In vitro evaluation of the antagonistic activity of native strains of Trichoderma spp. against Fusarium spp.

Five samples of agricultural soil and five samples of Aloe barbadensis (P. Mill., 1768) plants with symptoms of wilt and root necrosis were collected in five localities of the state of Tamaulipas, México. The aims of this study were the morphological identification, molecular identification and in vitro evaluation of the antagonistic activity of Trichoderma spp. on Fusarium spp. Four strains of Trichoderma asperellum, one strain of Trichoderma harzianum and five strains of Fusarium oxysporum were identified by morphological and molecular methods. The evaluation of the antagonistic activity of T. harzianum isolate (TP) showed the highest inhibition in Fusarium spp. (78.80%). The evaluation of the antagonistic activity of Trichoderma spp. extracts in Fusarium spp. did not show significant differences between treatments (P ≤ 0.05), with Trichoderma growth percentages that oscillated between 81.08 and 94.38%. The native isolate of T. harzianum (TP) showed significant competitive capability against the mycelial growth of F. oxysporum. Trichoderma species are promising agents of biological control in the central area of the State Tamaulipas, Mexico.

In vitro biocontrol of Fusarium oxysporum with antagonistic microorganisms and In vivo effect on Solanum lycopersicum L.

The objective was to evaluate the effects of In vitro biocontrol of Trichoderma spp. and Bacillus spp. against Fusarium oxysporum and its in vivo effect on Solanum lycopersicum plants. The antagonistic effect in vitro of microcapsules of Trichoderma spp. and Bacillus spp. against F. oxysporum, was evaluated by inhibition and antagonism classification, in the in vivo part growth variables in plant and fruit were measured. Trichoderma asperellum showed inhibition of 84.7% and class 1 and Bacillus spp., obtained an inhibition of 83.7% with a positive classification. The canonical correspondence analysis of the fruit, the T1 treatment indicates that the variables that highlight the effect of the treatment are the firmness of the fruit and the Brix. The canonical correspondence analysis of the plant, the height presents a significant difference (P < 0.05), highlighting B. subtilis, Bacillus liquefasciens, T. harzianum and T. asperellum + Bacillus amiloliquefasciens, with 1.05 and 1.1 m compared to the control of 74 cm, also highlighted the number of total fruits in the T. harzianum treatment with an average of 22.6 fruits and root weight in B. subtilis with 37.12 g. Strains of Trichoderma spp. and Bacillus spp. successfully inhibited F. oxysporum also induced growth in the tomato plant.

Insecticidal capacity of polyphenolic seed compounds from neem (Azadirachta indica) on Spodoptera frugiperda (J. E. Smith) larvae.

The objective of this study was to evaluate the insecticidal activity of the polyphenolic compounds found in neem on S. frugiperda larvae. Three neem extracts (1:12 (m/v) with 70% ethanol, 1:12 (m/v) with 0% ethanol (only water), and 1:4 (m/v) with 0% ethanol) were employed. Subsequently, the extraction of phytochemical compounds of each extract was performed using ultrasound and microwave technologies simultaneously. The compound characterization was performed by HPLC-mass. In addition, the insecticidal evaluation of the neem extract was performed against S. frugiperda of the second-stage larvae. The extracts were applied by spraying the larvae according to each bioassay. Results showed that the extract obtained with a 1:12 (m/v) relationship and 70% ethanol was effective for the control of S. frugiperda larvae. In this extract, the predominant organic compound families were: methoxyflavones, flavonols, hydroxycoumarins, anthocyanins, methoxycinnamic acid, and alkylflavones. Phytochemical compounds obtained from neem seeds with environmentally friendly solvents and alternative technologies (ultrasound and microwave) have potent insecticidal activity against S. frugiperda larvae.

Antifungal In Vitro Activity of Phoradendron sp. Extracts on Fungal Isolates from Tomato Crop.

Synthetic chemicals are mainly used for the control of fungal diseases in tomato, causing the phytopathogens to generate resistance to the chemical active ingredient, with a consequent risk to human health and the environment. The use of plant extracts is an option for the control of these diseases, which is why the main objective of this research was to study an alternative biocontrol strategy for the management of plant diseases caused by fungi through obtaining polyphenol extracts from mistletoe plants growing on three different tree species-mesquite (Prosopis glandulosa), cedar (Cedrus), and oak (Quercus), which contain flavones, anthocyanins, and luteolin. The overall chemical structure of the obtained plant extracts was investigated by RP-HPLC-ESI-MS liquid chromatography. The antifungal effect of these extracts was examined. The target phytopathogenic fungi were isolated from tomato plantations located in Altamira, Tamaulipas, Mexico. The microorganisms were characterized by classical and molecular methods and identified as Alternaria alternata, Fusarium oxysporum, Fusarium sp., and Rhizoctonia solani.