Many species of Trichoderma produce secondary metabolites such as volatile organic compounds (VOCs) that reduce plant diseases and promote their growth. In this work we evaluated the antagonistic effects of VOCs released by eight strains of two Trichoderma species against Pyrenophora teres Drechsler, the causal agent of barley net blotch. Antagonism was estimated based on the percentage of mycelial growth inhibition according to the confronted cultures method. VOCs extraction and identification were performed by gas chromatography and mass spectrometry, through different methodologies for VOCs emitted by antagonists and pathogens alone or when confronted. VOCs produced by all Trichoderma strains inhibited mycelial growth of the pathogen in a range of 3 to 32%, showing weak and unpigmented mycelia with vacuolization. In addition, P. teres stimulated the release of VOCs by both Trichoderma species. The major groups of VOCs detected were sesquiterpenes, followed by diterpenes, terpenoids and eight-carbon compounds. This is the first report about characterization of volatiles emitted by Trichoderma in the presence of P. teres.

The excessive use of chemical products to control thrips and the tomato spotted wilt virus (TSWV) is not only harmful to human health, the environment, and biodiversity, but also the resistance these generate in insects turns them inefficient in the long run. Consequently, to achieve sustainable and residue-free production, control alternatives must be explored. This work proposes the use of Beauveria bassiana (BB) in combination with inter-row cover (IC) to reduce the population of thrips and the incidence of TSWV on bell pepper. For this purpose, a trial was carried out in a bell pepper greenhouse, consisting of four randomly distributed treatments with four repetitions of 66 plants each. The treatments assayed were: T (without BB inoculation or IC), TC (without BB inoculation and with IC), B (inoculated with BB), and BC (inoculated with BB and IC). The B. bassiana CEP147 strain was used based on its effectiveness in previous laboratory tests. After detecting one thrips per flower, five foliar spray applications were made at weekly intervals. The trial lasted 4 months. During this time, the number of thrips in the three central plants of each repetition, the presence of symptoms compatible with TSWV, as well as the number of fruits, and their weight, length, width and health were monitored weekly. Between the fourth and sixth weeks after the last application, a significant reduction in the population of total thrips (nymphs + + adults) was observed in both treatments B and BC compared to T and TC. In addition, plants with symptoms compatible with TSWV were very scarce, and the fruits showed significant differences in their quality parameters, producing the longest and heaviest in the BC treatment. The results showed that combining biological and cultural control makes sustainable pepper production possible.