Luciana Zago Ethur

Fungos antagonistas a Sclerotinia sclerotiorum em pepineiro cultivado em estufa

White mold caused by Sclerotinia sclerotiorum may severely damage vegetables grown in greenhouses. To develop a biological control program for this pathogen proper antagonists are needed. This work aimed to select efficient fungi antagonists for controlling S. sclerotiorum on cucumber (Cucumis sativus) grown in greenhouses, and to evaluate the effect of the antagonist on the growth of the vegetable. An isolate of S. sclerotiorum obtained from cucumber and 112 fungi isolates belonging to four genera were used: Trichoderma, Fusarium, Penicillium, and Aspergillus. For the in vitro experiment, the cellophane method was used and eight Trichoderma virens isolates were selected that had inhibited the pathogen growth by 94 to 100%. Greenhouse experiments used sterilized and non-sterilized substrate in plastic cups and non-sterilized substrate in plastic bags. The substrate was inoculated with S. sclerotiorum and the eight isolates of T. virens were used as antagonists. All eight isolates controlled damping-off of plants caused by S. sclerotiorum, but the effect on cucumber growth varied according to the isolate and the substrate treatment.

Seleção de antagonistas fúngicos a Fusarium solani e Fusarium oxysporum em substrato comercial para mudas

Tests in vitro are usually used for the initial selection of biocontrol agents against soil fungi, lacking methodologies using soil and/or substrate. The objective of this research was to accomplish the mass selection of fungi isolates antagonistic to F. solani and F. oxysporum in commercial substrate for seedlings. Two experiments were conducted, with the pathogens F. solani and F. oxysporum, and 98 possible antagonistic fungi of the genera Penicillium claviforme, Penicillium, Aspergillus and Cladosporium. The suspension of the pathogens was inoculated in the substrate, in plastic cups, and the suspension of the other fungi was added five days later. The number of colony-forming unit of F. solani and F. oxysporum/g of substrate was counted after nine days. Of the 98 isolates used against F. solani, 43% did not differ from the control, and 57% reduced its development in the substrate, with the three best isolates belonging to the genus Penicillium claviforme. The three isolates of Penicillium claviforme selected for F. solani were also efficient against F. oxysporum.

Presença dos gêneros Trichoderma e Fusarium em solo rizosférico e não rizosférico cultivado com tomateiro e pepineiro, em horta e estufa

For the adequate elaboration of biocontrol programs of soil borne pathogens, it is necessary to understand the distribution of pathogens and antagonists in this environment. This research was aimed at studing the presence of the fungi Trichoderma and Fusarium in rhizosphere and bulk soil, cultivated with tomato and cucumber, in vegetable garden and greenhouse, and to quantify the isolates of Fusarium spp. pathogenic to the crops. For that, in a vegetable garden and a greenhouse, 40 samples of rhizosphere (cucumber and tomato) and 20 of bulk soil were taken,. The soil suspensions were diluted and plated in PDA media and the fungi identified. After that, the test of pathogenicity of the isolates for tomato and cucumber found in the samples, was performed. For tomato and cucumber, in greenhouse, the number of sampling points with the presence of Trichoderma spp. in the rhizosphere (95 e 45%, respectively) was significantly greater than in the bulk soil (10%). In the bulk soil, the presence of Trichoderma spp. and Fusarium spp. differed significantly, being found, respectively, in 10 and 55% of the sampling points. In the pathogenicity test, 5 isolates of Fusarium oxysporum of tomato and 6 of cucumber were pathogenic to the respective crops. In greenhouse, Trichoderma spp. occurs more frequently in the rhizosphere, whereas Fusarium spp. is distributed in the soil and the majority of the Fusarium spp. isolates are neither pathogenic to tomato nor to cucumber.

SANIDADE DE SEMENTES E EMERGÊNCIA DE PLÂNTULAS DE NABO FORRAGEIRO, AVEIA PRETA E CENTEIO SUBMETIDAS A TRATAMENTOS COM BIOPROTETOR E FUNGICIDA

The genus Trichoderma is represented by non pathogenic fungithat exercise antagonism to several phytopathogens through the parasitismand/or antibiosis and, have been used as biocontrole agents, growthpromoters and to improve the germination and sanity of seeds. The objectiveof this work was to compare the efficiency of the biological and chemicaltreatment in the sanity of seeds of forrage turnip (Raphanus sativus L.),black oat (Avena strigosa S.), rye (Secale cereale L.) and the emergency ofseedlings of forrage turnip. The evaluation of the sanity was done throughthe method of filter paper, and for evaluation of the emergency and seedlingsdevelopment, using styrofoam trays in the green-house.Were tested: T1 Rhodiauram®SC (500g/Kg of Thiram); T2 - Agrotrich®; T3 Rhodiauram®SC + Agrotrich®; T4 - Rhodiauram® SC (2:00) +Agrotrich® and T5 - Control. The treatments that controlled 100% theincidence of the fungi of the seeds of black oat were T1 and T4; of ryewere the treatments T1, T2, T4; and of forrage turnip the treatments T2and T4. The seeds of black oat and rye did not germinate due to physiologicproblems. For the forrage turnip, significant difference was not verifiedamong the treatments for the emergency test and emergency speed, andthe treatments T2, T3 and T4 presented the largest seedlings heights. Thebiocontrol product Agrotrich® alone or in combination with chemicalcontrol improved the sanity of forrage turnip, black oat, and rye and theheight of forrage turnip seedlings.