Volume 11, Issue 2                                                                                                    April 4, 2003




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


New Registrations and Restrictions



The following uses have been recently added to the Warrior label: apples and pears; edible podded, succulent shelled and dried shelled beans (included but not limited to black-eye pea, garden pea, lima beans, and snap beans) and peppers (bell and non-bell).


New 2ee Labels from Dupont:

(a) Avaunt – For the control of Colorado potato beetle in potatoes. This label is in effect in Delaware, Maryland, Virginia, New Jersey, Pennsylvania, Wisconsin, Maine and Michigan.  The use rate is 3.5 to 6 oz per acre. In areas where beetles are difficult to control (i.e. Delaware), the use of the synergist piperonyl butoxide (PBO) may be necessary to achieve optimum control. The rate of PBO should be 0.25 lb ai/acre.


(b) Vydate L - For control of leaf miners and supplemental control of root knot nematode used in conjunction with other marketed soil treatments as a Methyl bromide replacement program on the following crops: tomato, bell and non-bell pepper, eggplant, pumpkin, cucumber, cantaloupe, watermelon, honeydew melon, and squash using drip irrigation and soil injection systems.  This label is in effect in DE, MD, NJ, PA, PR, and VA.


Definition of Coastal Counties - We often get the question regarding the definition of coastal counties, especially as it relates to the use of Capture on field corn and sweet corn in Delaware.  The following is the official response from EPA: In 1994, FMC volunteered this restriction as a risk mitigation measure due to ecological risk concerns for estuarine and marine organisms and to get a waiver from conducting a marine invertebrate life cycle study. It originally pertained to the coastal counties of Texas and in 1998 expanded to all coastal counties in the U.S. We accepted this restriction and granted the waiver. The restriction was designed to limit concerns for these marine organisms by not allowing use in vulnerable areas such as coastal counties. We didn't get into a definition of coastal counties at that time, but since our concerns pertained to estuarine /marine organisms we interpreted the restriction as applying to those natural water bodies where these type organisms reside. So we would consider counties bordering the ocean, bays as well as tidal rivers as coastal counties.


Peas, Sweet Corn and Snap Beans.

Be sure to consider seed corn maggot control, especially where a green cover crop is plowed under close to planting, manure is used and/or a field is minimum tilled.  A seed treatment containing diazinon or permethrin should be used on early-planted sweet corn. Gaucho or Cruiser treated sweet corn seed will also provide seed protection. In fields with a high potential for seed corn maggot (combinations of the above conditions), a soil insecticide plus a seed treatment will be needed. On all 3 crops, the use of diazinon 50W as a planter box treatment has provided good control in recent years. Seed must be treated with a commercial fungicide; graphite may be needed to prevent bridging and you should not treat more than you plan to plant in any one-day. The diazinon 50W rate for seed corn maggot is 1/2 oz per bushel of seed.


Sweet Corn.

Although winter conditions have not been very favorable for overwintering flea beetles, flea beetle management should be considered on early-planted varieties susceptible to Stewart's Bacterial Wilt. If you are using a soil insect insecticide for flea beetle control, the only labeled products providing flea beetle control are Counter and Furadan. Regent is not labeled on sweet corn. Another control option is Gaucho or Cruiser treated seed. In 3 years of research trials, seed applied treatments have provided very effective beetle control and management of Stewart's Wilt.



Frozen Vegetable Inventories – Peas, Lima Beans and Sweet Corn Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu


The March 1 holdings of frozen peas reflects the reduction in pack on a national basis.  U.S. cold storage holdings were 115 million pounds as of March 1, as compared to 174 million pounds at the same time last year, a reduction of 33%.  Baby Lima beans, are also at lower holdings, with 40 million pounds in cold storage, down over 6% from last year.  Fordhook lima beans were at 8.8 million pounds, down 15% from 2002 levels.

The reductions reflect lower pack, increased movement, or some combination of the two.  Moving product out of cold storage to consumers is good for the processors in keeping inventory costs down, and good for producers who want to keep these vegetable crops as part of their farm enterprise.

The other big item on Delmarva, sweet corn, is experiencing high inventory levels on a national basis right now.  Cut corn is up nearly 14%, and cob corn is up 20% from inventories of the previous year.  This is reflected in the acreage being contracted on Delmarva and other regions for 2003.



Pea Production Update Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu

Cold, wet weather has made pea planting a struggle so far this season.  However, growers and processors have done a remarkable job of grabbing those opportunities for planting as they present themselves.


Many growers are using preemergence weed control programs that feature some combinations of Dual, Command, and/or Pursuit.  However, wet weather may prevent applications being made until the peas have emerged.


In that case, growers will need to consider post-emergence applications of Poast or Assure for grass control; and post-emergence applications of Basagran for broad-leaf weed control.  Scouting and checking fields for emerging weeds and grasses is critical, especially the broadleaf weeds.  Basagran will provide better control if applied when the weeds are small.  This is especially true for lambsquarter, but applies to all broadleaf weeds.


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



Be sure to rotate pea planting 4-5 years to avoid and reduce root rot. Ridomil Gold 4E applications broadcast after planting can be useful if Pythium control is needed.



Be sure to check overwintered fields for white rust. As soon as white rust is seen, apply Quadris as a foliar spray. If more sprays are needed, alternate with Actigard. Actigard is to be used at the rate of 0.75 oz/A. There is a 7-day preharvest interval for Actigard.


Phytophthora Blight and Fruit Rot.

Phytophthora Blight and Fruit Rot caused by the fungus Phytophthora capsici is still a concern for vegetable growers. The fungus is favored by wet conditions and flooded soil. It was seen last season again on lima bean pods from wet irrigated areas of fields in Kent County. On limas it can look like downy mildew,but it is different. It was also seen on pumpkins in Kent and New Castle Counties. It has caused significant losses in cucumbers both slicers and pickles, and summer squash in past years when we get lots of rain in a short period of time.


The best control is to grow the plants on raised beds, especially for peppers, to get them out of the water and to rotate for long periods of time (3 years or more) away from susceptible crops. For vegetable growers this is difficult because many crops are susceptible and irrigation availability limits rotation intervals. But a combination of rotation and other horticultural practices combined with fungicides may provide some relief. Fungicides alone have not provided a solution as results from New Jersey on Phytophthora blight on peppers has shown. Overuse of fungicides can result in the fungus becoming resistant or tolerant of the fungicide. What drives this disease is water. Choosing well-drained fields, avoiding planting wet areas, and planting on high beds combined with fungicides that are labeled for the crop, such as mefanoxam (Ridomil, UltraFlourish) on peppers, and Acrobat for cucurbits have provided a measure of control.


Be aware that this soil borne fungus is out there and could become a problem if introduced or identified on your farm. It infects a wide number of vegetables including cucurbits (cucumbers, cantaloupes, watermelons, pumpkins and summer and winter squash), peppers, eggplant, tomatoes and now lima bean pods.




Field Crops


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


New Registrations and Restrictions.

See Vegetable Insects page 1.



The first weevil larvae can be found in Kent and Sussex Counties; however, populations are significantly lighter compared to this same time last year. Since the alfalfa weevil overwinters in both the adult and egg stage, the larvae we are finding at this time are a result of eggs laid last fall. Overwintered adults can also lay eggs in stems any time temperatures are above 48 degrees F. Although egg laying occurs in the fall and spring, larvae hatching from spring-laid eggs cause the most damage. The weevil passes through four larval stages in approximately three weeks. No controls should be needed before 50% of the tips show feeding damage. A more accurate way to time an application and try to avoid multiple insecticide applications would be to sample stems and determine the number of weevils per stem. A minimum of 30 stems should be collected per field, placed top first in a bucket to dislodge larvae from the tips and then count the number of weevils per stem. The following thresholds, based on the height of the alfalfa, should be used to make a treatment decision: up to 11 inches tall  - 0.7 per stem; 12 inches - 1.0 per stem; 13 - 15 inch - 1.5 per stem; 16 inches tall - 2.0 per stem and 17-18 inches tall - 2.5 per stem. Numerous pyrethroids are now labeled for alfalfa weevil including Ambush, Baythroid, Mustang MAX, Pounce and Warrior. Furadan, Imidan, Lorsban and Lannate will also provide control.


Field Corn.

In cooperation with UAP Inc., we will again be running pheromone traps for black cutworm. The first moths were caught last week in a number of locations  (see table on last page of report). Although no precise numbers are available, moth catches of 9 to 15 moths per 7-day period have been associated with a moderate to high potential for cutworm outbreaks.  Larvae will be large enough to begin cutting when about 300 base-50 degree-days have accumulated since peak moth activity and egg laying. By calculating cutworm hatch and development over time, we can anticipate when to look for damage. Pheromone trap catches help us determine when peak moth flight and egg laying occurs; however, they cannot predict the amount or magnitude of cutting that will occur. The presence of a major flight only means that the potential for an outbreak exists. Adverse weather, lack of adequate food for newly hatched larvae, predation, and disease can reduce larval populations. You can use pheromone trap and degree-day information to estimate or predict when first cutting will occur. Scouting of seedling corn near the first cutting date is the best way to determine whether a problem exists. Just a reminder, if you plan to tank mix a pyrethroid with a herbicide for cutworm control, it should be done at or immediately following plantings. Pyrethroids combined with early burn-down applications, 2-3 weeks before planting, have not provided effective control.



Reports from around the region indicate that cereal rust mite populations are lower compared to last season. However, as soon as fields green up you should begin checking for mites and the early signs of infested leaves, especially in fields with problems in 2002. These mites are microscopic, so the use of a 20x-magnifying lens is necessary. If rust mites become a problem again in 2003, Sevin XLR Plus still has a 24C registration on timothy for rust mite management. The following are the use directions for this label: Apply 3 pts per acre (1.5 pounds ai per acre) using ground equipment only with adequate water for complete coverage (20 or more gallons by ground).  One application should provide enough suppression to prevent economic yield and quality losses. Apply at approximately 3-4 weeks after green-up in fields with a previous history of rust mites and/or when 25% of the plant tillers exhibit curled tips of the new leaf blades. It has a 30 day wait until harvest.



At a recent meeting of plant pathologist and entomologists in the Mid-Atlantic, the topic of the potential for barley yellow dwarf this spring was again discussed. The discussion focused on the fact that a great deal of small grain is still in a vulnerable stage for possible transmission of the virus. It was agreed that for most of us north of Virginia we find that 90% of the time a local aphid population and a local source of the virus are needed for BYDV (barley yellow dwarf virus) to develop. However, with the recent jet stream pattern the idea that we could have long distance transport of virus-bearing aphids and resulting infection is real but less likely to happen than from local sources.


Spring spraying for aphids to prevent BYDV should only be considered if there has been a recent history of BYDV in and around the field. Although Arv Grybauskas from Maryland feels that it's on the rise he still thinks that considerably less than 10% of the acreage is at risk.  In Delaware, we have only seen a slight increase --less than Maryland. The increase was probably the result of a series of mild winters allowing greater aphid survival, more opportunity for a longer transmission period and increase in the virus reservoir in surrounding weedy vegetation.  The harsh winter we had has burned back a lot of the weed reservoir harboring the virus. Even though we had snow cover, there were periods when cold conditions without cover existed.  Leaf tissue got burned back.  BYDV is a phloem limited virus so it can be translocated into the roots, and possibly get translocated back into new growth as the temperature increases.  However, this has never been documented in the field. So until new growth is formed with the current virus reservoir, we don't have much of a source of the virus in native vegetation, and the new growth may end up with a low amount of the virus anyway. In summary, although most wheat is in a very vulnerable stage, we think the vector is at a low population level and the most important local pool of virus inoculum (native vegetation) is also very low at this time. (Information from Arv Grybauskas, Bob Mulrooney, and Joanne Whalen).


Cereal leaf beetle could also be a threat to the later planted wheat. Since cereal leaf beetle is known to prefer small grain fields with thin canopies, many of our fields may be at risk this year. We have just found the first signs of adult feeding in Sussex County. In recent years, the threshold for cereal leaf beetle has been adjusted to include sampling for eggs, especially in high management wheat fields. The eggs are elliptical, about 1/32 inch long, orange to yellow in color when first laid changing to a burnt orange prior to hatching. Check our website for pictures of cereal leaf beetle adults, larvae and eggs (http://www.udel.edu/IPM/facts/clbpictures.htm) Generally, eggs are laid singly or in small scattered groups (end-to-end) on the upper leaf surface and parallel to the leaf veins. For high management fields, the threshold is based on the presence of eggs and small larvae. Cereal leaf beetle larvae are brown to black, range in size from 1/32 to 1/4 inch long, and eat streaks of tissue from the upper leaf surface. Since cereal leaf beetle populations are often unevenly distributed within the field, it is important to carefully sample fields so that you do not over or under estimate a potential problem. Eggs and small larvae should be sampled by examining 10 tillers from 10 evenly spaced locations in the field while avoiding field edges. This will result in 100 tillers (stems) per field being examined. Eggs and larvae may be found on leaves near the ground so careful examination is critical. You can also check stems at random while walking through a major portion of the field and sampling 100 stems. In high management fields with good yield potential and/or where the potential for cereal leaf beetle problems is high, the threshold of 25 or more eggs and/or small larvae per 100 tillers should be used. If you are using this threshold, it is critical that you wait until at least 50 – 60% are in the larval stage (i.e. after 50% egg hatch). If the egg/larvae threshold is not used, the threshold of 0.5 larvae per stem and 10% defoliation can provide enough lead-time to provide good control if fields are scouted on a routine basis. Sevin will provide good control of cereal leaf beetles although past experience demonstrated that it could result in aphid explosions by reducing predator populations. Furadan provides good control; however, it cannot be applied once grain is heading. Lannate, Mustang MAX and Warrior will provide good control of the entire insect complex present in small grains (cereal leaf beetles, aphids, armyworm and grass sawfly). Neither Mustang MAX or Warrior are labeled on barley at this time.



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


Soybean Cyst Nematodes.

It is still not too late to check for soybean cyst nematode. Soil test bags can be purchased at the Extension offices. If you have a fax machine and need results quickly, tests results can be sent via FAX if you provide the number on the Nematode Assay Information Sheet.


Soybean Seed Quality.

The weather pattern last fall was not favorable for good seed quality in soybeans. Prolonged wet weather caused weathering and infection by the fungus Phomopsis. Seed lots tested in the Dept of Ag seed lab are testing lower than normal in general. Growers that have saved their seed are encouraged to get it tested with and without fungicide.


What to do if you have reduced germination seed?

  1. Increase seeding rates to compensate for tests ranging from 75-85% germination test. To determine your adjusted seeding rate, divide your seeding rate goal by the % germination. For example if your goal is 6 seeds/ft and germination is 80%, then divide 6 seeds by .8 to get an adjusted seeding rate of 7.5 seeds per foot of row.
  2. Do not plant seed with germination below 70%. It would be better to find higher quality seed or you may end up replanting with its costs and delayed stand establishment.
  3. Do not plant low quality seed in stressful planting conditions. Plant when the soil temperatures are 65°F or above and adequate moisture is available.
  4. Handle seed carefully to avoid mechanical damage.
  5. Fungicide seed treatments can increase germination 10-20% if infected with seed born pathogens. However, seed treatments do little to increase seed germination due to mechanical damage. Seed treatment cannot turn low quality seed into high quality seed. It can only protect the quality that is there.



Reminders On Acetochlor Use Restrictions - Mark VanGessel, Extension Weed Specialist;  mjv@udel.edu


Acetochlor is a preemergence herbicide for corn that controls annual grasses and some broadleaf weeds.  It is in the following products: Harness, Harness Extra, Degree, Degree Extra, Topnotch, and Fultime.  There are restrictions that are important in our area.  The restrictions pertain to groundwater quality.  The restrictions are based on depth of groundwater within one month of planting and the combination of soil type and organic matter.  Do not apply acetachlor if the groundwater depth is 30 feet and you have sands with less than 3% organic matter, or loamy sands with less than 2% organic matter, or sandy loam with less than 1% organic matter.



New(er) Corn Products for 2003 - Mark VanGessel, Extension Weed Specialist;  mjv@udel.edu


Some of these products were available in 2002.

Callisto 4SC (Syngenta) has an active ingredient called mesotrione, with a new site of action.  It is a pigment inhibitor and causes sensitive plants to turn white.  It can be used either soil-applied or postemergence.  It is a component of Lumax (see below).  Postemergence are 3 fl oz/A, but other herbicides have it labeled for use with their product at lower rates.  (If crabgrass is a weed you are targeting for control, I suggest you do not reduce the rate of Callisto.)  There is excellent crop safety, up to 30-inch corn or 8 collars (whichever is most restrictive).  There are numerous broadleaf weeds listed as controlled on the label, with large crabgrass as the only grass species listed.  It is most effective with a little atrazine

(0.5 lbs/A or 1 pt/A atrazine).  Replant is 4 months to small grains and 18 months for most other crops.  There are precautions for use with Counter, refer to the label.


Lumax 3.95SC (Syngenta) is a pre-packaged mixture of Callisto, Dual II Magnum, atrazine, and a safener.  Use rates are 2.5 or 3.0 qts/A, based on organic matter.  At 2.5 qts/A of Lumax, it is 1.76 pt Dual II Magnum, 5.4 fl oz of Callisto, and 1.25 pt of atrazine.  No label restrictions for use with Counter, provided Lumax is applied before the corn emerges.  If Lumax is applied at planting, Callisto cannot be applied postemergence.  Lumax will be a good fit in fields with triazine-resistant weeds.  However, if the field often needs to be applied postemergence for weeds other than triazine resistant weeds, using Callisto postemergence would be a better option.


Cinch and Cinch ATZ (DuPont) same as Dual II Magnum and Bicep Magnum, respectively.


Define 60DF (Aventis/Bayer) is the single active ingredient of flufenacet (which is contained in Axiom and Domain).  Define is similar to Dual, Micro-Tech, Harness, Frontier, etc., and provides preemergence control of many annual grasses.  It will need to be tankmixed with atrazine for a broader spectrum of control.


Harmony GT 75DF (DuPont) is a more concentrated formulation of Pinnacle 25DF, and its use rate is much less than Pinnacle.  Harmony GT is used at one-twelfth of an ounce per acre.  It can be applied to 2 to 6 leaf corn (up to 12 inches tall).  Harmony GT provides excellent control of lambsquarters and pigweed (including triazine resistant).  In “Clarity-sensitive areas”, it can be a good alternative.  There are precautions on the label about use with Counter due to crop injury (see label).


Keystone 5.25 SE (DowAgroSciences) is a premix of acetochlor plus atrazine.  This is a new formulation of acetochlor and atrazine to improve handling and suspension.  There are the same restrictions for groundwater concerns as all other acetochlor formulations.


Option 35WDG (Aventis) is a postemergence herbicide from the same class of herbicides as Accent, Beacon, and Permit (ALS-inhibiting herbicides).  Use rate is 1.5 to 1.75 oz/A.  Application timing is emergence to 16 inches or V-5 stage, whichever is more restrictive.  The label recommends methylated or ethylated seed oil plus nitrogen fertilizer for additives.  There are numerous grasses and broadleaves listed as controlled on the label.  Corn can be replanted 7 days after application, soybeans 14 days, and all other crops can be planted 60 days after application.  There are precautions about use for corn previously treated with Counter or Lorsban, refer to label.


Outlook 6EC (BASF) contains dimethenamid-p which is the more active isomer of dimethenamid (Frontier, Guardsman, and LeadOff).  Since it is more active, the use rates will be lower by approximately 55%.  Outlook controls the same weed spectrum as Frontier; providing good control of annual grasses, some broadleaves and nutsedge.  Outlook is available as a pre-packaged mixture with atrazine and called Guardsman Max.


Steadfast 75WDG (DuPont) is a pre-packaged mixture of Matrix and Accent.  It is a postemergence herbicide with a use rate of 0.75 oz/A.  At this use rate, there is 0.75 oz/A Matrix plus 0.5 oz/A Accent.  This is a higher rate of Accent than what is in Basis Gold.  There are precautions with organophosphate insecticides, refer to label.



Herbicide/Insecticide Reminders - Mark VanGessel, Extension Weed Specialist;  mjv@udel.edu


Counter, Lorsban, and Fortress are organophosphate (OP) insecticides used in this area.  Many of the postemergence herbicides have precautions about applying them to corn previously treated with OP insecticides.  Herbicides that list restrictions or precautions include Python, Hornet, Accent, Basis Gold, Steadfast, Celebrity Plus, Harmony GT, Pinnacle, Beacon, Exceed, NorthStar, Spirit, Callisto, Lumax, Option, Permit, Yukon, and Lightning.


If you are considering using any of these herbicides, refer to the label regarding restrictions/precautions with OP insecticides before you plant.



Weed Science Publications Available on the Web – Links Provided BelowQuintin Johnson, ExtensionAssociate - Weed Science; quintin@udel.edu


Access the UD Research & Education Center Website at the following address: http://www.rec.udel.edu/ and look under “Publications” then “2003 Guides & Factsheets or type in the address below for a direct link to the articles.


2003 Corn Weed Management Guide



2003 Soybean Weed Management Guide


Determining Presence Of Glyphosate-Resistant Horseweed Under Field Conditions



WF1:      Perennial Weed Control



WF2:      Giant Ragweed Control in Cropland



WF3:      Canada Thistle Control in Cropland



WF4:      Burcucumber Control in Cropland



WF5:      Johnsongrass Control in Cropland



WF8:      Sprayer Clean-Out Guidelines



WF9:      Considerations for Herbicide Selection



WF14:    Herbicide Resistant Weeds



WF15:    Large Plot Test Demonstrations



WF16:    Soil Insecticide / Herbicide Interactions




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


Commodity Markets React to U.S. Planting Intentions and Grain Stocks Report


U.S. Planting Intentions

The March 31st release of U.S. Planting Intentions and the Grain Stocks Report provided a positive tone for the grain markets heading into this week. U.S. farmers intend to plant 79.02 million acres of corn this spring, slightly below the average of pre-report estimates and slightly less than last year.


U.S. soybean planting intentions were placed at 73.182 million acres, above the pre-report average estimate of 72.415 million acres and just below last year's 73.76 million acre level.


All wheat acres for the U.S. were reported at 61.697 million acres, below the average pre-report estimate of 62.482 million acres, and above last year's 60.36 million acre level.


Commodity traders will now turn attention to weather conditions and planting progress as the planting season advances.


U.S. Grain Stocks

Stocks of corn, soybeans, and wheat were all reported at levels that were less than the comparable period for last year. USDA estimated U.S. corn stocks at 5.132 billion bushels, slightly below pre-report estimates and 664 million bushels less than the same period last year. Of particular note to the corn market is the fact that corn use has outpaced the December estimates, and ending stocks for U.S. corn in the next Crop Report will be dropped back below the 1 billion bushel level. This is a big psychological boost to the corn market.


U.S. soybean stocks were placed at 1.202 billion bushels, on the high end of pre-report estimates and 134 million bushels less than last year. U.S. soybean stocks are noted as being at extremely low levels from an historical perspective. However, when one factors in the record crop now being harvested in the Southern Hemisphere combined soybean stocks are actually 367 million bushels greater than last year.


U.S. wheat stocks reported at 904.9 million bushels, 306.1 million bushels less than last year. This represents an obvious boost to the wheat market as well as recent reports indicating that the U.S. aid toward the war effort is likely to give a slight boost to wheat prices. In addition, the wheat market is technically oversold and with new crop '03 SRW wheat now trading in the bottom third of the predicted price range wheat prices may show some price strength in the near term. New crop wheat prices are currently $1.00 per bushel lower than the September '02 price level for '03 SRW wheat.


Cumulative Total Exports

Currently U.S. wheat exports are lagging year ago levels, and are at their lowest level since 1975. Some of the traditional U.S. business in recent years, particularly to Southeast Asia is being filled by the European Union.


Corn exports are also lagging last year's 1.023 billion bushel level, with a cumulative total of 851 million bushels reported thus far for the marketing year.


Cumulative U.S. soybean exports are running ahead of last year as we near about 40% progress on the Southern Hemisphere harvest. Soybean exports are now recorded at 856.3 million bushels as compared to 847 million bushels at the same time last year.


The marketing year begins June 1 for wheat and September 1 for corn and soybeans.


'03 Delaware Loan Rates

 Corn $2.21, Soybeans $5.11, and Wheat $2.50.



Helpful Steps to Take on Last Year’s Drought Stressed Pasture and Hay Fields - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu


Grass pasture and hay fields that were severely stressed during the drought last year need some careful attention this spring to ensure their recovery.  The first step is to apply nitrogen (N) fertilizer to the fields as early this spring as possible to stimulate vegetative growth to minimize weed invasion as well as renew vigorous grass growth and stand.  Many pastures are initially planted with both grass and legume species.  If last summer’s stress reduced the legume component to less than 25 percent of the ground cover or estimated biomass, the same rate of nitrogen (about 50 lb N/A per grazing or cutting cycle) should be applied to these mixed fields as to the pure grass fields.  If the field has 25 to 50 percent clover, the usual recommendation is for a N rate of 25 lb N/A/cycle.  However for the first grazing cycle, I would suggest keeping the rate at 50 lb N/A.  This one time increase will strengthen the grass component and help it compete against weeds while doing minimal damage to the legume component.


Another suggestion is to apply your spring maintenance phosphorus (P) and potassium (K) at the time of the spring growth flush rather than in late-May or early June.  Also, if legumes are present add in 0.5 to 1.0 lb boron per acre.  If the field’s fertility level is in the medium range (FIV of about 50) for P and K, consider adding about 50 lbs phosphate (P2O5) per acre and 100 to 140 lbs potash (K2O) per acre to help improve the root system and prepare the crop for future heat, drought, and pest stress this summer.


If the pastures were severely stressed last year, it might be a good idea to let them get a little more growth than normal before you begin grazing this year.  It may mean falling a bit behind the growth curve and having to move more of the pasture area into hay production, but the extra energy reserves the crop will be able to store should be worth your efforts and pay off in better stands later in the year.


Another item to consider is weed control.  Your choices are severely restricted if the pasture or hay field is mixed legume and grass.  Essentially for mixed swards under grazing, your options are limited to cultural methods such as mowing or using mixed animal species to put extra grazing pressure on problem weeds.  Pure grass stands do have some herbicide choices available plus the above options.  Mowing to reduce seed production for annual weeds is one of the most effective methods you can employ, plus it has the added benefit of removing more mature low quality forage and stimulating new growth that is high in quality.


Treat all pasture and hay fields that were over-stressed last year with extra care this spring and summer to ensure strong, healthy and productive stands.



Managing N on Corn When Fertilizer Prices Rise - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu


In the first issue of Weekly Crop Update, I covered the strategies to use when deciding on nitrogen (N) management for small grains.  In this issue, I’ll offer some suggestions on managing N for corn production.


Maximizing N use efficiency is a goal to shoot for that will ultimately help you to control your fertilizer costs.  To do this for dryland corn, a combination of at-planting N followed by sidedress N when the corn is 12 to 16 inches tall is the best approach.  Do not under fertilize with N at planting when you plan for it to keep the crop growing until sidedress time.  Many reproductive characteristics (row number and even kernel number per row) are impacted if early season nutrient stresses occur.  Over the winter, we received significant rainfall that likely has leached any residual N left from last year’s fertilization out of the top soil where seedlings could easily recover it.  Consider using phosphorus (P) at planting (i.e. using a starter fertilizer at planting) along with N since research often indicates more efficient use when the two nutrients are used in combination.  Also, do not use an excessive rate of N at planting since leaching and denitrification can reduce N-use efficiency if our winter rainfall pattern continues.  I feel that using a rate between 25 to 35 lbs N/A is your best choice.


For Bt corn hybrids, a recent article in Agronomy Journal suggests that early season N sufficiency is directly related to the amount of endotoxin the seedlings can produce and may affect the ability of corn plants to resist insect feeding.  I expect more research will be conducted on this topic so watch for further updates.


Some growers still prefer to apply all the fertilizer at planting rather than using a sidedress application.  Sidedressing N improves the N use efficiency enough that your total N rate can be 10 to 15 percent lower than that when it is all applied at once and yield will not be affected.  So, at sidedress time use a N rate of 0.9 to 1.1 lb N per bushel of expected yield (base this on a realistic yield goal) with the lower rate applicable for corn after soybean rotations and the higher rate applicable for corn after corn rotations.  If manure, compost, or some other organic material containing N has been applied either this spring or in the recent past, consider using the Presidedress Soil Nitrogen Test (PSNT) to adjust your N rate based on the amount of N that can be mineralized from the organic amendments you’ve used.  This will also help maximize N-use efficiency and minimize your fertilizer cost.


For irrigated corn, not only will the realistic yield goal be greater, but if you can fertigate with the system you can markedly increase your N-use efficiency by supplying N as the corn crop needs it.  Fertigation lets you apply small quantities of N more times during the growing season and reduce your total N use.  Tissue testing is one way to monitor the N status of your corn during the growing season to ensure you use enough but do not over fertilize with N.


What else can you do to maximize the efficiency of your fertilizer program?  First, whenever possible minimize the potential for yield limiting stress on your crop.  N-use efficiency is highest when corn develops under minimal crop stress conditions.  Be sure, too, to review your soil test results so your fertility status is optimal.


Understanding fertilizer differences can be helpful too.  Urea is often the least expensive of the granular fertilizers, but unless an effective urease inhibitor is used, it will convert to nitrate nitrogen within a few weeks of application with our spring conditions.  The nitrate will then be subject to loss by either denitrification and/or leaching.  Broadcast urea is subject to loss through ammonia volatilization especially if the weather turns warm and the soil or trash is moist.  This is very true for no-till situations since much more trash or crop residue covers the soil.  Incorporation of urea by tillage or rainfall is necessary if residue cover exceeds about 30 percent and air temperatures above 55˚ F are expected.


UAN solutions are also impacted by the above characteristic of urea plus a portion of the product is already in the nitrate form and subject to leaching loss.  The advantage of UAN solutions is that instead of broadcasting them you can dribble them on in a banded surface application that can minimize the amount of product that comes in contact with surface residue.  This reduces the risk of volatilization loss from the urea portion, but does not affect leaching or denitrification loss potential.  In addition, heavy downpours that cause significant rapid runoff can be another source of N loss.


Ammonium sulfate and ammonium nitrate can be broadcast in most tillage/soil systems since surface volatilization will be minimized, but both will quickly convert to nitrate that can be leached or denitrified.  The ammonium nitrate already has a portion in the nitrate form while the ammonium sulfate is the most acidifying of the N fertilizers.  Ammonium sulfate almost doubles the amount of lime needed to neutralize its effects on soil acidity as compared with other N sources.


For no-till systems, try to place the N fertilizer below the residue and in contact with the soil.  Adjust N rates for expected yield potential for the no-till system.


Finally, resist the temptation to add that insurance N so many of us feel we need to use.  Years ago, Dr. Allan Bandel at the University of Maryland found that the last units of N returned very few bushels of corn.  If you are having trouble getting enough N or getting N at a reasonable price, then you’ll find that reducing your N rate by 10 or 15 percent will have much less impact on your yields than that first 50 to 75 units of N.



A Corn Planting Note about Soil Temperatures - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu


To maximize corn yields it is best to plant when you can expect uniform emergence of seedlings.  Emergence of all seedlings within a 3 to 5 day window will ensure the top yield potential by minimizing competition that occurs when corn plants emerge over a long period of time.  Although germination can begin when soil temperature at planting depth reaches 50˚ F, more rapid, uniform germination will occur if the soil temperature has reached 55 to 60˚ F and is likely to remain stable or rise higher.  Keep in mind that soil temperatures in no-till systems are likely to be cooler and will require more heat input from the atmosphere to warm up since no-till soils are generally higher in soil water content.  The use of row cleaners or sweeps and strip tillage, where a small band of soil around the row is tilled, will help increase soil temperature and improve uniformity of emergence.


When checking a field’s soil temperature, look for lower areas that are likely to be wetter or areas with heavier soil type.  These areas are likely to have the coolest soil temperatures.  In addition, while checking soil temperature, you can observe and estimate the field’s capacity for supporting equipment without causing compaction problems.  With the amount of rainfall many areas of the state have received, there is significant potential for compaction and for soil structure damage if soils are worked while still too wet.  Although it can seem rewarding to finally get field work done, if it is at the cost of damaging soil structure and significantly reducing yield potential is it really worth it at the end of the day?






Delmarva Conservation Corridor Public Forums Scheduled


Public Input Sought for Plan


Michael Scuse, Delaware Secretary of Agriculture, is requesting the public’s help in developing Delaware’s portion of the Delmarva Conservation Corridor Plan.  According to Scuse, “Public input is essential to draft a plan that will effectively improve the agricultural economy and environmental health of Delaware and the Delmarva Peninsula.  I hope the citizens of Delaware will assist us in this effort by participating in the Public Forums, which will be held at the following locations.”


Delaware Department of Agriculture

2320 South Dupont Highway

Dover, DE


April 22, 2003

7:00 – 9:00pm


April 30, 2003

7:00 – 9:00pm


University of Delaware

Research and Education Center

16483 County Seat Hwy., Route 9

Georgetown, DE


April 25, 2003

7:00 – 9:00pm


Blackbird Community Center

Blackbird Forest Road

New Castle County, DE


April 28, 2003

7:00 – 9:00pm


For more information, contact: Mark Davis, DE Dept. of Agriculture, (302) 698-4534,




                   Weather Summary



Weeks of March 11 to April 2, 2003


0.06 inches: March 11

0.03 inches: March 13

1.23 inches: March 16

0.13 inches: March 17

0.50 inches: March 20

0.05 inches: March 21

0.17 inches: March 26

0.37 inches: March 29

0.25 inches: March 30


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

Air Temperature:

Highs Ranged from 77°F on April 2 to 36°F on March 11.

Lows Ranged from 55°F on March 21 to 20°F on March 11.

Soil Temperature:

56°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:




2003 Black Cutworm Pheromone Trap Counts


                        Trapping period: 3/25/03 – 3/31/03






















Georgetown (UD REC)
































Little Creek





(1) Moth catches of 9 to 15 moths per 7-day period have been associated with a moderate to high potential for cutworm outbreaks.

(2.) Moth catches of 5 per night for at least 2 consecutive nights have also indicated a high potential for problems.

(3.) You can expect to see cutting activity around 300 degree-days, base of 50 degree F from peak moth activity.



Compiled and Edited By:

Tracy Wootten

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, 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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