Volume 11, Issue 26 September 26, 2003



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



We can still find economic levels of DBM and an occasional cabbage looper and imported cabbage worm in fall cabbage fields. The treatment threshold is 5% of the plants infested. Avaunt (3.5 oz/acre), a Bt, Proclaim (3 oz/acre), or Spintor (4-5 oz per acre) will provide control of all 3 species. If cabbage looper and imported cabbage worm are the predominant species, a pyrethroid, Intrepid (8 oz/a) or Confirm (8 oz/acre) will also provide control.


Lima Beans.

Continue to scout fields for corn earworms until frost. A treatment is recommended for corn earworm if you find one worm per 6 foot of row.



Continue to spray peppers on a 5-7 day schedule for beet armyworm, corn borer, corn earworm, and fall armyworm. Also, continue to watch for aphids in fields where a continuous pyrethroid program was used. Actara, Assail, Fulfill, Lannate, or Provado will provide control. Be sure to check labels for days to harvest.


Snap Beans.

Sprays are still needed at the bud and pin stages on processing snap beans for corn borer control. A corn earworm material will also be needed at the pin spray for corn earworm. Although corn borer and corn earworm catches have decreased, 1-2 sprays will still be needed between the pin spray and harvest. Since this 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://www.udel.edu/IPM/traps/latestblt.html and our link to http://www.udel.edu/IPM/thresh/snapbeanecbthresh.html). As soon as pin pods are present, fresh market beans should be sprayed on a 5 to 7-day schedule. Lannate, Capture, Mustang MAX or Warrior should be used.



We have seen an increase in webworm moth activity and egg laying. Small to moderate size garden and Hawaiian beet webworms can now be found. Although not as high as last season, we can also find beet armyworms in the mix. As soon as plants emerge, fields should be scouted for webworm and beet armyworm larvae. Controls should be applied when worms are small and before they have moved deep into the hearts of the plants. Also, remember that both insects can produce webbing on the plants. Confirm, Intrepid or Spintor will be needed for beet armyworm control. If webworms are the predominant species, Ambush, Pounce, Confirm (6-8 oz/acre), Intrepid (8-10 oz/acre) or Spintor (4-8 oz/acre) should be used. Generally, at least 2 applications are needed to achieve control of webworms and beet armyworm.


Sweet Corn.

Any fresh market silking sweet corn should be sprayed on a 3-day schedule for the remainder of the season. 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 fresh market sweet corn (http://www.udel.edu/IPM/traps/latestblt.html and http://www.udel.edu/IPM/thresh/silkspraythresh.html ).



UD IPM Black Light and Pheromone Trap Counts

Average Number of Moths per Night: September 19 to September 22, 2003

Trap Location

European Corn Borer

Black Light

Corn Earworm

Black Light

Corn Earworm

Pheromone Trap

Kent County












Killens Pond




Little Creek








Rising Sun








Sussex County





























* Numbers can change quickly. For the most recent trap counts, access the website at (http://www.udel.edu/IPM/traps/latestblt.html) or call 1-800-345-7544 (in-state); 1-302-831-8851 (out-of-state). Counts are updated on Tuesday and Friday.




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


Lima Beans.

Downy mildew, white mold, Pythium, and lima bean pod rot (Phytophthora capsici) continue to be seen in lima bean fields. Keep scouting fields. Obviously we have had ideal conditions especially for downy mildew. Since some of the infected varieties have been C-elite Select we are presuming that Race F is out there. Although we have listed Cypress susceptible to race F it does not develop as quickly or severely as it does on C- Elite Select when race F is present. If this is not your experience we would like to know about it. Preliminary data from our field plots indicate that Ridomil Gold/Copper is providing excellent control of downy mildew when applied preventatively under heavy disease pressure. Protectant sprays of Ridomil Gold/Copper and copper are recommended for downy mildew.




Stinger Labels For Some Vegetables and Fruits - Mark VanGessel, Extension Weed Specialist, mjv@udel.edu


DowAgroSciences has labeled Stinger for a number of vegetables and fruits grown in Delaware. This includes turnip greens and roots, sweet corn, spinach, brassica leafy crops, and stone fruits. Brassica leafy crops include broccoli, broccoli raab, Brussel sprouts, cabbage, cavalo broccoli, cauliflower, bok choy, Chinese cabbage, Chinese broccoli, Chinese mustard cabbage, Chinese cabbage, collards, kale, kohlrabi, mizuna, mustard greens, mustard spinach, rape greens. All these uses are for postemergence broadleaf weed control. Rates and number of applications allowed per crop vary so refer to specific labels. Labels are available at www.cdms.net (click on US-Ag/Crop; type in Stinger in the search box; click on icon for label). Spray additives are not required or recommended. Control of common ragweed, galinsoga, chamomile, vetch, cocklebur, pineappleweed is good. Fair to good control of Canada thistle and mugwort. Nightshades are on the label, but we do not have much experience with these species. Stinger will not control grass species. Refer to the full Stinger label for precautions of crop rotations.




Field Crops


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



Corn earworm moth activity remains low and many pupating larvae have been triggered into diapause (overwintering stage), thus will not emerge as moths this fall. Double crop fields may still be susceptible until frost, particularly fields with flat pods or seeds just beginning to enlarge. Basically, once seeds are full sized and pods toughen up, they are no longer at risk. The treatment threshold for podworms is 3 per 25 sweeps in narrow fields and 5 per 25 sweeps in wide row fields (20 inches or greater). In addition, you should wait to treat until at least 1/3 of the populations is 1/2 -inch in size and you observe the first signs of pod-feeding.


Stored Grain.

The most important way to minimize insect problems in stored grain is the prevention of potential problems through good bin management. Before treating with a protectant insecticide, make sure that the bins are free of insect infested grain. Leftover grain should be removed from the bin, and the walls should be swept and vacuumed. All grain handling equipment including augers, combines, trucks and wagons should be thoroughly cleaned and grain residues removed before harvest. Residual bin sprays should be applied to all interior bin surface areas 2 to 3 weeks before new grain is placed in the bin. These treatments will kill insects that emerge from hiding places like cracks, crevices, and under floors. It will help to control insects crawling or flying in from the outside. Be sure to spray as many surfaces as possible, especially joints, seams, cracks, ledges, and corners. Sprays directed to the ceiling, walls and floors should be applied to the point of runoff. Use a coarse spray at a pressure of over 30 lbs. per square inch and aim for the cracks and crevices. Spray beneath the bin, its supports and a 6 ft. border around the outside foundation. Also, treat the outside surface, especially cracks and ledges near doors and fans. Materials available as residual bin sprays include Diacon II (methoprene- will not control adult insects), Malathion (may not provide control of Indian meal moth), Methoxychlor, Reldan 4E, Tempo, and Storcide. After the bins are cleaned and treated, insecticides called grain protectants may also be applied to grain as it is moved into storage. Insecticides may be applied as a spray or dust to the grain as it is being augered into the bin. These products may also be applied as a surface treatment on registered commodities. The following materials are labeled as grain protectants: Corn and Sorghum only - Acetellic; Wheat, Barley, Oats, Sorghum Diacon II, Reldan (not for malting barley) and Storcide (cyfluthrin in the mix does not have CODEX MRLs so check with your grain handler if you plan to export). If a grain protectant is not used, a surface insecticide should be used after all grain is placed in the bin. These treatments should be applied to the top 6-12 inches of grain and provide a barrier for migrating insects like Indian meal moth larvae. In order to provide effective control, all surface crusting and webbing should be removed prior to treatment. Bacillus thuringienesis (e.g.Dipel - Indian meal moth larvae only) or Insecto (diatomaceous earth) can also be used.




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



Septoria brown spot is increasing in severity on soybeans in some parts of the state and neighboring Maryland. Some have questioned the feasibility of trying to control it with fungicides such as Bravo or Quadris. I do not have any data to support this for brown spot here, but for other foliar diseases such as Cercospora leaf blight in Arkansas, Quadris significantly reduced disease and increased yields in one test even at half the labeled use rate (6.1 fl oz/A). The important thing to factor in is the timing of applications. The increase in control and yield was accomplished when the fungicide was applied at R3 (Beginning pod, pods in. long) or at R3 and R5 (beginning seed, seed 3 mm) but not at R5 alone. This was my experience years ago trying to control pod and stem blight and anthracnose with fungicides. The early application was critical. If you have soybeans that are still in the R3 stage of development, you may get a response from foliar fungicides. If applied at R5 or later, it is not likely you will get the desired response. The only way to tell is to leave a strip unsprayed and see what happens. The lowest labeled use rate for Quadris on soybeans is 12.3 fl oz/A.


Septoria Brown Spot




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


Commodity Markets Focus on '03 Harvest

Favorable harvest weather over the next two weeks should allow commodity traders to get a handle on U.S. corn and soybean crop size by the time the October 10th crop report is released. Currently, speculation suggests that the U.S. corn crop will get larger and the soybean crop will get smaller. Bulls and bears are likely to be evenly divided on that question until the production estimates are in. Corn and soybean futures are currently rallying due to a favorable weekly export sales report.


Market Strategy

Short crops are said to have long tails, meaning that prices typically peak just prior to, during or shortly after harvest. Just when prices peak depends upon what happens to the production forecasts from the September estimate to the actual harvest. The recent rally in new crop soybean prices should be rewarded with sales. The U.S. soybean crop, now projected at 2.643 billion bushels is well below previous production forecasts.


It may be advantageous to move early harvested corn at premiums currently being offered (+40 over Dec "03 futures), if available. Otherwise, further corn sales should be placed on hold, due to price level and basis considerations.




New Herbicide Label for Pastures, Hay and Non-Crop Sites - Mark VanGessel, Extension Weed Specialist, mjv@udel.edu


BASF has labeled Overdrive for use in pastures, hay, and non-crop uses. Overdrive is a combination of dicamba and difluenzapyr (same combination as Distinct). Overdrive controls a wide range of broadleaf weeds, but will not control grasses. Overdrive can injure newly seeded grasses, so it should be used only on established pastures and hay fields. There are no grazing or harvesting restrictions. Overdrive can be tankmixed with other herbicides.




Considerations for Weed Control in Small Grains - Mark VanGessel, Extension Weed Specialist, mjv@udel.edu


More and more fields are being planted as no-till small grains. These fields need a non-selective herbicide prior to emergence (either Gramoxone or glyphosate). Too often these fields look clean at planting time, but numerous weeds have emerged and are quite small. These weeds are much easier to control prior to planting than later. Harmony GT or Harmony Extra are not replacements for these non-selective herbicides.


Currently there are no soil-applied herbicides labeled or recommended for small grains. Harmony GT and Harmony Extra are labeled for applications as early as the 2-leaf stage of the small grain. These two products are very similar. Harmony GT contains thifensulfuron and Harmony Extra is thifensulfuron plus tribenuron. Three-tenths of an ounce of Harmony Extra contains the same thifensulfuron as 0.2 oz of Harmony GT plus tribenuron. As a result, Harmony Extra has a slightly broader range of control (and is better on vetch than Harmony GT). These products can be used in the fall, spring, and/or late spring. Winter annual weeds should be treated in the fall or spring. Fields treated with fall applications should be scouted again in the spring to determine if additional flushes of weeds developed that need to be controlled. Late spring timing is for perennial weed control. However, late spring applications are applied after substantial weed competition has occurred, so late spring applications should be a second herbicide application in most situations.


Hoelon is labeled for annual ryegrass. There are cases of Hoelon-resistant ryegrass in the region, in which case Hoelon is in-effective. There is no effective control of Hoelon-resistant ryegrass, and so do not plant small grains in field with it present.


Maverick (from Monsanto) will control annual bluegrass, roughstalk bluegrass, and provides suppression of bulbous oatgrass and brome species (including cheat) in winter wheat (not labeled for barley). This product is labeled for preemergence as well as postemergence application. Refer to the label for all precautions. Maverick is most effective when applied in the fall application to small grasses. Crop rotation is an issue with Maverick. STS-soybeans should be used after crop harvest. The label does not specify rotational intervals for other crops; rather it specifies a bioassay should be used to determine plant back intervals. Do not expect the interval to be shorter than 12 months. Furthermore, Maverick is not labeled for barley. These species are not effectively controlled by other herbicides. If Maverick does not fit the rotation for the specific field and any of these species are present at levels that can cause yield loss, do not plant winter wheat in the field.


Situations where no effective herbicidal control exists are with volunteer grain or cover crops (where rye strips were allowed to go to seed); hoelon-resistant ryegrass; large grasses (over a few inches tall); barley infested with annual bluegrass, roughstalk bluegrass, brome species, or bulbous oatgrass.



Tips for Late Plantings of Small Grains - Richard W. Taylor, Extension Agronomist, rtaylor@udel.edu


The extended and late planting window for corn and soybeans this past spring could mean that small grains will be planted on the late end of the planting window this fall. Following are some tips to help minimize yield losses associated with late planting:


      Try to plant as rapidly and early as conditions permit.

      Compaction likely will be an issue in some fields. Unless your fields are in a long-term no-till program, consider some type of tillage to manage the compaction problems.

      Seed treatments will be critical this fall (refer to Bob Mulrooneys article on Field Crop Diseases on Wheat in Issue 23 (August 29, 2003) for the best seed treatments and when to apply them.

      Choose varieties that have good cold vigor and tolerance when possible. With seed supplies tight, you may not have much choice. Whether you use certified seed (the best choice) or saved (bin-run) seed, avoid using any seed that with a seed treatment applied does not test at least 80 percent germination. The state seed lab reports that many seed lots are requiring a longer than usual period of cold incubation before germination will occur. Always have a germination test run before planting so you can adjust your seeding rate or decide if the seed lot is inappropriate to use for planting.

      After corn where little residual N may be left, apply about 40 lbs nitrogen (N) per acre to stimulate fall growth. After soybeans and if growth has been good, apply 20 to 30 lbs N/acre.

      Soil pH may be down this fall as well as the amount of potassium (K) and magnesium (Mg) in the soil. When time permits, consider a soil test to be sure of your nutrient levels or to know what to monitor for in the coming months.

      On light soils, consider adding N as ammonium sulfate to ensure adequate sulfur is available for rapid fall growth.

      Boost seeding rates by 10 to 20 percent and plant according to the number of pure live seed (PLS) per pound of seed (shoot for about 25 to 30 PLS per foot of row)

      After the third week of October, consider switching from barley to wheat if your plan had been to seed barley.

      After the third week of November the odds for a successful wheat crop begin to fall rapidly, so carefully consider the cost/benefit ratio for planting wheat that late.




Strengthening Pasture and Hay Fields for Spring - Richard W. Taylor, Extension Agronomist, rtaylor@udel.edu


Although we are rapidly running out of time this fall, if your pasture or hay fields are on the sparse side, it may be possible to thicken and strengthen the stand. For those producers with access to no-till drills, fall or early spring renovation of their pastures by overseeding with Ladino or red clover can be a key ingredient. For those producers without access to a no-till drill or with small acreages, a frost crack seeding next spring in February or early March can boost the percentage of legumes in their pasture or hay field. Growers sometimes overseed fields with some of the faster growing and establishing grasses such as orchardgrass. Grasses slow to establish such as tall fescue and reed canarygrass should not be overseeded since competition with the established plants will make their establishment unlikely.


Another approach to thickening and strengthening stands is to make sure you maintain soil fertility levels in the optimum range. If you do not periodically pull a soil sample and send it for laboratory analysis and recommendation, then you should start including that in your management plans. Take soil samples every second or third year and at the same time of year. If you do not own a soil probe, then be sure to purchase one from your Ag Supplier. A proper soil probe is critical to getting a representative sample of your soil. Soil samples often represent up to 25 to 30 acres. In an acre furrow slice (the surface to plow depth of about 6 to 7 inches for an area of land about the size of a football field); there are about 2,000,000 pounds of soil or 60,000,000 pounds in 30 acres to a 6 inch depth. From that you will take about one cup of soil to send to a soil testing laboratory that will use about 5 grams (a teaspoonful of soil) to determine your soils fertility status. If you think about those numbers, you can see why it is so important to use a soil probe rather than a shovel and to take soil from all over the sampled field.


If you havent applied fertilizer since last spring, consider adding at least some potash (K) this fall to help the plants prepare for winter. Potash is taken up by grasses and legumes and acts somewhat like antifreeze to help the plants survive the cold temperatures during winter. Next, apply some nitrogen (N) as soon as the grasses begin to green up in next spring. If you have legumes in your pasture or hay field, you should limit the amount of N applied next spring to no more than about 30 lbs per acre to avoid injuring new legume seedlings or reducing nodulation and nitrogen fixation on older legume plants.


Finally, whenever you are using equipment on pasture and hay fields, try to avoid times when the soil is too wet to support the equipment as this can cause significant compaction issues. Compaction is a reoccurring problem on pastures because of the grazing animals, so we should make every effort to avoid worsening the problem. This past season with all the rainfall received made compaction problems on hay fields a concern as well. Unless total renovation is planned, compaction is very difficult to alleviate. If your stand does warrant total renovation, consider fall deep ripping when soil moisture levels are low and the soil compacted layers are more likely to shatter and break apart. Straight-type ripping coulters have been shown to be the most effective tool for shattering deep compacted layers. If shallow compaction is your problem, then either chisel plowing or moldboard plowing can be effective in solving the problem. Late summer or early fall tillage followed by seeding immediately after tillage or seeding early next spring can be effective in reducing compaction problems.




Revisiting Those Compacted, Rutted Fields From Last Fall - Richard W. Taylor, Extension Agronomist, rtaylor@udel.edu


Early this year in the first issue of Weekly Crop Update (WCU), I talked about some of the options available to producers who had rutted and compacted fields after the wet fall in 2002. Who would have guessed that the frequent rainfall that began last fall would still be continuing this fall? In a more typical year, the subsoil and maybe even top soil would be dry enough for deep ripping or tillage to shatter the hardpans created during harvest in 2002. However, these conditions are not present in most areas of the Delmarva Peninsula, so fall deep ripping will again have to be postponed.


Generally winter and spring weather does not allow the soil to dry sufficiently for deep tillage to be effective. If next spring the soil has dried out enough for compacted layers to shatter, deep ripping can be used to help alleviate severe compaction. Straight-type ripping coulters have been shown to be the most effective tool for shattering deep compacted layers. Much more likely is that the soil will remain too wet for effective soil shattering during deep ripping. Ripping will need to be postponed until fall of 2004 when dry soil conditions are more likely and ripping is generally more effective.


Is there anything that can be done about compaction this fall? One I mentioned in the first issue of WCU was planting cereal rye to help reduce compaction effects. Rye reduces or moderates the effects of compaction, increases water infiltration rates, speeds the process of drying the following spring, improves tillage effectiveness in the spring, and rye roots help tillage break up the compacted soil. So, if you are considering using a cover crop this fall, you should think about planting cereal rye. Rye is the most winter hardy grain and will grow at lower temperatures than many other grasses. The rye also will add organic matter into your soil next spring if you till it in and this also will help alleviate compaction caused problems.




Nutrient Management Certification Sessions

The University of Delaware Nutrient Management Program will be offering certification sessions this fall. This is your last chance to become certified before the deadline. Anyone that applies nutrients (fertilizer or manure) to 10 or more acres of land or has 8,000 lbs of animals needs to attend the certification sessions. All certifications must be completed by December 31, 2003, and you must sign up for a Session I prior to October 15, 2003. Please sign up early to get the session you would like to attend because session size is limited. To sign up for classes, please contact Jeanie Johnson at (302) 856-2585 ext. 305.







Weather Summary



Weeks of September 11 to September 24, 2003 *


0.82 inches: September 12

0.43 inches: September 13

0.01 inches: September 14

0.87 inches: September 15

2.49 inches: September 18

0.07 inches: September 19

0.95 inches: September 23

Readings taken for the previous 24 hours at 8 a.m.

Air Temperature:

Highs Ranged from 85F on September 20 to 71F on September 12.

Lows Ranged from 70F on September 13 to 50F on September 11.

Soil Temperature:

72F average for the week.

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

* Data taken from Warrington Farm Weather Station.


Web Address for the U of D Research & Education Center:





Compiled and Edited By:

Tracy Wootten

Sussex County Extension Educator - Horticulture





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