer squash, but cannot be applied to pumpkin or winter squash because it contains mancozeb.


This approach (protectant applications of mancozeb until downy mildew is seen on the crop) also can be used for muskmelon (cantaloupe).  However, be aware that some preliminary reports indicate that muskmelons are more susceptible than pumpkins or squash to the cucumber strain.  While this is quite preliminary information, muskmelon growers may opt to apply the more targeted fungicides to manage downy mildew.



Potato Disease Advisory #19 – July 13, 2006, Bob Mulrooney, Extension Plant Pathologist


Late blight Advisory

Disease Severity Value (DSV) Accumulation as of July 12, 2006 is as follows:

Location: Byfield Farms field east of Magnolia, DE. Greenrow: April 23, flower buds present May 24.






Daily DSV

Total DSV

Spray Recs


P days*





















6/18- 6/20





6/20- 6/21






























6/29- 7/4





7/4- 7/5





7/5- 7/6





7/6- 7/9












Keep up with your preventative sprays with a high rate of chlorothalonil (Bravo or a generic) or mancozeb (Dithane, Manzate, Penncozeb, etc). Aerial stem blight or aerial black leg has been seen in the region. With high temperatures and abundant moisture, Pythium leak is always a threat during harvest at this time of year. Fungicide applications made for pink rot control are also effective for leak.



Agronomic Crops


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



In addition to defoliators, be sure to watch for spider mites. We can find economic levels of mites in soybeans throughout the state. In some cases, we are also seeing diseased mites so be sure to determine if diseases are helping to crash populations before making a treatment decision. A treatment is recommended if you find 20-30 mites per leaflet or 10% of plants with 1/3 or more leaf area damaged. The only materials available for mite control in soybeans are dimethoate and Lorsban. 


Be sure to continue to scout fields on a weekly basis for soybean aphids. We continue to find extremely low levels in isolated fields throughout the state. The action threshold – developed in the Midwest - is an average of 250 aphids per plant, on plants sampled throughout the field. In the Midwest, spraying at or beyond R6 has not been documented to increase yield. Conditions that favor aphid population growth are cool temperatures, plant stress, particularly drought stress, and a lack of aphid predators.



Agronomic Crop Diseases Bob Mulrooney; Extension Plant Pathologist; bobmul@udel.edu



We diagnosed gray leafspot on corn this week. Numerous small rectangular spots on the leaves with a thin purplish red border were present. Keep an eye out for foliar diseases at this time of year.



As stated in the Soybean Rust Update we are now seeing frogeye leafspot and downy mildew. In most seasons these diseases are not yield limiting but keep and eye out for frogeye leafspot. Varieties can vary in their resistance to this disease.

Frogeye leafspot


Downy mildew (upper leaf surface)


Downy mildew (lower leaf surface)



Double-Cropped SoybeansMark VanGessel, Extension Weed Specialist; mjv@udel.edu


In many situations, one application of glyphosate in double-cropped soybeans was sufficient for burndown and in-crop weed control. However, this year there are a lot of wheat fields with heavy grass or weed pressure that should be treated at planting or shortly after planting. The delayed harvest and high rainfall has resulted in a lot of grass in some of these fields. If you wait a few weeks before the glyphosate is applied it could result in poor weed control because the grasses will be quite large, loss of soil moisture if the rains do not continue, and soybeans that are taller and “leggier” because they are trying to get taller than the grass and maximize sunlight absorption. UD research has shown that glyphosate applied less than two weeks after planting should have a residual herbicide included to reduce the chance of a second application. If the soybeans have emerged, this will limit your choices of residual herbicides. Options include Classic, FirstRate, Pursuit, Raptor, and Synchrony. Most years there have not been so many weeds emerged at the time of wheat harvest and skipping the burndown was acceptable. But this year there are many fields that needed a burndown.


Control of morningglories in soybeans is another question that has come up. In Roundup Ready soybeans, using glyphosate is still the best option and adding other herbicides has little to no benefit. Adding additional glyphosate (increasing the rate by an additional 25 to 50% more) is advisable. Killing large morningglories is generally not an option; it’s trying to stunt them and allowing the soybean canopy to get over the top of the morningglory. In non-Roundup Ready soybeans, Blazer, Classic, FirstRate, and Reflex may provide some suppression, but generally it is not sufficient on large morningglory (greater than 8 inch runners).



Manganese Applications with Postemergence GlyphosateMark VanGessel, Extension Weed Specialist; mjv@udel.edu


Roundup Ready soybeans may require a postemergence application of glyphosate (Roundup, Touchdown or GlyphoMax) and a manganese application at about the same time. Glyphosate products can be tankmixed with manganese with some precautions. The manganese products can bind with glyphosate in the spray tank and reduce glyphosate’s effectiveness. The form of manganese has an impact. Manganese chelated with EDTA did not affect the performance of glyphosate, but other forms of manganese did. The addition of ammonium sulfate overcame the problem. Thus, when tankmixing glyphosate with manganese, use an EDTA form of manganese or add ammonium sulfate to overcome the reduced weed control. When using ammonium sulfate be sure to add the ammonium sulfate to the tank first and add the glyphosate last.



Comparison of Glyphosate Herbicides in NebraskaMark VanGessel, Extension Weed Specialist; mjv@udel.edu


We have tested a variety of glyphosate formulations the past few years and have found minor differences (if any) between the formulations. Other research has shown the same results. The following is a research report from the online Journal of Crop Management (July 2005). The authors are B. F. Kappler, S. Z. Knezevic, R. F. Klein, D. J. Lyon, A. R. Martin, F. W. Roeth, and G. A. Wicks. The summary: “the proliferation of glyphosate products into the glyphosate-resistant crop market is unprecedented. Due to widespread public interest in these products, field experiments were conducted to compare the efficacy of various glyphosate herbicides on weed control at six locations across Nebraska in various cropping systems. In general, generic glyphosate products provided equal level of weed control compared to the usually more expensive brand name products”. The products tested included Clearout 41 Plus, Cornerstone, GlyphoMax, GlyphoMax Plus, Glyfos, Roundup UltraMax, Roundup WeatherMax, and Touchdown IQ.



Time of Day of Application Effect on Glyphosate and Glufosinate EfficacyMark VanGessel, Extension Weed Specialist; mjv@udel.edu


The following is a research summary published in the online Journal of Crop Management (July 2005). The authors are K. B. Martinson, B. R. Durgan, J. L. Gunsolus, and R. B. Sothern. The summary reads: “the objectives of this study were to examine the influence of time of day of herbicide application, adjuvant, and rate of glyphosate and glufosinate (active ingredient in Liberty) on annual weed control. Time of herbicide application influenced annual weed control of both glyphosate and Liberty. Greatest annual weed control was observed between 0900 and 1800 h, while less weed control was observed at 0600, 2100, and 2400 h. Additional adjuvant or an increased rate of glyphosate or Liberty improved efficacy, but did not overcome the time-of-day effect”. The additional additive was a mixture of an 80:20 nonionic surfactant and ammonium sulfate. The study was conducted in Minnesota which has shorter day-length than DE, so the time of day may not match exactly. But the conclusion is pertinent to our situations, which reads “applicators should try to avoid early morning and evening hour applications of glyphosate and Liberty, especially under cooler environments and on difficult-to-control or taller weed species”. The study tried to determine which factors (herbicide rate, air temperature, weed height, additional adjuvant, relative humidity, or presence of dew) contributed most to the decline in control and found it difficult to conclude which, if any, one factor is most important.



Grain Marketing Highlights - Carl German, Extension Crops Marketing Specialist; clgerman@udel.edu


July Supply/Demand Report Termed Bullish

The June Acreage and Quarterly Grain Stocks in all positions reports are now history. In addition, USDA released the July Supply and Demand report this morning. Overall the report is termed bullish for U.S. corn and soybeans and neutral to bullish for wheat. The bullishness stems from the fact that USDA did not shift planted acres as much as pre-report expectations. The dominant factor driving the commodities markets remains the weather.


U.S. Corn S & D Highlights

Area planted to U.S. corn is now placed at 79.4 million acres as compared to 78 million acres indicated on March 30th. With the trend line yield projected at 149 bushels per acre and 72.1 million acres projected for harvest, corn production for the '06/'07 marketing year is now placed at 10.740 billion bushels, a 190 million bushel increase from last month's projection. Beginning stocks for the '06/'07 marketing year are now placed at 2.062 billion bushels, 114 million bushels less than last month. Imports are projected at 10 million bushels for a total U.S. corn supply of 12.812 billion bushels for the '06/'07 marketing year, an increase of 76 million bushels from the June estimate. However, increases in Feed and Ethanol for fuel demand from the previous month were enough to account for a slight reduction in the ending stocks estimate for U.S. corn from last month. Ending stocks for U.S. corn for the '06/'07 marketing year are now projected at 1.077 billion bushels, 14 million bushels less than the June estimate. Pre-report expectations were guessing that ending stocks for the '06/'07 marketing year could go as high as 1.4 billion bushels, with the average trade estimate at 1.257 billion bushels. The season average farm price range for U.S. corn for the '06/'07 marketing year is unchanged from last month at $2.25 to $2.65 per bushel.


World ending stocks for corn are now placed at 91.20 million metric tons (mmt) as compared to 92.18 mmt a month ago and 130.39 mmt a year ago.


U.S. Soybean S & D Highlights

Area planted to U.S. soybeans for the '06/'07 marketing year is now placed at 74.9 million acres, 2 million acres less than March 30th intentions. Beginning stocks were reduced by 25 million bushels from the June estimate and are now placed at 545 million bushels. A yield projection of 40.7 million bushels on 73.9 million acres harvested projects total U.S. soybean production for the '06/'07 marketing year at 3.010 billion bushels, 70 million bushels less than last month due to the reduced acreage estimate. Beginning stocks were reduced 25 million bushels, now projected at 545 million bushels. Import projections are placed at 4 million bushels bringing the total projected supply for U.S. soybeans for the '06/'07 marketing year to 3.559 billion bushels. With no changes in the demand projections from the June estimates ending stocks for U.S. soybeans are now placed at 560 million bushels, 95 million bushels less than the June estimate and 15 million bushels greater than the carry over from the '05/'06 marketing year. The season average farm price range is projected at $5.00 to $6.00 per bushel. It is interesting to note that the price range estimate is 10 cents per bushel lower on both ends of the range from the previous month.


World ending stocks for soybeans are now placed at 53.01 mmt as compared to 57.52 mmt a month ago and 55.5 mmt a year ago. Southern Hemisphere soybean production is now placed at 97.3 mmt for the '06/'07 marketing year as compared to 96.2 mmt a year ago. China corn production is projected at 138 mmt; Argentina corn production at 17.5 mmt; and Brazil corn production at 40.5 mmt.


U.S. Wheat S & D Highlights

U.S. wheat production for all wheat is now projected at 1.806 billion bushels, reflecting an 8 million bushel decrease from the June estimate. Both wheat acres planted and to be harvested were increased from the June estimates. Yield per acre, now placed at 38.3 bushels, is 1 bushel per acre less than the June estimate. Total wheat use declined by 5 million bushels from last month due to a 5 million bushel reduction in the estimate in wheat for feed use and is now placed at 2.040 billion bushels. Ending stocks for U.S. wheat for the '06/'07 marketing year are now placed at 438 million bushels, 22 million bushels more than last month's estimate and 130 million bushels less than the carry over from the '05/'06 marketing year. U.S. season average farm prices for wheat are now projected at $3.70 to $4.30 per bushel.


World ending stocks for wheat are now placed at 133.2 mmt as compared to 128.24 mmt a month ago and 143.99 mmt a year ago.


Marketing Strategy

Profit taking has the commodity markets declining in today's markets in spite of a slightly bullish USDA report. It is also likely that portions of the Corn Belt are getting some shower activity today. Non-commercial funds were heavy buyers in the corn pits earlier in the week. Timely rains are needed in the Corn Belt in order to produce a trend line or better yield in the U. S. this growing season. The weather over the next two weeks will determine the potential size of the '06 U.S. corn crop. Expect the market price activity to be volatile during this time period. Wheat sales for the '06 harvest should be completed if you have not already done so. Opportunities still exist to get up to 25 to 30 percent of the '07 wheat crop covered. For technical assistance on grain marketing decisions contact Carl L. German, Extension Crops Marketing Specialist.





Risk Assessment Workshops for Crop Producers


Risk Assessment Workshops sponsored by the USDA’s Risk Management Agency are scheduled in each county. Learn how to identify all types of risks in your farm operation, discover strategies to reduce or eliminate some or all of the risks (including crop insurance and Farm Service Agency programs), and develop your own risk management plan specific to your operation.


Coffee and donuts will be served.


Monday July 17, 2006   8:30 a.m.

Kent Co. Farm Service Agency

800 Bay Rd. Dover, DE


Tuesday July 18, 2006   9:00 a.m.

Blackbird Community Center

120 Blackbird Forest Rd. Townsend, DE


Wednesday July 19, 2006   9:00 a.m.

Carvel Research and Education Center

16483 County Seat Hwy. Georgetown, DE


If you need additional information contact

Cory Whaley (302) 856-7303



Weather Summary


Week of July 6 to July 12, 2006

Readings Taken from Midnight to Midnight



0.37 inch on July 6

0.02 inch on July 12


Air Temperature:

Highs Ranged from 89°F on July 11 and July 12 to 75°F on July 6.

Lows Ranged from 74°F on July 12 and to 59°F on July 7 and July 9.


Soil Temperature:

78°F average.

(Soil temperature taken at a 2" depth, under sod)

The Weekly Crop Update is available online at



Weekly Crop Update is compiled and edited by Emmalea Ernest, 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. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Delaware Cooperative Extension, University of Delaware. It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, color, sex, disability, age or national origin.