Volume 1, Issue 1 March 13, 1998


Vegetables

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

Seed Corn Maggot. Once again the warm winter conditions have favored early fly emergence and in many cases egg laying will occur before spring tillage because of wet soil conditions. If spring conditions remain cool and wet, seed corn maggot will be a problem in many spring planted vegetables including cole crops, early melons, peas, snap beans, spinach and sweet corn. The most effective controls are achieved with a combination of early, complete tillage and a seed treatment (containing diazinon or chlorpyrifos) and/or a soil insecticide. All the soil insecticides labeled for sweet corn provide seed corn maggot control (Counter, Lorsban, Force, Fortress); however, a seed treatment is still needed when conditions are extremely favorable for maggot problems. Diazinon (AG 600) is labeled on many vegetable crops. It must be broadcast and incorporated in the top 3-4 inches of soil close to planting to be effective. If conditions are extremely favorable for maggot problems, a seed treatment must also be used in combination with this treatment. One treatment that has worked well with peas and is also labeled on corn and succulent beans is diazinon 50W as a planter box treatment. The use rate is ˝ oz per bushel of seed. It should also be combined with a ˝ oz of graphite per bushel of seed to reduce friction between seeds. To reduce the chances of phytoxicity, seed must also be treated with a fungicide and you should only treat seed that will be used immediately.

Sweet Corn. On February 27, 1998, EPA granted the conditional registration for Attribute TM sweet corn with YieldGard R insect protection, the first Bt sweet corn hybrids cleared for sale to commercial growers. It was developed by Novartis Seeds Inc., Vegetables of Boise, Idaho and marketed under Rogers brand name Attribute TM. It will provide season long protection of European corn borer and corn earworm. Growers will be able to distinguish Attribute seed by its blue seed coating and the Attribute logo on the package. At this time, seed will only be available for processing sweet corn. The fresh market variety (VP 0966: 78 day, mid-season, yellow supersweet ) will be limited to large-scale trial quantities until the fall of 1998. In keeping with EPA restriction against sale to the home garden industry, dealers will only distribute seed to commercial growers. Preventing insect resistance will be critical to maintaining long-term effectiveness of this technology. Attribute growers will be required by EPA to use the following insect resistance management practices: 1.) plant hybrids in large blocks, 2.) scout for non-targets (e.g. sap beetles) and use IPM strategies, 3.) scout for resistant corn borers and corn earworms, 4.) do not spray Bt microbial pesticides on Attribute fields, 5.) destroy any remaining Attribute stalks immediately following or within one month of harvest, 6.) do not repackage or resell Attribute seed, and 7.) cooperate with Novartis Seeds in efforts to monitor grower compliance with above insect resistance management practices. v

NY87 - New Potato Variety Released as REBA - Ed Kee, Extension Vegetable Crops Specialist ; kee@udel.edu

Reba, tested as NY87, was released by Cornell University to New York Foundation Seed Growers in 1996, and named Reba in 1997. It has performed well in the Delaware trials and in trials across the Northeast . It is a mid-season variety, with early sizing which can produce larger tuber size. It has excellent appearance, with round tubers and a bright, white skin. The best performance in trials in Delaware and throughout the Northeast has been at 7 to 9 inch seedpiece spacing and 150 lbs. of nitrogen per acre. It has resistance to scab at levels between Monona and Superior, which is very resistant. Reba is resistant to golden nematode and moderately resistant to verticillium wilt and early blight. It has average susceptibility to late blight.

Several Delaware growers have grown it in the past with good results. Its best fit may be as a high quality, attractive potato with good yields that could be harvested in August, to compete with other regions. v

 

Section 18 Emergency Label Approved for Sinbar and Command on Watermelons and Dual on Spinach – Ed Kee, Extension Vegetable Crops Specialist ; kee@udel.edu

EPA has granted a Section 18 Emergency label for the use of Sinbar on watermelons at the rate of 3 to 4 ounces/acre. This is a preemergence treatment. We recommend 2 to 3 ounces/acre. A 70 day pre-harvest interval is required.

Dual has been granted a Section 18 Emergency label for use on Spinach at the rate of 0.75 to 1.00 pints/acre. This is a preemergence treatment. Both of these Emergency labels are similar to those granted last year.

Command has also received a Section 18 Emergency label for use on watermelons at 4 to 6 ounces/A applied preemergence. This is also the same as last year.

We have also applied for Section 18 labels for Reflex as a post-emergence treatment on snap beans. We will notify you as to EPA’s decision on these requests as soon as we receive a decision. v

Delagra Signs Letter of Intent with Pro-Fac CooperativeEd Kee, Extension Vegetable Crops Specialist ; kee@udel.edu

Charles H. West, President of Delagra, Bridgeville, Delaware and Charles H. West Farms, Milford, has announced that Delagra has signed a letter of intent with the Pro-Fac Cooperative, headquartered in New York State. Pro-Fac is the parent company of Comstock, located in New York, Southern Frozen Foods, and Nally’s Fine Foods in Tacoma, Washington. West reports, "We are engaged, but not married yet. All systems are go at this point, the due diligence process is well underway. We expect to have a formal agreement within the next 30 to 45 days." West said that due to time, the product line will stay essentially the same this year, but will expand in the future.

"The Bridgeville plant is roughly equidistant to the Comstock plant in New York and the Southern Frozen Foods plant in Montezuma, Georgia, which offers real advantages and efficiencies. We believe this commitment will be good for the area."

Congratulations to the West family and to the folks at Pro-fact for creating a win-win situation and their commitment to our local vegetable industry. v

 

Vegetable Diseases - Kate Everts, Extension Plant Pathologist, University of Maryland and University of Delaware ; everts@udel.edu

Crop rotation is an invaluable tool in avoiding many devastating diseases of vegetables. It is not too late to review your field histories to avoid planting crops where a high level of inoculum could exist. A growing problem on the Delmarva is Phytophthora blight on squash. This disease also infects several other hosts which must be avoided (tomatoes, peppers, eggplant and cucurbits). Fields which have had these crops during the previous two years should be avoided. Other common rotations which cause problems locally when not followed are:

 

Crop

Rotation

Disease Benefit

Water-melon

minimum of 5-6 years

to avoid Fusarium wilt

All cucurbits

2 years

(use wilt resistant varieties)

to reduce gummy stem blight pressure

(remember that pumpkins, squash, watermelon, muskmelon and cucumber are susceptible)

Beans

3-4 years

to reduce root rot pressure

Peas

3-4 years

to reduce root rots and ascochyta blight

Spinach

2 years

to reduce white rust pressure

For a more complete list of rotation periods see University of Delaware Extension publication PP-27 by Bob Mulrooney. v

 

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

Sanitation of Greenhouse Trays. Vegetable growers that grow their own transplants and greenhouse growers can benefit from the following information provided by Dr. Bill Nesmith from Kentucky. He works with tobacco growers that produce large numbers of transplants using the float system. His research applies to the styrofoam trays used in that system as well as flats, pots, and trays used in traditional methods of plant production. Sanitation is extremely important in avoiding disease problems in the greenhouse. These sanitation measures are aimed at eliminating or greatly reducing losses from damping-off fungi such as Pythium, Rhizoctonia, Fusarium, and others.

A diligent sanitation program is a must! The media and water being used should be pathogen-free. All equipment and tools that come in contact with the system should be pathogen-free. That means either new trays must be used or re-used trays must be properly washed and sanitized.

What is available to disinfect trays? Steam, methylbromide fumigation, chlorine-bleach, and quaternary ammonium chloride salts are available in Delaware. None of these materials have been totally effective in killing all the pathogens and exactly how to best use them at the farm-level is not fully understood. Each has positive and negative points.

STEAMING TRAYS: In our studies, steam has been the most effective disinfectant - does the best job of killing the range of pathogens we are facing in Kentucky. But its cost is high and some items are damaged by steaming. Most studies indicate that the trays need to reach at least 160 °F for 30 minutes, but lower temperatures have been effective in others. Some commercial transplant producers are successfully using steam, the temperature/times being used mainly depends upon the assessment of risk potential.

FUMIGANTS: Methyl bromide with 1% chloropicrin has been almost as effective as steam in some of the tests. It provides excellent control of Rhizoctonia and other fungi on the surface of the tray. It will greatly reduce the level of Pythium, but has not been as effective as steam or proper bleaching in reducing Pythium, probably because a significant amount of Pythium is found embedded in the tray. We find great variation in the amount of control provided within the lot of trays, also. It is important to use an air-tight plastic seal, to pre-wet the trays, and to avoid large stacks of trays. Methyl-bromide is heavier than air, so it sinks, therefore best results occur with long, short stacks rather than tall, deep stacks. We have found little control is provided at the low rates, so use the maximum labeled rates (3 lbs/1000 cubic feet). Certain types of Styrofoam trays appear to be more easily damaged with this chemical. Pay special attention to ALL label precautions related to

safety.

CHLORINE BLEACH: Chlorine bleach solutions have given a high level of control, but, overall, are not as effective as either steam or properly conducted fumigation. Just dipping the trays in the solution and allowing them to dry is not highly beneficial. We have found little benefit to using more than 10% solution (one part bleach to 9 parts water). Without proper aeration and post-washes, salt residues can cause serious problems, especially with older trays that tend to soak up more material. Bleaches work best when the trays are washed with soapy water, then dipped several times into clean 10% solution, followed by covering them with a tarp to keep them wet overnight with bleaching solution. Afterwards, the bleach solution should be washed from the trays with clean water or water plus a Q-salt listed below, followed by aeration - to eliminate the chlorine and salts. Worker safety issues are also important with bleach. It is important that the bleach solution remain below pH 6.8 and that new solutions be made-up every 2 hours or whenever it becomes dirty, whichever comes first. Organic matter will remove the active ingredients quickly.

 

Q-SALTS (Quaternary ammonium chloride salts): These are marketed under such names as Greenshield, Physan, and Prevent as solutions containing 20% ammonium chloride. Many growers are using them, but the effects are not as positive as some believe, based on our testing. I believe the greatest benefit is in the final wash and on exposed surfaces in the greenhouse. In all our tests, Q-salts have always provided some control, as compared to using soap washes only, but have always been inferior to any of the above mentioned methods. v

Greenhouse Cleanup for Transplant Production - Jay Windsor, Extension Agricultural Agent ; windsor@udel.edu

It's that time of year again; time to get the greenhouse ready for transplant production. Hopefully everyone cleaned out at the end of last season, but if you did not, the time to do so has arrived. A quick "to do" list would include:

The greenhouse should be sanitized with a 10% chlorox solution sprayed on all surfaces, benches, floors (stones, soil, weedmats), sidewalls. Any used trays you are re-using should be dipped.

If you have weedmat covering the floor, you should not have a weed problem. If weedmat is not used, then you may have to pull and rake. The only labeled herbicide safe to use in the greenhouse is Roundup. This should be used while the house is empty. Do not use pramitol or other volatile herbicides in the greenhouse, even if the greenhouse is empty. v

 

Winter Temperature Index For Predicting Stewarts Wilt in Delaware Sweet Corn-1998 .

The winter temperature index is severe for both Georgetown and Newark as you may have guessed from the very mild winter we experienced. The mean temperature for Dec., Jan., and Feb. were measured at both sites. The sum of these averages provides the bacterial wilt index for predicting Stewarts wilt severity. Since the disease is transmitted by overwintering flea beetles that have the disease-causing bacteria in their alimentary tracts, conditions affecting flea beetle survival influence the occurrence of this disease. The index is as

follows:

Index

Predicted Severity

< 90

Usually absent

90-100

Intermediate

>100

Usually severe

The index for Newark is 119.9, and 122.5 for Georgetown. This is the warmest winter yet since I have been keeping these figures starting in 1993. The use of bacterial wilt resistant varieties is encouraged as well as at-planting insecticides (Counter 15G or Furadan 4F) to control the flea beetle vector on susceptible varieties. Scouting at emergence and applying foliar insecticides if needed is another option. v

 

Field Crops

 

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

Alfalfa.

Alfalfa Weevil : With the warm late winter conditions, be sure to check your fields by late March (in Sussex County) to early April (Kent and New Castle Counties) for alfalfa weevil activity. Check 5 areas for the presence of tip feeding. If no feeding is observed, a full sample is not needed and the field should be rechecked within one week. Once feeding damage is noted, collect 30 stems at random throughout a field and determine the number of larvae per stem. As a general rule, a treatment should be applied if 50% or more of the stems exhibit tip feeding. In alfalfa less than 12-inches tall, a treatment should be applied if you find 20 larvae per 30 stems. Insecticides labeled for alfalfa weevil include Ambush, Baythroid, Furadan, Imidan, Lannate, Lorsban, and Pounce. Warrior has recently received a registration for alfalfa. The use rates for alfalfa weevil are 2.56 – 3.84 oz per acre. It can not be applied within one day of harvest for forage and 7 days of harvest for hay.

Field Corn.

Soil Insects and Soil Insecticide Placement: Since there are no rescue treatments for many soil insect pests in field corn, the decision to use a soil insecticide should be based on a combination of factors including knowledge of the conditions favoring a soil insect problem, history of a pest problem in a particular field, planting date, and field scouting.

  1. Rootworms: Although adult beetle populations in August of 1997 were not as high in Delaware compared to some areas of Pennsylvania, the overwintering numbers are higher than in years past. In continuous corn situations, the decision to treat for rootworms can be based on a number of factors. If fields were scouted the previous season and adult beetle counts are available, you can use this information to make a treatment decision. The use of Furadan 4F at side-dressing has worked in some areas where applications are precisely timed, weather conditions are favorable (i.e. adequate moisture), and fields are scouted accurately for larvae. If scouting data is not available, the following factors are known to favor rootworm problems and can be used to decide if an at-planting soil insecticide is needed: continuous corn planted on heavier soil types, especially if you are in your second to fifth year of continuous corn; or rotated corn planted on heavier soils following soybeans in 1997 where heavy populations of rootworm beetles were observed and/or there were heavy infestations of volunteer corn or weeds. Adequate control can be achieved when soil insecticides are placed either in-furrow or t-banded. Counter, Force, Fortress, Lorsban, or Regent (new for 1998 ) all provide rootworm control. If Regent is used, fields can not be planted to small grains and other rotational crops for 12 months.
  2. Wireworms: High organic matter content, sod covers, and heavy grass pressure the previous season all favor wireworm populations. In addition, continuous corn fields with one or more of the above conditions are very susceptible to wireworm problems. Since wireworm larvae spend multiple years in the larval stage and their movement in the soil is easily affected by moisture gradients, good control is often difficult to achieve. Soil insecticides should be used at the higher end of the labeled rates and placed in-furrow to achieve economic control.
  3. White Grubs: Populations are favored by a number of factors including planting into double crop or full season soybean stubble as well as planting into old sod, hay, pasture or set-aside acreage. Larvae are also affected by moisture gradients in fields and are most commonly found on sandy knolls. If conditions remain cool and wet after corn is planted, damage can be very severe since plants are unable to grow ahead of the damage. Under these conditions, larvae stay in the larval stage longer resulting in an extended feeding period. Soil insecticides must also be placed in furrow to achieve effective control.
  4. Seed Corn Maggot: Cool, wet conditions during planting and plant emergence favor seed corn maggot problems. This years warm weather in late winter has favored early fly emergence and egg laying before spring tillage. Additional factors favoring this pest include use of manures, late plowing of cover crops, poorly drained soils and freshly plowed ground. In most cases, seed treatments containing diazinon will provide adequate control in field corn. However, if a number of the above factors are present and cool, wet conditions persist through the planting season, a seed treatment plus a soil insecticide is often necessary.
  5. Black Cutworm: This insect pest is favored by late planting, broadleaf weed growth before planting, planting into soybean stubble, poorly drained fields and reduced tillage. This is the one soil insect pest where a rescue treatment can be applied if you are able to scout fields at least twice a week once leaf feeding is detected. However, if field conditions become extremely dry after planting and cutworms feed below the soil surface, it will be extremely difficult to obtain adequate control with a rescue treatment. If you are unable to scout and you plan to plant into a field with a history of cutworms and/or a number of the conditions favoring cutworms are present, a treatment may be needed at planting. One effective option is the combination of a pyrethroid (Ambush, Asana, Pounce or Warrior) with a pre-emergence herbicide. If you are using an at-planting soil insecticide, Force, Lorsban , and Fortress are labeled for cutworm control but they must be applied as a t-band to be effective.

Small Grains.

Aphids and Cereal Leaf Beetles: Although there have been reports of hot spots of aphid infestations, aphid populations in general remain low so far in most locations. Populations in our area as well as in Virginia were low last fall, except in some early-planted barley. If conditions remain cool and beneficial insect activity is reduced, then increases in aphid populations could be seen. Begin scouting fields in late March and early April for potential problems. In addition, very little cereal leaf beetle adult activity has been observed. New research from Virginia and North Carolina continues to emphasize the importance of the stem leaves and flag leaf in achieving optimum yields. Therefore, thresholds continue to be adjusted to avoid economic loss. Treatments should not be applied too early. Although a number of fields were treated at top-dress time in 1997, this timing is too early (supported by Virginia and North Carolina research) and often results in the need to retreat at a later date. This strategy may have appeared to work in 1997; however, there was an extended period of cold weather in 1997 where many of the eggs died and controls may not have been needed. As long as economic levels of cereal leaf beetle are present, the better time for treatment may be in combination with standard fungicide applications (mid- late April depending on the weather). In high management fields with a good yield potential and /or where the potential for problems is high, the new threshold of 25 eggs and/or larvae per 100 tillers may be used. If you are using this threshold, it is critical that you wait until at least 50 – 60 % are in the larval stage. If the egg/larvae threshold is not used, the threshold of 0.5 larvae per stem will provide enough lead-time to provide good control if fields are scouted on a routine basis. A number of products are labeled for cereal leaf beetle control. Sevin will provide good control although experience in 1996 demonstrated that it could result in aphid explosions by reducing predator populations and its low effectiveness on aphids. Furadan provides good control; however, it can not be applied once grain is heading. Lannate and Warrior provide good control of the entire insect complex present in small grains (cereal leaf beetles, aphids, armyworm and grass sawfly). If you are using the egg threshold, Warrior may be the best option due to its longer residual nature. However, Warrior is still only labeled on wheat. v

 

Two Diagnostic Field Days - Mark VanGessel, Extension Weed Specialist ; mjv@udel.edu

There will be two Crop Diagnostic Field Days this year, both on May 21 at the UD, Research and Education Center. We will look at crop management and pest problems on small grains this year, with the goal of improving diagnostic skills. The morning event is for people wanting CCA credits and more in-depth information. This begins at 8:00 am. The second one is a shorter program that will provide pesticide credits for participants. This one begins at 3:30 pm. Both will have a meal included, but requires a fee and prior registration, call Mabel Hough at 856-7303 for registration and a flier. v

Don’t Go By The Calendar This Year - Mark VanGessel, Extension Weed Specialist ; mjv@udel.edu

If you are used to spraying your small grains in mid- to late March with a herbicide, you may want to check your fields now. With the mild winter, a lot of the weeds have been growing as well as the wheat. The temperatures have been warm enough for the weeds to grow, and so the herbicides will be taken up by the plant and control them. If you have wild garlic or canada thistle, the time of application should be delayed since you need to spray these weeds when they have fully emerged. Coverage is important for these species. If weed pressure from winter annuals is great, it may not be possible to get control of the winter annuals and perennial with one application. In that case, two applications may be required. You can mix your Harmony Extra with nitrogen. If spraying Harmony Extra with nitrogen, be sure to pre-mix it in water first. With nitrogen, there is no need for a surfactant unless wild garlic is over 8 inches tall. Applying Harmony Extra in nitrogen diluted with water, use a non-ionic surfactant at ˝ to 1 pint/100 gallons of solution. If applying it in water use non-ionic surfactant at 1 qt/100 gallons. v

Early Pre-Plant Herbicides - Mark VanGessel, Extension Weed Specialist ; mjv@udel.edu

Mid to late March is time to consider applying early pre-plant for no-till corn. The early pre-plant is applied to smaller weeds than an application at planting. This provides better control (often at lower rates), and results in less green plants to contend with at planting. Weeds will continue to emerge from time of early-plant applications until planting. You have a few options to consider. 1)include your residuals at time of early pre-plant (check label for rate), 2) apply the residuals that need the most amount of water to incorporate them at this time (ie. Princep), 3) Another option is apply a third of your residual herbicides with the early-preplant and then apply the remainder at planting. Plan on a second application of a non-selective herbicide at planting. The option you choose depends on the weed spectrum and which is most convenient for your operation.

Two things to keep in mind from my test plots the last few years. Applying herbicides 30 to 45 days ahead of planting is asking a lot of those products to then provide residual for six or more weeks into the season. Granted you use a higher rate, but that also includes more cost. Second, if all your herbicides are applied prior to planting, you can get a narrow band of weeds emerging right in the row from where the planter works up the soil. This is going to be more of an issue if you have row cleaners. I like to see the bulk of the residuals applied after planting. v

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

Background.

This month's report will focus on an update on the current 1997/98 marketing year and USDA's initial projections for the next 1998/99 marketing year. Demand for grains and oilseeds has been rather strong throughout the winter months of the current marketing year, which began September 1. Ending stocks of corn and soybeans for the 1997/98 marketing year are now projected at 949 million bushels for U.S. corn and 245 million bushels for soybeans, based upon the February USDA crop report. Those ending stock projections are 66 million bushels greater than last year for corn; and 114 million bushels above last year's ending stocks for soybeans. USDA issued their initial forecast for the 1998/99 marketing year at the Ag Outlook Forum held the end of February. Ending stocks for U.S. corn and soybeans for the next crop year are projected to increase to 1,014 billion bushels and to 400 million bushels respectively. In a nutshell, these numbers become the basic premise that we are working from to begin marketing 1998 crop production.

The South American soybean harvest is getting underway and the last estimates made are calling for a southern hemisphere crop of 46 million metric tons. Providing this crop size materializes, this will become South America's largest crop on record.

Market Strategy.

It appears to be almost a consensus in the grain trade that now may well be a good time to begin sales for the 1998 crop, for those who haven't made initial sales as yet. The level and amount contracted depends in large part upon individual cost of production, as well as local basis offerings. Generally speaking, initial sales of 10 to 20% of anticipated production are suggested. Stronger basis levels would suggest pushing initial sales slightly higher. Weather, crop development, and demand will dictate which direction crop prices go from here. Technically speaking, the corn and soybean markets have been in a downtrend for the past few weeks. v

 

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

Wheat. Early season diseases that may be present now are powdery mildew, Ascochyta leafspot, barley yellow dwarf virus, and soil-borne wheat mosaic virus. Ascochyta leafspot often appears at green-up and resembles Septoria leafspot. Symptoms include large gray-brown spots on the lower leaves that tend to be oval shaped. It will also produce small black to brown pin-head sized fungal structures in the dead leaf tissue. This fungus leafspot gets established on winter damaged tissue, but has been of minor importance and does not need to be controlled. This early in the season if you see circular areas in the fields where the wheat is shorter than the surrounding areas and lighter in color barley yellow dwarf (BYD) or wheat soil-borne mosaic virus (WSBM) may be the cause. Closer observation may reveal that the oldest leaves are bright yellow which may mean BYD, if leaves are mottled yellow-green it may indicate WSBM. The only way to be sure is to have a sample of infected plants tested for the presence of the virus. BYD is transmitted by aphid feeding in the fall and spring, WSBM is transmitted by a soil inhabiting fungus. These viruses can be confused with manganese deficiency caused by high pH, so take a soil test also and check the pH from the good and bad areas.

Soybeans.

It is still not too late to check for the soybean cyst nematode. Soil samples can be checked for the presence of SCN at any time of the year as long as the ground is not frozen or flooded. If you are planting susceptible soybeans in an area where SCN is present, I would not plant them without a nematode test. Nematode Assay bags are available from each of the county Extension offices. The Delaware Soybean Board pays for half the cost with check-off funds. Growers in Delaware pay $5.00 per sample. If a soybean grower with a 40 acre field with a yield potential of 40 bushels per acre, plants a susceptible variety on SCN infested ground, he can lose 30-50% of the yield to SCN. If you figure a 30% loss which is 12 bu/A over the 40 acres that is 480 bushels lost at $6.50/bushel. This results in a loss of $3,120 as a result of not taking a $5.00 Nematode Assay Test. Can you afford not to test? PP-2 Management of Soybean Cyst Nematode is available from the county Extension offices. This fact sheet outlines the SCN situation in Delaware, and makes management suggestions for growers. If you do not have a copy yet, please stop by a county office or request one. v

 

Using Stand Counts and Tissue Nitrogen Concentration for Managing Fertilizer on Wheat

Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu

Currently, research is underway at the University of Delaware to evaluate various methods for managing your nitrogen (N) fertilizer program. A number of the methods being evaluated come from work at Virginia Polytechnic Institute and State University for high management wheat. These are the use of stand and tiller counts in the fall and spring and tissue N tests. Other methods under evaluation are the soil nitrate test and the SPAD or chlorophyll meter reading.

I think you will find the stand/tiller counts and tissue test useful in estimating how to split your N rates. With the weather pattern in place this year, split N applications, especially on small or late planted wheat, will be needed for best yields. Split N applications under good growing conditions, show a 3 to 5 bu/A yield increase but this advantage will increase if the wheat is not well tillered.

Since many of you will not have fall stand counts for comparison, let’s concentrate on growth stage 3 (GS3--tillering) at spring greenup time. If the stand count is 30 or more plants per square foot (15 per foot of row on 6 inch rows or 18 to 19 per foot of row on 7 or 7.5 inch rows) or 70 or more tillers (a tiller has 3 leaves emerged) per square foot, the stand is adequate for optimum yield. If stand tiller counts are more than 100 per square foot, no N is needed until GS 5 (leaf sheaths erect). For stands this good, use your regular fertilizer program but split the N with 1/3 to 1/2 of the total N at greenup and the remainder at GS5. Early season N tends to stimulate more vegetative growth, taller plants, and more potential for lodging. GS5 N improves yield and protein content of the grain. After the first N application observe the crop for possible manganese deficiency problems about a week to 10 days after active growth occurs.

If the stand count is less than 25 per square foot and tiller counts are 50 to 70 tillers per square foot, early N at greenup will help stimulate further tillering and maintain current tillers. Apply as a split application but with 40 to 50 percent of the total N early and the remainder at GS5.

When stand counts are 16 to 24 plants per square foot and tiller counts are low, yield potential is less than optimum. Do not over fertilize with N but do split N applications with at least 50 percent early to stimulate tillering. If the stand count is below 15 plants per square foot, Kentucky data indicate yield potential is 70 percent or less.

For no-till wheat, data from several sources indicate that an extra 20 lb N/A (applied at greenup in mid- to late-Feb.) will be needed. Apply a larger proportion of total N at greenup if splitting N applications. Why? Conditions in early spring are more unfavorable for growth with no-till compared to reduced or conventional till wheat. The extra N improves the plant’s growth and vigor.

Finally, just a few comments on tissue testing for N concentration in wheat. The test is offered by a number of commercial labs. Check with the labs to get details on how to do the tissue test and how to get the fastest turn around time. The Va. Tech method involves taking the tissue sample at GS5 and then comparing the tissue N concentration with a graph. Essentially, the graph is straight line so I will summarize it here.

N Content

Apply lbs of N/A

2%

120 lbs. ( split in proportions mentioned above)

2.5%

100 lbs.

3.0%

80 lbs.

3.5%

60 lbs.

4.0%

40 lbs.

4.5%

20 lbs.

4.85%

No Response

As more data becomes available, this will provide you with a good guide for managing N plus provide you with documentation for the crop’s need for N. v

 

Hybrid Wheat Has Returned - Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu ;

Bob Uniatowski, Extension Associate ; bobuni@udel.edu

Hybrid wheats appeared on Delmarva several years ago but did not persist in part due to the expensive process of breeding the hybrids. Then in 1997, Monsanto gained registration for Genesis, a chemical hybridizing agent. With registration of this compound, hybrid wheat became commercially viable. The company set to market hybrid wheat is HybriTech and the brand name of the hybrid wheats will be Quantum®. Currently, we have four of these new hybrid wheats in the 1998 Small Grain Variety Performance Trials.

Hybrid wheat now may be at the point that hybrid corn was in the 1930's. In the U.S. this year there will be 16 commercial hybrid wheat varieties available. Across the country in company and university test trials, the hybrid wheats have had a 10 to 15 percent yield advantage (especially under stress conditions or less than ideal growing conditions) and better consistency (better yield stability across locations, environments, years).

What does this mean economically? The yield increases seen to date translate to a $20 to $50 incremental income opportunity. The return on investment (the seed is more expensive and can not be saved for seed use in future years as many growers do) is $2.72 to $2.80 over a 3-year period. This averaged an extra $20.23/A return.

The hybrids will be a platform for many new biotechnology characteristics.

Future Biotechnology Characteristics:

Anti-fungal genes (possibly some scab resistance)

Protection against viruses (WSMV)

Yield enhancement genes

Roundup Ready® gene

(about 2005, but likely first in Canada)

Hybridization solutions

Moisture tolerance

Nitrogen utilization efficiency

Winter hardiness

Saline tolerance

According to what we have read about the new hybrid wheats, the most important point with these hybrids at least at first will be their yield stability. Higher yields over the best current varieties occur in less than ideal growing conditions. When growing conditions are favorable, hybrid wheat may not yield any more than the best current varieties. This will change with time as the potential for yield increases with hybrid vigor is quite substantial. We will be closely monitoring the performance of the hybrid wheats under Delaware conditions and keep you informed on how well they live up to expectations. v

1998 Pest Management Recommendations for Field Crops and the 1998 Commercial Vegetable Recommendations Guide Available at Local Extension Offices

You may obtain copies of the Pest Management Recommendations for Field Crops and the Commercial Vegetable Recommendation Guide from your local county extension office or by mail from the Research & Education Center in Georgetown. The cost of the Pest Management Recommendations for Field Crops is $8.00. The cost for the Commercial Vegetable Recommendation Guide is $7.00. Please use the enclosed form and make checks payable to "University of Delaware" and allow one week for the delivery of the books. v

Weekly Crop Update Begins Weekly on April 3, 1998 - Tracy Wootten, Extension Associate - Vegetable Crops

The Weekly Crop Update will begin its weekly issues on April 3, 1998. This newsletter is designed to provide subscribers with the latest information on disease and insect problems as they are developing, weed control information, crop progress reports, and other timely topics related to agronomic and vegetable crop production in Delaware. This current issue is the only issue for the month of March. The weekly issues will begin in April and continue through September. The Weekly Crop Update can be obtained by mail, by fax or from the internet. If you would like to receive Update by mail or by fax, the cost of the subscription will remain at $30 (same as last year). Use the enclosed form to subscribe. If you can access the internet, there is no charge for the newsletter. Weekly Crop Update is mailed each Friday. The newsletter is placed on the internet by 4:30 p.m. on Fridays. If you choose to receive the newsletter by fax, it will be sent to subscribers on Friday evening. I would like to ask those of you who plan to access the newsletter from the internet to let me know of any problems that you may experience throughout the season. Please forward any comments or concerns to me at 302-856-7303 or at wootten@udel.edu v

Thank You To Those Who Responded To The Survey Last Fall

The responses were excellent and very informative. The information that you provided has helped us to convey the impact of this newsletter to others. Again, thanks for taking the time to complete the information. It has been most helpful. v

New Internet Address for the Research & Education Center Webpage

The new web address for the University of Delaware Research & Education Center is http://www.rec.udel.edu . Please make a note of the change. You can’t access the Weekly Crop Update and hourly weather information with the old address. v

 

Week of March 6 to March 12

Rainfall:
0.30 inches: March 8
1.03 inches: March 9
0.02 inches: March 10
Readings taken for the previous 24 hours at 8 a.m.
Air Temperature:
Highs Ranged from 68 °F on March 10 to 34 ° F on March 12.
Lows Ranged from 44 °F on March 8, 9 & 10 to 21 °F on March 12.
Soil Temperature:
42 °F average for the week.
(Soil temperature taken at a 2 inch depth)

I would like to subscribe to the WEEKLY CROP UPDATE NEWSLETTER for 1998

Please send $30 and this form to:

Tracy Wootten

University of Delaware Research & Education Center

16483 County Seat Highway,

Georgetown, Delaware 19947

Please make checks payable to "University of Delaware"

Check#  
Name:  
Address:  
 
Telephone:  
Fax:  
E-Mail:  

Do you want to receive the "Weekly Crop Update" via FAX o YES o NO _______________________________________________________________________________________________

Please send me __ copy (ies) of the 1998 Commercial Vegetable Recommendations Guide. They are $7.00/book.

Check#  
Name:  
Address:  
 

Please make checks payable to "University of Delaware" .

Please send check and this form to:

Tracy Wootten

University of Delaware Research & Education Center

16483 County Seat Highway,

Georgetown, Delaware 19947

_______________________________________________________________________________________________

Please send me __ copy (ies) of the 1998 Pest Management Recommendations For Field Crops.

They are $8.00/book.

Check#  
Name:  
Address:  
 

Please make checks payable to "University of Delaware" .

Please send check and this form to:

Tracy Wootten

University of Delaware Research & Education Center

16483 County Seat Highway,

Georgetown, Delaware 19947

_______________________________________________________________________________________________

Compiled & Edited By:

Tracy Wootten

Extension Associate - Vegetable Crops


Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State College and the United States Department of Agriculture cooperating, John C. Nye, Dean and 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, color, sex, disability, age or national origin


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