Influence of the Sulphur Application Method on Pests, Diseases and Natural Enemies in a Greenhouse Pepper Crop

Nowadays, sulphur is used frequently on greenhouse production in the Mediterranean area for its acaricide and anti-oidium properties, and is applied mainly by a duster (powder sulphur) or sprayed (wattable powder, liquid or colloidal sulphur). The use of sulphur evaporators is a very common technique in The Netherlands and also in some areas of the Spanish south-east (Murcia), for pepper and rose crops, not of common use in Almeria. However, although it is expected to increase its use in the short term due to the increase of biological control on greenhouse cultivation. An experiment has been conducted on a pepper greenhouse crop with the aim of analyzing the influence of the sulphur application method (duster, spraying or evaporation) on: a) the incidence of pests, diseases and natural enemies; b) crop yield and c) evaluating the risk of evaporated sulphur inhalation. None of the three sulphur application methods affected the yield or establishment of the biological control, although there was a small decrease in the populations of Amblyseius swirskii in the evaporation and dusting powder treatments, in relation to spraying. The three application methods efficiently prevented oidium (Leveillula taurica (Lev.) Arn.), the higher efficiency with evaporated and dusting powder sulphur. No toxic levels for workers have been measured of sulphur dioxide in the evaporated sulphur treatment.