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Small grains — wheat, rye, oats, barley, and triticale — are important agricultural crops in Georgia, South Carolina, Alabama and northern Florida. Winter wheat is a significant cash grain crop in the Southeast, and rye, oats and wheat are planted on hundreds of thousands of acres in each state for winter grazing. Currently, winter barley production is limited, and triticale is a potential cash crop but is not grown extensively in the Southeast.

Small grains are adaptable to multiple-cropping systems, and high grain and forage yields under dry land conditions are attractive features. Wheat is the most important winter grain crop in the southern United States and is typically grown in a doublecrop system with soybean or cotton. Wheat grain acreage in the four southeastern states has been as high as 2+ million acres but currently is about 0.5 to 0.7 million acres, with an estimated gross value of $120 million per year. Furthermore, Georgia is the No. 1 producer of rye in the country.

State average wheat yields have gradually increased over the past 15 years from about 30 to 35 bushels per acre (bu/A) to 45 to 50 bushels per acre. However, a disparity exists between state average yields and yields achieved by top producers, who often reach 80 to 100+ bu/A. The potential for greatly increasing production of small grains exists, but better use of management technologies in needed to realize this potential.

The objective of this handbook is to provide rapid and extensive transfer of modern management technologies for small grain production. The intended audience includes Extension agents, industry personnel and dedicated producers. It is multidisciplinary in scope and includes extension and research scientists from agronomy, agricultural economics, agricultural engineering, animal science, entomology and plant pathology from four southeastern states: Georgia, Alabama, South Carolina and Florida.

This is a revision of the Small Grain Handbook originally published by the University of Georgia College of Agriculture in 1989. This handbook revision was developed by the Southeastern Small Grains Team and is jointly published by the University of Georgia and Auburn University Agricultural Experiment Stations and Cooperative Extension Services.

From the Editors:

G. David Buntin
Barry M. Cunfer

Proper management of wheat for optimum yields requires that certain practices such as nitrogen fertilization and application of pesticides be timed at specific stages of wheat growth. To benefit from these management practices, the grower should understand the growth and development of the plant.

Growing Degree Days

The pattern of development of the wheat plant can be used to guide crop management. Plant development is timed by growing degree days (GDD). Wheat grows and develops when the average daily temperature exceeds 32ºF. Wheat development in relation to temperature can be determined by the number of wheat GDD. Wheat GDD are based on Celsius temperatures and are calculated by the formula: average daily (ºF) = (max. + min.)/2; then convert degrees F to degrees Celsius (ºC) = (5/9) (ºF-32). Average daily temperatures less than 32ºF are recorded as 32 because this is the lowest threshold for growth and development. Examples of GDD at several average daily temperatures (ADT) are: ADT of 32 = 0 GDD, ADT of 50 = 10 GDD, ADT of 60 = 16 GDD and ADT of 70 = 21 GDD. A GDD calculator can be found on the Web at www.griffin.uga.edu/bae/.

Germination

Figure 1. Anatomical description of wheat at the vegetative stage

Figure 2. Comparison of leaf characteristics between wheat and other small grains

Wheat germinates at temperatures between 39º and 90ºF with optimal germination occurring at 68º to 77ºF. Germination is indicated by radicle (primary root) protrusion through the seed coat, followed by emergence of the coleoptile (first leaf) which surrounds and protects the emerging stem and primary leaves. Germination normally is complete within four to six days at optimum temperatures. The number of wheat GDD it takes to germinate is 80 and to emerge is 50, for a total of 130 GDD in the Southeast.

Wheat produces a root and crown (nodal) system that develops sequentially according to a pattern typical of grasses. The wheat plant has two types of roots: the seminal and the crown (nodal). Seminal roots form from groups of cells already present in the seed (Figure 1). This system usually comprises three to six main roots and their branches. The first seminal root to appear is called the radicle. It is the first root produced when a seed germinates. The rest of the seminal roots arise from the nodes. Variety and seed size are the main factors that affect the number of seminal roots in the germ.

Crown roots are produced on main stems, primary tillers and secondary tillers (Figure 1). Each main-stem node develops two roots after the leaf first appears. If a tiller is produced at the node, one and sometimes two roots elongate after the first appearance of a leaf at the node. Generally, each leaf takes about 100 GDD to develop.

Crown roots generally begin to grow from tillers after a tiller has at least two leaves. The root axes on tillers elongate in an orderly and predictable way with respect to time. After a tiller has three emerged leaves, the length of roots increases. The depth of rooting increases directly with root number and is also influenced by the soil profile. By the time wheat reaches jointing or early boot stage, new root production ceases, and growth continues in the existing roots. Each tiller has its own roots, which begin to appear when the tiller has two to three leaves.

Seedling Growth

Seedling growth occurs from coleoptile (first leaf) emergence to tiller development. Generally, the wheat plant develops three or more leaves prior to tillering. The rate of individual leaf growth as well as the final shape and size of the leaf are affected by the environment. During vegetative growth, wheat can be distinguished from other small grain crops by its short hairy auricles, which are located at the point where the leaf blade and sheath meet (Figure 2).

Tillering

Tillering is the development of shoots from buds at the base of the main stem (Figure 1). The count of leaves on the main stem is a good way to measure plant development and is linearly related to GDD. Planting to six leaves on the main stem (three tillers) requires about 730 GDD. During initial development, the tiller is dependent upon the main shoot for nutrition, but once the tiller develops approximately three or more leaves, it becomes independent of the parent plant for nutrition and will form its own roots. Varieties show relatively little variation (5 percent to 10 percent) in leaf development rate. Planting date or season-to-season climate variation, appear to create greater change in leaf development rate than variety.

Secondary tillers may also arise from primary tillers. The extent of tillering is dependent upon genetic and environmental factors. Tillering increases with high light intensity, reduced plant populations, and high soil nutrient (primarily nitrogen) availability. High temperatures, high plant populations, soil moisture stress and pests can reduce tillering. Although each tiller has the potential to bear a productive seedhead, generally, about one-half of the tillers do not survive to bear grain. Aborted tillers are affected early in tiller development, long before visual evidence of tiller death is evident.

If a plant that has been stressed during vegetative development is exposed to a favorable environment, rapid tiller growth can improve grain yield. Often low plant populations compensate by increasing numbers of tillers per plant.

Vernalization

The onset of reproduction is controlled by vernalization. Vernalization is the induction of the flowering process by extended exposure of the shoot apex to low temperatures. Vernalization has been shown to occur in seeds as soon as they absorb water and swell. The effectiveness of vernalization declines with increasing plant age. Vernalization is affected by photoperiod, in that exposure of the plant to short days replaces the requirement for low temperatures in some varieties. Also, if wheat is exposed to high temperatures (86ºF or 30ºC) shortly after low temperatures, vernalization will not occur. After vernalization, the initiation of flowering may be hastened by longer photoperiods, because wheat is a long-day plant requiring night periods to be shorter. Generally, early maturing varieties require fewer chilling hours of vernalization than late maturing ones.

The ability of plants to survive low temperatures depends on whether the plants have been exposed to low temperatures — a hardening process. Later maturing varieties usually survive lower temperatures better than earlier maturing ones. Wheat will go into winter dormancy and grow very slowly when the temperature decreases to 40ºF or below. The vernalization requirements for varieties grown in the Southeast range from one day to six weeks.

Jointing

Jointing or stem elongation begins when the first internode of the stem is visible. Generally, wheat stems possesses six internodes, with internodes increasing in length from the base of the plant to the top. Stem height is under genetic control, but the environment affects genetic expression. The end of the jointing stage is indicated by the appearance of the "flag" leaf, which is the last leaf to develop before grain head emergence. From planting to jointing requires about 1,350 GDD.

Boot Stage

Reproductive development is first observed when the head begins to swell within the flag leaf sheath (boot stage). The head is composed of rows of spikelets on the terminal end of the last stem internode (rachis). Each spikelet produces two to five florets, and each floret may produce a single grain. The number of spikelets formed depends upon environmental conditions during early jointing. High temperatures increase the rate of spike development but reduce the number of spikelets per head. Moisture stress reduces spikelet number. High light intensities and optimal nitrogen fertilization increase spikelet numbers. The boot stage ends when the grain head first emerges from the flag leaf sheaf.

Heading Stage

The heading stage is first observed when the head emerges from the flag leaf sheath. Small grains are normally self-pollinated. Pollination begins in the middle region of the head and progresses to the tip and base. High temperatures and drought stress during heading can reduce pollen viability and reduce grain number.

Freezing temperatures may result in head injury and partial or complete sterility during jointing and heading. Few differences among varieties have been found for cold damage during this growth stage. However, short-season (early maturing) wheat varieties are usually more susceptible to injury by freezing temperature because they produce heads earlier in the year than full-season varieties.

Grain Filling

The grain filling stage follows the heading stage. Environmental factors, primarily high temperature and moisture stress, affect kernel survival and the rate and duration of grain development. Starch and protein are the primary storage reserves in the mature kernel. Starch deposition within the grain is under greater environmental influence than protein accumulation. Under high temperature and moisture stress conditions, starch concentration and final grain dry weight are reduced.

Grain Ripening

Small grains are physiologically mature in the hard dough stage. The moisture content may range from 25 percent to 35 percent. The entire plant then loses chlorophyll and assumes a characteristic straw color. At this point, the crop is ready for harvest (13 percent to 16 percent moisture).

Yield is a function of genetics and environment. The yield of a given variety is dependent upon the following yield components:

The factor most directly associated with yield is kernel number per unit area, yet, this factor is dependent upon tiller production, head development, and seed development.

Development Scales

Several small grain development scales have been developed. The two scales most frequently used are the Feekes’ and Zadoks’ scales (Table 1, Figure 3). The Feekes’ scale provides a numerical system for describing wheat growth, but is not very specific during the germination, seedling, jointing, and booting stages. The Zadoks’ scale is based on a two digit descriptive system, which allows for more detail in quantifying wheat development. These growth scales allow for comparisons of development among varieties in varying environments and they aid the proper timing of management practices such as nitrogen fertilization and pesticide treatments.

Figure 3. Diagrammatic comparison of Zadoks’ and Feekes’ scales of wheat development

Table 1. Description and comparison of Zadoks' and Feekes' wheat development scales

Well-adapted, high-yielding wheat varieties with resistances to the prevalent diseases and insects are essential for profitable wheat production. Varieties adapted to one area are not necessarily suitable for other areas. Even recommended varieties within a production region vary in yield potential, disease and insect resistance, straw strength, and maturity. Therefore, it is important to carefully evaluate available varieties and plant those that best fit field needs. Errors made in variety selection may result in loss of yield or additional input costs.

Factors to Consider

Yield

Grain yield is normally the primary consideration. Consistent high yields over several years are usually a good indication of well-adapted varieties. However, growers should also consider other factors listed below.

Maturity

Early-maturing varieties ripen about one to two weeks before medium maturing varieties. Early-maturing varieties are most suitable for doublecropping systems. If you are planting a large acreage, use several adapted varieties of differing maturities to increase planting and harvesting efficiency. Late varieties should be planted first, followed by medium, and finally, the early-maturing varieties. If you have to plant later than the recommended date, note that early-maturing varieties usually perform best.

Disease Resistance

Leaf rust, Stagonospora nodorum blotch, and powdery mildew are important wheat diseases. Resistance to these diseases should be considered when selecting varieties. Resistance to leaf rust is most important in the lower Coastal Plain and resistance to powdery mildew is most important under high nitrogen fertility or maximum yield conditions.

Insect Resistance

Hessian fly is the major insect pest of wheat in the Southeast. The most effective and economic means of controlling the Hessian fly is by using resistant varieties. Because Hessian fly populations vary greatly from region to region, varieties reported as resistant in one area of the USA may be susceptible here. See the section on insect management and control for more information.

Straw Strength

Select varieties with good straw strength to prevent harvest losses associated with lodging. Semi-dwarf varieties are short in height and usually have good straw strength, even when high rates of nitrogen fertilizer are used.

Test Weight

Standard test weight for U.S. No. 2 soft red winter wheat is 58 pounds per bushel (lb/bu). Test weights below this standard can result in a price dockage at the elevator. Light wheat with a test weight of 48 to 52 pounds per bushel has low feeding value and lower energy content due to increased fiber content. Environmental conditions, disease and insect damage, and variety strongly influence test weight.

Selecting Varieties for Forage Production

Make sure that varieties selected for forage production have a record of high forage yield. Varieties that produce high grain yield do not always produce high forage yield. Varieties that steadily produce forage throughout the season may be more desirable than varieties with only seasonal growth. If you plan to use wheat for forage and also produce a grain crop, select varieties with high yield potential for both forage and grain production. Use a Hessian fly resistant variety to reduce damage associated with early planting required for fall and early winter forage production.

State Wheat Performance Tests

Each year variety performance tests are conducted to determine the adaptability of available and prospective wheat varieties. Both forage and grain tests are conducted at locations that represent all the major production regions. These results are presented annually in agricultural experiment stations publications and are available at your local Cooperative Extension office by late August each year. These performance data help you judge the merits of wheat varieties.

How to Use the Small Grains Performance Tests Report

1. Select the test location that best represents your production area.
2. Use multiple year averages, because they are the best predictors of performance.
3. Select current varieties you are familiar with and use them to compare other entries.
4. Identify those varieties that out-yielded your current varieties.
5. If the yield difference between varieties is greater than the LSD value, the varieties are considered statistically different in yield. Yield differences smaller than the LSD value may be due to random variability rather than actual variety differences.
6. Check the other columns for test weight, lodging, height, winter survival and heading date. Avoid varieties with low test weight, high lodging or low winter survival. Be cautious about any wheat variety that heads substantially earlier or later, or is significantly taller or shorter than your current variety.
7. Refer to supporting tables presenting variety characteristics for general ratings of agronomic characters, disease resistance, and insect resistance.
8. Once you have identified one or more varieties that you would like to try, refer to the table titled "Sources of Seed" and contact the variety source for information on availability of seed.

Your soils and management may differ from those of the test location. Therefore you may first wish to plant strips or a small acreage of the better-performing varieties before planting large acreages of them.

Recommended Varieties

Recommended varieties are determined by a critical evaluation of variety performance by research and extension scientists. Recommendations are based on the relative performance of a variety for three or more years, taking into account the importance of diseases, insects, and weather conditions in each of the production regions.

For a list of recommended varieties in your production region, consult the Cooperative Extension Service fall planting schedule or the Small Grains Performance Tests report. Both are available at your local Extension office.

Selecting high-yielding varieties and high-quality seed is one of the most important planning decisions in the planting of small grains. Most economic analyses list seed costs as less than 10 percent of total production costs. On the other hand, seed quality and variety selection determine yield potential and many times are the difference between profit and loss.

Seed quality is a collective term to describe the expected performance of a seed, bag of seed or seed lot. It includes standardized measurements of germination percentage, genetic purity, other crop seed, weed seed and inert material. The term seed quality may also include non-standardized measurements of physiological health, vigor and the presence of pathogenic organisms. The standardized measurements are routinely determined by state or private seed laboratories and are required to be listed on each seed tag. The non-standardized measurements are normally used for quality control to select superior lots of seed for sale. However, the non-standard measurements are also available to individuals by special request and need.

Commercial Seed Classes

Farmers can be best assured of high seed quality by purchasing their planting seed from reputable seedsmen. Seed purchased and/or planted by farmers can be placed into one of three classes: certified, non-certified and farmer-saved seed.

• Certified seed, produced by professional seedsmen who are members of crop improvement associations, is distributed by commercial seed dealers. Seed certification is a third party, limited generation, quality control program covering seed fields, conditioning plants, and other critical areas. A major role of the certification program is to deliver new varieties with superior disease resistance, yield, or quality characteristics to commercial growers. The certification staff monitors the seed multiplication process and verifies that the production has met the criteria necessary to protect the genetic identity of new varieties. In addition certification ensures that the genetic purity of older, but highly productive varieties remains stable and the variety remains true to type. While varietal purity is the first consideration in seed certification, other quality standards are important including germination, weed seed, other crop seed, and inert matter content. Certified seed must meet significantly higher standards than is required by state seed laws.
• Non-certified seed also is distributed by commercial seed dealers, but usually do not have third party verification of quality. Seed companies with large breeding programs do not always participate in certification, but many times establish company seed standards which are usually higher than the minimum standards of the state seed law. Non-certified seed may or may not be grown by professional seed producers, but seed quality is known and labeled according to state laws.
• Farmer-saved seed is saved by a farmer to plant on their farm or to sell to a neighbor. They are not required to meet any provisions of the state seed law, provided the seed are sold at the farm, not advertised, or transferred by public carrier. Labeling of farmer to farmer seed is not required. Therefore, little if any recourse is available if the seed fails to produce a stand. Numerous seed surveys conducted by extension and research personnel across the United States report farmer-saved seed consistently produced lower yields. Weed seed contamination, low germination, and unknown or mixed varieties generally lead to the lower yields and lower profits.

State Seed Laws

State departments of agriculture regulate labeling of commercial seed. Seed laws are designed to prevent the misrepresentation of seed and set minimum standards for important seed quality criteria (Table 2). They require all seed offered for sale to be labeled with an analysis tag. Any accredited seed laboratory can determine the seed quality data for the analysis tag. However, the data collected by state departments of agriculture from official samples determine final suitability for sale in the individual states. In addition to the state departments of agriculture, the Federal Seed Branch also regulates seed sales, but it is concerned only with seed traded across state lines.

Table 2. Comparison of analysis requirements as percentage of net weight for classes of seed (Example: wheat, state of Georgia)

A typical seed tag provides the following information:

• Kind and variety – The kind of a crop refers to the species (wheat, oats, barley, rye, etc.) The variety is a subdivision of a kind characterized by growth, yield, fruit or other characteristics that differentiate it from other plants of the same kind. Maturity date, cold tolerance, and disease and pest resistance are variety specific. Contamination of one variety by another may compromise the desirable characteristics of superior varieties. Therefore, genetic purity of planting seed is an extremely important quality factor. Knowledgeable and expert farmers select genetically superior varieties and buy professionally grown seed to ensure varietal purity and trueness to type.
• Germination percentage – Germination is the ability of a seed to produce a normal seedling under favorable conditions. The laboratory analysis report of percent germination is based on pure seed and not on the total contents of a bag. Actual seed germination potential is greatly influenced by weather conditions during the growing and harvesting seasons. Drought during the growing season may result in immature seed, whereas excessive rainfall may increase disease levels. The storage environment, moisture, temperature and presence of insects also will determine final seed quality. Mechanical damage will cause low seed quality and is caused by improperly adjusted combines, poorly maintained augers, excessive drying temperatures, and high speed impact on hard surfaces in elevators, bins, and trucks.
• Pure seed – Pure seed percentage gives the percentage of total weight of each kind and variety tested. If more than one kind and/or variety is named, the pure seed percentage of each component must be listed. High quality small grain seeds should always be at least 98 percent pure seed and of one kind and variety.
• Inert matter – Inert matter includes sand, stones, dirt, sticks and plant parts including pods, chaff and broken seeds. A broken seed is considered inert if it is 50 percent or less of a whole seed. Broken seeds greater than 50 percent of a whole seed are included in pure seed percentage and are considered whole seed for germination purposes. High quality, professionally grown and conditioned small grain seed should have below 2 percent inert matter.
• Other crop – Other crop may be a contaminant of another kind of small grain or a different variety. In some instances the other crop may be a weed in small grains, but an economically important crop in another planting environment (i.e., ryegrass, cheat, clover or canola). These other crop seed may suggest poor quality controls in seed production and conditioning. Crop plants other than the intended kind may reduce yield and grade and should be avoided.
• Weed seed – The presence of weed seed is expressed in percentage of total bag weight. It includes seeds, but also bulblets of wild garlic and plant parts of wild radish. High quality seed should contain no weed seed.
• Noxious weed seed – Noxious weeds are plants that are extremely difficult to control and prolific seed producers. Weeds are declared noxious by state departments of agriculture in a cooperative effort to limit their spread and economic damage. See Table 3 for a listing of the noxious weeds as declared by regulations of the Georgia Department of Agriculture. Other states have similar lists. High quality seed should not contain noxious weed seed.

Table 3. Comparison of noxious weed seeds allowed in various classes of seed

Other data required on the seed tag gives information about the specific lot of seed and individual containers. Required labeling information is listed below and in the example in Figure 4a.

• Lot number is a designation placed on each container to serve as a reference of lab reports, producer, year of production, etc. The lot number may be a simple numeric designation as "3" or quite complex as R-6036-JC. The latter number can code for several variables useful in quality control and inventory management.
• Net weight is the quantity of seed in the container exclusive of container weight.
• Origin is the state where the seed was grown. Origin may be an important consideration for crop adaptability when purchasing seed.
• Hard seed does not germinate with standard germination tests, but will germinate upon special treatment such as scarification after ripening, etc. Small grains normally do not have hard seed.
• Dormant seed are viable seeds, other than hard seed, which fail to germinate when provided favorable conditions. Dormant seed may normally germinate over time with exposure to proper conditions.
• Test date is the date that the seed laboratory reported the germination test. State seed regulations require that the test date be within nine months of the date of sale, not including the month of the test. Federal regulations require that the test date be within five months of the date of interstate sale, not including the month of test.
• Name and address of vendor refers to the company responsible for the seed in the bag. In most cases, the vendor is the business that conditioned and bagged the seed for sale or the owner of the seed if another party accomplished conditioning.

Figure 4a	Figure 4b

Certified Seed

Every state seed producer has access to a certification agency to assist in the production of high quality seed. These certification agencies administer the production and quality standards established by the membership. The certification label gives the highest level of assurance that the seed in the bag meets the highest quality standards in the seed industry. The certification office also maintains records for each certified seed lot, which includes the following: source of seed planted, application for field inspection and certification, field inspection, bin, conditioning, laboratory report and a sample label from each lot of seed.

The state crop improvement associations were first organized to educate seed growers and consumers about the advantages of high quality seed and provide assurance of seed quality in the bag. During recent seasons and years, with the advent of the Plant Variety Protection Law (PVPA) and expansion of private breeding programs, many private breeding companies have relied on certification for third-party, unbiased quality control. Certified seed is recognized as the best assurance for quality control from the field to the bag. Certification identifies member seedsmen as supporters and providers of high quality planting seed.

Membership in the state crop improvement association is available to qualified seed producers who desire to make certified seed growing a part of their operation. The local county Extension agent can provide appropriate information, addresses and telephone numbers.

There are four classes of certified seed: breeder, foundation, registered and certified. These classes are designed as a four-generation seed increase program to reduce genetic drift and the risk of mechanical contamination. The specific standards for each crop are more restrictive in the foundation class than the registered class and less restrictive in the certified class. In all cases, the standards for foundation and registered seed are established to ensure that the certified class has a high level of genetic purity. Each class of certified seed is described in detail as follows:

• Breeder seed are produced under the direct supervision of the originating plant breeder or institution.
• Foundation seed are grown from breeder seed. Foundation seed are tagged with a white label. The production of foundation seed is highly specialized and usually managed by an organization that has foundation seed production as its primary responsibility. Private companies usually have a specific department for foundation seed production. Foundation seed lots do not normally enter the commercial seed channels but are used by professional seed producers to produce registered and certified seed.
• Registered seed are grown from foundation seed. Registered seed are tagged with a purple label. Recently private and public breeding programs are eliminating the Registered class to provide greater assurance of varietal purity and to limit the unauthorized production and sale of PVP protected varieties.
• Certified seed are grown from foundation or registered seed. Certified seed also are inspected and must meet state seed certification minimum standards. These seed with known pedigree and performance are distributed by commercial seedsmen. Certified seed are tagged with a blue label (Figure 4b). The familiar blue tag found on each bag of certified seed assures the farmer that the seed have passed an unbiased field and laboratory inspection process.

Selecting Good Seed

Yields and profits are greatly dependent on the proper selection of planting seed. Many quality factors must be considered before purchasing seed. An acceptable level for each quality factor must be established.

Perhaps the first and most important decision to make is selection of an adapted variety. The choice of variety sets the upper limit on yield and quality. Trueness to type and varietal purity is just as important as selecting a high yielding variety name. By purchasing professionally grown seed, especially certified seed, the farmer has more assurance of receiving the correct variety with high varietal purity.

Be a seed tag reader. The seed tag reveals the quality of the seed so that the farmer can make a rational decision. It is best to purchase seed with germination above 80 percent, pure seed content above 98 percent, low inert matter and preferably no weed seed. Other crop seed should be less than 0.10 percent.

Remember, cheap seed is usually cheaper for a reason. Seed offered for sale without a seed tag may have a quality problem that could result in poor stands, noxious weeds or a lower yielding variety than the one selected. Saving a few dollars per acre at planting may result in lower or no profit at harvest.

Small grain seed should be treated for diseases and insects. If appropriate chemicals are used, seed treatment will control loose smut and will give partial to complete control of other seed-transmitted small grain diseases. In addition, seed treatments also are important in reducing seedling disease caused by soil fungi. State law requires that all seed commercially treated be tagged with a warning label stating the chemical used and application rate.

Other Considerations

All seed producers and especially farmers who save their own seed or sell seed to other farmers should be aware of the Plant Variety Protection Act (PVPA). The PVPA allows the owner of a variety to determine who may market or sell a variety for planting purposes.

For varieties protected under the 1970 PVPA (normally those varieties developed between 1970 and 1995), a farmer may save the seed from a crop of a protected variety for his own use or sell to another farmer, if he does not normally grow seed for sale and the amount of seed saved is no more than the amount needed to plant his normal acreage.

The 1994 PVPA amended the original PVPA and applies to varieties protected after 1995. This act prohibits the sale of seed for planting purposes unless specifically given permission by the variety owner. To determine which act applies, read the analysis tag on the seed planted or contact the seed certification agency or state department of agriculture in your state.

Determining Stand Problems

Each year, county agents, seed dealers and certification agencies receive complaints from farmers who fail to get adequate stands. But, often times, a thin stand under proper management will produce high yields. As a result each individual situation should be evaluated on its own merits to determine if replanting is desirable and also to establish a reasonable cause for poor seedling establishment.

There are several potential causes of poor stands. Usually, the first assumption is low quality seed. In actual practice though, poor seed accounts for only a small percentage of deficient stands. Most stand problems are related to improper planting depth, soil moisture and/or seed-soil contact. In other cases, chemical injury and improper fertilizer placement have resulted in poor stands from otherwise high quality seed. Seedborne and soilborne diseases, as well as soil insects, can cause reduction in stands. Diagnosing and understanding the reason for stand failure is the first step toward correcting the deficiency, whether it is a seed problem or it is a result of the planting process.

If the probable diagnosis of a poor stand is seed related, it is usually best to immediately contact the seed dealer. In addition, you may wish to notify the county agent, certification agency and state department of agriculture arbitration officials if it is a serious problem that may be difficult to resolve. The process of gathering data should begin at the first indication of a poor stand and should include seed source records, photographs and verified stand counts.

The discussion of poor stands usually leads to questions about seed vigor. Seed vigor is defined by the Association of Official Seed Analysts as "those properties which determine the potential for rapid, uniform emergence and development of normal seedlings under a wide range of field conditions." Several vigor tests are available to assess seed quality, but none are sufficiently standardized for seed control or labeling purposes. Therefore, seed control officials and the American Seed Trade Association do not encourage labeling or advertising with respect to vigor. However, seed vigor information when properly interpreted may prove valuable when making management or seed storage decisions.

Doublecropping winter wheat with soybeans has become a popular and profitable practice in the Southeast. The long frost-free growing season of the region allows farmers to successfully doublecrop, but higher costs, time and labor constraints, and a desire for less soil erosion have all contributed to increased interest in conservation tillage systems for both crops. New equipment technology for dealing with crop residues, both for drills and deep tillage tools, better herbicides, and the availability of herbicide-resistant soybeans have all enhanced the chances for success.

Soil Compaction

Soil particles (various proportions of sand, silt, and clay, depending on the soil type) are grouped together into aggregates. Aggregates that occur normally are called peds. The larger the aggregates, the more pore space there is for oxygen and water, two important requirements for optimum root growth. When physical forces are exerted on the soil, such as tire traffic and/or tillage, aggregates are broken, or are pressed closer together, reducing the amount of pore space. Less pore space means reduced soil water movement, aeration, and nutrient exchange. The result is a denser, more compact soil, making root growth, rainfall infiltration, and drainage more difficult.

Bulk density is an indicator of how dense or compact the soil is, and is measured as grams of dry soil per cubic centimeter of soil volume. The higher the bulk density, the more compact the soil. For soils with traffic from equipment or livestock, or for soils that have been excessively tilled, the bulk density of the various compacted zones may be so high that crops have difficulty achieving good root growth, and are thus more subject to the detrimental effects of pests or weather extremes such as drought.

Controlled traffic systems reduce the effects of wheel traffic on soil compaction. Tramlines are used so that pesticide and fertilizer application equipment is confined to specific lanes across the field. Electronic tramline systems can be installed on drills so that certain seed drops are blocked so some rows do not get seed to create the tramline areas.

Deep Tillage

Soil compaction can reduce crop yields by restricting root growth. If roots are shallow and do not grow into the subsoil or clay of most soils, they cannot access available soil moisture and nutrients. For most soils, especially those in the Piedmont, there will be a shallow compacted zone about 4 to 6 inches deep that is the result of tillage, primarily with the disk harrow. Because the compacted zone is shallow, chisel plowing to a depth of 8 or 9 inches is usually adequate to break it and allow good crop growth under normal rainfall conditions.

Most doublecropping in the Southeast occurs on the sandy soils of the Coastal Plain. These soils are inherently low in fertility and water holding capacity. They are also susceptible to leaching and often experience significant runoff during the growing season when most rainfall occurs as thunderstorms. The organic matter content of these soils is low, usually less than 1 percent. With excessive tillage, the organic matter content is very difficult to improve and may be as low as 0.5 percent in the lighter textured soils. The low organic fraction contributes to poor soil tilth, which can cause lower rainfall infiltration rates as well as soil crusting. The result is reduced crop productivity, especially under conditions of weather stress, of high or low rainfall.

Most upland sandy soils of the Coastal Plain have a compacted zone or hardpan about 6 to 12 inches below the surface and 2 to 3 inches thick. This is called the E horizon and must be broken so that roots can grow into the subsoil or B horizon for top crop performance. The clay has not only additional moisture but also available nutrients such as nitrogen, potassium, sulfur, manganese and boron.

Deep tillage implements like the chisel plow increase wheat yields in soils typical of the southeastern Coastal Plain. However, in the sandy soils with a highly compacted E horizon, the chiselplow’s spring-loaded shanks will ride on top of the hardpan without rupturing it. Consequently, the effective depth of chisel plowing is often only 7 to 10 inches, rather that the 13 or 14 inches usually needed.

Subsoilers with shanks 20 inches apart or less can be pulled deeply enough to break through most hardpans, but as with chisel plows the deep tillage is done in a furrow-like fashion. With the combined effects of later trips plus the natural effects of reconsolidation, especially during heavy rainfalls, there is potential for compaction to reoccur. Also, subsoilers and chiselplows often leave ridges or a rough surface, which make seeding depth control for wheat difficult.

New Tools for Deep Tillage

Farmers are interested in reducing tillage trips, leaving crop residues for wildlife and to control erosion, while doing a better job of soil hardpan breakage. A number of new conservation tillage/deep tillage implements leave a large percentage of surface residues while essentially breaking compaction zones in almost a broadcast manner. Examples are the Tye Co. and Bigham Bros. Paratill, Worksaver’s Terra-Max, and the French Durou plow. The Paratill uses a slanted shank with subsoiler type points and an adjustable shatter plate behind each shank. The shanks slice through the soil at a 45-degree angle, gently lifting the soil and allowing it to fracture along natural cleavage planes. This action loosens the soil along the bottom of the curved shank without disturbing surface residue. The Terra-Max II plow has one shank per row curved in one direction followed in the same row by another shank curved in the opposite direction. The Durou plow has slanted shanks (20 degrees from the vertical) with a 10-inch-long wing attached to the side of the shank. As with the Paratill, these implements lift the soil and drop it with very little surface disturbance. For these plows, however, there is usually a need for a spike-toothed roller mounted to run just behind the shanks. This is because these implements cause some ridges to form behind the shanks, and smoothing or leveling is needed to help assure uniform depth control.

Wings can be attached to conventional subsoiler shanks to enhance hardpan breakage. The DMI and Yetter companies have optional winged subsoilers commercially available.

Farmers who are considering attaching wings to subsoilers should consider the energy requirements for operating these tools. The w