Volume 12, Issue 2                                                                     April 2, 2004

 

The Weekly Schedule Begins – April 2, 2004

 

This is the first weekly issue for Crop Update in 2004.   If you are accessing the newsletter via the web, please notify me if you encounter problems.  Sometimes problems arise that may not affect the computers on our network here at the Research & Education Center.  Send me an email, wootten@udel.edu, or call me at 302-856-7303 ext. 312 with your comments. 

 

If you received Weekly Crop Update via an email reminder last year and have not sent me a request for 2004, please do so. 

 

 

 

Vegetables

 

Nitrogen Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu

To understand why nitrogen is used so widely, it is important to understand where, how, and why it is utilized by plants.  Those of us old enough to remember the drenching rains of Hurricane Agnes in June, 1972, remember the acres and acres of pale, yellow knee-high corn in the weeks after the storm.  This image brings to focus two characteristics of nitrogen.

 

First, it is easily leached from most soil profiles on Delmarva.  After Agnes, nitrogen fertilizer moved out of the young crops root zone, creating the pale, yellow appearance rather than the rich, dark green color that bodes well for a good, healthy, productive plant.

 

This phenomenon of color relates to chlorophyll, that amazing molecule that captures the sun’s energy and converts it to sugars, or a stored energy utilized by the plant for its maintenance and growth.  Chlorophyll is a complex molecule, with nitrogen as a key component.  At the risk of bringing back painful memories from high school chemistry; its molecular formula is C55H70O5N4Mg.  The carbon, hydrogen, and oxygen are obtained by the plant in the gaseous form from the atmosphere.  Nitrogen and Magnesium are the two mineral constituents of the molecule, and must be obtained from the soil, or in the case of legumes, the nitrogen is fixed from the atmosphere by Rhizobium bacteria on the roots.

 

In short, nitrogen and magnesium are at the core of the chlorophyll molecule, and in non-legume plants, must be supplied from the mineral environment of the soil.  The nitrogen component is four-times greater than the magnesium component.  A nitrogen deficiency is quickly manifested in lost production through impaired efficiency of the chlorophyll in the plant.  Of course, nitrogen has other roles in amino acid and protein synthesis and much more, so any deficiency results in negative impacts.

 

While I’ve concentrated on the need for nitrogen, vegetable growers are very much aware that too much nitrogen, besides being a waste of money and generating potential negative environmental impacts, can also hurt crop yield and quality.  Hollow heart on watermelons and potatoes, can be related to excess nitrogen.  Too much nitrogen can cause tomatoes to be “viney” and delay maturity.  Many vegetable crops will experience delayed maturity if nitrogen applications are too high.

 

Nitrogen recommendations from the University’s and most commercial labs are based on research and field experience.  They are just that, a recommendation, not a prescription.  Each grower does have, and must have, some flexibility to tailor those recommendations for conditions in his field and farm.  Quite often I encountered a grower who used ten percent more, or ten percent less than the recommendation.  They have a logic and rationale for those decisions that are farm-based and cost-driven.

 

Pea Planting.

Progress in pea planting as of March 30 is about 25-30% of the total intended plantings.  Earliest plantings are up and look good.  Although the weather has been cool, the lack of wet weather has allowed plantings to proceed fairly well.  Typically, about 8,000 acres of peas are planted.  Four processing companies contract with Delaware producers.

 

PictSweet Frozen Foods Obtains Former Agri-Link Plant in Bridgeville.

PictSweet Frozen Foods has obtained the former Agri-Link Plant in Bridgeville.  PictSweet has done business in Delaware for several years, shipping product to their plant in Bells, Tennessee.  They will concentrate on peas and lima beans at the Bridgeville facility.

         

 
 

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

 

Peas.

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. Avoid compacted, poorly drained fields when planting peas to avoid root rots.

 

Spinach.

Be sure to check overwintered fields for white rust. As soon as white rust is seen or discovered in the area, apply Quadris as a foliar spray on susceptible varieties.

 

 

 

Field Crops

 

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

 

Alfalfa.
Lower weevil populations in 2003 in combination with colder winter temperatures may result in lower populations this spring. However, you should still begin sampling fields for early feeding signs. We can now find low levels of  larvae in alfalfa in Kent and Sussex Counties.  Look for small larvae feeding in the tips of plants producing a round, pinhole type of feeding. Once you detect tip feeding, a full field sample should be taken. You will want to avoid treating fields too early since it may result in multiple applications. In general, no treatment should be needed before you observe 50 percent of the tips with 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,  Lannate and Steward  will also provide control.
 

Field Corn.
We will again be cooperating with UAP Inc. in a pheromone trapping program for black cutworm moths. The first moth was caught last week in Leipsic.  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 planting. Pyrethroids combined with early burn-down applications, 2-3 weeks before planting, have not provided effective control.
 

Just a reminder, the lowest labeled rate of Poncho 600 on field corn is 0.25 mg ai/kernel (Poncho 250) and the lowest labeled rate of Cruiser is 0.125 mg/kernel.  No data is available for the use of lower than labeled rates. Since a high percentage of corn seed has been treated with Cruiser or Poncho this season, remember that these two products have not provided bird repellency. If you are in an area where birds have been a problem, you should consider using a hopper box treatment that has lindane in the mix.  Based on grower and personal experience, the use of hopper box treatments containing lindane have helped with bird repellency. In addition, depth of planting has a large impact on the amount of bird damage you will see. Remember, birds pull corn out of the ground to feed on the seed. If you anticipate a bird problem, you should avoid shallow planting and plant corn 1 ¾ to 2 inches deep. This will to reduce their ability to pull corn out of the ground. However, be sure to watch your seed depth carefully when planting 1 ¾ inches and deeper, especially in sandy soils, to avoid emergence problems.


Timothy.
Reports from around the region indicate that cereal rust mites can now be found in timothy. 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 past years.  These mites are microscopic, so the use of a 20x-magnifying lens is necessary. If rust mites become a problem , 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.


Wheat.
Although we are starting to find fields with symptoms of barley yellow dwarf virus (BYDV), it still appears that the most important time to control aphids and help reduce problems from BYDV is the first 30 to 60 days after plant emergence.  Although it is possible to have virus vectored in the spring, if you see BYDV in wheat this spring it was likely vectored late last fall and early winter.  Information from Kentucky indicates that there is generally no yield impact after Feeke’s growth stage 4 (stem elongation).

Be sure to begin sampling fields by mid-April for cereal leaf beetle activity. Since a number of fields experienced economic levels in 2003 and we are finding the first evidence of adult feeding, fields should be scouted early for the presence of egg masses. In recent years, the threshold for cereal leaf beetle has been adjusted to include sampling for eggs, especially in high management wheat fields or areas where problems were experienced the previous year.  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. 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. The treatment threshold is 25 or more eggs and/or small larvae per 100 tillers.  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 can provide enough lead-time to provide good control if fields are scouted carefully and fields are visited twice a week when populations are approaching threshold levels.  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). Two years of research data from Ames Herbert in VA indicates that Warrior has provided longer residual control if applications are made based on the egg threshold. However, if applications are made when larvae are the predominant stage, all products have provided similar levels of control. Neither Mustang MAX nor Warrior are labeled on barley at this time.

 

 

 

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

 

Wheat.

We are getting samples of wheat plants already from irregular spots in the fields that have a mottled yellow appearance. This could be barley yellow dwarf, but the samples have been sent for virus identification and confirmation and we will be keeping you updated as the season progresses. Barley yellow dwarf is transmitted by aphids either in the fall or spring. It is generally fall infections that cause the most yield loss. Other virus diseases of wheat include wheat spindle streak and wheat soil born mosaic virus. These two viruses are soil born because they are transmitted by fungi that have the virus and transmit the virus when they infect the wheat roots in the fall. All three viruses can produce irregular patches of yellow stunted wheat in the early spring. The soil born viruses will be worse in low areas of the field in contrast to barley yellow dwarf infections which are random. Wheat soil born mosaic almost always will be found in the low spots of the field. There is no control for the viruses once they appear. The soil born viruses can be controlled in the future by planting resistant wheat varieties.  Researchers in Virginia and North Carolina have determined that fall control of aphids can control barley yellow dwarf. Aphid control in the spring for virus control is not warranted.

 

Soybean Cyst Nematodes.

It is not too late to soil test for the soybean cyst nematode (SCN). If soybean stubble is present, sample with a soil probe 6-8 inches deep between the plants in the row.  Samples should be taken before any spring tillage. Sample size should be 20-25 cores taken in a zig-zag pattern across the field. Ideally samples should represent no more than 10-20 acres. Sample bags and information sheets are available from the county extension offices. The cost is $10 per sample. New fields and those to be planted with susceptible varieties are the most critical to sample at this time.

 

Keep in mind, that most Roundup Ready varieties do not have resistance to race 1 of the soybean cyst nematode (SCN) but carry some resistance.  This makes monitoring SCN populations more important if you are growing continuous soybeans and using Roundup Ready varieties. Periodic sampling can indicate if SCN populations are increasing. Soybean variety trial results are available from the county Extension offices and on the web at http://www.udel.edu/varietytrials/soybeans/ so you can see how a few varieties performed locally.  Make use of this information. Without aggressive management such as planting SCN-resistant varieties and rotating with non-host crops, yields can be reduced by 75 percent or more in hot, dry growing seasons.

 

 

 

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, Steadfast ATZ, Celebrity Plus, Harmony GT, Pinnacle, Beacon, Exceed, NorthStar, Spirit, Callisto, Option, Equip, and Lightning.

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

 

 

 

Section 18 for Sinbar in Watermelons - Mark VanGessel, Extension Weed Specialist;  mjv@udel.edu

 

The State of Delaware has been granted a section 18 label for use of Sinbar 80 WP in watermelons as a preemergence treatment.  It is the same type of label we have had the past few years.  It is for 3 to 4 oz per acre of Sinbar, applied preemergence to bare ground.  Copies of the label are available by calling 302/856-7303 ext 380 (Lisa Dorey).

 

 

 

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, Fultime, and Keystone.  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 acetochlor if the groundwater depth is within 30 feet and you have sands with less than 3% organic matter, loamy sands with less than 2% organic matter, or sandy loam with less than 1% organic matter.

 

 

 

New(er) Corn Products for 2004 - Mark VanGessel, Extension Weed Specialist;  mjv@udel.edu

 

Some of these products were available in 2003.

 

Equip 32WDG (Bayer) is a premix of Option (foramsulfuron) and a new ALS-inhibiting herbicide called iodosulfuron.  (Iodosulfuron is not available in any other herbicide at this point.)  In addition to the two herbicides, it contains a crop safener.  It is for postemergence use at a rate of 1.5 oz/A.  The label requires that it be applied with MSO and nitrogen.  Equip can be applied over the top of corn up to 12 inches tall (or V4 stage) and from 12 to 36 inches (or V4 o V8 stage) with drop nozzles.  There are numerous grasses and broadleaves listed as controlled on the label.   There are precautions about use for corn previously treated with Counter or Lorsban, refer to label.  There is no problem with planting small grains in the fall, but there are a number of vegetable crops that are listed as 18 month plant back intervals.

 

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.  There is also a formulation called Keystone LA for situations where lower atrazine is needed.

 

Lumax (Syngenta) was available last year.  There were some mixing problems with liquid fertilizer and now Syngenta recommends a compatibility agent with phosphate ester when using suspension or liquid fertilizers with N-P-K-S as the carrier.  There were also a few cases when after the tank was mixed, the products were allowed to settle out and it was difficult to resuspend the mixture.  Syngenta developed some guidelines for situations if the spray solution sits for over two hours without agitation.  It is recommended to use clay suspension agents (Attagel 50 or Min-U-Gel 200) if water is the carrier.  Unfortunately, these clay suspension agents will deactivate paraquat and glyphosate products and may require separate application for paraquat and glyphosate to control weeds that have emerged.  Syngenta is developing a new formulation of Lumax to overcome these problems.

 

Steadfast 75WDG (DuPont) is a pre-packaged mixture of Matrix and Accent.  It was available in 2003.  It is a postemergence herbicide with a use rate of 0.75 oz/A.  This use rate is equivalent to 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. 

Steadfast ATZ 89.3 WDG contains atrazine.  It is the equivalent of 0.75 oz/A of Steadfast, but with 0.75 lbs of atrazine.

 

Prowl H2O 3.8AS (BASF) is new pendimethalin formulation.  Same uses as Prowl and other formulations of pendimethalin, only it is a water-based formulation, and the use-rate structure is different from the 3.3EC formulation.  The new formulation makes the product more user-friendly.  The pendimethalin (active ingredient) is inside capsules that rupture through wet/dry cycles of the soil.  Planting precautions with corn remain the same to prevent root pruning of the corn plants.

 

 

 

Dicamba Formulations for Horseweed Control - Mark VanGessel, Extension Weed Specialist;  mjv@udel.edu

 

There has been some confusion about use of Clarity and/or Banvel for weed control prior to planting soybeans.  Both Clarity and Banvel contain only dicamba as the active ingredient and both are labeled prior to planting soybeans.  Both require a period of time between application and planting.  Banvel restriction is 30 days regardless of rate.  The Clarity label requires a cumulative amount of rain or irrigation of 1 inch (meaning the rain does not have to fall all at one time) followed by 14 days before planting if less than 8 oz of product is used (longer interval is required if more than 8 oz/A is used).  University of Delaware research has shown 4 oz of Banvel or Dicamba at this time of year is adequate for horseweed control.

 

 

 

Preemergence Herbicide Rates in Corn - Mark VanGessel, Extension Weed Specialist;  mjv@udel.edu

 

I have been asked about comparable rates of various premixed soil-applied herbicides for corn.  That is very difficult to come up with.  All of these pre-mixes have varying ratios of atrazine and chloroacetamide herbicides.  Chloroacetamide herbicides are the grass herbicides such as metolachlor (Dual) or acetachlor (Harness), or dimethenamid-p (Outlook).  Some of the basic manufacturers in our area encourage the use of their products at rates above what is recommended on the label to ensure consistent performance.  I have told people when they ask about comparable rates, that you have to look at the label and see what the companies themselves recommend for a given soil type and organic matter content.  The soils in our region (high percentage of sand and low organic matter) are not well suited to hold enough herbicide for full-season weed control.  Unless we have ideal conditions that allow for early activation of the herbicide and excellent growing conditions for vigorous corn growth immediately after planting, the soil-applied herbicides are not likely to provide season-long weed control and will need some postemergence herbicides to keep the fields clean until harvest.

 

There have been changes in formulation and ratios of products for many pre-packaged herbicides over the past few years.  As a result, check the label for your product of choice since often the new formulations recommend lower use rates than what was previously labeled.  Below is a chart on rates of the most common pre-packaged mixtures used in the area, general use rate, and the amount of products they are providing:

 

 

Herbicide

Rates

atrazine

chloroacetamide

(grass herbicide)

Bicep II Magnum

1.6 qts

1.24 qt

1.0 pt Dual II Magnum

 

Fultime

3.0 qts

1.2 qt

2.25 qt Topnotch

 

Guardsman Max

2.0 qts

1.3 qt

14.5 oz Outlook

 

Keystone

2.6 qts

1.5 qt##

2.4 qt Topnotch$$

 

Harness Xtra  5.6L

1.7 qts

1.1 qt

0.76 qt Harness

 

Lumax

2.5 qts

0.625 qt

1.76 pt Dual II Magnum

AND 5.4 oz Callisto **

 

     ##The atrazine formulation in Keystone is not available in other products.

     $$Not a true comparison since Topnotch is a capsule suspension formulation and the acetachlor in Keystone is a suspo-emulsion formulation.

    **Callisto is not a chloroacetamide

 

 

 

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

 

U.S. Planting Intentions and March 1 Stocks Reports Released.

The March 31st release of farmer's '04 Planting Intentions and the March 1 Stocks in All positions reports will likely have only a minor impact upon commodity prices. Within reason, the planting intentions were well within range of the pre-report trade estimates. After commodity traders have had an opportunity to work through the

 

initial impact of the report, trader attention will likely return to spring planting conditions and the corn/soybean price ratio to see if further adjustments to the planting intentions reported can be made. The ratio stands at 2.36:1 this morning, still favoring soybeans. Truth be known, the Chicago markets would like to see some additional corn acres and a few less soybean acres for the '04 crop. With tight corn stocks and 'ration' level soybean stocks, this is likely to make for some interesting bidding in both the corn and wheat pits over the next couple of weeks. These markets are also likely to remain extremely volatile for the foreseeable future, if not into pollination and podding time.

 

Planting Intentions.   

U.S. Farmers intend to plant 79 million acres of corn in 2004, 1.29 million acres less than the average pre-report trade estimate for the current cropping season. They also intend to plant 75.41 million acres of soybeans, 90,000 acres more than the average pre-report trade estimate of 74.51 million acres. U.S. wheat acres were reported at 59.46 million acres, slightly below the pre-report average trade estimate of 59.85 million acres.

 

March 1 U.S. Stocks.

U.S. corn stocks in all positions were reported at 5.27 billion bushels, in line with the average trade pre-report stocks estimates. U.S. soybean stocks reported at 906 million bushels, were only 39 million bushels above the average pre-report trade estimate and are 25% less than a year ago. Stocks of all U.S. wheat, reported at 1.02 billion bushels were slightly less than the average trade estimate.

 

Market Strategy.

The next USDA Supply/Demand report will be released on Thursday, April 8th.

It is possible that U.S. corn ending stocks for the 2003/04 marketing year are likely to be reduced. It is also possible that the size of the Southern Hemisphere soybean crop will get smaller than previous estimates. With the exception of maybe taking some new crop wheat sales, new crop corn and soybean sales should be placed on hold.

 

 

 

 

Making a Decision on Alfalfa Stand Density - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu

 

Farmer experience has shown that if soil fertility levels are adequate or high and weed problems are minimal, alfalfa stands of 4 to 5 plants per square foot can yield as much as a stand with 10 to 15 plants per square foot (Photo 1 and 2).  This is a result of an individual alfalfa plant's response to decreasing stand density.  Decreasing stand density causes an increase in the number of stems produced per plant.  This effect helps the crop compensate for fewer plants and maintains yield potential.

 

 

Photo 1.  Alfalfa crowns beginning spring growth in an older stand (Photo by R. Taylor).

 

 

Photo 2.  New Stand alfalfa beginning spring growth in fall seeded field (Photo by R. Taylor).

 

Research from Wisconsin conducted by Dr. Dennis Cosgrove showed that stem number rather than plant number is a more accurate determination of when to plow down or interseed an alfalfa stand.  Cosgrove suggests using a value of 55 or more stems per square foot for production of maximum yields.  A reduction in stem number per square foot to 40 stems or less will result in a 25 percent yield reduction.  Cosgrove further suggests that this level is the critical point when alfalfa fields begin to lose profitability and should be rotated out of alfalfa.  Again, interseeding a very high-quality productive grass should add one or more additional production years, but can speed up the loss of alfalfa plants from the stand.

 

The number of stem or stand counts you make depends on the size of the field and the uniformity of stand reduction.  In general, the larger or less uniform a field, the greater the number of counts.  For uniform fields 20 to 30 acres in size, count about 20 randomly chosen square foot areas and average the results.

 

As was noted in the Weekly Crop Update last year, alfalfa stands were very often severely injured by a number of factors such as annual grass invasion, ponding water, ice sheeting in both last winter and this winter, and other problems such as potato leaf hopper injury and compaction issues.  If your fields are mostly light sandy soils and you want to replant alfalfa in late summer/early fall, you should decide on whether to destroy the current stand early this spring.  For this type decision, base your decision on either the 4 to 5 plants per square foot threshold level or the 40 stems per square foot threshold (Photo 3).  If you plan to reseed a year or more from now and a decision can be made during the growing season, use below 40 stems per square foot as the threshold value.

 

 

Photo 3.  Old stand of alfalfa beginning spring growth, note the sparse number of crown shoots (Photo by R. Taylor).

 

 

 

Winter Heaving of Barley May be Slowing Barley Spring Growth  - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu and Derby Walker, Jr., Extension Agent, Sussex County derby@udel.edu

 

While recently looking at a barley field that was not responding to spring nitrogen (N), we noticed something we’ve not seen all that often.  That was winter heaving of small grains.  As you can see from Photo 1 and 2, the heaving either killed small barley plants or severely impacted the root system delaying their growth this spring.  Plants that were still alive and green were dug up and we found that new secondary crown roots were developing from the crown region.  Most of the roots were less than an inch long and seldom were there more than three per plant.  The lack of a vigorous root system probably accounted for the very slow growth following an earlier N application

 

 

Photo 1.  Winter heaving can either outright kill barley plants or severely delay spring growth until a new root system becomes established (Photo by R. Taylor).

 

 

Photo 2.  Note the injured and dead roots at the crown node of barley damaged by winter heaving (Photo by R. Taylor).

 

When we viewed the field, the higher sand ridges were actually growing more rapidly and showed less damage from winter heaving.  Other areas that were protected by wind breaks or houses also showed better growth.  The most impacted areas of the field were those areas where it appeared that water had been standing.  The soils in these areas were heavily cracked (Photo 2) even though loamy sand in texture.  We felt that areas that were poorly drained, compacted (less water percolation, but also smaller root systems and less vegetative cover of the soil), and open to north or northwestern winds contributed to the severity of winter heaving (Photo 3).

 

 

Photo 3.  Field view of heaved barley with less damaged on protected areas (Photo by R. Taylor).

 

Not all fields that are slow to respond to spring N will have been impacted by winter heaving.  We also have seen some fields that were planted late (or replanted due to crusting) have also been slow to grow this spring.

 

 

 

Pest Management Recommendations for Field Crops 2004 Available

 

 

You may obtain copies of the Pest Management Recommendations for Field Crops 2004 from the Research & Education Center by mail, cost is $15.00 (includes shipping and handling) contact Sharon Webb (302-856-7303), or purchase a copy for $13.00 by stopping by the Research & Education Center in Georgetown.  Please make checks payable to “University of Delaware” and allow one week for the delivery of the books.

 

 

 

UPCOMING MEETINGS:

 

University of Delaware

Beekeeping Short Course

 

Saturday, April 17, 2004

9:00 a.m. – 4:00 p.m.

 

Course Fee $25 (individual/family); Youth (18 or less) $10

 

Lunch included.

 

 

Topics to be covered: 

¨       Honey Bee Biology

¨       Basic Beekeeping Equipment

¨       Honey Bee Diseases & Parasites

¨       In the Apiary

¨       Care & Feeding of Your New “livestock”

¨       Where Do We Go From Here??

¨       Time & Labor Saving Tips/Suggestions

 

 

 

Registration required.  For more Information on the Program, Contact Dewey Caron, University of Delaware, 302-831-8883 or dmcaron@udel.edu .

 

 

 

 

 

 

                   Weather Summary

http://www.rec.udel.edu/TopLevel/Weather.htm

 

Weeks of March 12 to March 31, 2004

Rainfall:

0.66 inches: March 16

0.02 inches: March 17

0.04 inches: March 18

0.26 inches: March 19

0.01 inches: March 21

0.04 inches: March 25

0.21 inches: March 30

0.04 inches: March 31

 

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

Air Temperature:

Highs Ranged from 74°F on March 26 to 39°F on March 22.

Lows Ranged from 56°F on March 27 to 19°F on March 23.

Soil Temperature:

46°F average.

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

 

Web Address for the U of D Research & Education Center:  http://www.rec.udel.edu

 

Compiled and Edited By:

Tracy Wootten

Sussex County Extension Agent – Horticulture

University of Delaware

 

 

 

 

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.