Chapter 3. PEANUT PRODUCTION PRACTICES

Successful production of quality peanuts requires growers to plan an effective production and marketing program and to implement that program on a timely basis during the season. Each cultural practice and marketing decision must be effectively integrated into the total farm management plan to produce optimum profits from the whole farm.

Germination and Sprouting

Germination begins when soil temperatures are above 60^o F and viable and non-dormant seeds absorb about 50 percent of their weight in water. Soil temperatures need to be above 65^o F for germination to proceed at an acceptable rate. Large-seeded Virginia-type peanuts planted under favorable moisture and temperature conditions will show beginning radicle (root) growth in about 60 hours. If conditions are ideal, sprouting of young seedlings should be visible in 7 days for smaller-seeded varieties like NC-V 11 and VA 98R, and 10 days for larger-seeded varieties like NC 12C or Gregory.

Root Growth

The peanut root grows rapidly following germination. The root tip grows downward in the soil through cell division and enlargement. By the time the main shoot breaks through the soil, the taproot will be 5 to 6 inches deep. Lateral roots develop from the taproot and may be 1 to 2 inches long at seedling emergence. The cotyledons supply the food for early root growth. Once the vegetative tissues are producing a food supply (photosynthate) greater than their needs, some of the food is transported to the roots.

Roots take in water and dissolved nutrients from the soil solution. The moisture and dissolved nutrients move through the roots and stems to the leaf tissue where it is used in photosynthesis. The taproot continues to grow downward and lateral roots outward as long as favorable soil conditions exist. Root growth will slow or may even cease during periods of drought, cool temperatures, or when soils are waterlogged. Root growth may be slowed or stopped by soil hardpans, soilborne diseases, and excessive fertilizer salts or pesticides. Adverse soil conditions also can interfere with development of nodules, which are required for nitrogen fixation by the peanut plant.

Any condition that subjects peanut roots to stress should be avoided so that adequate root capacity exists to supply the plant with moisture and nutrients. Lack of an adequate and efficient root system may limit yields.

Vegetative Growth

Vegetative tissues (leaves and stems) are the food assembly area of the peanut plant. Leaves capture energy from sunlight, and through photosynthesis, they combine that energy with air, moisture, and nutrients to produce food (carbohydrates) for both root and leaf growth. Photosynthesis, the biological assembly of inputs into photosynthate, occurs only in green, living tissues exposed to light.

Vegetative growth is slow for the first 3 to 4 weeks, as leaf tissue is limited. As leaves develop and fully expand, the capacity for photosynthate production increases and vegetative growth is more rapid. In early growth stages, cool temperatures cause slow growth. As temperatures rise, vegetative growth increases rapidly. Scientists have determined that optimum peanut growth occurs at 86^o F. Excessively high (above 95^o F) or low (below 60^o F) temperatures will slow growth.

High temperatures are often accompanied by drought conditions, and vegetative stress can be observed as the plants wilt. The end result is a shutdown of the photosynthetic process and cessation of growth. Irrigation is the only man-made way to alleviate the stress of high temperatures or drought. Water movement through the plant from roots to stomates (structures on surface of leaves that allow exchange of gasses between plants and the atmosphere) cools plants.

Other stress factors reduce the photosynthetic efficiency of the plant and limit yields. Leaf or stem diseases, insect infestations, and chemical phytotoxicity may reduce the vegetative surface area, slow photosynthate production, and reduce plant growth.

Reproductive Growth

Peanuts are indeterminate in growth habit. An indeterminate growth habit means that vegetative and reproductive growth occurs simultaneously. The plant must produce enough food to continue vegetative growth, as well as provide food for seed development.

The first flower develops about 30 to 40 days after emergence. Daily flower production is slow for the next 2 weeks. By mid-July, dozens of flowers may be visible each day on each plant. Temperature (about 86^o F) and moisture must be favorable for flowering to continue at a steady rate. Any environmental stress may interrupt flowering. Oftentimes, excessively high temperatures and drought stress can result in abortion of flowers and sterilization of pollen. These factors greatly influence yield potential.

Pollination and fertilization occur quickly in the flower. If fertilization of the ovule is successful, the peg begins to grow downward. It takes about 10 days for the peg to penetrate into the soil. A week later, the peg tip enlarges and pod and seed development begins. With favorable temperatures, nutrient, and moisture conditions, mature fruit develops in 9 to 10 weeks. For example, pollination of a flower on June 25 will result in a mature fruit (kernel) by approximately September 15, if no major stress occurs. Oftentimes, we experience moisture or heat stress at some point during the growth and maturation process, and this can delay maturity until later in the fall.

Weather or biotic stresses may interrupt normal flowering and fruit development. High or low temperatures and big differences between day and night temperatures may stop flowering and fruit development. Drought conditions will slow growth. Diseases, insects, or weeds that effectively reduce leaf or root surface area also may result in slower maturation.

Yield and quality are two major factors that influence variety selection. Growers with significant disease history may need to choose a variety with disease tolerance or resistance. Planting two or more varieties with different maturity dates permits efficient use of limited harvesting and curing equipment. Planting varieties with different genetic pedigrees reduces the risk of crop failure because of adverse weather or unexpected disease epidemics.

The selection of a variety should be based on more than 1 year's data. The 4-year average performance at two digging dates of our most popular peanut varieties is presented in Tables 3-1 and 3-2. Peanut were dug September 15 (DIG 1) and during the first week of October (DIG 2). Varietal characteristics are listed in Table 3-3.

NC 7 has an intermediate growth habit and matures up to 10 days earlier than NC 6. NC 7 produces a high percentage of extra-large kernels (ELK), has excellent flavor, and has a longer shelf life than other varieties. NC 7 is susceptible to most peanut insects and diseases but shows some tolerance to southern corn rootworm and leafspot.

NC 10C is a large-seeded Virginia-type variety with moderate resistance to Cylindrocladium black root rot (CBR) disease. It has a runner growth habit and CBR resistance similar to NC 8C, but is superior to NC 8C in pod and seed shape and size and milling quality. It is a few days later in maturity than NC 9. Discontinued in certified seed program.

NC-V 11 is a large-seeded Virginia-type peanut with a runner growth habit that is similar to NC 7 in maturity. Its major advantage is a high yield and value per acre. Although NC-V 11 has a lower percentage of fancy pods than NC 7 and NC 9, its percentage of extra large kernels is greater than for NC 9.

VA-C 92R is a high-yielding, large-seeded Virginia-type variety with prostrate vegetative growth. Under similar production practices, VA-C 92R maturity is considered to be about the same as NC 9 and NC-V 11. The percentage of fancy pods is less than many available varieties; however, percentage of ELKs is equal to NC 6 and higher than any other variety except NC 7. Seeds are cylindrical with tapered ends, pink in testa color, and smooth in appearance when mature. VA-C 92R is susceptible to the same disease and insect problems as NC 7.

VA 93B is a large-seeded Virginia-type peanut with resistance to Sclerotinia blight and characterized by an erect growth habit. Plants are similar in appearance and market grade characteristics to VA 81B. Pods are larger than those of NC-V 11 and VA-C 92R, while the percentage of extra large kernels is greater than that of NC 9, NC-V 11, and VA-C 92R. Discontinued in certified seed program.

NC 12C is a large-seeded CBR-resistant variety similar in maturity, plant type, seed size, shape, and color to NC 7. It also has a moderate level of resistance to early leafspot. NC 12C has high meat content and a thin hull with a tendency to darken upon roasting. Growers of NC 12C should take care to avoid pod damage at harvest and price penalty associated with excessive loose-shelled kernels. Under close plant spacing or conditions of high water availability, NC 12C produces excessive vine growth.

Gregory is a large-seeded Virginia-type peanut with growth habit intermediate between bunch and runner, pink seed coat, and a high percentage of jumbo pods and extra large kernels. It is susceptible to most diseases and insect pests. Because of its large seed size, Gregory has a high calcium requirement and may show reduced seedling vigor compared with other varieties.

VA 98R is a early maturing large-seeded peanut with some tolerance to Sclerotinia blight and is characterized by a runner growth habit. It is susceptible to all other peanut diseases in the region. It matures approximately 7 days earlier than NC 7 or NC 12C.

Perry is a large-seeded peanut with partial resistance to CBR and some tolerance of Sclerotinia blight and is characterized by a semi-runner growth habit. It matures later than NC 12C or NC-V 11 and similar to NC 10C.

Peanuts are best adapted to well-drained, light-colored, sandy loam soils, such as the Norfolk, Orangeburg, and Goldsboro sandy loam. These soils are loose, friable, and easily tilled with a moderately deep rooting zone for easy penetration by air, water, and roots. A balanced supply of nutrients is needed, as peanuts do not usually respond to direct fertilization. Soil pH should be in the range of 5.8 to 6.2. Peanuts grown in favorable soil conditions are healthier and more able to withstand climatic and biotic stresses.

Each grower should maintain soil maps to understand the potential of each field for crop production. Records over several years will help determine the suitability of fields for peanuts and other crops. This information will help identify the limiting factors of all soil resources.

Growth=growth habit (SR-semi-runner, SB-semi-bunch, R-runner, B-bunch)
Maturity=days to maturity; PR=pod retention
Seed color=seed coat color; STA=soil-type adaption (L=light, M=medium and H=heavy)
Calcium=ability of the seed to absorb calcium
Fertility=fertility requirements (N=nonsensitive; Mn=generally low in manganese
0=Same as NC 7; + =Higher than NC 7; - =Lower than NC 7)
 

Most peanut growers cannot plant peanuts every year in the most suitable soil types. A grower must plan the long-range use of fields considering rotations and disease, insects, and weed problems, along with all crops grown on the farm. Maximum income normally results when the best balance between all crop factors is found.

Crop Rotation

A long crop rotation program is essential for efficient peanut production. The peanut plant responds to both the harmful and beneficial effects of other crops grown in the fields. Research shows that long rotations are best for maintaining peanut yields and quality. A 3-year rotation with 2 years of grass-type crops has been effective in reducing nematode and soilborne disease problems and permits better control of many weeds. These crops respond to heavy fertilization but leave adequate residual nutrients for healthy peanut growth.

Peanuts following tobacco, soybeans, or other legumes and some vegetable crops, generally have higher disease losses than peanuts following corn, grain sorghum, or small grains.

Collar rot is frequently more severe if peanuts follow cotton. A small-grain cover crop can be planted to reduce the disease and nematode problems and to lessen the possibility of soil erosion during the winter. Growers with a short rotation program can expect a long-term buildup of diseases like southern stem rot, black root rot, and Sclerotinia blight.

Long-term rotation experiments were established in North Carolina in 1997. Peanut was planted in all rotation systems in 2000. Results from these studies underscore the value of long rotations on peanut yield and pest reaction. Results also suggested that soybeans were a better host for CBR development than peanut. Cotton was a better rotational crop than corn with respect to peanut yield.

Peanuts respond better to residual soil fertility than to direct fertilizer applications. For this reason, the fertilization practices for the crop immediately preceding peanuts are extremely important. Grass-type crops generally respond well to direct application of fertilizer. Growers can fertilize these crops for maximum yields and, at the same time, build residual fertility for the following crop of peanuts. Peanuts have a deep root system and are able to use soil nutrients that reach below the more shallow root zone of the grass-type crops.

The peanut crop is usually produced without applying any fertilizer materials during the production year. If peanut fields need fertilizers, they should be broadcast before land preparation. Fertilizing peanuts requires an understanding of the growth characteristics and nutrient needs of the plant and the ability of the soil to provide these needs.

Lime

Peanuts grow best on soils limed to a pH of 5.8 to 6.2, provided other essential elements are in balance and available to the plant. Dolomitic limestone is the desired liming material since it provides both calcium and magnesium. Strongly acidic soils reduce the efficient uptake and use of most nutrients and may enhance the uptake of zinc to potentially toxic levels. The efficiency of nitrogen fixation is reduced in acid soils. Molybdenum is an essential element in biological nitrogen fixation, and can be limiting at low soil pH. Soils too high in pH are not desirable because some elements are less available to the peanut plant. Manganese deficiency is often observed in fields that are overlimed.

Increased broiler production in North Carolina and use of manure as a fertilizer source has increased concern over micronutrient toxicity. Several peanut fields have exhibited severe and yield-limiting zinc toxicities. These toxicities are increased in fields with low pH. Zinc is more available at a lower pH. Maintaining soil pH around 6.0 is important in minimizing the adverse effects of zinc, and growers are cautioned not to overload fields with high levels of waste products. Micronutrient levels can build up quickly. Peanut generally are able to tolerate zinc indices of 250. However, zinc toxicity can occur with lower index values if soil pH is low.

Nitrogen

Roots of peanuts can be infected by Rhizobium bacteria. Nodules form on the roots at the infection sites. Within these nodules, the bacteria can convert atmospheric nitrogen into a nitrogen form that can be used by plants. This symbiotic relationship provides sufficient nitrogen for peanut production if the roots are properly nodulated. Direct applications of nitrogen to peanuts are not generally needed. However, application of nitrogen fertilizers can increase yield, but only when peanuts are not nodulating and nitrogen deficiency is obvious. Best results are obtained when applications are made early in the season. Peanut grown on deep sandy soils often respond to nitrogen fertilization and may lap middles more quickly.

Growers should inoculate their peanut seed or fields to ensure that adequate levels of Rhizobia are present in each field. Commercial inoculants can be added to the seed or put into the furrow with the seed at planting. In-furrow inoculants are available in either granular or liquid form. In the past few years, yield increases from inoculation have been observed, even in fields that were planted in peanuts within the past 2 years. In-furrow inoculants often provide a more uniform source of inoculum than hopper box treatments. This is especially true on virgin land, on land that has been out of peanut production for more than 3 years, or on land that is fumigated.

Potassium and Phosphorus

The most efficient and easiest way to apply potassium is to apply it to the crop preceding peanuts. This usually increases the yield of the preceding crop and allows the potassium to leach into the area where the peanut root system obtains most of its nutrients. Generally, fields testing medium or higher in a soil test do not need additional potassium applied for peanut production. However, if North Carolina Department of Agriculture and Consumer Services (NCDA & CS) recommendations indicate that potassium and phosphorus should be needed, then the appropriate levels of these nutrients should be added.

Many growers and researchers feel that high levels of soil potassium in the fruiting zone (the upper 2 or 3 inches of soil) result in more pod rot and interfere with the uptake of calcium by pegs and pods, which results in a higher percentage of "pops" and calcium deficiency in the seeds. If the potassium level is high in the fruiting zone, a higher rate of gypsum is needed.

Most of the peanut soils in North Carolina have adequate levels of phosphorus for good peanut production. Once a medium or higher level of phosphorus is achieved, it remains quite stable over a number of years. The addition of phosphorus-containing fertilizer to peanuts is generally not needed if it is applied to other crops in the rotation. However, soil testing is the only sure way to address this.

Calcium

Perhaps the most critical element in the production of large-seeded Virginia-type peanuts is calcium. Lack of calcium uptake by peanuts results in "pops" and darkened plumules in the seed. Seeds with dark plumules usually fail to germinate. A Scrubber Residue product has been developed and may be marketed by VFL Technology Corporation in 2002. This product has been researched in Virginia but not in North Carolina.

Calcium must be available for both vegetative growth and pod growth. Calcium moves upward in the peanut plant but does not move downward. Thus, calcium does not move through the peg to the pod and developing kernel. The peg and developing pod absorb calcium directly, so it must be readily available in the soil.

Adequate soil calcium is usually available for good plant growth but not for pod development or good quality peanuts. It is important to provide calcium in the fruiting zone through gypsum applications. Gypsum should be applied to all Virginia-type peanuts, regardless of the soil type or soil nutrient levels. The calcium supplied through gypsum application is relatively water soluble (compared to other calcium sources) and more readily available for uptake by peanut pegs and pods. Each pod must absorb adequate calcium to develop normally.

Gypsum is available in three forms—finely ground, granular, and phosphogypsum. Several additional by-product gypsums are now on the market. The by-product materials vary in elemental calcium content. Studies show that all forms of gypsum are effective in supplying needed calcium when used at rates that provide equivalent calcium levels in the fruiting zone. General recommendations for application rates are given in Table 3-4.

The use of gypsum on large-seeded peanuts is very effective in improving peanut seed quality and grades. Some research data indicate that high rates of gypsum may control or reduce the pod rot disease complex. Gypsum should not be broadcast before land preparation or before planting. This practice may result in the calcium being leached below the fruiting zone if there is high rainfall.

The best results are obtained when gypsum is applied in late June or early July. The availability of calcium supplied by gypsum application is also influenced by the amount of rainfall. Moisture is needed to make gypsum soluble and make the calcium available to the peanut fruit. In unusually dry years, peanuts may show symptoms of calcium deficiency, even when recommended rates of gypsum are applied.

Manganese and Boron

Two other elements often found to be deficient in peanuts are manganese and boron. Manganese deficiency usually occurs when soil is overlimed. Increasing the soil pH reduces the plant's uptake of manganese. The symptom of manganese deficiency is interveinal chlorosis. This symptom can be confused with carryover of atrazine (from corn) or Cotoran/Meturon (from cotton). A deficiency can be corrected by a foliar application of manganese sulfate. The usual practice is to apply Tecmangam at 3½ to 4 pounds per acre when the deficiency is observed.

Boron plays an important role in kernel quality and flavor. Boron deficiency may occur in peanuts produced on deep, sandy soils. Deficient kernels are referred to as having hollow hearts. The inner surfaces of the cotyledons are depressed and darkened and are graded as damaged kernels. A general recommendation is to apply half a pound of boron per acre as a foliar spray in early July. Several formulations of boron are available. Some growers apply boron with their preplant incorporated herbicides and others have boron added to their fertilizers.

Growers are advised to make sure boron sources provide sufficient elemental boron. Several liquid boron and manganese formulations are available. Although these sources are more convenient to use than dry products, they often contain only a fraction of the desired boron or manganese that may be needed.

Land Preparation

Historically, peanut growers have used the moldboard plow equipped with trash covers to prepare a smooth, uniform, and residue-free seedbed for planting. The burial of old crop residue and weed seed has been effective in the long-term suppression of soilborne diseases and short-term suppression of some weed problems. However, there is a growing trend in reduced-tillage crop production in North Carolina, and some growers are successfully using these practices.

In conventional tillage, land preparation begins with the disposal or management of the crop residue from the previous crop. In order to promote decomposition during the winter, crop litter should be chopped or shredded and disked lightly. Seeding a cover crop can help reduce soil erosion during the winter months. Lime, phosphorus, and potassium can be applied at this time, if needed.

There is concern about stratification of nutrients in reduced-tillage systems. For example, repeated applications of potassium in reduced-tillage cotton may result in excessive amounts of this nutrient in the pegging zone if peanut is planted in a reduced-tillage system. Growers are encouraged to test soils for excessive potassium levels and incorporate this nutrient with tillage, if needed.

In conventional tillage, harrowing to break up clods and leave a smooth, firm, and clean seedbed usually follows plowing. Many peanut growers are bedding their peanut fields either in the fall or spring. Beds should be prepared several weeks before planting to allow them to warm up and gain uniform moisture levels. Many growers prefer planting on raised beds rather than flat planting. The beds often give faster germination and early growth, provide drainage, and may reduce pod losses during digging.

Planting

While the best planting dates for peanuts in North Carolina are generally between April 20 and May 10, it is best to plant according to field conditions and expected weather patterns rather than calendar dates. As a general rule, peanuts should be planted as soon as the risk of a killing frost is over. Varieties grown in North Carolina require 142 to 165 days to reach full maturity. Early plantings usually give higher yields, more mature pods, and permit earlier harvesting. However, planting date can affect disease and insect development (see Chapters 5 and 6).

The Transition from Conventional Tillage to Reduced Tillage

Reduced-tillage systems can be as successful as conventional tillage systems. However, peanut yields in reduced-tillage systems often are less consistent than in conventional tillage systems. Results from a survey of tillage practices in North Carolina are listed in Table 3-5. Growers planning on making the transition from conventional tillage systems to reduced-tillage systems should consider the following:

• Stand establishment may be more difficult depending upon crop residue and existing winter vegetation. There is also some concern about excessive "blow out" on certain soils, most notably clayey soils. This can create a trench in the seed furrow that may cause stand reductions if rainfall is excessive. This can be an even greater problem if peanut is planted flat.
• Early-season weed management will be critical. Appropriate burndown herbicides will have to be selected for adequate weed control (see Chapter 4 on weed management decisions). Certain weeds, such as cutleaf evening primrose, marestail, and swinecress, are much easier to control when small. Preplant applications of 2,4-D in February or March can be an inexpensive and highly effective option and can reduce pressure on burndown herbicides, such as paraquat (Gramoxone Max) or glyphosate (Roundup Ultra), which are often applied at or shortly before planting. Research suggests that peanut are tolerant to 2,4-D applied relatively close to planting. However, peanut seed is the most expensive single input in peanut production. Therefore, growers are cautioned not to plant peanuts within 3 weeks of 2,4-D application. Rainfall is often required to dissipate residues of 2,4-D.
• Benefits of preplant-incorporated herbicides may be minimized. In strip-tillage systems incorporation is possible, but only in the tilled area. Weeds that are routinely controlled by dinitroaniline herbicides may become a greater problem if growers begin relying on preemergence herbicides. Pursuit, which is often incorporated for purple and yellow nutsedge control, will be less effective when not incorporated.
• Research suggests that thrips and other insects may be less of a problem in reduced-tillage systems. Effects of tillage on black root rot, Sclerotinia blight, white mold, leafspots, and tomato spotted wilt virus are not fully understood in North Carolina. Research in Georgia suggests that tomato spotted wilt virus may occur less in reduced-tillage systems, compared with conventional systems. There appears to be no major shift in disease incidence when comparing reduced and conventional tillage systems (see Chapter 6, Peanut Disease Management).
• While still widely debated, some research suggests that digging peanuts may be more difficult in reduced-tillage systems. However, some growers who have successfully adopted reduced-tillage practices in North Carolina indicate that this is not a problem. Long-term reduced-tillage systems often enhance soil tilth and ease of digging. However, response during transition years must be considered. Digging peanut on a bed may be easier than digging peanut on flat ground.
• Harvest efficiency may be reduced depending upon the amount of residue remaining from the preceding crop. Several growers have indicated that cotton stalks can cause problems. However, this does not seem to be a major deterrent to reduced-tillage peanut production.
• It is recommended that fertilizers needed for peanuts be applied to the previous crop. This becomes more critical in reduced-tillage systems where lime, potassium, and phosphorus cannot be incorporated at planting. Current recommendations indicate that these elements can increase pod rots and that potassium can interfere with calcium uptake by developing pegs if it is not incorporated throughout the soil profile.
• Overall management of peanuts, especially early in the season, may increase for growers adopting reduced-tillage systems. This applies especially to weed management and the requirement of controlling winter weeds with herbicides that are normally controlled by tillage.

A variety of reduced-tillage studies are being conducted in peanuts throughout the state. Results continue to demonstrate that response of peanut to tillage can vary from location to location, depending upon soil characteristics, equipment, and the degree of tillage performed. Growers should experiment with tillage on a small scale on their farms before adopting reduced tillage on a high percentage of their peanut acres.

Peanuts should not be planted until the soil temperature at a 4-inch depth is 65° F or above at noon for 3 days. Favorable weather for peanut germination should also be forecast for the next 72 hours after planting. The soil should be moist enough for rapid water absorption by the seed. The planter should firm the seedbed so there is good soil-to-seed contact.

Seeding rates vary considerably among North Carolina peanut producers. Seeding rates may vary according to seed quality, but most growers seed at rates exceeding 100 pounds of seed per acre. Growers should average planting three to four seeds per foot of row. Growers using air planters should be able to reduce seeding costs by using a 3- to 4-inch seed spacing. Growers planting small-seeded runner varieties can decrease seeding rates to approximately 85 pounds per acre and still establish an adequate stand. The key is to obtain a plant population of three to four plants per foot of row.

Table 3-6 provides the conversion of seed per foot of row to pounds per acre in order to establish the desired plant population for a given variety. Germination percentage is not considered in this conversion, but should be considered when making plans for planting.

Table 3-6. Pounds of Peanut Seed Required Per Acre to Provide 3, 4, and 5 Seeds per Foot of Row on 36-inch Rows

		Pounds Per Acre (36-Inch Rows)
Variety	Seed/lb	3 Seeds/ft	4 Seeds/ft	5 Seeds/ft
NC 7 NC9 NC 10C NC-V 11 VA 93B NC 12C VA-C 92R Gregory VA 98 R Perry	500 600 600 625 575 460 550 450 575 525	87 73 73 70 76 95 79 97 75 83	116 97 97 93 101 126 106 129 101 111	145 121 121 116 126 158 132 161 126 138

In the Southeast, less tomato spotted wilt virus has been associated with twin row plantings than single rows. Similar results have been observed in North Carolina. Higher plant populations and closer row spacings often result in less virus.

Growers in several counties produce peanuts on twin rows. Although higher seeding rates are needed and higher rates of in-furrow insecticide may be required, twin rows tend to produce a greater taproot crop rather than a limb crop. This can improve uniformity of harvested peanuts, and in a dry season when peanut vines do not lap, higher yields in twin row plantings often occur. One of the detriments of twin row plantings, especially with the higher plant populations, is excessive vine growth, which can make digging more difficult.

Adequate plant available water throughout the life cycle of peanut is important for optimum growth and development. Extremes in water available, either as drought or flood, can have tremendously negative impacts on yield and quality of peanut. Likewise, pest infestation and severity of damage from these pests is influenced by available water, either in the form of rainfall or irrigation. Understanding how environmental conditions, and in particular irrigation, affect pest complexes is important in developing appropriate management strategies. Although in North Carolina less than 20 percent of peanut acreage is irrigated, irrigation is a powerful production tool. Irrigation minimizes risk and enhances consistency of yield. Additionally, irrigation improves consistency of pesticide performance and in many ways the predictability of pest complexes. The major production and pest management practices employed in North Carolina peanut production with brief comments on how irrigation or ample rainfall affect efforts to manage pests or supply peanut with adequate nutrition (Table 3-7).

Maturity affects flavor, grade, milling quality, and shelf life. Not only do mature peanuts have the quality characteristics that consumers desire, they are worth more to the producer. However, the indeterminate fruiting pattern of peanuts makes it difficult to determine when optimum maturity occurs. The fruiting pattern can vary considerably from year to year, mostly because of the weather. Therefore, each field should be checked before digging begins.

Many attempts have been made to develop precise methods to predict peanut maturity. The most widely used methods are the shell-out method and the hull-scrape method. The hull-scrape method, currently the most objective method, requires the use of a peanut profile board that is available at county Extension centers. It is important to follow a specific maturity prediction method to achieve maximum dollar value for peanuts.

Heat units or growing degree days are being evaluated as a means of determining maturity. One growing degree day (base 56^o F) is accumulated when the average daily high and low temperature is 57^o F. If the average daily high and low temperatures were 76^o F, then 20 growing degree days would be accumulated for that day. Research has shown that 2,600 growing degree days are needed for earliest varieties to mature.

Based on results from studies evaluating the influence of digging dates on six varieties grown at several locations in North Carolina, growers can loose between 4 and 19 pounds pod yield per acre per day by digging too soon (data not shown). When grades are considered, growers can loose $6 to $11 per acre per day (quota peanuts). These trends can also be seen in the PVQE data discussed at the beginning of this chapter (compare yield and market grade characteristics for DIG 1 and DIG 2). A balance between digging too soon and digging before frost or inclement weather needs to be reached in order to maximize yield and quality.

Some growers harvest immature peanuts because they fear freeze damage. The risk of freeze injury can be reduced by planting as soon as weather and soil conditions are favorable. Land preparation should be completed early so that little time is lost at planting time. Growers should get the better seed available for early planting. Irrigate fields to eliminate the danger of drought conditions, which delay maturity. At harvest, growers should follow the weather forecast closely and not dig peanuts when freezing temperatures are expected. It is also important to have adequate harvesting and curing equipment so that the peanut crop can be handled within a reasonable period of time.

In 1997, interest in producing runner-type peanuts in North Carolina increased. This demand has since declined but concerns about future farm legislation and the federal peanut program could rekindle demand for production of runner market types in the Virginia-Carolina region. Part of this interest relates to market demand while an appealing aspect of growing runners is potential savings in productions costs relative to Virginia-type peanuts (approximately 80 to 90 pounds of seed for runners versus 115 to 140 pounds of seed for Virginia peanuts and lower requirements for supplemental calcium by runner peanuts). However, Virginia-type peanuts offer a premium based on the percentage of extra large kernels. Also, Virginia-type peanut varieties may mature earlier than many of the runner peanut varieties.

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county Cooperative Extension agent.