Trichoderma spp. isolates with potential of phosphate solubilization and growth promotion in cherry tomato

Trichoderma fungi are considered relevant plant growth promoters for increasing the efficiency in the use of nutrients, as well as acting as biological control agents. This study aimed to select Trichoderma spp. isolates with potential for phosphate solubilization and their application as growth promoters in interaction with homeophatic preparations, in cherry tomato. Among 16 Trichoderma spp. isolates obtained from soils of organic tomato growing areas tested in vitro, together with a commercial product (Trichodermil®), two of them showed the ability for indole-3-acetic acid production and phosphate solubilization. The Trichoderma “R” had the highest mycelial growth speed index and presented twice as much spores than the commercial product. An in vivo experiment was also conducted in a greenhouse, in order to observe the potential of Trichoderma spp. isolates and homeophatic preparations on the cherry tomato growth promotion, using a randomized block experimental design, in a 4 x 3 factorial arrangement, with three Trichoderma isolates and two homeopathic preparations (Phosphorus 6CH and Carbo vegetabilis 6CH) + treatment without homeopathic preparation. The leaf area and dry mass of leaves and roots were determined. It was possible to observe that the isolate “R”, identified as Trichoderma asperellum, was effective in the cherry tomato growth promotion, while the homeopathic preparations applied did not show any effect

Biological control of citrus postharvest phytopathogens

Citrus are vulnerable to the postharvest decay caused by Penicillium digitatum, Penicillium italicum, and Geotrichum citri-aurantii, which are responsible for the green mold, blue mold, and sour rot post-harvest disease, respectively. The widespread economic losses in citriculture caused by these phytopathogens are minimized with the use of synthetic fungicides such as imazalil, thiabendazole, pyrimethanil, and fludioxonil, which are mainly employed as control agents and may have harmful effects on human health and environment. To date, numerous non-chemical postharvest treatments have been investigated for the control of these pathogens. Several studies demonstrated that biological control using microbial antagonists and natural products can be effective in controlling postharvest diseases in citrus, as well as the most used commercial fungicides. Therefore, microbial agents represent a considerably safer and low toxicity alternative to synthetic fungicides. In the present review, these biological control strategies as alternative to the chemical fungicides are summarized here and new challenges regarding the development of shelf-stable formulated biocontrol products are also discussed118COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informação2018/03670-0; 2016/20547-2; 2018/13027-8; 2017/24462-

Controle alternativo de Colletotrichum acutatum agente causal da queda prematura dos frutos cítricos

A queda prematura dos frutos cítricos (QPFC), causada por Colletotrichum acutatum, dados os grandes prejuízos que têm causado aos produtores, constitui-se numa doença de grande importância econômica. O controle da doença é feito predominantemente mediante uso de fungicidas, que eleva o custo de produção e afeta negativamente o meio ambiente. Diante disso, este trabalho teve por objetivo buscar um método alternativo de controle da QPFC, mediante o uso de agentes de biocontrole ou de biofertilizantes. Diferentes concentrações de biofertilizantes (originários de duas fontes distintas e denominados de Bio1 e Bio 2); três isolados de Bacillus subtilis (ACB-69; 72 e 77) e três isolados de Trichoderma spp. (ACB-14; 37 e 39) foram testados, isoladamente ou em combinação, sob condições de laboratório, quanto à capacidade inibitória da germinação de conídios de C. acutatum. Estudaram-se, ainda, a produção de metabólitos termoestáveis por B. subtilis e o efeito sobre a germinação do patógeno. Quinze isolados de B. subtilis foram testados quanto à capacidade de prevenir a infecção por C. acutatum em flores destacadas de lima- ácida 'Tahiti' e, no campo, foram instalados dois experimentos, visando a testar ACBs e biofertilizantes no controle da doença. Verificou-se que o isolado ACB-72 (B. subtilis) e ACB-37 (T. pseudokoningii) foram os que mais inibiram a germinação do patógeno. Quanto à produção de metabólitos termoestáveis, ACB-69 e 77 foram os mais eficientes em produzir substâncias antifúngicas, e em quantidades suficientes para inibirem a germinação do patógeno. A mistura dos quatro isolados de Bacillus (ACBs: 69; 72; 77 e AP3) foi o que apresentou maior porcentagem de inibição (73%). Os biofertilizantes (Bio1 e Bio2), em concentrações acima de 10% e, quando em associação com isolados de Trichoderma spp., promoveram maiores inibições na germinação de C. acutatum. em testes com flores destacadas, verificou-se que, onde foram aplicados os ACBs 69; 76; 74 e 77, as porcentagens de pétalas sem sintomas de infecção por C. acutatum foram de 83; 92; 92 e 97%, respectivamente. Mediante avaliações a campo, verificou-se a potencialidade de B. subtilis e de biofertilizantes em controlar a doença.Postbloom Fruit Drop of Citrus (PDF), caused by Colletotrichum acutatum, has caused losses to citrus producers and therefore it is economically very important. This disease is generally controlled by fungicide sprayings, which increase the production cost, and affects the environment. Thus, this work aimed at developing an alternative control method through the use of biocontrol agents, or biofertilizers. Different concentrations of biofertilizers (from two distinct sources and named Bio1 and Bio2), three strains of Bacillus subitlis (BCA-69, 72 and 77) and three isolates of Trichoderma spp. (BCA-14, 37 and 39) were tested, in vitro, alone or in combination, for the inhibitory capacity of conidia germination of C. acutatum. It was studied the production of thermo-stable metabolites by B. subtilis and their effect on the germination of C. acutatum conidia. Under in vivo conditions, 15 isolates of B. subtilis were tested for the ability to prevent C. acutatum infection on 'Tahiti' lime detached flowers and in the field, where two experiments were installed, for testing the BCA and biofertilizers in the control of the disease. It was found that the isolate BCA-72 (B. subtilis) and BCA-37 (T. pseudokoningii) were the most efficient in inhibiting conidia germination. BCA69 and BCA-77 were the most effective in producing anti-fungal substances, and in quantities sufficient to inhibit the germination of C. acutatum. The mixture of four strains of Bacillus (BCA: 69, 72, 77 and AP3) presented the highest percentage of inhibition (73%). Regarding the use of biofertilizers (Bio1 and Bio2), it was observed that concentrations above 10% of the product, when combined with the strains of Trichoderma spp. decreased the pathogen germination. The experiments with detached flowers showed that the flowers where the BCA: 69, 76, 74 and 77 were applied presented 83, 92, 92 and 97% respectively, of the petals without symptoms of infection by C. acutatum. Field tests showed the potential of B. subtilis and biofertilizers in controlling the disease

Mycorrhizal dependence of citrus rootstock

Abstract Plant growth promoting microorganisms, such as mycorrhizal fungi, have been widely used in agriculture because they help plants in the absorption of nutrients and water, influencing their growth. The objective of this work was to verify the effect of the mycorrhizal association of Glomus clarum and Glomus etunicatum on the initial growth of the rootstocks Rangpur lime, Swingle citrumelo and Sunki mandarin. The experimental design was completely randomized with a 3 x 4 factorial arrangement, with five replications, corresponding to three rootstocks, four managements: mineral fertilization, inoculation with G. clarum (IGC), inoculation with G. etunicatum (IGE) and Control. The seedlings were produced in greenhouse, using as substrate the vermicompost earthworm, distributed in polyethylene bags, depositing three seeds of each rootstock / bag. The inoculation with mycorrhizal fungi was carried out at the time of sowing (45 spores of each species / bag). The mineral fertilization was divided into two phases: phosphorus application before sowing (40g of single superphosphate / bag); nitrogen application (1.7 g dissolved in 40 ml of water), divided in eight applications of 5 ml of the solution, via irrigation water, manually and weekly; and micronutrients (B, Cu, Fe, Mn and Zn), sprayed manually every two weeks. The following parameters were evaluated: height, stem diameter, number of leaves, shoot dry mass, colonization and mycorrhizal dependence. There was a significant interaction between the rootstocks and treatments applied in this study for most of the evaluated variables. Rangpur lime and Swingle citrumelo obtained higher height and the management that conferred higher height to the rootstocks was the mineral fertilization and IGE. The largest diameter of the stem was reached by Swingle citrumelo and the management that provided the largest diameter was the inoculation with G. etunicatum. Rangpur lime presented moderate mycorrhizal dependence for G. clarum and marginal for G. etunicatum. Mycorrhizal colonization did not show a significant interaction between rootstocks and the management with inoculation. The mycorrhizal association of G. clarum and G. etunicatum was not presented as the best management for the growth of Rangpur lime, Swingle citrumelo and Sunki mandarin, when compared to the mineral fertilization. However, the inoculation of mycorrhizal fungi provided a positive effect on the uptake of some nutrients by the rootstocks, especially K, Mg, N and P

Control of Guignardia citricarpa by Bacillus subtilis and Trichoderma spp.

A habilidade de isolados de Bacillus subtilis e Trichoderma spp. em controlar a mancha preta dos frutos cítricos (MPC) foi avaliada em pomares de laranjeira 'Natal'. O primeiro experimento foi conduzido durante a safra de 2001/2002, no qual foram testados quatro isolados de B. subtilis (ACB-AP3, ACB-69, ACB-72 e ACB-77) aplicados de forma isolada ou em mistura, em intervalos de 28 dias, comparando-se com o tratamento fungicida. Dois outros ensaios foram conduzidos durante a safra de 2002/2003, em que os mesmos quatro isolados de B. subtilis e dois isolados de Trichoderma spp. (ACB-14 e ACB-40) foram testados, sendo os isolados aplicados em intervalos de 28 dias no segundo experimento e em intervalos de 15 dias no terceiro experimento. No primeiro experimento, o tratamento com ACB-69 diferiu estatisticamente do tratamento-testemunha, porém não diferiu dos outros agentes de controle biológico ou da mistura dos isolados de Bacillus. No segundo experimento, os tratamentos com ACB-69 e ACB-AP3 resultaram em menores índices de doença em comparação com o tratamento-testemunha. Entretanto, este resultado não se repetiu no terceiro experimento, em que os isolados foram aplicados em intervalos de 15 dias. A severidade de doença foi alta em ambas as safras avaliadas, e o tratamento com fungicida foi o mais efetivo para o controle da doença.The ability of isolates of Bacillus subtilis and Trichoderma spp. to control citrus black spot (CBS) was investigated in ´Natal´ sweet orange orchards. The first experiment was conducted during the 2001/2002 season and four isolates of B. subtilis (ACB-AP3, ACB-69, ACB-72 and ACB-77), applied every 28 days, alone or in combination were tested and compared with fungicide treatments. Two other experiments were carried out during the 2002/2003 season, where the same isolates of Bacillus and two isolates of Trichoderma (ACB-14 and ACB-40) were tested being applied every 28 days in the second experiment, and every 15 days in the third experiment. In the first experiment, the treatment with ACB-69 differed statistically from the control, but did not differ from other biological control agents or mixture of Bacillus isolates. In the second experiment, the treatments with ACB-69 and ACB-AP3 resulted in smaller disease index compared with the control treatment. However, this result was not repeated in the third experiment, where the isolates were applied every 15 days. Disease severity was high in both evaluated seasons and the fungicide treatment was the most effective for disease control.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Avaliação de microrganismos antagônicos, Saccharomyces cerevisiae e Bacillus subtilis para o controle de Penicillium Digitatum

Citrus fruits are affected by diverse diseases, mainly the fungal infections, which affect productivity and quality, especially when it targets the market of fresh fruit. Among the fungal diseases that occur in postharvest, there is the green mold caused by Penicillium digitatum. The control measures are based mainly in the treatment of fruits with different combinations of fungicides in packing-house. Due to restrictions on the presence of residues of fungicides in citrus fruits and the increasing development of resistant strains of pathogens to the fungicide used, it is necessary to search for control alternatives such as biological control. Therefore, this study aimed to: (i) verify the antagonistic effect of biological control agents (BCA), being 13 isolates of Bacillus subtilis and 06 isolates of Saccharomyces cerevisiae against P. digitatum, (ii) study in vitro interactions between pathogen and BCA (iii) determine the effect of integration of antagonists with sodium bicarbonate and carnauba wax in the control of green mold. The results showed that the majority of the isolates, and all yeast isolates inhibited the mycelial growth of the phytopathogen. Only one isolate of B. subtilis (ACB-84) was able to inhibit the germination of P. digitatum (72% of inhibition), whereas ACB-K1 and ACB-CR1 (S. cerevisiae) were the most effective with inhibition from 78 and 85.7% respectively. The addition of sucrose (0.5%) favored the inhibition of conidia germination by the yeast isolates. The results from the in vivo control showed the viability of S. cerevisiae ACB-K1 and ACB-CR1 to control P. digitatum in 'Tahiti' lime fruits and orange 'Hamlin' fruits, respectively. The combination of sodium bicarbonate and biocontrol agents did not result in improvements in the curative control of the green mold. Carnauba wax (18% of TSS) favored the antagonistic activity of S. cerevisiae, and this effect depended on the variety of fruits in the study and of the yeast isolate used for the biocontrol