Effects of Herbicides on in vitro Growth of Mycorrhizae of Pine (Pinus spp.)

Effects of various herbicides on growth of ectotropic mycorrhizal fungi were determined over a 3-week period on modified Melin-Norcrans agar amended with the herbicides at rates of 0, 1, 3, 5, 10, 40, 80, 100, and 500 μg active ingredients/ml. Considerable variation in effect was observed among the herbicides for certain fungi and among the fungi for certain herbicides. All of the test fungi grew in the presence of each of the test herbicides at a rate of 80 μg/ml, and some growth was observed at the 500 μdg/ml rate in a majority of the herbicide-fungus combinations. Significant decreases (P = 0.05) in growth were observed for specific herbicide-fungus combinations at herbicide rates of 1 and 3 μg/ml; however, 50% or greater decreases in fungal colony areas were observed in only 12 of 112 of the combinations at such low rates. The herbicides, in decreasing order of activity against the fungi, were: diphenylethers > dinitroanilines > s-triazines > substituted amides > perfluidone [1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl] methanesulfonamide]. With few exceptions, the herbicide concentrations necessary to affect fungal growth significantly were considerably higher than would be expected to occur in soil treated with the test herbicides at recommended application rates.

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Secondary metabolites from endophytic Streptomyces aureofaciens CMUAc130 and their antifungal activity

Microbiology ◽

10.1099/mic.0.27758-0 ◽

2005 ◽

Vol 151 (5) ◽

pp. 1691-1695 ◽

Cited By ~ 96

Author(s):

Thongchai Taechowisan ◽

Chunhua Lu ◽

Yuemao Shen ◽

Saisamorn Lumyong

Keyword(s):

Culture Filtrate ◽

Fungal Growth ◽

Zingiber Officinale ◽

Phytopathogenic Fungi ◽

Active Ingredients ◽

Streptomyces Aureofaciens ◽

Mass Spectral ◽

Causative Agents ◽

Fungal Growth Inhibition

Streptomyces aureofaciens CMUAc130 was isolated from the root tissue of Zingiber officinale Rosc. (Zingiberaceae). It was an antagonist of Colletotrichum musae and Fusarium oxysporum, the causative agents of anthracnose of banana and wilt of wheat, respectively. Evidence for the in vitro antibiosis of S. aureofaciens CMUAc130 was demonstrated by the zone of fungal-growth inhibition. Microscopic observations showed thickness and bulbous structures at the edges of the inhibited fungal hyphae. The culture filtrate and crude extract from this strain were all inhibitory to tested phytopathogenic fungi. The major active ingredients from the culture filtrate of S. aureofaciens CMUAc130 were purified by silica gel-column chromatography and identified to be (i) 5,7-dimethoxy-4-p-methoxylphenylcoumarin and (ii) 5,7-dimethoxy-4-phenylcoumarin by NMR and mass-spectral data, respectively. Bioassay studies showed that compounds (i) and (ii) had antifungal activities against tested fungi, and their MICs were found to be 120 and 150 μg ml−1, respectively. This is the first report of compounds (i) and (ii) from micro-organisms as active ingredients for the control of phytopathogenic fungi.

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Quantifying the growth of arbuscular mycorrhizal fungi: usefulness of the fractal dimension

Botany ◽

10.1139/b09-006 ◽

2009 ◽

Vol 87 (4) ◽

pp. 387-400 ◽

Cited By ~ 9

Author(s):

Christine Juge ◽

Annie Champagne ◽

Andrew P. Coughlan ◽

Nicolas Juge ◽

Lael Parrott ◽

...

Keyword(s):

Fractal Dimension ◽

Mycorrhizal Fungi ◽

Growth And Development ◽

Time Course ◽

Glomus Intraradices ◽

Fungal Growth ◽

Arbuscular Mycorrhizal ◽

Hyphal Growth ◽

Growth Cycle

The present study is, to the best of our knowledge, the first to investigate the use of the fractal dimension (FD) to quantify the growth and development of undisturbed, fully functional arbuscular mycorrhizal (AM) hyphae developing in vitro. The majority of the work focused on the model AM fungus Glomus intraradices DAOM 181602. The time course study and final measurements of an intact mature extraradical mycelium allowed us to compare the development of the mycelium and the FD value. The final FD value of 1.62 for the mature mycelium is similar to that obtained for highly branched root systems and tree crowns. The FD method was used to characterize the morphology of germinative and presymbiotic hyphae in the presence of stimulatory (strigolactone GR-24, 0.1 µmol·L–1 and bisphenol A, 10 µmol·L–1) and inhibitory (NaCl, 80 mmol·L–1) molecules, and the extraradical phase in the presence of an inhibitory molecule (NaCl, 80 mmol·L–1). Where possible, results were compared with those obtained using the traditional grid-line (GL) technique. The FD approach allowed treatment effects to be accurately quantified, both in germinative and extraradical phases. In the second case, this technique provided a single quantitative value of extraradical hyphal growth that included runner hyphae (RH) networks, and fine-branching (FB) ramifications. This is in contrast to the GL technique, which provides a value for the estimation of RH, but which is not suitable for accurately measuring FB hyphae. Given the ease with which the FD values can be calculated, and the fact that this method can provide a single value for the quantification of extraradical hyphal growth and development, we suggest that this method is useful for in vitro studies. Furthermore under certain situations of germinative or presymbiotic growth, it may be used in concert with the GL method to provide a greater degree of information about hyphal morphology. The usefulness and limits of the FD method at different stages of the AM fungal growth cycle are discussed.

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Will Triazoles Still Be of Importance in Disease Control of Zymoseptoria tritici in the Future?

Agronomy ◽

10.3390/agronomy11050933 ◽

2021 ◽

Vol 11 (5) ◽

pp. 933

Author(s):

Holger Klink ◽

Joseph-Alexander Verreet ◽

Mario Hasler ◽

Tim Birr

Keyword(s):

Control Strategies ◽

Fungal Growth ◽

Current Control ◽

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Significant Shift ◽

Active Ingredients ◽

Zymoseptoria Tritici ◽

Wheat Diseases

Septoria tritici blotch (STB), caused by Zymoseptoria tritici, is one of the most important foliar wheat diseases worldwide. Current control strategies of STB rely mainly on fungicides, whereby triazoles (demethylation inhibitors; DMIs) have been the backbone in the control of Z. tritici in the last decades. However, in recent years a gradual loss of sensitivity of Z. tritici to several active ingredients of the triazole group has been reported in several European wheat-growing areas. Nevertheless, a new triazole fungicide, namely, mefentrifluconazole, has recently become available in disease management of STB, which belongs to a completely new triazole subclass, the so-called isopropanol triazoles. In this study, the trend in sensitivity development of Z. tritici towards older triazoles (tebuconazole, prothioconazole, and propiconazole) and the new isopropanol triazole mefentrifluconazole was determined in microtiter assays using Z. tritici field populations isolated in 1999, 2009, 2014, and 2020 in a high-disease-pressure and high-fungicide-input area in northern Germany in order to investigate whether the loss of sensitivity of Z. tritici to older triazoles also applies to mefentrifluconazole. For the three triazole fungicides tebuconazole, prothioconazole and propiconazole, a significant shift towards decreasing sensitivity of Z. tritici field populations was observed from 1999 to 2020, whereas the efficacy of mefentrifluconazole in reducing the in vitro fungal growth by 50% (EC50) remained unchanged over the investigated period, demonstrating a stable sensitivity of Z. tritici towards mefentrifluconazole. Although older triazoles are suffering from a loss of sensitivity of Z. tritici field populations due to the selection and spread of less triazole sensitive strains within the Z. tritici population, the efficacy of the new triazole mefentrifluconazole with its unique isopropanol unit was not affected by these changes within the Z. tritici population. Thus, the introduction of such new molecular units could also represent an important contribution for older groups of active ingredients, which previously suffered from a loss of sensitivity.

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Effects of Some Polyamine Biosynthesis Inhibitors and Calcium Chloride on In Vitro Growth and Decay Development in Apples Caused by Botrytis cinerea and Penicillium expansum

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.122.3.380 ◽

1997 ◽

Vol 122 (3) ◽

pp. 380-385 ◽

Cited By ~ 11

Author(s):

Robert A. Saftner ◽

William S. Conway ◽

Carl E. Sams

Keyword(s):

Botrytis Cinerea ◽

Fungal Growth ◽

Soft Rot ◽

Penicillium Expansum ◽

In Vitro Growth ◽

Polyamine Biosynthesis ◽

Pressure Infiltration ◽

Biosynthesis Inhibitors ◽

Decay Development

Three polyamine biosynthesis inhibitors, α-difluoromethylornithine (DFMO), α-difluoromethylarginine (DFMA), and α-methylornithine (MeOrn), alone and in combination with CaCl2, were tested for their ability to reduce in vitro growth and soft rot development in apple (Malus domestica Borkh.) fruit caused by Botrytis cinerea Pers.:Fr. and Penicillium expansum Link. All three inhibitors reduced the in vitro growth of the pathogens. Calcium had no effect on fungal growth in vitro. Pressure infiltration of millimolar concentrations of DFMO or DFMA or 25 g·L-1 CaCl2 solutions into apples reduced subsequent soft rot development by B. cinerea and P. expansum >40%. A combination treatment of Ca and DFMO or DFMA reduced decay >67%. Treatment of apples with MeOrn was less effective at inhibiting decay development. None of the inhibitors affected polyamine levels in apple cortical tissues. Some injury to the fruit surface was observed with Ca treatments. Fruit treated with Ca and any of the inhibitors were less firm than those treated with Ca alone. Specific polyamine biosynthesis inhibitors in combination with Ca may prove useful in reducing postharvest decay in apples.

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Fungicide Efficacy Against Calonectria pseudonaviculata, Causal Agent of Boxwood Blight

Plant Disease ◽

10.1094/pdis-04-13-0373-re ◽

2014 ◽

Vol 98 (1) ◽

pp. 99-102 ◽

Cited By ~ 18

Author(s):

J. A. LaMondia

Keyword(s):

Mycelial Growth ◽

Fungal Growth ◽

Conidial Germination ◽

In Vitro Assays ◽

Active Ingredients ◽

Action Committee ◽

Selection For ◽

Stem Lesions ◽

Fungicide Insensitivity

Calonectria pseudonaviculata causes leaf spot and stem lesions resulting in defoliation and dieback of boxwood. Fungicides representing 20 different active ingredients from 13 different Fungicide Resistance Action Committee groups were evaluated for their effects on conidial germination and mycelial growth using in vitro assays, and the concentration that suppressed fungal growth to 15% of that on unamended media (EC85) values were determined. A number of fungicides strongly inhibited mycelial growth of C. pseudonaviculata. Four demethylation inhibitor fungicides had EC85 values of 1.2 μg a.i./ml or less. Thiophanate-methyl, fludioxonil, pyraclostrobin, trifloxystrobin, kresoxim-methyl, mancozeb, and chlorothalonil also had activity against mycelial growth. Fludioxonil + cyprodinil had a lower EC85 than the same rate of fludioxonil alone, suggesting that cyprodinil had activity against mycelial growth. Fungicides that inhibited C. pseudonaviculata conidial germination include pyraclostrobin, trifloxystrobin, and kresoxim-methyl as well as fludioxonil, mancozeb, chlorothalonil, and boscalid. Quinoxyfen, etridiazole, fenhexamid, hymexazol, famoxadone, and cymoxanil did not inhibit either C. pseudonaviculata conidial germination or mycelial growth. In comparison with values found in the literature, EC50 values for kresoxim-methyl were up to 10 times higher than reported previously, suggesting that fungicide insensitivity may have developed. Protectant fungicides with activity against conidial germination and systemic fungicides with activity against mycelial growth, such as those identified here, may be complementary to achieve the high levels of pathogen management required for control of this disease. In addition, multiple fungicide active ingredients from different mode-of-action groups used in mixtures or over time may also act to slow selection for fungicide insensitivity.

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