In Vitro Induction of Resistance to Alternaria Leaf Blight Disease in Carthamus tinctorius L. (Safflower)

Sunflower is an important oil seed crop of Pakistan, comprising 20% proteins and 38-45% oil contents. Alternaria leaf blight (ALB) caused by Alternaria alternata, is one of the devastating diseases of sunflower. Six different fungicides viz., difenoconazole, hexaconazole, azoxystrobin, dimethomorph + mancozeb, myclobutanil and Sulphur were tested at different concentrations (10, 20, 30 ppm) in laboratory and in greenhouse. Fungicides performed best in the laboratory were also investigated in greenhouse against Alternaria leaf blight of sunflower. In in vitro study, Hexaconazole showed 100 % growth inhibition of A. alternata at 30 ppm followed by 70% at 20 ppm and 62% at 10 ppm. Difenoconazole proved as the 2nd best fungicide with 77% fungal inhibition at 30 ppm, 75.8% at 20 ppm and 71% at 10 ppm. Azoxystrobin was the least effective fungicide with 24%, 28%, 34% fungal inhibition at 10, 20 and 30 ppm, respectively. Twelve cultivars of sunflower were screened against blight disease in pot experiment to check the fungicides at different level of susceptibility in greenhouse. Screening result showed that FH 702 was the highest susceptible variety with mean value 7.6. Greenhouse study of disease inhibition effect of fungicides also showed that hexaconazole fungicide produced the best results against A. alternata with 42% disease reduction in FH 702 cultivar and 25 % in FH 696 cultivar as compared to control (83%). The results showed that no fungicide provided full disease inhibition, so, further investigation is needed to find the new chemistry against blight disease of sunflower crop

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Thymol and its Derivatives for Management of Phytopathogenic fungi of maize

Current Bioactive Compounds ◽

10.2174/1573407218666211230142546 ◽

2021 ◽

Vol 18 ◽

Author(s):

Jyoti Gaba ◽

Sunita Sharma ◽

Harleen Kaur ◽

Pardeep Kaur

Keyword(s):

Pathogenic Fungi ◽

Bioactive Compound ◽

Mannich Bases ◽

Phytopathogenic Fungi ◽

Leaf Blight ◽

Significant Control ◽

Thymol Derivatives ◽

Potential Alternative ◽

Blight Disease

Background: Thymol is a bioactive compound having many pharmacological activities. Objective: The present study was carried out to evaluate the fungi toxic effects of thymol and derivatives against phytopathogenic fungi of maize. Method: Thymol was derivatized to get formylated thymol, Mannich bases, and imine derivatives. All the synthesized thymol derivatives were characterized by their physical and spectral properties. Synthesized thymol derivatives were screened for their in vitro antifungal effects using poisoned food technique against three maize pathogenic fungi namely Fusarium moniliforme, Rhizoctonia solani and Dreschlera maydis. Results: Thymol and formylated thymol showed promising results for control of D. maydis with ED50 values less than standard carbendazim and comparable to standard mancozeb. These two compounds were further evaluated for control of D. maydis causative maydis leaf blight disease on maize plants grown in the field during the Kharif season (June to October) 2018. Conclusion: Thymol exhibited significant control of maydis leaf blight disease of maize and emerged as a potential alternative to synthetic fungicides used in cereal crops.

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Influence of weather parameters on alternaria leaf blight severity of makhana under the agro-climate of Koshi region of Bihar

Journal of Agrometeorology ◽

10.54386/jam.v23i1.88 ◽

2021 ◽

Vol 23 (1) ◽

pp. 54-59

Author(s):

SANTOSH KUMAR ◽

MD. NADEEM AKHTAR ◽

SANTOSH KUMAR ◽

MAHESH KUMAR ◽

TRIBHUWAN KUMAR

Keyword(s):

High Temperature ◽

Relative Humidity ◽

Disease Severity ◽

Infection Process ◽

Leaf Blight ◽

Alternaria Leaf Blight ◽

Weather Parameters ◽

Maximum Temperatures ◽

Blight Disease ◽

Cent Disease

Weather parameters play a pivotal role in the infection process and spread of pathogen. It also influences the expression of susceptibility/resistance of the host plant during post-infection phases. Therefore, an experiment was conducted for two consecutive cropping seasons (2018 &2019) to study the influence of weather parameters such as temperature, humidity, rainfall and wind direction on the emergence of alternaria leaf blight of makhana in Koshi region of Bihar. Maximum per cent disease severity of alternarialeaf blightwas observed during the peak monsoon months (June to August). Highest disease severity of leaf blight (14.80% & 15.7%) was observed in the mid June during crop season, 2018 and 2019. High temperature (36.9oC & 38.1oC), and relative humidity (94% & 96.4%) of both the year 2018 and 2019 were found correlated with higher severity to alternaria leaf blight. Similarly average HTR values (3.1) were also found correlated with the average high temperature and relative humidity of both years (2018 and 2019) in terms of severity of leaf blight disease. Maximum temperatures, relative humidity and rainfall exhibited strong positive linear relationship and influenced the occurrence of alternaria leaf blight disease significantly. We also developed a geo-phytopathological model for the prediction of alternaria leaf blight disease of makhana on the basis of congenial mean temperature and relative humidity.

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EFFECT OF NORMAL AND ACTIVATED HUMAN MACROPHAGES ON TOXOPLASMA GONDII

Journal of Experimental Medicine ◽

10.1084/jem.139.5.1154 ◽

1974 ◽

Vol 139 (5) ◽

pp. 1154-1174 ◽

Cited By ~ 77

Author(s):

Seth E. Anderson ◽

Jack S. Remington

Keyword(s):

Toxoplasma Gondii ◽

Cell Mediated Immunity ◽

Blood Monocytes ◽

Effector Cells ◽

Human Macrophages ◽

Obligate Intracellular ◽

Normal Human ◽

Induction Of Resistance ◽

In Vitro Induction

Human macrophages derived from in vitro culture of peripheral blood monocytes were studied under a variety of conditions to determine their microbicidal capacity for the obligate intracellular protozoan, Toxoplasma gondii. The effect of macrophages on intracellular Toxoplasma was evaluated morphologically by light and phase microscopy and by autoradiography. When macrophages from dye test (DT)-negative or DT-positive individuals were infected with Toxoplasma in the presence of normal human serum, the organisms were able to multiply intracellularly with resultant destruction of the monolayer. Once organisms were intracellular, the presence of antibody-containing serum in the medium did not alter this inability of the macrophages to kill Toxoplasma. However, when Toxoplasma were incubated in the presence of heat-inactivated DT-positive serum just before infection of the monolayers, the intracellular organisms were inhibited or killed by normal macrophages. Attempts were made to activate macrophages in vitro to kill Toxoplasma. Macrophages incubated in the presence of sensitized lymphocytes and Streptokinase-Streptodornase (SK-SD) or Toxoplasma lysate antigen (TLA) were found to kill Toxoplasma when compared to macrophages incubated in the presence of lymphocytes from DT-negative individuals and TLA or lymphocytes alone. Thus, in vitro induction of resistance (both specifically and nonspecifically) in human macrophages was accomplished by culturing these cells in the presence of specifically sensitized lymphocytes and antigen. These results suggest that, as in the mouse model, activated human macrophages have the ability to inhibit or kill intracellular Toxoplasma and that these cells may be important as effector cells in cell-mediated immunity (CMI) to toxoplasmosis in man.

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Management of Alternaria leaf blight in tomato plants by mentha essential oil

Plant Protection Science ◽

10.17221/100/2019-pps ◽

2020 ◽

Vol 56 (No. 3) ◽

pp. 191-196

Author(s):

Kahkashan Perveen ◽

Najat A. Bokhari

Keyword(s):

Antifungal Activity ◽

Essential Oil ◽

Mycelial Growth ◽

Leaf Blight ◽

In Vitro Test ◽

Tomato Plants ◽

Conidia Germination ◽

Alternaria Leaf Blight

The essential oil obtained by the hydro-distillation of the leaves of Mentha arvensis Linnaeus was evaluated for its antifungal activity against the causal agent of the Alternaria blight of tomatoes, i.e., Alternaria alternata (Fries) Keissler. The antifungal activity of the mentha essential oil was assessed both in vitro and in vivo. The chemical composition of the mentha oil was also identified by GCMS analysis. The in vitro test revealed that the maximum inhibition in the mycelial growth (93.6%) and conidia germination (90.6%) was at the highest concentration (40 µL/mL), furthermore, it was found that the inhibition of the mycelial growth and conidia germination was dose dependent. The in vivo test proved that the application of the mentha essential oil (40 µL/mL) significantly increased the plant height (84.6%), fresh weight (81.5%) and dry weight (80.0%) when compared to the untreated tomato plants. The disease incidence was 3.5 in the untreated plants, while it was 0.93 for the mentha essential oil treated plants and was 0.08 in the carbendazim treated plants. The GC-MS analysis of the mentha essential oil identified 18 compounds in total, among which the percentage of menthol was the highest (69.2%). The mentha essential oil was successful in managing the Alternaria leaf blight in the tomato plants. Therefore, it can be explored further for the development of a natural fungicide.

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Prevalence and Severity of Leaf Blight Disease of Chrysanthemum in Southern regions of Karnataka and in-vitro Fungicidal Effect on Alternaria alternata

International Journal of Life Sciences ◽

10.3126/ijls.v9i3.12465 ◽

2015 ◽

Vol 9 (3) ◽

pp. 38-45 ◽

Cited By ~ 2

Author(s):

G. Shamala ◽

G. R. Janardhana

Keyword(s):

Alternaria Alternata ◽

Disease Incidence ◽

Life Sciences ◽

Leaf Blight ◽

Cut Flowers ◽

In Vitro Evaluation ◽

Karnataka State ◽

Commercially Important ◽

Blight Disease

Chrysanthemum is one of the commercially important flower crop with great potential both as loose and cut flowers in Karnataka state. In the present study, prevalence and incidence of leaf blight disease was studied in six major growing districts of South Karnataka during 2012 - 2013. The pathogen associated with leaf blight disease was isolated and identified as Alternaria alternata. The study revealed that, the disease was distributed in Southern districts of Karnataka wherever Chrysanthemum is grown. The varieties Chandini and Karnel were more susceptible to blight showing highest disease incidence (100%) and severity (100%) recorded from Mandya and Mysore regions. The lowest disease incidence, severity and PDI of 18.40%, 38.68% and 24.89% were recorded on Rajawhite variety in Bangalore region. During 2013, the highest disease incidence, severity and PDI with 100%, 98.47%, and 45.71% were recorded in Mysore district on Chandini variety. In vitro evaluation of four fungicides on Alternaria alternata revealed that Carbendazim+Mancozeb was most effective with 95.65% inhibition followed by Carbendazim, Mancozeb and Metalaxyl+Mancozeb with 68.26%, 91.30% and 91.30% inhibition of the mycelium at 2.0% concentration.DOI: http://dx.doi.org/10.3126/ijls.v9i3.12465 International Journal of Life Sciences 9 (3): 2015; 38-45

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