**7. Field studies**

5.**Stopping vivipary.** Under some conditions, there is vivipary in sesame—the seeds will germinate in the capsules (**Figure 13**). Not only are the germinated seeds lost, but the roots of the seedlings bind the rest of the seed and keep it in

*Pests, Weeds and Diseases in Agricultural Crop and Animal Husbandry Production*

Many growers have felt that the opening of the capsules allows water to enter and germinate the seed. The opposite occurs. Seeds in open capsules do not germinate because the moisture will evaporate out of the capsule before the seed can germinate. Vivipary occurs in closed capsules. It is believed that this is a dispersal mechanism to open the capsule and allow the seed to fall out. The exception in dry capsule is if the tip of the capsule has a minimum opening. Not only can there be vivipary, but there is also the danger of mold forming inside the dry capsules. When there is vivipary, the seedlings persist as the capsules continue to dry. Vivipary is controlled genetically through seed dormancy with some varieties having a greater propensity than others. Vivipary is rare in the USA because normally at harvest the night temperatures are below 15°C, the minimum germination temperature. Glyphosate will kill the sesame plants and

6.**Prepare to plant a new crop**. In many areas of the USA, wheat and sesame are double cropped. The earlier the sesame is harvested, the earlier the wheat can

The first testing in the USA was done by D.M. Yermanos (personal communication, 1982) in California in the mid-1970s. He used paraquat-dichloride; however, the varieties at the time were shattering and leaving the plants standing even for 2 weeks longer resulted in lower yields than cutting and drying in shocks. In addition, a paraquat-dichloride application at harvest would not be acceptable in the US food market since there would be the potential to get the paraquatdichloride on the seed in an open capsule. Paraquat-dichloride, a restricted use pesticide, is considered to have oral, dermal, and inhalation toxicity to humans (skull and cross bone symbol) [36]. In 1975, St. Andre et al. [37] reported that diquat-dibromide, either alone or in combination with products called 'Bolls Eye' or

There was no additional harvest aid research until 2003 after the 2002 harvest season showed that weather had significantly affected sesame yield in some areas. Getting the crop out of the field earlier became a priority. Many felt that sesame should follow the cotton harvest pattern of first defoliating the plants and then drying the sesame down. In 2003, test strips in a nursery were sprayed with paraquat-dichloride, diquat-dibromide, glyphosate, carfentrazone-ethyl, and pyraflufen-ethyl when the plants had stopped flowering but still had their leaves. Paraquat-dichloride and diquat-dibromide caused spotting on the leaves where the drops contacted the plants; however, this did not kill the sesame. The amount of spotting was greater at the top of the plant than at the bottom. Glyphosate killed the sesame but retained its leaves and did not mature the seed in the upper capsules.

At this point in time, it was thought that the sesame plant had to have the leaves to allow the herbicide (particularly glyphosate) to be absorbed and translocated to the roots. However, sesame is different from cotton in that there is sesame germplasm that will allow plants to self-defoliate as the capsules mature. Parallel to this, a

the capsule when combined.

stop vivipary.

be planted.

**220**

**6. Harvest aid research in the USA**

'Dinitro", had potential to serve as dessicants in sesame.

Carfentrazone-ethyl and pyraflufen-ethyl produced no visible effect.

The weather was variable and it was very difficult to predict when PM would occur to schedule the sprayings. As mentioned previously, PM proceeds between 1 and 7 node pairs per week depending on the weather. The variability can be exacerbated when planting sesame under pivots. In several years of successive droughts, the moisture below 30 cm was depleted and the soil was very dry; therefore, no roots could penetrate the soil. Water in Texas can be scarce and when irrigating with an overhead irrigation system pivot, the minimum amount necessary is used. The results are roots that are often in the top 20–30 cm of soil. Irrigation is terminated when the crop stops flowering. If there is hot weather with low humidity, the sesame can go to drydown in less than 2 weeks instead of the normal 5–6 weeks. One harvest aid experiment in Uvalde was cancelled because the plants were in the late drydown stage at the predicted 1 week before PM. In another study, near Lorenzo, Texas, the crop was sprayed at least 2 weeks before PM because a cold front had delayed PM and the plants still had their leaves.

#### **7.1 Materials and methods**

#### *7.1.1 Research sites*

Field studies were conducted from 2006 through 2008 near Uvalde (29.468° N, 99.7061° W) in the south Texas sesame growing region and near Lorenzo (33.6684° N, 101.5354° W) in the Texas High Plains sesame growing region to evaluate sesame response to harvest aids. Soil type at Uvalde was a Winterhaven silty clay loam (fine-silty, carbonatic, hyperthermic Fluventic Ustochrepts) with less than 1.0% organic matter and pH 7.8. Soil type at Lorenzo was an Amarillo sandy clay loam (fine-loamy, mixed, thermic Aridic Paleustalf) with 0.8% organic matter and pH 7.8.

#### *7.1.2 Herbicides and application*

A randomized complete-block experimental design was used, and treatments were replicated three times. Treatments consisted of a factorial arrangement of four herbicide treatments (carfentrazone-ethyl, diquat-dibromide, glufosinateammonium, and glyphosate) at two rates. A non-treated control was included for comparison. Herbicides included glyphosate (Durango® Herbicide,

Dow AgroSciences, 9330 Zionsville Rd., Indianapolis, IN 46268 in south Texas and Roundup Weathermax, Bayer CropScience, 800 N. Lindberg Blvd., St. Louis, MO 63167 in the Texas High Plains) at 0.63 and 0.84 kg ae ha<sup>1</sup> ; diquat-dibromide (Reglone® Herbicide, Syngenta Crop Protection, Inc., P.O. Box 18,300, Greensboro, NC 27409) at 0.28 and 0.56 kg ai ha<sup>1</sup> ; glufosinate-ammonium (Bayer CropScience) at 0.47 and 0.58 kg ai ha<sup>1</sup> ; and carfentrazone-ethyl (FMC, 1735 Market St., Philadelphia, PA 19103) at 0.018 and 0.035 kg ai ha<sup>1</sup> . Carfentrazoneethyl was only evaluated in 2006 and 2008 at Lorenzo.

*7.1.4 Data analysis*

**8. Results**

the drydown and yield data analysis.

*DOI: http://dx.doi.org/10.5772/intechopen.91011*

treatment and application timing.

ammonium at 0.47 and 0.58 kg ai ha<sup>1</sup>

**8.1 Sesame drydown**

and 0.84 kg ae ha<sup>1</sup>

**223**

*8.1.1 Lorenzo*

Data for percentage of sesame drydown were transformed to the arcsine square

Since weather conditions and sesame development varied from year-to-year and across locations no attempt was made to combine data across years or locations. Also, in some years (2006 at Lorenzo, 2007 at Uvalde), the PRE PM stage occurred sooner than anticipated and a timely herbicide application was not made. Since drydown in 2008 at Uvalde occurred so quickly due to the extreme drought conditions, an accurate assessment of sesame drydown could not be obtained. An herbicide treatment by application timing interaction was noted in each year for drydown and sesame yield; therefore, data are presented separately for herbicide

In 2006, when the PM applications were compared, diquat-dibromide and

carfentrazone-ethyl (**Table 2**). With the POST PM timing, a rate effect was noted with carfentrazone-ethyl, diquat-dibromide, and glyphosate but not glufosinateammonium. The high rates of glyphosate and diquat-dibromide improved drydown 44–54% while the high rate of carfentrazone-ethyl improved drydown 29% when compared with the lower rates while virtually no difference was noted between glufosinate-ammonium rates. The high rate of glyphosate resulted in the greater drydown than other herbicides. All treatments improved drydown over the untreated check. In 2007 at the PRE PM and PM stage, diquat-dibromide at 0.28 and 0.56 kg ai ha<sup>1</sup> accelerated sesame drydown greater then glufosinate-

glufosinate-ammonium performed similarly at the POST PM stage (**Table 2**). Diquat-dibromide at either rate applied POST PM provided ≥87% sesame drydown. Sesame drydown with the untreated check was ≤39% at all application stages. In 2008 at the PRE PM stage, diquat-dibromide at 0.28 and 0.56 kg ai ha<sup>1</sup> and glufosinate-ammonium at 0.47 kg ha<sup>1</sup> produced 63–80% drydown while both rates of glyphosate and the untreated check resulted in <10% drydown (**Table 2**). Carfentrazone-ethyl at 0.018 and 0.035 kg ai ha<sup>1</sup> was intermediate in sesame

; however, the high rate of glyphosate and both rates of

, which was greater than glyphosate at 0.63

glufosinate-ammonium accelerated drydown more than glyphosate or

root prior to analysis; however, non-transformed means are presented because arcsine transformation did not affect interpretation of the data. Data were subjected to analysis of variance (ANOVA) and analyzed using SAS PROC MIXED with locations and years designated as random effects in the model. A mixed model was chosen because the actual environments experienced at both locations in Texas where the experiments were conducted are unlikely to occur again in the future. Allowing the four environments to be random allows estimates of treatment responses to be made over a range of environments. Treatment means were separated using Fisher's Protected LSD at P ≤ 0.05. The untreated check was used for yield comparison and a visual comparison for sesame drydown and was included in

*Effects of Harvest Aids on Sesame (*Sesamum indicum *L.) Drydown and Maturity*

These herbicides were applied prior to physiological maturity (PRE PM), at physiological maturity (PM), or after physiological maturity (POST PM). The PRE PM treatment was not applied in 2006 at Lorenzo or 2007 at Uvalde due to sesame development that was farther alone than anticipated. At Lorenzo, the PRE PM treatments were applied 99 and 103 DAP in 2007 and 2008, respectively; PM treatments applied 97, 105, and 112 DAP in 2006, 2007, and 2008, respectively; and POST PM treatments applied 113, 112, and 121 DAP in 2006, 2007, and 2008, respectively. At Uvalde, the 2006 treatments were cancelled because drydown developed much faster than anticipated. The PRE PM treatments in 2008 were applied 104 DAP; PM treatments were applied 102 and 110 DAP in 2007 and 2008, respectively; and POST PM treatments were applied 114 and 119 DAP in 2007 and 2008, respectively.

In the original concept in designing the experiment, herbicide sprays would be done within 2 weeks: the PRE PM followed by PM a week later followed by POST PM a week later. However, scheduling and weather problems prevented the exact 1 week intervals. Sprayings were postponed when the sesame was wet or rains were imminent.

Plot size was five rows (76 cm apart) by 9.1 m in south Texas (Uvalde) and four rows (101 cm apart) by 7.3 m in the Texas High Plains (Lorenzo). Only the two middle rows were sprayed and the other rows were untreated and served as buffers.

Herbicides were applied in water using a CO2-pressurized backpack sprayer with either Teejet 11002 DG, TeeJet® 11002DG, or Turbotee 110015 flat fan spray tips (Teejet Spraying Systems Co., P.O. Box 7900, Wheaton, IL 60188) nozzles calibrated to deliver 190 L/ha at 180 kPa at Uvalde and Turbotee 110015 calibrated to deliver 140 L/ha at 207 kPa at Lorenzo.

#### *7.1.3 Sesame plantings, observations, and harvest*

The sesame variety 'S29' was planted at Lorenzo in 2006; however, in 2007 and 2008 at both locations 'S32' was grown since it was the main variety used in all sesame growing areas of the US at that time [17]. Planting dates at the Uvalde location were June 2 in 2007 and May 30 in 2008 while at the Lubbock location, sesame was planted May 26 in 2006, June 18 in 2007 and June 26 in 2008. Each sesame cultivar was seeded approximately 2.0 cm deep at 9 kg/ha at both locations.

Sesame drydown was evaluated 7–14 days after herbicide application based on a scale of 0 (no drydown, plants still green) to 100 (complete drydown, no green tissue). Due to the extremely dry conditions at Uvalde in 2008, an accurate assessment of drydown could not be obtained. Plants in each plot were hand-cut, bagged, and threshed with a harvester to obtain sesame yield. Sesame yields were not obtained from the PRE PM and PM diquat-dibromide and glufosinate-ammonium treatments at Uvalde in 2008 because they had been dry long before the other treatments and comparisons were invalid. One of the problems with the methodology was that all plots were harvested at the same time regardless of treatment drydown (other than 2008 as stated above).

*Effects of Harvest Aids on Sesame (*Sesamum indicum *L.) Drydown and Maturity DOI: http://dx.doi.org/10.5772/intechopen.91011*

#### *7.1.4 Data analysis*

Dow AgroSciences, 9330 Zionsville Rd., Indianapolis, IN 46268 in south Texas and Roundup Weathermax, Bayer CropScience, 800 N. Lindberg Blvd., St. Louis, MO

These herbicides were applied prior to physiological maturity (PRE PM), at physiological maturity (PM), or after physiological maturity (POST PM). The PRE PM treatment was not applied in 2006 at Lorenzo or 2007 at Uvalde due to sesame development that was farther alone than anticipated. At Lorenzo, the PRE PM treatments were applied 99 and 103 DAP in 2007 and 2008, respectively; PM treatments applied 97, 105, and 112 DAP in 2006, 2007, and 2008, respectively; and POST PM treatments applied 113, 112, and 121 DAP in 2006, 2007, and 2008, respectively. At Uvalde, the 2006 treatments were cancelled because drydown developed much faster than anticipated. The PRE PM treatments in 2008 were applied 104 DAP; PM treatments were applied 102 and 110 DAP in 2007 and 2008, respectively; and POST PM treatments were applied 114 and 119 DAP in 2007 and

In the original concept in designing the experiment, herbicide sprays would be done within 2 weeks: the PRE PM followed by PM a week later followed by POST PM a week later. However, scheduling and weather problems prevented the exact 1 week intervals. Sprayings were postponed when the sesame was wet or rains were

Plot size was five rows (76 cm apart) by 9.1 m in south Texas (Uvalde) and four rows (101 cm apart) by 7.3 m in the Texas High Plains (Lorenzo). Only the two middle rows were sprayed and the other rows were untreated and served as buffers. Herbicides were applied in water using a CO2-pressurized backpack sprayer with either Teejet 11002 DG, TeeJet® 11002DG, or Turbotee 110015 flat fan spray tips (Teejet Spraying Systems Co., P.O. Box 7900, Wheaton, IL 60188) nozzles calibrated to deliver 190 L/ha at 180 kPa at Uvalde and Turbotee 110015 calibrated

The sesame variety 'S29' was planted at Lorenzo in 2006; however, in 2007 and 2008 at both locations 'S32' was grown since it was the main variety used in all sesame growing areas of the US at that time [17]. Planting dates at the Uvalde location were June 2 in 2007 and May 30 in 2008 while at the Lubbock location, sesame was planted May 26 in 2006, June 18 in 2007 and June 26 in 2008. Each sesame cultivar was seeded approximately 2.0 cm deep at 9 kg/ha at both locations. Sesame drydown was evaluated 7–14 days after herbicide application based on a scale of 0 (no drydown, plants still green) to 100 (complete drydown, no green tissue). Due to the extremely dry conditions at Uvalde in 2008, an accurate assessment of drydown could not be obtained. Plants in each plot were hand-cut, bagged, and threshed with a harvester to obtain sesame yield. Sesame yields were not obtained from the PRE PM and PM diquat-dibromide and glufosinate-ammonium treatments at Uvalde in 2008 because they had been dry long before the other treatments and comparisons were invalid. One of the problems with the methodology was that all plots were harvested at the same time regardless of treatment

; diquat-dibromide

. Carfentrazone-

; glufosinate-ammonium (Bayer

; and carfentrazone-ethyl (FMC, 1735

63167 in the Texas High Plains) at 0.63 and 0.84 kg ae ha<sup>1</sup>

Greensboro, NC 27409) at 0.28 and 0.56 kg ai ha<sup>1</sup>

ethyl was only evaluated in 2006 and 2008 at Lorenzo.

CropScience) at 0.47 and 0.58 kg ai ha<sup>1</sup>

to deliver 140 L/ha at 207 kPa at Lorenzo.

*7.1.3 Sesame plantings, observations, and harvest*

drydown (other than 2008 as stated above).

2008, respectively.

imminent.

**222**

(Reglone® Herbicide, Syngenta Crop Protection, Inc., P.O. Box 18,300,

*Pests, Weeds and Diseases in Agricultural Crop and Animal Husbandry Production*

Market St., Philadelphia, PA 19103) at 0.018 and 0.035 kg ai ha<sup>1</sup>

Data for percentage of sesame drydown were transformed to the arcsine square root prior to analysis; however, non-transformed means are presented because arcsine transformation did not affect interpretation of the data. Data were subjected to analysis of variance (ANOVA) and analyzed using SAS PROC MIXED with locations and years designated as random effects in the model. A mixed model was chosen because the actual environments experienced at both locations in Texas where the experiments were conducted are unlikely to occur again in the future. Allowing the four environments to be random allows estimates of treatment responses to be made over a range of environments. Treatment means were separated using Fisher's Protected LSD at P ≤ 0.05. The untreated check was used for yield comparison and a visual comparison for sesame drydown and was included in the drydown and yield data analysis.
