Biological Control of Damping-off Fungi of Agoho (Casuarina Equisetifolia L.) Using Antagonistic Bacteria

A series of laboratory and nursery experiments were conducted specifically to determine the efficacy of 85 strains of Bacillus species and 15 actinomycetes against six fungal pathogens isolated from damped-off agoho. These damping-off fungi were: Fusarium oxysporum Schet., Rhizoctonia solani Kuhn., Phytophthora parasitica Dastur, Pythium debaryanum Hesse, and two unidentified pathogens temporarily designated as Unk 1 and Unk 2. Preliminary test using the agar-plug technique revealed that 18 of the bacterial isolates could suppress two or more of the six damping-off fungi. Fusarium oxysporum was inhibited by 17 bacterial isolates, R. solani by 8 isolates, P. parasitica by 14 isolates and P. debaryanum by 15 isolates. The unidentified damping-off fungi Unk 1 and Unk 2 were inhibited by 13 and 9 isolates, respectively. Further screening using the agar-diffusion method disclosed that 10 isolates were effective antagonists with Bacillus subtilis (Code No. R060), Bacillus sp. (Code No. R071), and Streptomyces sp. (Code No. R086) as the consistent and most effective inhibitors. Application of the three most promising antagonistic bacteria as seed treatment s howed that they effectively inhibited the growth of the damping-off fungi in the laboratory as exhibited by an increase in percent germination. Bacillus subtilis however, was not able to antagonize the effect of P. debaryanum in this particular experiment. Seed germination and seedling survival were likewise improved with the application of the three most promising antagonistic bacteria as seed treatment. This was shown after three months under nursery conditions. There were possible mechanisms of control by the antagonistic bacteria against the damping-off fungi. The mycelium and spores of the pathogenic fungus may have been attacked and parasitized by the antagonist when they were simultaneously grown in culture media. There must have been a competitive interaction between the two microorganisms. Any essential requirement of microorganisms can serve as potentially possible basis for competition. Another was antibiosis which is an inhibitory effect exerted by an organism upon another organism through the production of antibiotic compounds. Moreover, several strains of bacteria are effective in lysing cell walls of pathogenic fungi under laboratory conditions. Lysis is often attributed to production of cell wall degrading enzymes like chitinase and gluconase that may hydrolyze major constituents of fungal cell walls

Soybean damping-off this season

Excessive moisture this planting season has promoted damping-off problems. ISU Extension has received numerous reports on damping-off across Iowa, especially in southern Iowa. Both preemergence damping-off and postemergence damping-off have been found. This year seedling diseases are more complicated than in past years because of the alternating warm and cool weather. If the soil temperature is warm (70-80°F), damping-off by Phytophthora or Rhizoctonia is more likely to occur. If the soil temperature is cool (60°F or below), Pythium or Fusarium are more problematic

Control of Damping Off and Increased Growth of Tomato Seeds by Utilizing Trichoderma Harzianum Based on Solid Organic Materials

Low soil fertility and the presence of damping off disease which is a inhibiting factor in the nursery of tomato plants. This can be overcome by utilizing the biological agent Trichoderma harzianum based on solid organic matter (Trichocompost). The aim of the study was to determine the effect of giving Trichocompost and obtain the optimal Trichocompos dose to reduce the intensity of damping off disease and increase the growth of tomato seedlings. The treatments tried were Trichocompos with doses of 20, 40 and 60 tons/ha, designed using a complete randomized design with 10 replications. The plant response observed was the intensity of the disease; height, fresh weight and dry weight of canopy; length, fresh weight and root dry weight. The results showed that the monitoring of Trichocompost can reduce the intensity of damping off disease to 54.80% and increase the growth of tomato seedlings. The recommended Trichocompos dosage is 60 tons/ha or as much as 30 g/1 kg of soil. The results of this study can be used to increase agricultural production and also a solution in an environmentally friendly and sustainable farming system

Soybean damping-off and replanting

In spring 1998, damping-off caused by Phytophthora was a production problem in parts of Iowa, especially southern and some central areas. Many disease questions that I received last spring were related to damping-off. Because most areas in Iowa have had plenty of rain so far this spring, damping off may become a problem. In this article I address two important aspects related to damping-off: identification and replanting

Use of Phenols, Peroxidase and Polyphenoloxidase of Seed to Quantify Resistance of Cotton Genotypes to Damping-off Incited by Fusarium oxysporum

A greenhouse test was conducted in 2011 and 2012 growing seasons at Giza Agricultural Research Station to evaluate the reaction of six cotton genotypes to damping-off incited by Fusarium oxysporum. Damping-off incidence on the genotypes ranged from 70-88%. In general, the genotypes could be divided into highly susceptible, susceptible, and moderately susceptible. Data for damping-off incidence and level or activity of some biochemical components (phenols, peroxidase, and polyphenoloxidase) were entered into a computerized linear regression analysis. The analysis contrasted seven predictive models by using the biochemical components, singly or in combination, as biochemical predictors. It was evident that models nos. 2 and 6 were the best models for predicting incidence of damping-off. The superiority of these models was attributed to their high RІ values (0.748 and 0.902, respectively) and the significance of their F. values (P = 0.026 and P = 0.031, respectively). The results of the present study suggest that peroxidase alone or both peroxidase and polyphenoloxidase, which may or may not parts of damping-off resistance mechanisms, can be used as biochemical markers to predict resistance to damping-off incited by F. oxysporum

EC59-1831 Plant Diseases : Soil Treatments for Damping-Off

Extension Circular 59-1831 is about plant diseases specifically the soil treatments for damping – off. This includes the fungicides for damping-off, nematicides, soil sterilants, and the precautions

Biocontrol of cantaloupe damping-off disease caused by Fusarium semitectum by using formulations of antagonistic fungi

oai:ojs.ppmj.net:article/2Antagonistic capability of 19 isolates of fungi isolated from rizosphere of cantaloupe plants was tested in vitro against growth of Fusarium semitectum isolate the causal pathogen of damping- off of cantaloupe. Trichoderma viride (isolate no. 17), T. harzianum (isolate no. 19) and Fusarium concolar  (isolate no.4) showed  significant  percentage of inhibition  against  to  F. semitectum. The effect of carrier formulations of antagonistic fungi (talc based powder and rice bran) on damping-off of cantaloupe were tested under greenhouse and field conditions.  In greenhouse experiments, application of antagonistic fungi with rice bran formulation two weeks before planting caused the highest percentage of survival plants in pre and post damping-off (83.33 and 75%, respectively), whereas application of talc based powder formulation significantly increased percentage of plant survival at the time of planting in pre and post damping-off (91.67 and 75%, respectively). In field experiments, application of tested formulations of antagonistic fungi to infested soil with F. semitectum two weeks before planting resulted in higher percentage of plant survival in pre and post damping-off in both teste

Phytophthora race 25 and soybean 1k gene strategy

Soil moisture in many regions of Iowa is at field capacity or more so planting will occur in wet soils this spring. Wet soils increase the risk of damping-off in soybean by the fungi Phytophthora and Pythium. Seedling disease concerns are further compounded this year by low-to-poor seed quality. If damping-off occurs this year, growers may have difficulty finding soybean seed for replanting and may want to consider the following strategies for controlling Phytophthora and Pythium damping-off

Damping-off within natural and disturbed kwongan plant communities

Fungal and oomycete damping-off pathogens kill pre- and post-emergent seedlings and can regulate the abundance of plant species to help maintain diversity in natural ecosystems. However, damping-off pathogens may be detrimental to post-mining ecological restoration, a key hurdle in the process is the loss of pre- and post-emergent seedlings. Recently, several putatively native Phytophthora species, soil-borne oomycete plant pathogens, have been recovered from hyper-diverse kwongan vegetation in southwest Australia and may be damping-off pathogens. Damping-off pathogens may contribute to maintaining the diversity of natural kwongan plant communities and reduce seedling establishment within ecological restoration. Four experiments were designed to identify the distribution and role of Phytophthora and other potential damping-off oomycetes in natural and restored kwongan plant communities. Putatively native Phytophthora arenaria, introduced P. cinnamomi and Pythium irregulare were identified as damping-off pathogens with wide host ranges of native kwongan plant species through a glasshouse pathogenicity trial. Fungicide seed coat treatments improved seedling emergence for five of the 14 plant species studied in ecological restoration field trials, identifying low to moderate levels of pre-emergent damping-off caused by oomycetes and fungi. Natural kwongan soils collected from different plant species affected seedling emergence and survival in a glasshouse experiment. Damping-off caused conspecific negative plant-soil feedback for Jacksonia floribunda and Xanthorrhoea sp. Lesueur, a process that contributes to the maintenance of diversity in plant communities. Although, the presence and abundance of oomycetes detected using metabarcoding from the same natural kwongan soils were not associated with reduced seedling emergence or survival. In a regional metabarcoding survey of natural kwongan plant communities, the Phytophthora species richness and abundance were far lower than previously hypothesised due to the elimination of sources of sampling biases. Plant species and host age were strong drivers of the oomycete communities detected at a local scale using metabarcoding. These studies provided an insight into the distribution of important plant pathogens in a species rich Mediterranean shrubland and identified damping-off pathogens could be a mechanism contributing to maintaining the diversity of natural kwongan plant communities and low seedling establishment in ecological restoration

Pengaruh Pemberian Ekstrak Daun Sirih (Piper Betle L.) untuk Mengendalikan Damping-Off pada Tanaman Cabai Capsicum Annum)

Sclerotium roflsii is the causal agent of damping-off disease on pepper which difficult to control. The use of chemical pesticides cause several damage to the environment. The used of Piper betle leaves extract which is contains antifungal compounds becomes one of the solution. The aim of this study to obtain the optimum concentration of piper betle leaves extract and dipping periode of Chili seed in leaves extract to control damping off disease caused by Sclerotium rolfsii. The study consists of two experiments. The first experiment was isolation and multiplication of damping off disease in chilli, this stage was conducted in laboratorium. The second experiment was performed to investigate effectivity of piper betle leaf extract to control damping off using dipping method, this stage conducted in Greenhouse. The study arranged in Completely Randomized Design (CRD) with single factor experimental design consist of 13 treatment, namely consentration of 0%, 40%, 60% and 80% Piper betle leaves extract (v/v) with 1 hour, 2 hour, and 3 hour dipping time. The result showed that Piper betle leaves extract of 60% with 1 hour dipping time had the best ability among the other treatment to control damping off disease cause of Sclerotium rolfsii in Chili seedlings