WTSB AG News

Updated: May 9, 2008

CEREAL LEAF BEETLES INVADING SMALL GRAINS

The Cereal Leaf Beetle has returned to Johnston County small grains
fields. Cereal Leaf Beetle adults have been detected in wheat fields all across the county. Growers need to begin scouting fields 2 times per week for these damaging insects. Damage to wheat, oats, and barley is caused by the larvae feeding on leaves during April and May. Although adults will feed on young small grains plants, their feeding does not affect the plant's performance at that stage of growth. However, cereal leaf beetle larvae can reach very high numbers in small grains and larger larvae can defoliate entire plants. The larvae  eat long strips of green tissue from between leaf veins and may skeletonize entire leaves, leaving only the transparent lower leaf surface tissue. Severely defoliated fields can take on a white "frosted" cast when lots of green tissue is lost on the upper leaves. Often cereal leaf beetle populations will be somewhat localized and damage will be confined to spots or sections of fields or farms.

Damage can build‑up in as little as five days after larvae become large and warm temperatures make the insects very active. Leaf feeding reduces the plant's ability to make it's food and limits reproductive growth, particularly if the upper leaves are destroyed. Yield reduction to 45 percent has been observed when defoliation was near 100 percent and the damage occurred very early in the heading period. Damage later in the head‑fill period does not have a great impact. Yield reductions of 10 to 20 percent are typical in infested fields. Recent research has indicated that the three stem leaves (flag leaf and two leaves below) all contribute to filling grain heads and achieving favorable grain test weight. This research suggests that the flag leaf is about as important as the two stem leaves. Damaged leaves will not be replaced by the plant.  Late‑planted fields are more attractive to cereal leaf beetles
for egg laying in the spring.  Additionally, thick planted well tillered
wheat fields are less subject to develop high cereal leaf beetle
populations. In general, following sound agronomic practices for high
yield small grain production reduces the impact of cereal leaf beetle.

Scouting should begin immediately while both eggs and mostly small
larvae are in the field.  Be sure to count both forms. If the population is mainly made‑up of eggs, then scouting should be at a later date, when a minimum of 50 percent is in the larval stage. Thresholds for Egg/larval counts are 25 eggs and/or larva total per 100 tillers. This is an average of one per each four tillers.


SOYBEAN PLANTING

It is time to begin planting soybeans. Recommended row widths for May planting is 21 inches or more.  Row widths should be narrower for later planted beans to obtain optimum yields. Seeds should be planted based on number of seeds per foot of row rather than pounds per acre. Set planters and drills on 50 pounds per acre as a starting point to determine how many seeds per foot it is planting. Recommended planting rates are 2 to 3 seeds per foot in 7 to 8 inch rows (180,000 seeds per acre), 3 to 4 seeds per foot in 14 to 15 inch rows 175, 000 seeds per acre), 6 to 7 seeds per foot in 30 inch rows (135,000 seeds per acre), and 9 to 10 seeds per foot in 36 inch rows (125,000 seeds per acre). Early maturing varieties should be planted the next 3 weeks.

Two sources of variety information is available from the Cooperative
Extension Service office in Smithfield.  The Official Variety Test Book
(green book) gives yield performance from across the state. North
Carolina Soybean Variety Information is a publication prepared by NCSU Soybean Extension Specialist, Dr. Jim Dunphy, gives detailed
descriptions of every variety available in North Carolina, and predicted yield performance of conventional varieties and Round Up Ready varieties in separate comparisons on 20, 40 and 60 bushel per acre soil types. Seed supplies are predicted to remain short, so early purchasing is recommended. Call 919-989-5380 or come by the Extension Office in Smithfield for copies.

--
Eric V Spaulding, Agricultural Extension Agent
North Carolina State University
College of Agriculture and Environmental Sciences
North Carolina Cooperative Extension, Johnston County Center
2736 NC 210 Hwy., Smithfield, NC 27577
E-Mail  : eric_spaulding@ncsu.edu
Phone   : (919)989-5380

Updated: May 6, 2008

Fertilizer Additives and Increasing Fertilizer Efficiency
As fuel prices have increased, so have the cost of many fertilizer materials.  Commodity prices are also up dramatically from last year but many farmers wonder if the increase in commodity prices will offset the increased input costs.  Prices are changing and fluctuating daily, but on average fertilizer materials to supply nitrogen, phosphorus and potassium are costing farmers about twice as much as they cost at this time last year.

Because of the increased prices, there is increased interest in products that stabilize nitrogen fertilizers to reduce volatilization.   Still other products are available that contain various acids to increase nutrient availability, improve root growth or improve nutrient uptake.  No one knows how many of these products exist, but the numbers are substantial.  Farmers often question, “Will they work?”  This question cannot be answered in a general manner for all of these products or for all of the crops/situations where they may be used.

There are several questions that may help farmers and homeowners alike evaluate the efficacy of fertilizer additives or even pesticides and other crop protection agents.  The first question is, “Has this product actually been tested in the crop that I am considering using it on?”  If the answer is no, then you do not need to go any further.  Farmers and homeowners should never use products that have not been tested in actual field conditions to determine if they are effective.  If the product is proven effective on corn, then it should be used on corn and not on tobacco or other crops until tested.

If the product has been tested, the next series of questions should be, what methods were used for the testing?  Was the testing performed in multiple locations and years?  Was an independent research firm or university involved in the product testing?  Was the research data subjected to statistical analysis to prove that differences were a result of the treatments applied and not due random variation?  In general, products should be tested in multiple years, in multiple locations and some independent research group should be involved in the testing.  All of these factors add validity to product claims and give assurance that the investment will be worthwhile.

One simple product test for NC farmers is to see if the product is recommended in a NC Cooperative Extension publication.  For instance, tobacco farmers can turn to the Flue-Cured Tobacco Guide.  If a product is not mentioned or recommended in the Tobacco Guide, then that product has not been tested or it has not been proven effective on tobacco.  If a product provides an economic benefit, then it is an advantage to a company to have it tested and validated.  Other guides exist for many other crops like peanuts, cotton, lawns and many other plants.  Information like this can be requested from the Johnston County Extension Center at 919-989-5380.

Updated: April 18, 2008
Blue Mold Alert

Blue mold has been confirmed in the northern Florida tobacco-growing region.  In addition, Cuba had a significant problem with blue mold during their recent growing season.  It is highly likely that blue mold arrived in Florida from Cuba via transport events during the February 20-21 time frame.  Allowing for a 5-7 day latent period after infection, spores would have been available for transport from the last several days of February through the present time.  During this time, there have been a number of opportunities for airborne spores to move over the growing regions to the north.  The North American Plant Disease Forecast Center indicates that airborne spores could have moved across the Eastern portions of both North and South Carolina at least 5 times.  All of these occurred during the first 3 weeks of March.

Conditions for survivable transport are unknown for most of these cases. However, it is likely that live spores were carried over other growing regions during some of these events.  Therefore, it is strongly advised that all tobacco growers in Johnston County scout tobacco plants in greenhouses for signs of disease.  If blue mold is suspected, it should be reported immediately to Bryant Spivey, County Extension Director at the Johnston County Extension Center.

In addition to scouting, it is prudent for growers to begin treating tobacco plants with Dithane Rainshield or Manzate Pro-Stick.  The appropriate concentration for tobacco greenhouses is ½ pound of Dithane Rainshield or Manzate Pro-Stick per 100 gallons of water.  Growers should apply enough water to obtain complete coverage of foliage.  The label suggests 3 to 12 gallons of water per 1,000 square feet.  Large plants are now present in most houses and justify the higher rates of water.  This treatment should be repeated every 5 to 7 days until plants are transplanted.  These are protective treatments only and no effective remedial treatments are available.

Growers can follow the blue mold forecast at the North American Plant Disease Forecast Center.

Updated: April 15, 2008
TOBACCO REPORT
Tobacco Greenhouse Notes

Temperature: With warm weather, plants are growing rapidly.   Once plants have been clipped, minimum temperature settings should be lowered to 55 degrees Fahrenheit.  Lowering temperatures will slow growth, save fuel and reduce the potential for disease development.

Ventilation: Provide as much ventilation as possible from now until the time the plants are moved to the field.  This will reduce humidity and the potential for disease development and it will result in better quality transplants.

Disease: Pythium root rot has been found in a few greenhouses over the past couple of weeks.  Terramaster is labeled to control pythium and is quite effective as a curative treatment.  Pythium is characterized by soft, mushy, brown roots and wilted foliage.  Lower leaves will be yellow while the bud leaves remain green.

Clipping:  Keep the mower blade height at 1.0 to 1.5 inches above the bud.  Clipping plants closer than this will result
in short stems at transplanting.  Dispose of all clippings at least 100 yards away from the greenhouse.  Sanitizing the mower with a 10% bleach solution will help prevent disease spread.

Tobacco Fertilization

Even though the tobacco crop is still in the greenhouse, many farmers are already making decisions about fertilizer programs for this year.  Since fertilizer prices have increased dramatically in the past 12 months, the decision about which fertilizer materials to use is more important than ever.  In spite of the recent price increases, it is still possible to provide the necessary nutrients for a tobacco crop for less than $200 per acre.  This cost can be reduced substantially below $200 in some fields.

Growers should always remember that there is no “magic” with fertilizer or various fertilizer analyses.  A good fertilization program will simply provide the correct amount of nutrients from appropriate sources at the proper time in the proper place at the least cost possible.

Step 1: Begin with the proper soil pH.
This step should be complete in most tobacco fields.  Lime should always be applied in accordance with soil test recommendations.  If the soil pH is too low, many essential plant nutrients will not be available at optimum levels.  Proper soil pH is critical for efficient nutrient uptake.  The proper soil pH for tobacco is 5.8 to 6.0.  High pH (greater than 6.0) can also be detrimental and may result in increased disease pressure.

Step 2: Determine phosphorus needs.
Most Johnston County tobacco soils are high to very high in plant available phosphorus.  In 2007, NCDA analyzed 684 soil samples for tobacco from Johnston County.  Of these samples, 65% had very high phosphorus levels (P-I > 100) while 28% of soils had high phosphorus levels (P-I of 51 to 100).   Simply put, additional phosphorus fertilizer will not improve yield or quality on at least 65% of our soils in Johnston County.  This fact has been proven again by recent NCSU research.

Phosphorus fertilizers often improve early season growth and decrease days to flower.  This is often true even in soils with high to very high phosphorus levels.  However, research has shown similar responses in growth and flowering with 40 pounds of P2O5 per acre in a band, 20 pounds per acre in a band or with only 5 pounds of P2O5 per acre applied in the transplant water.

If your soil samples indicate that phosphorus fertilizer is needed then you should follow the recommendations.  Otherwise, 5 pounds of P2O5 in the transplant water is an economical and effective method to stimulate early growth.

Step 3: Select the appropriate base fertilizer.
I know that many people still have fond memories of 3-9-9.  If this is the case, departing from 6-6-18 or 8-8-24 may be quite painful for you.   A farmer once told me,  “3-9-9 fertilizer produced the tobacco that paid for this farm.”  However, with current fertilizer costs, blends like 6-6-18 and 8-8-24 may not be economically feasible. 

Fertilizer blends produced from potassium-magnesium sulfate (0-0-22) and potassium sulfate (0-0-50), are the most economical way to meet potassium needs.  A combination of these products will supply potassium, magnesium and plenty of sulfur to meet crop needs.  Research has again shown this strategy to be effective and some farms have used these fertilizer blends exclusively and effectively for 3 years.  If phosphorus is needed, it could be added to the blend, to the liquid nitrogen source or to the transplant water.  

Some are applying blends of these materials broadcast.  While this has proven effective for some, it does not provide the best placement or allow the best timing of application. 

Step 4: Select the appropriate sidedress fertilizer/nitrogen source.
NCSU research has shown that UAN solutions like 24% and 30% can be used effectively to provide either the sidedress nitrogen for tobacco or to supply all of the nitrogen needs.  If you use a blend of potassium sulfate and potassium-magnesium sulfate, you can use a UAN solution to supply all of the nitrogen needs of the crop.  UAN solutions are the cheapest source of fertilizer nitrogen and have produced similar yield and quality of flue-cured tobacco to traditional sources.  I

Liquid Nitrogen Fertilizers

I have answered several questions about using liquid nitrogen on tobacco during the past few weeks.  The answers to some of these questions may help you make plans for this year.
Question: Should I apply the liquid nitrogen in 2 bands or in one band?
A: NCSU research has shown that liquid nitrogen can be applied to tobacco using two bands 5 to 6 inches deep, one band 5 to 6 inches deep and in one or two bands surface applied and incorporated with a cultivator.  All application methods provided similar results.

Question: How far should I apply the liquid nitrogen from the plant?
A: Whether applied in two bands or one band the liquid nitrogen should be about 6 inches to the side of plant.

Question: What is the proper timing of application for liquid nitrogen sources?
A: If you are using liquid nitrogen to supply all of you nitrogen, it should definitely be split applied as with all other nitrogen sources.  The first application should occur at or within 10 days of transplanting.  The remaining nitrogen should be applied at normal sidedress time.

Question: Is nitrogen from 24% or 30% more likely to leach than nitrogen from traditional sources like Calcium Nitrate?
A: The short answer is no.  With liquid nitrogen a good portion of the nitrogen will be in the ammonium form.  Ammonium is less likely to leach than nitrate nitrogen.  However, the conversion from ammonium to nitrate occurs rapidly.  You should expect roughly the same leaching potential.

Caution: Liquid nitrogen sources like 24%, 30% and 32% are extremely harmful to tobacco in transplant water.  Never allow liquid nitrogen to be added to your transplant water or transplant water nurse tanks.  Nurse tanks for transplant water must be clean!  If liquid nitrogen has been in the tank it must be cleaned thoroughly with water.

 

Black Shank Management

If ph gene varieties have been failing in your fields due to black shank, then you have race 1 black shank.  Varieties known to have ph gene resistance include: NC 71, NC 72, NC 196, NC 291, NC 297, NC 299 Sp 225, Sp 227, Sp 168, Sp 220, Sp 234, GL 350, CC 37, CC 27, RGH 51 and others.  These varieties are immune to race 0 but they have varied and somewhat unknown levels of resistance to race 1.

Crop rotation and partial resistance in varieties are still effective management tools.  However, variety decisions are basically final at this time.  Chemicals such as Ridomil Gold and Ultra Flourish continue to be effective management tools.   Research has shown that fumigation followed by 1 pint of Ridomil Gold or 2 pints of Ultra Flourish at first cultivation can provide good black shank control.  Additional applications can further improve protection from this disease.  Always read and follow the label directions.

Disclaimer: The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina State University nor discrimination against similar products or services not mentioned.