Agronomy Notes

August, 2004

Rice specialist named
for the state of Mississippi...

MISSISSIPPI STATE -- A new specialist assumed the responsibility of supporting the rice industry in the state when Mississippi State University's Extension Service appointed Nathan Buehring to the job.

Buehring assumed his duties July 16 and will work from the Delta Research and Extension Center in Stoneville. Before being named rice specialist, Buehring established a background in weed control and pest management in various agronomic crops.

"Nathan will work to transfer technology to the rice producers in the Delta from MSU researchers and researchers from surrounding states," said Jim Smith, interim head of the Delta Research and Extension Center. "He has real good credentials and has been well trained. He'll be a great addition to our rice research and Extension team."

Buehring will receive his doctorate in weed science from MSU in August, having earned a master's degree in the same from the University of Arkansas in 2001. He received his bachelor's degree in agricultural pest management from MSU in 1998. He is from Tupelo.

Buehring was an Extension Associate with the Arkansas Cooperative Extension Service for two years working with rice weed control. He returned to MSU as a graduate research assistant for three years before being named rice specialist.

Buehring replaces Joe Street, who was recently named head of the North Mississippi Research and Extension Center in Verona. Although he was the Extension rice specialist, Street's time was divided by research duties.

"Mississippi State administration felt that rice was important enough to the economy of the state of Mississippi to make this person a full-time rice specialist," Smith said of Buehring's appointment.

Soil and Nutrient Management

By Larry Oldham

As growers go into the fall soil amendment season they should look at soil test recommendations for lime requirements. Liming is a major investment for producers, but soil acidity control is the most important management factor for getting the most benefit from the entire nutrient management program.

Someone recently said that the best thing that could happen for Mississippi crop production would be to start at Highway 90 on the coast, and spread 1 or 1.5 tons of lime on every acre in agronomic production between it and the Tennessee border. Tempting as that may be, it is more efficient to target applications through the use of soil testing and following the recommendations.

Liming materials are expensive in Mississippi because, with the exception of what were once the state-owned marl facilities, we have to transport it in from other states. The state's calcitic and dolomitic limes are produced in Alabama, Kentucky, Missouri, and a few other states.

By law, all brands and grades of lime must be registered with the state agriculture department and the State Chemist before they can be sold in Mississippi. A few years ago, regulations written under the law were changed to define two grades of calcitic and dolomitic liming materials that could be registered (see Table 1).

Table 1: Standards for Mississippi-graded agricultural liming materials

Grade A %

Grade B %

Calcium Carbonate Equivalent (CCE)

90

80

Passing a 10-mesh sieve

90

80

Passing a 60-mesh sieve

50

30

This has resulted in some different materials becoming available in the state over the past few years. Some reports indicate that Grade A lime can be difficult to locate. However, the MSU Extension Service has always recommended that growers use the best quality lime available. Information and techniques on comparing the relative values of different lime materials is available at local Extension offices, and on MSUcares at http://msucares.com/pubs/infosheets/is1587.htm.

Water is required for lime to react with soil, therefore fall application is preferred. Finer lime particles (Grade A) will react more quickly than coarser particles, thus providing faster neutralization of soil acidity. It is poor business to spread large particles, hoping they will react some day.

How much lime to apply at one time? In a number of situations, particularly in the Delta, producers have faced enormous lime bills. This writer's preference is to not see more than 2 or 2.5 tons per acre applied per year; if a tillage operation is planned, 4 tons can be applied. However, research and commercial applications on farms have shown variable rate application of lime based on intensive soil sampling and mapping may be the best practical application of precision agriculture technology.

In summary, if your soil test recommendations call for lime this fall:

  • 1. use the best quality liming material available
  • 2. get it applied ASAP
  • 3. explore money saving application alternatives for large recommendations.

Soil Testing

By Keith Crouse

As harvest begins, growers need to start thinking about soil sampling. MSU-ES Soil Testing Laboratory analyzed many fertility related problem soil samples this past fiscal year. These problems could have been avoided by sampling the field prior to planting. A low soil pH is still a major fertility problem. For most crops, lime should be incorporated into the top 5 to 6 inches of the soil, preferably at least 3 months in advance of planting. MSU-ES Soil Testing Laboratory's lime recommendations assume that limestone being used has a calcium carbonate equivalent (CCE) of 100 %. Remember that Mississippi has two limestone grades, A and B, which also determine the amount of lime needed.

Remember to always take the soil sample from a given area and the size is usually about 10 acres or less. Take enough separate cores within the soil area for a representative soil sample. Generally, this is about 15 to 20 cores. Take the soil cores from the surface to plow layer. Mix them thoroughly. Send a full soil box or a pint of soil, completed form(s) and payment of $ 6.00 per sample. All results completed during this will be on the web after 6:00 p.m. The address for clientele is http://www.ext.msstate.edu/special/soiltest.cgi. However, your local Extension office can access recent test results for all customers in your county through Extension Intranet.

Weed Control in Mississippi…

By John Byrd

DuPont has reduced the price of Velpar DF for smutgrass control in bermudagrass and bahiagrass pastures. Research was done in the late 1980's that demonstrated Velpar L was effective for smutgrass control, but the price of the treatment made it almost prohibitive for all but the most severe infestations. The price of the DF formulation has been reduced by approximately one-third, making it a more economically feasible smutgrass treatment.

DuPont has asked for evaluations of combinations of Velpar DF and several other herbicide that will help expand the spectrum of weeds controlled. One limitation of Velpar DF and Velpar L is the grazing and haying restriction of 60 days after treatment. A petition has been submitted to EPA through the Bureau of Plant Industry to reduce the grazing and haying restriction to 0 days after treatment by reducing the treatment size to 0.1 acre. Care should also be taken to avoid applications within the dripline of desirable trees in the pasture with Velpar.

A section 18 request has been submitted to EPA to use Maverick (also sold in the right of way market as Outrider) to control johnsongrass, annual and perennial sedges in bermudagrass and bahiagrass pastures and hayfields. Texas, Louisiana, Arkansas, and Georgia also were supposed to submit petitions. A decision has not yet been made by the agency whether or not to grant the request.

Dow has received registration for two additional herbicides: PastureGard and Surmount. PastureGard received registration earlier this season, but Surmount was registered just a few weeks ago. PastureGard is a premix of 1.5 lb. acid equivalent of triclopyr and 0.5 lb. acid equivalent of fluroxypyr per gallon. The spectrum of weeds controlled will be similar to that of Remedy. PastureGard application rate ranges from 3 to 8 pints per acre per season, or 1 to 2% solution for spot applications, with 0.25% nonionic surfactant. Most annual broadleaf weeds can be controlled with 1.5 to 2 pints per acre, while most perennial broadleafs will need 2 to 3 pints per acre for adequate control. PastureGard offers the same application flexibility as Remedy, with broadcast foliar, high volume foliar, individual stem basal or streamline, or cut stump treatments. Applications should not exceed 8 pints per acre per season. Lactating dairy animals should not be grazed or fed green forage the same season of treatment. Other livestock have no grazing or green forage feeding restriction, although they should be removed from treated fields and taken off treated hay 3 days before slaughter. Hay can be harvested 14 days after treatment.

Surmount is a premix of 0.67 lb. acid equivalent of picloram and 0.67 lb. acid equivalent of fluroxypyr. The rate range for Surmount is 3 to 6 pints per acre per season or 1 to 2% solution with 0.25 to 0.5% nonionic surfactant. Small brush can be controlled with 3 to 4 pints per acre, while larger brush will require 4 to 6 pints per acre. Surmount can be applied as a broadcast foliar or high volume foliar treatment. Lactating dairy animals should not be grazed in treated fields or hay harvested within 14 days after application. There is no grazing restriction for other livestock, including nonlactating dairy animals. Hay should not be harvested within 7 days after treatment. Slaughter animals should be removed from treated fields and taken off treated hay 3 days before butchering. Picloram can pass through livestock digestive tracts, so manure from animals grazing treated fields or consuming treated hay can damage sensitive plants, such as clovers in nontreated fields or vegetables and ornamentals to which the manure is added as fertilizer. Like Grazon P+D, Surmount is a Restricted-Use pesticide. However, this product does not contain 2,4-D, so may not posses the potential for off target drift due to volatility associated with other forage herbicides.

CCA Update

CCA Notes: About 60 Certified Crop Advisers and MSU Extension Service staff participated in training on Delta soil and water issues at the Delta Conservation Demonstration Center on July 15. This opportunity at the unique DCDC provided 5 Soil and Water CEU's. Current plans are to make this a regular summer event and the Mississippi Certified Crop Adviser program thanks the DCDC for their cooperation in planning and implementing this opportunity.

The Mississippi/Arkansas regional CCA exam is only offered in February of each year. A few local boards, chiefly in places with very long growing seasons such as Florida, still offer the exam twice each year. The next date for our exam is February 4, 2005. Registration is open October 6 - December 17, 2004. Any registration received after December 17, 2004 will not be processed.

The simplest way to request registration materials is through the Internet at:
http://www.agronomy.org/cca exam_registration.html.

Forage

By Richard Watson

Using Stockpiled Bermudagrass To Carry You Through the Early Winter

Why Stockpile Forage?: It is an unavoidable fact of all forage production systems that we will experience seasonal differences in forage growth. During the year we will have times of forage surplus (when forage growth is greater than animal needs) and times of deficit (when forage growth is not enough to meet animal needs). The foundation of successfully raising livestock on forages is being able to effectively use the surplus forage growth to fill in the times of deficit. The most common way of doing this in Mississippi is to make the surplus forage into hay during the spring and summer, and feed it back during the times of forage shortage, which are typically the winter months. While hay making will always remain an effective and important part of the beef cattle industry, it also represents one of the most significant production costs. In addition, as we have seen the last two years, hay making is always at the mercy of the weather and there is always the risk that we could lose a lot of our forage production as spoiled hay. One of the keys to reducing the costs and risks in the Mississippi beef cattle industry is to reduce our reliance on hay as a feed source. Therefore, finding an alternative to harvesting this surplus could solve many of these problems.

The practice of "stockpiling" forage is one alternative way that excess forage growth can be 'saved' for later use. The practice of stockpiling essentially takes surplus growth that is not currently needed by cattle and accumulates this in a chosen area for grazing when forage growth is not enough to meet animal demand (i.e. the winter months). While we usually should try to avoid accumulating excess forage growth over 8"-10" in height, due to the associated loss in forage quality, stockpiling is certainly preferable to making and feeding large quantities of hay. The major advantage of stockpiling forage is an economic one, with a significant reduction in costs associated with the production, storage, and feeding of hay.

While most forage types can be stockpiled, some are better than others. Grasses are far more suited to stockpiling than legumes as they generally have greater fiber content. The fiber helps the forage maintain its structure during the winter, whereas the less fibrous clovers tend to breakdown and rot when stockpiled, particularly where there is a lot of freezing and thawing action. Stockpiling of forage is most commonly associated with tall fescue, however, bermudagrass can also be effectively stockpiled for winter feeding.

Stockpiling Bermudagrass: Stockpiling bermudagrass usually involves accumulating extra growth in August, September, and early October for grazing during the late fall and winter. This can be an effective way to bridge the gap between the end of warm-season growth and the time when you will, hopefully, have enough cool-season forage to graze. The amount of stockpiled bermudagrass you need to achieve this will depend on the length of the 'gap' in forage growth. In South Mississippi, due to the use of annual ryegrass as the major source of cool-season forage, bermudagrass might have to be grazed longer into the winter. This will give the annual ryegrass time to get established and grow enough forage for grazing. However, the growth season of bermudagrass is also longer in South Mississippi, so the overall time spent grazing the stockpiled bermudagrass may be as short as 2 months. In North Mississippi, cool-season grasses such as tall fescue can generally be utilized much earlier in the fall, so there is often less need for stockpiled bermudagrass. In fact, in North Mississippi, tall fescue offers a better option for stockpiling forage for the winter than bermudagrass does.

Some preparation is required for areas on which you intend to stockpile bermudagrass. Quality of the stockpiled forage will be much better if you have removed the old growth beforehand and fertilize to promote fresh growth. Pastures that have just had hay made in mid to late August are ideal for stockpiling. Applying 50-100 lb. N/acre in late August will promote fresh forage growth through September and October. Depending on climatic conditions, this should be between 2000 and 3000 lb. of stockpiled forage dry matter per acre by November.

Nutrient levels in the bermudagrass will vary depending on the amount of growth accumulated, fertility, and the weather during and after stockpiling. Bermudagrass will not typically hold its quality during the winter as well as tall fescue will, since the plant tissue will be dead and more prone to weathering. It is always a good idea to forage test your stockpiled grass to determine whether additional supplementation is required. The need for supplementation may become more likely the further you graze into winter. Stockpiled bermudagrass will generally be above 10% crude protein and between 47-55% TDN during November and December, which is more than adequate to graze gestating beef cattle.

With forage utilization of 70-80%, an acre with 3000 lb. of stockpiled bermudagrass could hold 25 gestating cows for a week. This would mean that you would need about 15-20 acres to graze these 25 cows from the 1st of November through the end of January with minimal hay required (0.6-0.8 acres/cow). To ensure good forage utilization, it is important to reduce the potential for wastage by not giving the animals any more than 2 weeks worth of grazing at a time. Using the 25-cow example above, you would not allow the cattle to graze an area greater than 2 acres at a time (12.5 cows/acre). Strip grazing behind a temporary electric fence is the best way to ensure good forage utilization.

Fall Grazing School: This fall the Mississippi State Extension Service will be running a two day grazing school at the Prairie Research Unit on 21st-22nd October. This school will cover practical solutions to winter forage and grazing management in North Mississippi, including the use of stockpiled forage to reduce stored feed requirements. This school represents the start of annual Spring and Fall grazing schools that will be held throughout North and South Mississippi. Each grazing school will be designed to deal with the specific forage management issues in each region. Registration for the fall grazing school will be advertised soon.

Rice

By Nathan Buehring

Crop Situation: The rice crop looks good so far within the state. Some producers south of Highway 82 are beginning to drain some fields and will be ready to harvest in a couple of weeks. In the upcoming weeks, more fields will be drained in preparation of harvest. As a whole, producers have done a good job with their weed control programs this year, especially with the poor weather conditions that faced producers in June. Even though rice prices have dropped, now is not the time to cut production cost.

Drift: Since Select was used on a large amount of acreage this year in soybeans and cotton, a few Select drift complaints have surfaced. Select drift on rice at midseason results in a dead terminal leaf that can easily be pulled out of the plant. Select injury to rice can be comparable to injury that is seen with Clincher or RiceStar on barnyardgrass, since these herbicides are very similar in chemistry. So far, glyphosate drift has not been widespread this year. Hopefully, the upcoming weeks will be problem free as well.

Stinkbugs: As this is written, stinkbug populations have been very light and for the most part have been below threshold. As the harvest season begins in corn and soybeans, expect stinkbug populations to rise as they move into rice. Apply an insecticide when a threshold of 3 stinkbugs per 10 sweeps is reached during the first two weeks of heading (75% panicle emergence) or 10 per 10 sweeps until two weeks before harvest. Products such as Karate, Mustang Max, and Prolex will be effective on stinkbugs. The rate will depend on stinkbug pressure and how much residual will be needed to protect the crop. Methyl parathion will also be effective; however, it does not have as much residual as the pyrethroids.

Sheath Blight: In early planted rice crops, most of the rice is beyond the stage for sheath blight treatment. In the later planted rice, if the field is fully headed and sheath blight is below the flag leaf, treatment will probably not be of significant benefit. Treat only after the threshold of greater than 35 percent positive stops is reached and the sheath blight is moving up the plant on susceptible varieties such as Cocodrie or CL 161. With Wells, Francis, and Priscilla, a fungicide will generally not return the investment.

Smut Control: Cocodrie, Priscilla and CL 161 are varieties that are susceptible to kernel smut. Smut has not been a big problem in recent years; however, a preventative fungicide application should be considered. If the weather pattern continues to be hot and dry, this should reduce any occurrence of kernel smut. Weather conditions during flowering that favor kernel smut are high humidity, light showers, and cooler temperatures of 77 to 86 degrees. Kernel smut is more severe under high fertility conditions and rank growth.

Blast: A light amount of leaf blast has been confirmed at a few locations on Wells and Francis. Careful scouting should continue on these varieties. Cocodrie is rated susceptible to blast but no problems have been observed in the field. Once again, if the weather pattern continues to be hot and dry, this should reduce any occurrence of blast. Weather will play a very important role in the severity of blast. Optimum conditions for blast development are average daily temperatures of 73 to 86 degrees, prolonged leaf wetness and high humidity. Blast fungicides must be applied as a preventative treatment to protect the heads. Scout carefully for blast, and if symptoms occur, treat before the heads are fully emerged.

Harvesting: Harvest season will be earlier this year due to early crops of rice, soybeans, and corn. Rice needs to be harvested in between 18 to 23% grain moisture and dried slowly for the best milling yield. For Priscilla, this is very important. If at all possible, harvest Priscilla before it goes below 16 percent grain moisture. Cocodrie has a wider window for harvesting without reducing milling yield.

Corn

By Dr. Erick Larson

Blight may necessitate prompt harvest: Northern and Southern corn leaf blight has infected numerous fields across the state and is causing severely infected fields to die prematurely. The return of hot, dry weather during July has promoted premature leaf senescence as well. This limits and/or ceases leaf photosynthesis, causing plants to mobilize energy from the stalk to finish filling kernels as well as possible. This redirection of energy reserves may weaken stalk strength and promote lodging, particularly if the corn crop is not harvested promptly. Thus, growers should harvest fields severely infected with leaf blight as soon as possible.

Grain moisture dockage: Corn may be harvested any time after grain reaches physiological maturity, which occurs at around 30% moisture. However, corn may not be safely stored until considerable moisture loss occurs. Thus, grain elevators discount wet corn to account for drying expenses and moisture weight loss during drying. Moisture dockage schedules between elevators may vary significantly, so thoroughly compare rates. Most schedules discount about 2.5% per each percent moisture above the standard, and may increase as moisture content rises. Water evaporated during drying (shrinkage) accounts for 1.18% of the dockage per each percent moisture. The producer loses this weight regardless of whether they sell wet grain to the elevator, dry it mechanically or let the grain field dry. Thus, a producer should subtract this value from the dockage rate to show their realized or "actual" dockage.

Harvest losses: Harvest losses are just as important as moisture dockage rate in evaluating your harvest timing decision. The longer corn stays in the field, the greater the likelihood of substantial field losses. Factors such as stormy weather and southwestern corn borer damage can cause considerable lodging in unharvested fields. Abundant summer rainfall has also promoted morningglory growth in some corn fields, which can greatly inhibit harvest efficiency. Each of these factors may cause substantial field loss, which would considerably outweigh moisture savings. Producers should also consider their harvest capability -- the longer it takes to complete harvest, the earlier you should start harvest. Growers should harvest non-Bt hybrids infested with corn borers, early maturing hybrids, and those possessing below average stalk quality promptly and before other hybrids. Producers should closely check for loss while the combine is harvesting and make adjustments accordingly. Two corn kernels per square foot or one dropped ear per 100 feet of row equals about 1 bushel per acre yield loss. Research generally indicates combine efficiency is best (harvest losses are lowest) when corn grain moisture is about 20-22%. Thus, growers seeking maximum profitability should always strive to finish harvest before grain moisture falls below 15%.

Don't Give Away Corn: Producers selling corn at less than 15% moisture are giving away profit. A producer harvesting 150 Bu./A. corn at 14% moisture is losing $3.54 per acre or $7.08 per acre at 13% moisture (at $2.00/Bu.). This loss is solely from reduced grain weight due to lower moisture content. This moisture weight loss closely approximates the "actual" dockage most elevators charge for high moisture corn. Since corn loses approximately 0.6% per day during the harvest season, begin harvest early enough to guarantee all corn is harvested before it reaches 15%.

Aflatoxin tips: Although the likelihood of aflatoxin is very remote this year, since it is usually associated with extreme drought and stress, improper grain handling can quickly promote aflatoxin development after harvest. High moisture grain should be immediately dried to below 15% moisture or hauled to an elevator (which will dry the grain). Wet grain should not be stored in trucks, combines, bins or any non-aerated site more than 4-6 hours before beginning drying. These conditions are critical to grain quality, because the fungal growth which causes aflatoxin will escalate to excessive levels very quickly in wet, warm grain. Conversely, fungal growth becomes dormant when grain moisture drops below 15%. Producers should also thoroughly sanitize handling and storage facilities before and during harvest.

Cotton

By Tom Barber

Crop Situation: Mississippi's cotton crop is still in a wide range of maturity and conditions. Early planted cotton, in general, has a better root system and has not been affected as badly by the rainfall as the later planted. The later planted cotton has been set back by the heavy rains in June, but should be ready to defoliate by mid-September. Later planted cotton in some cases is struggling and attempting to adjust for the poor root system and some will have to be played out till the end. Generally the crop is in good condition. Some areas of the state are looking at a high crop potential while other areas are just hoping for a crop. Over all, the potential is there for an average to better than five year average crop, if it can be harvested. Growers are reporting good fruit retention in most areas, despite the environmental conditions.

Late season nitrogen: With all the rainfall and possibilities of denitrification, there are some fields showing signs of nitrogen shortages. Before you apply nitrogen to cotton at this late date, be absolutely sure it is needed. Some fields may be showing yellow colors due to reasons other than nitrogen deficiency such as insufficient oxygen to the roots. Is the field one that had all the nitrogen applied pre-plant or quite early pre-plant? If so, and it is well fruited, it may indeed be running out of nitrogen. Is that all bad? Keep in mind that if the crop is carrying a good fruit load, it is doubtful that the plant has time to produce new growth that will develop into harvestable bolls. If the field is one that had a split application of nitrogen applied, it is doubtful that it is really running out. An exception would be low areas of the field that received extreme amounts of rainfall and where the soil stayed saturated for long periods of time. If soil-applied nitrogen is indeed low, more can be applied either as a solid material applied to the soil or as a foliar spray. A soil application will deliver more N to the crop in a single application, while a foliar program will be limited to about 5 pounds of N per application. However, it is getting too late for a soil application of 30 or so pounds, especially in dry land cotton. Materials such as ammonium nitrate, Bulldog Soda, Calcium nitrate, urea, ammonium sulfate (or other solid source) may be used as a soil-surface-applied treatment. A nitrate source would be preferred for this treatment.

This late in the season, a foliar feeding program using a suitable source of N is an alternative. An application of solid nitrogen to the soil could deliver more nitrogen to the crop than is needed, while applications of foliar material could be tailored to meet the needs of the crop. All decisions must be made carefully. At this late date, such an application may be a little dangerous. Excessive nitrogen will delay maturity, increase rank growth, cause the crop to be more attractive to insects, and could reduce yields and grade. Prevent as much plant stress as possible. Do not apply additional nitrogen unless you are absolutely sure it is needed, especially this late. Another good point to

mention is that especially in the later planted cotton, the roots are not in very good shape and may not be able to take up the nutrients available in the soil. It does not matter how much nutrients are applied to the soil if the roots are not able to take them up. It would be better to wait until the roots recover and begin to forage for the nutrients before making another application.

Defoliation: The time to apply the defoliant is often a tough decision to make. Above all else, it should be based on the maturity of the plants and field. Harvest schedules, prevailing weather conditions, and forecast are also prominent considerations. The maturation processes stop when the leaves are taken off a cotton plant. Anytime the decision is made to apply a defoliate or harvest-aid chemical, there will probably be some immature bolls on the plant. However, a grower cannot wait until 100 percent of the bolls are mature; some will have to be sacrificed. As a general rule of thumb, the last boll to be consistently picked will probably be the first position boll on the fourth or fifth node down from the terminal. The maturity of this boll should be used as the key for timing an application of defoliant. The yield and quality of the bottom crop and middle crop are far more important than those last two or three little tiny bolls in the terminal. This decision is often hard to make.

Boll Maturity: It is generally safe to apply a harvest-aid chemical when the crop is 50 to 60 percent open, and the last boll expected to be picked is mature. To determine maturity of this boll, a visual field check is recommended. Bolls from the last fruiting position desired to be picked (usually the first position boll on the fourth or fifth node below the terminal) should be cut in a cross-section with a sharp knife. A mature boll is difficult to cut, but the real test is looking at the seed. The seed cavity should be filled, no jelly present, and the seed coat should be dark in color. When the seed is mature, the boll is mature enough not to be adversely affected by a harvest-aid chemical treatment. Generally, the boll is mature enough to be defoliated at about 38 days of age, depending on the growing season.

Cutout + DD 60's: Where a plant-monitoring program is employed, growers might want to look at heat unit accumulation after what is considered "cutout" has occurred. Depending on location, cutout is generally defined as that point when the crop has progressed to a point of development where the first position white flower is within four or five nodes of the terminal. The technique to make these counts is described in the Plant Monitoring booklets available from your local Extension office or the National Cotton Council. "Nodes above white flower" (NAWF) is a powerful tool that can help crop managers make or verify several decisions. Potential timing of defoliation is one of those. Count heat unit accumulation after NAWF 5 and when 750 to 800 DD 60's are accumulated, because the field may be ready for defoliation. Before any treatments are made, the fields should be physically examined to determine maturity. Long-term weather records, if available, could be used as a tool to predict defoliation date several weeks in advance.

Nodes Above Cracked Boll: This technique is valuable in verifying field maturity. It has been found in research that boll maturity extends four nodes above the uppermost first position cracked boll (NACB). To use this technique, plants must be selected to represent the majority of the field, and they must have a cracked boll (one where lint is visible through a cracked suture) on a first position site. When this is done, determine how many nodes are between the cracked boll and the youngest boll to be harvested. The crop will be mature four nodes above that cracked boll. At defoliation time, the NACB should be within four of the youngest bolls you want to harvest. When you are counting heat units or cutting bolls, the NACB technique can be valuable for confirmation. If you are not sure the boll you cut is mature, count down the plant, and if you find a first position cracked boll within four nodes, the bolls are mature enough not to be adversely affected by a defoliant.

Soybeans

By Alan Blaine

This has been a very challenging year thus far. Although much of this crop is early, many growers had to deal with water logged conditions and flooding in early July. In some areas, planting could not be completed until the week of July 12th. Although this represents a small portion of the crop, it remains large for those producers facing these extremes.

Many calls have been received regarding foliar fungicides. This decision is really some what of a guessing game. Under most situations, there are usually several options that will work. But no one option is the total answer.

The use of foliar fungicides in soybeans is affected by time of planting, crop history, variety disease package, and weather (current and future). Some soybean acreage will benefit from a foliar fungicide, but other acreage will not.

Growers have made high yields without using fungicides (some years) and will continue to do so. However, the use of fungicides and late season insect management are two inputs that will be essential in achieving high yields consistently. The early planting system is an avoidance mechanism for many foliar diseases. This system is at a greater risk for seed deterioration than losses from foliar diseases. There is some frogeye leaf spot and late season cercospora, but it makes an application decision a little harder when there are only two weeks left.

Weather over the last several weeks has caused many problems. Aerial blight, downy mildew, SDS, and frogeye have increased rapidly. In some fields,

Foliar fungicides can provide excellent benefits depending on when used and what they are used to control. The best benefits will come from use before diseases get out of hand. Unfortunately, control is often delayed until symptoms are visible. Foliar fungicides are insurance.

A large portion of this crop is extremely early. In fact, some of the Mississippi soybean crop on July 11 was about two weeks from being at the R6 (complete seed fill) growth stage. This crop needs little help, and some acreage will be a candidate for a fungicide application.

There are some basic strategies for fungicide applications. A late shot (R5-R6) can aid in controlling late-season cercospora and/or improve seed quality. There are two options, Quadris or Topsin M. Thus far, Quadris has not controlled late-season cercospora -- at least not at the current rates or timings. Seed quality can be improved with Quadris at the 6-ounce rate, but 4 ounces will do the job.

A well-timed application of Topsin M can control late-season cercospora and benefit seed quality. If it is applied too early, it might not have the staying power to help late in the season. Cercospora appears to have gotten worse the last few years, particularly on early planted Group 4 varieties. If you want to control cercospora, do not wait too late.

Topsin M has a generic counterpart called Thiophanate-methyl (TM 85). The rates are 0.75 pound of formulated product for Topsin and 0.6 pound for TM 85.

Plantings after mid-April to mid-May have excellent yield potential. The exception may be where flooding or prolonged wet feet have affected yields. Growers experiencing a good crop without any major problems may consider a fungicide and Dimilin combination. We are not applying Dimilin to the early crop. However, our plans are to apply Quadris (4-ounce rate) or Topsin M 0.75 pound) or TM 85 (0.46 pound) plus Dimilin (2 ounces per acre) to beans planted in this window.

Applications to late plantings should be based on yield potential, cropping history, and the outlook for future weather.

Blanket applications of fungicides should not be made. To avoid what happened in 2001, consider a quality shot on early-planted beans (prior to mid-April). How much should be treated depended on the number of acres, growth stage and capacity.

Although elevators want this crop early, they do not want problems. Growers should consider if the disease situation is going to get worse and if August is going to be dry.

Conditions over the last few weeks had the potential to greatly enhance disease development, but dry conditions could halt development. These decisions are not cut and dried, but year after year, even if a fungicide application does not allow a big increase in yield, the increase will be sufficient to pay for the application.

There is a certain amount of disease pressure this year due to the three weeks of rain in June. Nothing could have changed that.

There are numerous ways to accomplish crop objectives regarding disease control. Crop potential and weather should be used when making this decision.

Do not forget to pay attention to irrigation needs and insects, primarily stink bugs.

Rice

By Tim Walker

Mississippi's rice crop has progressed very well through the summer. As fields are beginning to be drained, most growers are cautiously optimistic that yields will be good. The cloudy and wet weather in Mississippi broke just prior to heading and flowering. However, the effects that the unusually wet summer has had will not be know until harvest. Yield reports from southern Louisiana and Texas are not good. Cloudy and wet conditions are being blamed for low yields.

A large percentage of the rice acreage has received a fungicide application this year for sheath blight and/or kernel smut. Most of the fungicide applications have performed quite well. In many situations, a low rate of Quadris applied two weeks after midseason provided ample control until the weather became less favorable for sheath blight infection. In fields where sheath blight infection continued beyond the residual control, Stratego or Quilt were applied to extend sheath blight control and prevent kernel smut. In situations where sheath blight did not pose a problem, Tilt or Propimax were applied.

From mid-July until now, problems have been isolated. Contrary to some reports, blast has only occurred in isolated fields where a combination of weather and cultural practices exacerbated the problem. However, on later planted rice varieties that are susceptible to blast, fields should be scouted. If leaf blast is found, a deep flood (approximately 4 in.) should be maintained and preparations to apply the high rate of Quadris or Gem at late boot should be made. If conditions are favorable for blast, a second application should be made approximately one week later. Another isolated problem that has been encountered is Select drift onto rice. The wet conditions have caused grass problems in cotton and soybean fields. Some of these fields were treated with Select. Depending on the drift rate of Select that comes in contact with the rice, yields can be largely reduced.

In closing, Dr. Joe Street, and this writer, have been asked numerous times over the last few years about reports in neighboring states that address when to drain the rice crop. MSU-ES recommendations have not changed. On silt loam soils, fields should be drained when the top two-thirds to three-fourths of the panicles are yellow and turned downward. On clay soils, fields should be drained with the top one-half of the panicles are yellow and turned downward.

Irrigation needs in Mississippi

By Jim Thomas

Depending on weather patterns, irrigation could continue thru August and even into September for soybeans and some cotton if it stays hot and dry. Late season or full season beans will need irrigation at least thru physiological maturity. That is counting 4-5 nodes from the terminal and the beans are touching in the pods. If weather would continue to stay hot and dry, one irrigation after that stage of development will help the plant mature naturally and keep the weight in the beans for a higher yield.

Cotton needs to be irrigated at least to first open bole. Make sure the open bole that is being considered is a position that can be picked. If heat continues, the crop irrigation should remain for a week or two after first open bole to ensure good bole maturity of the entire crop. Irrigation can continue with either surface systems or sprinklers. There has never been documentation that sprinklers deteriorated the quality of the cotton.

Irrigation and rainfall have made a wonderful crop to this time and it would be a disaster to let the crop stress for water now when it has been so abundant all season.

Dr. Michael Collins, Department Head
Department of Plant and Soil Sciences
Box 9555
Mississippi State, MS 39762
(662) 325-2701

A black line that separates the body text from footer information