Mean Mycelial Growth Research Articles

In vitro Efficacy of Different Fungicides against Leaf Blight of Sunflower

Sunflower is one of the major oilseed crops cultivated in India. Alternaria leaf blight is one of the fungal diseases of Sunflower caused due the pathogen Alternaria helianthi, which is one of the significant limitations in the cost-effective cultivation of Sunflower in India. It is estimated that 20 to 80% losses in yield and heavy defoliation have been observed due to A. helianthi causal agent of leaf blight of Sunflower. Present investigation on evaluation on efficacy of different fungicides against leaf blight of Sunflower under in vitro condition by using Completely Randomized Design was conducted at Department of Plant Pathology, Dr. Sharadchandra Pawar College of Agriculture, Baramati during. Under this study seven fungicides viz., Chlorothalonil 75% WP, Hexaconazole 5% EC, Carbendazim+Mancozeb 75% WP, Carbendazim 50% WP, Tebuconazole 25.9% EC, Propiconazole 25% EC and Azoxystrobin 23% SC were evaluated against the pathogen Alternaria helianthi causing leaf blight in Sunflower at their recommended concentration and observation on mean radial mycelial growth and percent mycelial growth inhibition of pathogen was calculated. Results revealed that among various fungicides the three fungicides viz., Hexaconazole 5% EC, Tebuconazole 25.9% EC and Propiconazole 25% EC were found most effective with minimum mean mycelial growth and having maximum and similar (94.44%) percent growth inhibition of pathogen and rest of the fungicides tested were comparatively less effective against the pathogen A. helainthi associated with leaf blight of Sunflower.

Evaluation of different fungicides against Alternaria solani causing early blight disease of potato under in vitro conditions

Potato (Solanum tuberosum) is a widely cultivated starch crop known for its edible underground storage organ, providing essential nutrients globally. Early blight, caused by the fungal pathogen Alternaria solani can lead to significant yield losses in potato crop, reports indicated that average annual yield losses due to early blight range from approximately 50 per cent to 75 per cent of production. Chemical protection have been a prominent approach in controlling early blight. Under in vitro evaluation fungicides, among non-systemic fungicides, mancozeb 75% WP exhibited the highest mean mycelial growth inhibition at 96.25 per cent, followed by thiram 75% WP with a mean mycelial growth inhibition of 92.51 per cent. Among six systemic fungicides evaluated, hexaconazole 5% EC and tebuconazole 25.9% EC recorded cent per cent mycelial growth inhibition at all four concentrations (0.025, 0.05, 0.1, 0.15%) tested which were significantly superior over rest of fungicides followed by difenconazole 25% EC. Among seven combi product fungicide tested, (captan 70% + hexaconazole 5%) 75% WP showed the mycelial growth inhibition of 100 per cent at all three concentrations tested, significantly over other combi-product fungicides.

Chemical composition and antifungal activity of the essential oil from the Hymenaea stigonocarpa Mart. Ex Hayne (jatobá-do-cerrado) fruit peel

This study investigated the chemical composition and the antifungal activity of the essential oil extracted from the Hymenaea stigonocarpa fruit peel (HSFPEO) against Botrytis cinerea, Sclerotinia sclerotiorum, Aspergillus flavus and Colletotrichum truncatum. The HSFPEO obtained through hydrodistillation was analyzed with gas chromatography coupled to mass spectrometry. The antifungal activity was determined by the mean mycelial growth inhibition of the fungus treated with essential oils and growth control. The major constituents of HSFPEO were spathulenol (25.19%) and caryophyllene oxide (13.33%). HSFPEO demonstrated antifungal activity against all fungi tested in all concentrations evaluated in a dose-dependent behavior. The best results were observed against B. cinerea and A. flavus, in which the lowest concentration tested inhibited more than 70% of mycelial growth. Based on the current knowledge, this study describes for the first time the chemical composition and the antifungal activity of HSFPEO against the phytopathogenic fungi B. cinerea and C. truncatum.

Bioefficacy of bacteria and yeast bioagents on disease suppression and quality retention of stored Kinnow mandarin fruits

Kinnow mandarin is a high value citrus crop in the fruit industry. However, the fruits are vulnerable to a variety of phytopathogens and suffer huge quantitative and qualitative losses. Pathogenic filamentous fungi like Penicillium digitatum, Penicillium italicum, and Geotrichum candidum are mainly responsible for postharvest losses. Alternative to synthetic fungicides, the bacteria and yeast-based biocontrol approaches are the most efficient means for controlling postharvest diseases. The antagonistic potential of five biocontrol agents such as Debaryomyces hansenii, Lactobacillus plantarum, Metschnikowia pulcherima, Pichia guilliermondi and Rhodotorula minuta var. minuta was assessed under both in vitro and in vivo conditions against the mycelial growth of postharvest pathogens using dual culture method. The results revealed that R. minuta var. minuta was the most promising antagonist with 71.98%, 76.18% and 67.46% mean mycelial growth inhibition of P. digitatum, P. italicum and G. candidum respectively, over untreated potato dextrose agar (PDA) plates after 192 h of incubation under in vitro. Further, under in vivo, the fruits treated with R. minuta var. minuta did not impair the quality and sensory attributes during ambient storage. Hence, R. minuta var. minuta proved an eco-friendly and safer substitute to synthetic fungicides for postharvest disease management of Kinnow mandarin fruits.

Efficacy of chitosan synthesized from shrimp (Penaeus notialis) shell against Aspergillus flavus of groundnut and wheat

Chitosan is a natural safe biopolymer that has received great attention in agriculture, food, biomedical, pharmaceutical and environmental industries because of their biocompatible, biodegradable and non-toxic. Chitosan used in this study was synthesized using shrimp shell through chemical processes viz. demineralization, deproteinization, decolourization and deacetylation. Antifungal activity of Chitosan Synthesized from Shrimp Shells (CSSS) was evaluated at different concentrations of 0.25mgml-1, 0.50 mgml-1, 0.75 mgml-1 and 1.0 mgml-1 against Aspergillus flavus. Shrimp shell synthesized chitosan gave off-white to light brownish semi-crystallized product. The protocol for the synthesis yield chitosan with 98.9% degree of deacetylation and Ultra Violet-visible spectra (UV-vis) at a wavelength of 232 nm. There were variations in mean mycelia growth of A. flavus at different concentrations of CSSS and incubation days. With increasing incubation days there was accompanying increase in mean mycelial growth of A. flavus. At day one mean mycelia growth were 0.75±.05, 1.40±.10, 1.55±.15 and 1.60±.10cm whilst at the fifth day of incubation, mycelia radial growth were 7.55±.55 3.10±2.4 , 6.45±.15 and 6.95±.95cm respectively at concentrations of 0.25, 0.50, 0.75 and 1.0 (mgml-1) of CSSS. Control had highest mycelia radial growth (8.05) as compared to the different concentrations of treated samples. Highest Percentage Inhibition of A. flavus (61.7%) by CSSS was recorded in 0.5mgml-1, however 6.80%, 20.4%, 14.2% inhibition were recorded in 0.25, 0.75 and 1.0mgml-1 concentrations respectively which were significantly different. It is evident from the study that shrimp shell synthesized chitosan are likely biocontrol agent capable of preventing A. flavus growth and toxin production.

Eco-friendly management of false smut disease of rice incited by <i>Ustilaginoidea virens</i> through the application of <i>Trichoderma</i> spp

False smut disease of rice incited by Ustilaginoidea virens is an organ-specific pathogen that causes chalkiness of grain which leads to a reduction in 1000 grain test weight and yield. The dual culture assay results revealed that each Trichoderma isolates suppress the mean mycelial growth of U. virens under in-vitro conditions. Among the nine different Trichoderma isolates, 3 isolates were selected as effective isolates viz., TKM1, TKT9 and TTN5. Among these three effective isolates, maximum mycelial growth inhibition was recorded in the isolate TKM1 with 80.18 percentage reduction over control. The SEM photographs revealed that the hyphal round off in U. virens which is mainly due to the production of volatiles through direct antagonistic activity and competition through indirect antagonistic activity in which conidial adherence of T. harzianum over the surface of the mycelial mat of U. virens was observed. In 2020, the field experiment results revealed that the minimum disease severity was recorded when the Trichoderma isolate TKM1 was sprayed during booting stage with 4.61%, 50% PE stage with 17.91% and 100% PE with 21.86%. In 2021 the disease severity varied from 9.21% to 69.59%. The lowest disease severity was recorded in the plots sprayed with propiconazole fungicide with 9.21%. However, the disease severity recorded in fungicide treated plots were statistically on par with the Trichoderma isolate TKM1 treated plots at 50% PE spray with 10.60%. The disease severity recorded in the plots sprayed with TKM1 showed non-significant relationship with the fungicide treated plots which clearly revealed that the control efficacy of both TKM1 and Propiconazole treated plots were similar with each other. Among the Trichoderma treated plots the yield gain varied from 10.01% to17.20%. The yield gain was found to be 18.35% in fungicide treated plots. The yield and yield gain obtained by the effective isolate TKM1 (yield = 6405 kg/ha and yield gain = 17.20%) was statistically on par with propiconazole treated plots and significantly showed better yield and yield gain than the control plots. In 2021 among the Trichoderma treated plots the yield gain varied from 4.10% to 10.16%. The maximum yield gain was recorded in the fungicide treated plots (12.00%).

In vitro Evaluation of the Antifungal Activity of Essential Oils of Some Medicinal Plants on Phytopathogenic Strains in the Kisangani Region (DRC)

Purpose: The present study evaluates the antifungal activity of essential oils of Curcuma longa and Eucalyptus globulus on strains of Lasiodiplodia theobromae and Pseudocercospora fijiensis in the Kisangani region (DR Congo).
 Methods: The essential oils were obtained after extraction by the hydro distillation method. The isolation of strains of L. theobromae was made from the fragments of mesocarp taken from the diseased cocoa, previously cut with a Scarpel and then disinfected with bleach water, while the strains of P. fijiensis were obtained by the method of discharging ascospores on agar medium
 (H2O Agar) and then transplanting on potato dextrose agar (PDA). In addition, inhibition of mycelial growth on a PDA was used as a method to assess the sensitivity of strains to the essential oils of the medicinal plants studied.
 Results: The results obtained show that the essential oils of the rhizomes of C. longa and the leaves of E. globulus showed a low yield of essential oils (EOs) of 0.50% and 0.48% respectively. However, the EOs of the rhizomes of C. longa and the leaves of E. globulus exhibited inhibitory action on the mycelial growth of strains of L. theobromae and P. fijiensis.
 Conclusion: The ANOVA test applied to the mean mycelial growth values of these two strains (L. theobromae and P. fijiensis) on the Eos of C. longa showed that the difference is not significant (p-value = 0.47). In addition, there is also no significant difference (p-value = 0.51) between the mean mycelial growth values of these two fungal strains on the essential oil of E. globulus.

Selection of filamentous fungi that are resistant to the herbicides atrazine, glyphosate and pendimethalin

The objective of the present study was to isolate fungi from agricultural soils and evaluate fungal growth in culture medium contaminated with atrazine, glyphosate and pendimethalin. Filamentous fungi were isolated from agricultural soils and cultured in a modified culture medium containing 0, 10, 20, 50, and 100 μg mL-1 atrazine, glyphosate and pendimethalin for 14 days at 28°C. The fungi that presented optimal and satisfactory growth were plated in Sabouraud culture medium with 4% dextrose and containing the herbicides at concentrations of 0, 10, 20, 50, and 100 μg mL-1 for seven days at 28°C. The mean mycelial growth values were submitted to analysis of variance and the Tukey test (p < 0.05%) for comparison and relative growth determination, and maximum inhibition rates were calculated. The isolated fungi Aspergillus fumigatus, Fusarium verticillioides and Penicillium citrinum were shown to be resistant to atrazine, glyphosate and pendimethalin. F. verticillioides showed higher mean mycelial growth in the culture media contaminated with atrazine and glyphosate than the other two fungi. In the culture medium contaminated with pendimethalin, F. verticillioides, and A. fumigatus presented the highest mean mycelial growth values.

Inhibition of the fungus Colletotrichum lindemuthianum in the presence of different potassium sorbate concentrations

One of the major problems of in vitro plant cultivation is caused by contaminations such asfungal, which represent great losses for plant cultivation laboratories. In view of the problem about contamination and gaps in efficient disinfection protocols, the present study aimed to evaluate the inhibition of the fungus Colletotrichum. lindemuthianum in the presence of the potassium sorbate food preservative at different concentrations (0 g L-1; 0.076 g. L-1; 0.15 g. L-1; 0.30 g. L-1; 0.45 g. L-1; 0.60 g. L-1 and 0.75 g. L-1). The analyses of the Percentage of Micelal Growth Inhibition (ICP) and the growth at 24 and 72 hours at different concentrations were quantified. It was observed that Potassium Sorbate was effective in the analysis of ICP at different concentrations in relation to control, with greater effectiveness for T4 to T7. The highest percentages of inhibition (T5 to T7) presenting an inhibition rate of mean mycelial growth of 17.5 % in relation to the control for the 72h period, indicating, therefore, that with further studies this preservative can be used to combat fungal microorganisms in vitro culture.

Cold Plasma Treatment Strategies for the Control of Fusarium oxysporum f. sp. basilici in Sweet Basil

Fusarium wilt of basil (FOB), caused by Fusarium oxysporum f. sp. basilici, is an economically damaging disease of field- and greenhouse-grown sweet basil. Growers have observed a resurgence of FOB and susceptibility in FOB-resistant cultivars. Because currently available chemical, biological, and cultural control methods are costly, unsustainable, ineffective, or challenging to implement, new strategies of FOB control are needed. Cold plasma is becoming an increasingly important experimental technology in the food and agricultural industry for pathogen decontamination. To understand the effect of cold plasma treatment on FOB incidence and severity, experiments were conducted by treating FOB mycelium, inoculated sweet basil seedlings, and seeds with various experimental cold plasma treatment devices, all using helium as a feed gas. Initial results indicated that while the cold plasma jet treatment did not result in a significant reduction in mean mycelial growth rate or virulence of the pathogen, direct cold plasma jet treatments on seedlings, as well as a cold plasma dielectric barrier discharge treatment on seeds, did exhibit varying efficacies against FOB. Control of FOB appeared to be strongly dependent on the exposure time to cold plasma. These findings can aid in the standardization of a cold plasma treatment for the commercial basil seed and transplant industry.

First Report of Mucor spp. Causing Root Rot of Radix pseudstellariae in Guizhou Province of China.

Radix pseudostellariae L. is one of the most common and highly-prized Chinese medicinal plants with various pharmacological effects, and mainly produced in acid soils in the Guizhou and Fujian provinces of southwestern and southeastern China, respectively (Wu et al. 2020). However, consecutive monoculture of R. pseudostellariae results in severe root rot and decline in biomass and quality of underground tubers. Root tubers of R. pseudostellariae are typically planted in December and harvested in next June. Root rot commonly starts developing in May. The disease incidence of root rot was ranging from 37 to 46% in root portions and basal stem of R. pseudostellariae under the consecutive monoculture fields in Shibing County, Guizhou Province, China (108°12'E, 27°03'N) (Li et al. 2017). Severe root rot was observed in Shibing County in May 2018. Infected plants displayed curly, withered, and yellow leaves, blight, retarded growth, root rot, and yield losses. Abundant whitish mycelia were observed on roots and surrounding soil. Two fungal isolates, designated GZ20190123 and GZ20190124, were obtained from symptomatic roots cultured on potato dextrose agar (PDA). The optimum temperature range for growth of the two isolates was 25 to 30°C. The optimum pH range for the growth of GZ20190123 was 5 to 5.5, whereas GZ20190124 grew better between pH 5 to 8.5. The mean mycelial growth rates of GZ20190123 and GZ20190124 at 30°C were 2.1 and 1.5 cm/day, respectively. Conidia of the two isolates were ovoid or obclavate and were produced in single or branched chains. The internal transcribed spacer (ITS) region was amplified with primers ITS1 and ITS4 (White et al. 1990). The sequences were deposited in GenBank as accession No. MN726736 for GZ20190123 and MN726738 for GZ20190124. Sequence comparison revealed 99% (GZ20190123) and 97% (GZ20190124) identity with previously reported isolate xsd08071 of Mucor racemosus Bull. (accession No. FJ582639.1) and isolate BM3 of Mucor fragilis Bainier (accession No. MK910058.1), respectively, which was confirmed by phylogenetic analysis. The two isolates were tested for pathogenicity on R. pseudostellariae. Six roots of R. pseudostellariae were surface-sterilized with 75% ethanol and stab inoculated with mycelia using a sterile toothpick for each isolate. Sterile distilled water was stab inoculated to twelve roots to serve as the control. Treated roots were incubated in a greenhouse with 16 h day length [light intensity 146.5 μmol/(m2·s)] and day/night temperature 26°C/18°C. The inoculated roots showed the expected symptoms on roots and sprouts 7 days after inoculation, whereas the control roots with sprouts did not show any symptom. The fungi were re-isolated from the diseased roots and confirmed as expected M. racemosus or M. fragilis based on the ITS sequences, which satisfied Koch's postulates. Thus, isolate GZ20190123 was identified as M. racemosus and GZ20190124 as M. fragilis. Previously, M. racemosus and M. fragilis have been reported as a pathogen on tomato (Kwon and Hong 2005) and grape (Ghuffar et al. 2018), respectively. To our knowledge, this is the first report of M. racemosus and M. fragilis causing root rot of R. pseudostellariae in southwestern China, where the disease could cause a significant loss to production of this important medicinal plant.

Isolation, identification, and assessment of soil bacteria as biocontrol agents of pea root rot caused by Aphanomyces euteiches

Aphanomyces euteiches is a soil-borne pathogen that causes root rot of pea and can significantly affect pea production in western Canada. This study aimed to isolate and identify soil bacteria with antagonistic activity towards A. euteiches mycelial and zoospore developmental stages under in vitro conditions and assess their potential as biocontrol agents against aphanomyces root rot in field pea under growth chamber conditions. In vitro screening of soil bacteria identified 184 antagonistic isolates, including 22 from an existing culture collection. Mean mycelial growth inhibition zones ranged from 1 to 12 mm, and mean zoospore germination inhibition ranged from 0% to 100%. Use of 16S rDNA sequence analysis placed isolates into 18 different bacterial genera. Screening of 47 bacteria that inhibited both infective stages identified 29 potential biocontrol strains, including Rhizobium spp. that significantly (α = 0.05) suppressed aphanomyces root rot in field pea grown in vermiculite, suggesting the intriguing possibility of using N-fixing Rhizobium inoculants as biocontrol agents for aphanomyces control. Further screening of 20 isolates as soil inoculants identified K-Hf-L9 (Pseudomonas fluorescens), PSV1-7 (Pantoea agglomerans), and K-Hf-H2 (Lysobacter capsici) isolates as having the highest biocontrol activity, significantly (α = 0.05) suppressing aphanomyces root rot in field pea in growth chamber trials. This study demonstrates the possibility of aphanomyces root rot management using biocontrol agents.

Optimization of Culture Conditions for Mycelial Growth and Basidiocarp Production of Cyclocybe cylindracea (Maire)

Agrocybe cylindracea is an exotic and unknown species of mushroom among Filipinos. In our intention to develop production technology for this mushroom, the influences of culture media, pH and physical factors such as aeration, illumination and temperature for optimum mycelial growth and fruiting body production were investigated in the present work. Among media evaluated, potato sucrose gulaman, rice bran decoction gulaman and malt extract agar recorded the highest mycelial growth rate (9.00 mm/day), shortest incubation period (10.00 days) with very thick mycelial density. Potato sucrose gulaman (most common culture medium) at pH 6 incubated in either sealed or unsealed, lighted or dark, and in room temperature (28-33°C) or air-conditioned temperature (23-25 ºC) registered the highest mean mycelial growth rate. Corn grit was the best grain spawning material. The substrate formulation of 7:3 rice straw- sawdust ratio recorded the shortest incubation period and primordial initiation, and the highest total yield of 106.94 g. Therefore, A. cylindracea is an addition to the list of exotic edible mushrooms with great potential for cultivation in the Philippines.

Sensitivity of Colletotrichum acutatum Isolates from Citrus to Carbendazim, Difenoconazole, Tebuconazole, and Trifloxystrobin.

Postbloom fruit drop (PFD) of citrus is caused by the Colletotrichum acutatum and C. gloeosporioides species complexes. The disease is important when frequent rainfall occurs during the flowering period of citrus trees. In Brazil, until 2012, PFD was mainly controlled by preventive applications of the methyl-benzimidazole carbamate (MBC) carbendazim and demethylation-inhibitor (DMI) fungicides such as difenoconazole. Since then, mixtures containing the DMI tebuconazole and the quinone-outside inhibitor (QoI) trifloxystrobin have been commonly used. Fungicides are often applied preventively, sometimes even when conditions are not conducive for PFD development. Excessive fungicide applications may favor the selection of resistant populations of Colletotrichum spp. In this study, we assessed the fungicide sensitivity of C. acutatum isolates collected during the two distinct periods of PFD management in Brazil: before and after the trifloxystrobin and tebuconazole mixture became widely employed. The sensitivity of 254 C. acutatum isolates to carbendazim and difenoconazole and of 164 isolates to tebuconazole and trifloxystrobin was assessed. Mycelial growth inhibition of these isolates was evaluated for all the fungicides using either serial dilution of fungicide rates or the spiral gradient dilution method. In addition, inhibition of conidial germination was also assessed for trifloxystrobin. Analysis of partial β-tub, cytb, and cyp51b gene sequences did not reveal any mutations related to resistance to MBCs, QoIs, and DMIs, respectively. In mycelial growth assays, mean EC50 values were 0.14, 0.11, and 0.21 μg/ml for difenoconazole, tebuconazole, and trifloxystrobin, respectively. The conidial germination inhibition by trifloxystrobin was similar among the tested isolates, and the mean EC50 value was 0.002 μg/ml. All isolates had similar mean mycelial growth inhibition for carbendazim, regardless of the fungicide concentrations. Therefore, based on similar EC50 values and molecular analyses, no shift in the sensitivity of isolates has been observed to the fungicides commonly used in different citrus-producing areas in Brazil.

Efficacy of different fungicides and weedicides against Macrophomina phaseolina (Tassi) Goid causing groundnut root rot

In this study, different systemic, non-systemic, combination fungicides and weedicides at four different concentration were evaluated in vitro against groundnut root rot pathogen Macrophomina phaseolina. Among the non-systemic fungicides, Mancozeb 75% WP and Propineb 70% WP were found most effective and showed (99.98 and 99.96 per cent) mycelia growth inhibition at all concentrations. Whereas in systemic fungicides, Carbendazim 50% WP were found most effective with (94.24 per cent) mean mycelial growth inhibition. Among different combination fungicides tested, Carboxin 37.5% + Thiram 37.5% WP were found most effective with mean mycelial growth inhibition of (97.16 per cent).. In case of weedicides tested, Quizalofo-p-pethyle 5% EC found as most effective inhibiting the mycelial growth of M. phaseolina at all concentrations with (90.92 per cent) mean mycelial growth inhibition. Sclerotial formation was also absent in all this treatments.

Phytochemical Content and <i>In Vitro</i> Antimycelial Efficacy of <i>Colocasia esculenta</i> (L), <i>Manihot esculenta</i> (Crantz) and <i>Dioscorea rotundata</i> (Poir) Leaf Extracts on <i>Aspergillus niger</i> and <i>Botryodiplodia theobromae</i>

TheIn Vitroefficacy of aqueous leaf extracts of common edible root crops (Colocasiaesculenta,ManihotesculentaandDioscorearotundata) were investigated againstAspergillusnigerandBotryodiplodiatheobromae. The fungi were isolated from rotten tubers of yam using antibiotic-amended potatoes dextrose agar. Graded aqueous leaf extract concentrations (25 g/L, 50 g/L and 75 g/L) of each plant were applied against each test fungi on PDA plates and their mycelial growth inhibition activities were monitored for 144 hrs. Camazeb (5 – 10 g/L), a fungicide, was used as positive control agent. The phytochemical constituents of each extracts were also analyzed using standard techniques. The patterns of antifungal activities of the extracts were concentration and pathogen dependent. The most effective mean mycelial growth inhibitions were found withD.esculentaandC.esculentaagainstB.theobromae(61.9 – 80.9 %) andA.niger(63.8 – 82.8 %), respectively. Though,M.esculentaleaf extracts generally demonstrated the least antifungal activities against both pathogens, their activities were significant at 75 g/L. The antifungal potency of bothD.esculentaandC.esculentawere comparable to Camabez (chemical fungicide), which demonstrated 100 % inhibition at both 5 and 10 g/L concentrations. Higher concentrations of saponins (5.64 - 6.71 mg/100g), tannins (4.42 – 7.23 mg/100g) and flavonoids (3.64 – 5.25 mg/100g) were detected in the extracts, and could probably be linked to the observed antifungal activities. Findings from this study showed thatD.esculenta,C.esculentaandM.esculentaposses bioactive molecules that could be exploited in the bio-control of phyto-pathogens of tubers crops, which are the main staple food in most tropical countries.

Collection and in-vitro optimization of growth factors of Ganoderma lucidum

Ganoderma lucidum is one of the most popular medicinal mushrooms, cultivated in India but its optimum growth factors are still not established. So, mycelial growth of Ganoderma lucidum isolates were observed on different media at various temperatures (15- 35°C) and pH levels (4- 8). Results indicate that all the five isolates of G. lucidum grew well on malt extract agar (MEA) media followed by potato dextrose agar (PDA) media and isolate GA (Ganoderma -Almora) with mycelial growth of 5.37 cm was found to be superior to isolate GP (Ganoderma -Pantnagar) on 8th day observation. Mean diametric growth for MEA was maximum (4.60 cm) and that for isolate GA (3.69 cm). Temperature range of 20–25°C was found to best for isolate GA with mycelial growth of 6.38 cm followed by isolate GP (6.06 cm). Optimal mean mycelial growth (5.05 cm) was exhibited at 25°C where isolate GA gave maximum mycelial growth (3.70 cm). All isolates preferred acidic pH 5–6 for their growth. Isolate GP was found to be superior with maximum mycelia growth (6.79 cm) followed by isolate GA (6.62 cm). pH of 6 with 4.72 cm of mycelial growth was superior for all the isolates and isolate GP (4.38 cm) gave maximum mycelial growth. Different Ganoderma lucidum isolates favoured MEA media with a temperature of 20–25°C and pH of 5–6 for optimal mycelial growth. Isolate GA and isolate GP were found to be superior to others.

Nutritional and physiological studies of Fusarium oxysporum f. sp. ciceri (Padwick) Snyder and Hansen causing wilt of chickpea

Nutritional and physiological requirements of Fusarium oxysporum f. sp. ciceri were studied using most virulent isolate FOC-2 (Jalna). Effect of different culture media on mycelial growth of Fusarium oxysporum f. sp. ciceri showed significant differences in growth and sporulation. In vitro , culture media studied, Potato dextrose agar (89.66 mm) and Richard agar medium (85.66) produced significantly highest mean mycelial growth and sporulation. The temperature in the range of 25°C to 30°C and pH having range of 6.0 to 7.0 produce significantly highest mean mycelial growth and sporulation of the test pathogen.

Effect of different culture media, temperature and pH on growth and sporulation of Alternaria carthami

All eight culture media tested encouraged better growth of Alternaria carthami . However, Potato dextrose agar gave significantly highest growth (90.00 mm). The second and third best culture media found were Potato malt agar (84.16 mm) and Yeast manitol agar (73.33 mm). Rest of the culture media recorded good amount of mycelial growth in the range of 41.66 mm (Yeast extract agar) to 69.16 mm (Malt extract agar). Colony growth was circular, cottony, grayishblack or olivaceous-black coloured with fair to excellent sporulation. The mean colony growth recorded with all the different temperature ranged from 5.66 mm at 5°C to 85.66 mm at 30°C. However, significantly highest mean mycelial growth (85.66 mm) was recorded at 30°C with excellent (++++) sporulation. The second and third best temperature found were 25°C (83.83 mm) and 20°C (66.33 mm). The mean colony growth recorded with all the pH values ranged from 30.50 mm at pH 4.0 to 85.83 mm at pH 6.5. However, significantly maximum mean mycelial growth (85.83 mm) was recorded at pH 6.5 with excellent (++++) sporulation. The second and third best pH values found were pH 6 (82.00 mm) and pH 7 (70.33 mm) with excellent and good sporulation, respectively.

Fungicide Resistance of Two Species of Alternaria from Potato in the Columbia Basin of Washington.

Fungicides are extensively used in the Columbia Basin of Washington in an effort to manage early blight and brown spot on potato caused by Alternaria solani and A. alternata, respectively. Azoxystrobin and boscalid interfere with cellular respiration, and fungicide resistance is expected to occur in fungal populations due to the narrow modes of action dictated by each fungicide. The objective of this research was to assess A. solani and A. alternata populations in the Columbia Basin of Washington for azoxystrobin and boscalid resistance by initially screening isolates at a threshold concentration using mycelial growth and spore germination. Fifty isolates of A. solani and 58 of A. alternata were randomly selected for screening from 671 isolates collected from potato in the Columbia Basin from 2009 to 2011. Screening at a threshold concentration was done to estimate the range of fungicide resistance within the populations of A. solani and A. alternata in the region. Resistance of five isolates that differed in sensitivity to azoxystrobin and boscalid were then assessed for mycelial growth and spore germination at three fungicide concentrations in order to determine where rates were no longer effective. A. solani mycelial growth ratios and percent spore germination on azoxystrobin-amended media did not change from 2010 to 2011. A slight decrease in resistance of mycelial growth to azoxystrobin was exhibited among A. alternata isolates collected between 2010 and 2011. No change in sensitivity to azoxystrobin was observed in mycelial growth ratios among A. alternata isolates collected between 2010 and 2011. Resistance to boscalid by A. solani increased as indicated by a significant increase in mean mycelial growth ratio from 2010 to 2011, whereas A. alternata showed no change. Spore germination of A. solani was less at 100 μg/ml than at 1 or 10 μg/ml azoxystrobin. Spore germination of A. alternata did not differ among 1, 10, or 100 μg/ml azoxystrobin. Spore germination of A. solani and A. alternata did not differ among 0.5, 5, or 50 μg/ml boscalid. Resistance to azoxystrobin and boscalid in A. solani and A. alternata populations was shown to be present in the Columbia Basin and will likely become widespread with continued used of site-specific fungicides.