Volume 14, Issue 13                                                                                June 23, 2006

Soybean Rust Update



Intensive scouting continues in soybean sentinel plots especially in the South as soybeans reach maturity. Most of the soybean sentinel plots have been planted throughout the country with plants in some early planted plots starting to reach maturity. Scouting continues on kudzu patches from Florida to the north as far away as Nebraska. The rust find on June 15th in a sentinel site in Martin County, FL, is still the only soybean rust find in this season's soybeans (from the National Soybean Rust website for 6-21-06).


Keep current on the soybean rust situation by visiting the PIPE (Pest Information Platform for Extension and Education) website at http://www.sbrusa.net


Locally, the sentinel plots are in the V-6 growth stage and the early Group III varieties may be flowering in a week or two. The delay in rust development in the South means that soybean rust will likely be late rather than early or miss us altogether similar to last season. We just need to be vigilant and ready to respond if necessary.


Bob Mulrooney





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



Continue to scout all melons for aphids, cucumber beetles, and spider mites. In many cases, multiple applications will be needed to control these pests. If spider mite populations are high at the time of treatment, 2 sprays spaced 5 days apart may be needed. Be sure to watch for bees foraging in the area and avoid insecticide applications on blooming crops.



In fields with small fruit, a corn borer treatment is needed. 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.



Continue to scout fields for Colorado potato beetle (CPB), leafhoppers and aphids. As a general guideline, controls should be applied for leafhoppers if you find ½ to one adult per sweep or one nymph per every 10 leaves. We have also started to find green peach aphids; however, we have not detected economic levels. Controls will be needed 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 ½.


Snap Beans

We have seen an increase in leafhopper and thrips activity, so continue to scout all seedling stage fields for these two insects. At this time, 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. Acephate can be used at the bud and pin stages on processing beans but remember it has a 14 day wait until harvest. 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. Lannate, Asana, Capture (bifenthrin), Proaxis, Warrior (lambda-cyhalothrin) or Mustang MAX are labeled for European corn borer on snap beans.


Sweet Corn

The first silk sprays will be needed for corn earworm as soon as ear shanks are visible. 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). We are also starting to see the first fall armyworm larvae 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.



Sandea and Other Herbicide Programs for Lima Beans Ed Kee, Extension Vegetable Specialist; kee@udel.edu


For many years, Dual and Pursuit has been the standard for preemergence weed control programs in lima beans. Sandea (halosulfuron) is labeled for use preemergence and for post-emergence uses. The rate is 0.5 to 1 ounce of Sandea 75 DF preemergence to control or suppress yellow nutsedge and other broadleaf weeds. However, the effectiveness on many broadleaf weeds is essentially equivalent to that of Pursuit, with the exception of yellow nutsedge. It is effective post-emergence on jimsonweed, pigweed, ragweed, and velvetleaf while providing fair control of morningglory and Pennsylvania smartweed. Always check the label for rates and for residual carry-over restrictions for subsequent crops.



Potato Disease Advisory #13 – June 22, 2006, Bob Mulrooney, Extension Plant Pathologist


Late blight Advisory


Disease Severity Value (DSV) Accumulation as of June 21, 2006 is as follows:

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

Remember that 18 DSV’s is the threshold to begin a spray program for late blight






Daily DSV

Total DSV

Spray Recs


P days*

5/31- 6/1










6/3- 6/4















6/8- 6/9

























6/18- 6/20





6/20- 6/21






Continue to make fungicide applications for late blight and early blight control. Once 400 P-days has been reached early blight spraying for susceptible varieties becomes more important. Fungicide rates should be at the high end of the rate range at this time of the season.


Late blight was reported on tomato in the Lancaster, PA area on June 16th. There have been no new reports of late blight on potato or tomato in our area. Here is an update from Alan MacNab, Extension Plant Pathologist from Penn State on the late blight found in PA last week. “Current isolate of the late blight fungus from PA tomatoes is not expected to be a problem on potatoes: Thanks to quick work at the PDA lab, early electrophoresis analysis of the late blight isolate collected from tomatoes late last Friday, early indication is that the isolate is US-14 (similar to US-17 except that the US-14 isolate is Mating Type A2). This is similar to the 2004 situation in PA. In 2004, the US-14 isolate did not become troublesome on potatoes, so we expect this new news is "good news" for the potato growers”. Basically this means that this tomato isolate is not aggressive on potato, like US8 is.



Agronomic Crops


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



Small grasshopper nymphs continue to be found in full season, no-till fields as well as in recently planted barley fields. The treatment threshold for grasshoppers is 1 per sweep and 30% defoliation. Multiple applications are often needed for grasshopper control. As a reminder, OP insecticides (like dimethoate or Lorsban) can not be combined with SU/ALS herbicides (like Harmony GT). Since other materials may also state restrictions regarding combinations of insecticide and herbicides, you should be sure to check all labels carefully before combining insecticides and herbicides. Combinations of certain formulations, especially emulsifiable concentrates (ECs), can cause significant phytoxicity. The first spider mites have been detected; however, populations are still low.



Leafhopper populations remain above threshold in many fields. Continue to sample fields within a week of cutting for leafhopper 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. Remember, leafhoppers can quickly damage regrowth, so be sure to routinely sample fields.



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



There was a report of a late infection of stripe rust in Dorchester County, MD recently, but the change in weather will make any impact on yield unlikely. There have also been reports of small scattered infections of take-all in wheat. These infections have been very late but the infection results in small areas of white heads with no grain. Plants can be pulled out easily and the diagnostic blackening of the lower stem under the leaf sheaths is evident. This can be confused with scab, which produces white bleached out heads as well. Fortunately head blight or scab was not an issue this year.



Most field corn will be tasseling soon, which brings up the issue of applying strobilurin fungicides such as Quadris and Headline in the absence of disease for plant health benefits. Many growers have done this or may be experimenting with it. From the labeling and experience in this area, generally a single application is made at tassel emergence through tasseling for the best effect. The real question is whether the corn will respond with a yield increase to pay for the treatment. For many growers that is a question only they can answer for themselves. Experimental work has shown that corn does respond in many cases, but not all the time. We conducted three separate trials in 2004 and saw a slight reduction in disease in one test but no significant yield increases. There is so much that determines yield and profitability that it is not a sure thing. Irrigated corn with high inputs may respond if diseases become a limiting factor later in the season. Hybrid selection may play a role as well as many other factors such as stress, fertility, plant population, etc. The lowest rate that I have seen used in this area is 6 oz/A for Headline and 6.2 oz for Quadris (lowest label rates for corn) and would not expect to see a response at lower rates unless someone can show you that information. The bottom line is to try it and see if it improves your bottom line.



Understanding Soybean Growth Stages: V. V6 up to R1 – Sixth Node to Beginning BloomRichard Taylor, Extension Agronomist; rtaylor@udel.edu


For double-cropped soybean varieties and early maturity group beans, beginning flower can occur after a minimum vegetative state or minimum amount of biomass has been reached or accumulated. This generally occurs sometime around the V4 to V5 growth stage. Currently in the field, some of our maturity group II soybeans are at R1 or beginning bloom. Once flowering has begun, we often ignore the V-stages but you can still use the V staging procedure to determine the number of nodes on the main stem; although from a management perspective for fungicides, diseases such as Asian soybean rust, and insect problems, the R staging is the important growth stage to recognize.


To continue soybean growth staging for the V-stages, count the number of nodes on the main stem with fully developed leaves. Remember that a leaf is fully developed when the leaf immediately above it on the main stem has opened so that the leaflet edges do not touch. The V6 stage is illustrated in Photo 1.


                                                                                                            R. Taylor

Photo 1. Soybean plants in the V6 or Sixth Node stage at which time the leaflets on the sixth trifoliate to emerge have unfurled. This means that the fully developed leaves include the unifoliate leaves and the first to the fifth trifoliate leaves.


Beginning Bloom or R1 occurs when there is one open flower at any node on the main stem in at least 50% of the plants in the field. Photo 2 shows a view of the flower buds that form in each leaf axil and Photo 3 shows a flower open and in bloom.


                                                                                                            R. Taylor

Photo 2. Close-up of leaf axil showing developing flower buds of a soybean plant.


                                                                                                            R. Taylor

Photo 3. Close-up of leaf axil with open flower on a soybean plant.


In general, flowering in soybeans is triggered by the continuous decrease in day length and corresponding increase in night length for each successive day after June 21. Fewer hours of darkness are required to trigger flowering in a group II variety than in a group IV variety. Therefore, if planted on the same date, a group II variety will flower before a group IV variety. With all the recent advances in variety development, it will be interesting to see how closely the new cultivars hold to this effect. Also, determinate varieties reach R1 or Beginning Bloom and R2 Full Bloom at about the same time whereas the indeterminate varieties usually reach the R2 or Full Bloom stage 3 to 4 days after R1 or Beginning Bloom. Soybeans (full-season or single-cropped) usually flower for a period ranging from 3 to 6 weeks with determinate (group V and some group IV beans) varieties flowering for a shorter period of time than the indeterminate varieties.


Soybeans are very sensitive to drought and heat stress during the flowering stage, so for irrigated beans this and pod development/seed fill is the time when the maximum effort should be made to alleviate moisture stress. Also, be sure to check for nodulation as flowering begins in order to be certain adequate nitrogen is available to the plant. Soybeans are sensitive to nutritional stress (especially manganese and potassium) so if symptoms have appeared prior to R1 be sure to apply enough to carry the crop through to maturity. Soybeans are also very sensitive to shading from tall-growing, uncontrolled weeds during this phase. Heavy weed infestations will compete for available water, nutrients, as well as sunlight and carbon dioxide so control your weeds prior to flowering.



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


Is It Raining On La Salle Street?

La Salle Street is where the Chicago Board of Trade is located in Chicago, Illinois. Two reports, released this morning were termed 'bullish'. The export report is alluded to below. The other bullish factor reported this morning was the U.S. Census May crush report. U.S. soybeans crushed for oil were reported at 146.2 million bushels (mb), above the pre-report estimate of 144.5 mb and well above the 135.5 mb crushed in April. Bean oil stocks, reported at 2.852 billion pounds (bp), were below the average pre-report guess of 2.888 bp and are considered neutral to bullish. Meal stocks of 303.5 thousand short tons (tst) were well below the pre-report estimate of 377.3 tst and should be considered bullish.


U.S. Corn and Soybean Export Report Termed Bullish

Weekly export sales data released this morning for the week ending June 15th should be viewed as bullish for corn and soybeans. U.S. corn exports were reported at 1,575,300 metric tons (mt) or 62 million bushels (mb) and were well above the 13.8 mb needed to stay on pace with USDA's projection for the '05/'06 marketing year (2.075 billion bushels). U.S. soybean exports were reported at 200,100 mt (7.4 mb), well above the 41,700 mt (1.5 mb) needed to stay on pace with the 900 mb '05/'06 marketing year USDA projection. U.S. wheat exports were reported to be slightly below the 14.7 mb needed this week to stay on pace with USDA's projection. Wheat exports were reported at 316,200 mt (11.6 mb).


Marketing Strategy

A quick call to La Salle Street confirmed my suspicion, rain clouds are hanging over Chicago this morning. The reason for my suspicion was observing the markets to be trading in a lackluster fashion thus far this morning. The Chicago markets are keeping a close watch on weather forecasts while awaiting the June 30th Acreage & Quarterly Grain Stocks in all Positions reports. Rain showers that occur on La Salle Street during the summer months are generally considered a 'rain event' and have a tendency to effect trading accordingly on a given day. Today, June 22nd, marks the 2nd day of summer. We have a long way to go before the size of this year's U.S. corn and soybean crops become known. So far the general prognosis appears to be that temperatures are moderate and precipitation is occurring in parts of the Corn Belt. It is important to remember that subsoil moisture was short going into the '06 growing season in many parts of the Corn Belt. In the event that temperatures rise, precipitation will need to occur in a very timely manner in order to make a normal or better crop. USDA's June 30th Acreage report is important in order to confirm whether corn acreage is more or less than farmer's March 30th planting intentions. Thus far, trading the last few weeks has banked on U.S. corn acres showing an increase and soybean acres declining from the March 30th report. Weather remains the dominant factor in determining commodity price direction. Dec corn is currently trading at $2.57 per bushel; Nov soybeans are trading at $6.11 per bushel. For technical assistance on making grain marketing decisions contact:

Carl L. German, Extension Crops Marketing Specialist





2006 Delaware Weed Day

Wednesday June 28, 2006     8:15 a.m.

Carvel Research and Education Center

Georgetown, DE


The day will begin with registration at 8:15 a.m. and opening remarks at 8:30 a.m. at the Picnic Grove near the farm buildings and new office building on the north side of Rt. 9.


A variety of herbicide programs for conventional tillage and no-till are being evaluated. Almost all registered corn herbicides are included, as well as evaluation of reduced rates of soil-applied corn herbicides, herbicide evaluation for watermelons, sweet corn tolerance to newer herbicides and a number of studies with traditional soybean herbicide programs.


For more information contact Mark VanGessel at

(302) 856-7303




Weather Summary


Week of June 15 to June 21, 2006

Readings Taken from Midnight to Midnight



0.28 inch on June 19

0.29 inch on June 20


Air Temperature:

Highs Ranged from 88°F on June 18 to 81°F on June 15.

Lows Ranged from 69°F on June 19 to 54°F on June 16.


Soil Temperature:

75°F average.

(Soil temperature taken at a 2 inch 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.