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

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

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

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

grower sprayed glyphosate on a sesame crop with no leaves to eliminate volunteer sorghum and weeds within the crop and the glyphosate also killed the sesame without leaves. It was postulated that the capsules and stems absorbed the glyphosate and it translocated to the roots. In addition, the lack of leaves allowed the glyphosate to reach the lower stem and capsules. Subsequent testing was done at PM when the leaves had dropped naturally.

With the above field observations, research was conducted to answer some questions. Previous experience, when sesame was swathed at maturity, had shown that if the sesame was cut earlier than PM, yield and quality of the seed would be reduced. Other experience had shown that even though sesame had been bred with improved non-dehiscence, weather could reduce the yield. Therefore, the objective of this research was to identify herbicides that may help promote desiccation of sesame and the effect of these herbicides on sesame development and also determine the optimum application timing to determine the amount of loss if the harvest aid was applied too early or too late.
