Carl E. Motsenbocker

Evaluation of biological and chemical seed treatments to improve stand of snap bean across the southern United States

Thirteen bacterial, four fungal, and four chemical fungicide seed treatments were evaluated one or more years in multiple field locations across the southern United States. Snap bean seed was treated in bulk with fungicides and most biocontrol agents, shipped to individual locations, and stored until planting or treated on site immediately before planting. Populations of biocontrol agents on seeds were assayed after seed treatment and planting. Analysis of variance of percent plant stand at 28 days after sowing revealed highly significant (P<0.01) effects of location and treatment in 1996, 1997 and 1998. A treatment by location interaction also occurred in 1996 and 1997. When treatments tested in two or three years were analyzed together, no biological seed treatments significantly affected percent stand. Carboxin significantly increased percent stand compared with nontreated seed in data sets combined from 1997 and 1998 and 1996 to 1998; captan and carboxin plus metalaxyl also increased stand in 1997 and 1998. Improvements in efficacy and consistency of biological seed treatments are necessary before they can be recommended for use in snap bean production.

Anatomy of fruit detachment in tabasco pepper (Capsicum frutescens, Solanaceae)

amined in an easy-pick and a hard-pick line of Tabasco peppers. The anatomical parameters examined included: sclereid development, size and shape of parenchyma cells, volume of intercellular space, and crystal development across the diameter of the separation zone. During ripening, sclerification proceeded centripetally in both lines but was more pronounced in the hard pick line. Parenchyma cells in the central zone of both lines were nearly isodiametric and did not enlarge significantly during fruit maturation. In the peripheral zone, parenchyma cells of easy-pick fruits elongated significantly more than corresponding cells in the hard-pick line. There was a greater volume of intercellular space in the central zone than the peripheral zone of both lines, but more so in the easy-pick line. The number of crystals in the central zone decreased in both lines during fruit ripening. This study suggests that several anatomical factors are associated with ease of fruit separation from the peduncle in pepper.