A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

Effect of Temperature

In vitro antagonism of Trichoderma species against six fungal plant pathogens [Biological disease control]

Article history: Received on: 27/09/2016 Accepted on: 29/12/2016 Available online: 20/03/2017 The biocontrol measures against pathogens are widely recognized as a step towards organic agriculture. In the present study, nine species of endophytic fungi and four plant pathogenic fungi were tested against antagonistic activity of a root endophyte, Trichoderma viride. Out of nine endophytic fungi, eight were inhibited. The inhibitory effect was maximum against Alternaria sp. and Pythium sp. The minimum zone was noticed against Nigrospora sp. after 14 days of incubation. It showed no inhibitory effect against an isolate of Aspergillus sp. and overgrew it after 9 days of incubation. T. viride showed antagonistic activity against all the four plant pathogenic fungi. The antagonistic zone was highest against Colletotrichum capsici and lowest was observed in Alternaria solani after 14 days of incubation. The study suggests the potential of an endophytic strain of fungus and it may be used in biocontrol programmes of plant diseases in the region.

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In vitro antagonistic activity of a root endophytic fungus towards plant pathogenic fungi

Variations in total phenolics and antioxidant enzymes cause phenotypic variability and differential resistant response in tomato genotypes against early blight disease

Leaf spot disease caused by Curvularia lunata is one of the major constraints affecting the cultivation of maize in India. Recently, it has been reported that the severity of curvularia leaf spot was prevalent in moderate to severe intensities and cause extensive damage to the crop thus lowering the yields. In the present study, in vivo preventive effect of Lawsonia inermis Linn. bioformulation on curvularia leaf spot disease of maize has been studied. All the experiments were conducted in pots. Percent disease index (PDI), percent efficacy of disease control (PEDC), chlorophyll contents, total carotenoids, and others various growth characteristics like plant height, number of leaves per plant, total carbohydrate and protein content were recorded. Percent seed germination was also observed for seeds treated with all formulations. A significant control of leaf spot disease was recorded with bioformulations treatment T3 [seeds were treated with partially purified acetone extract (4 ml): 100% clove bud oil cake (4 ml): 100% cow dung (2 ml)], T4 [seeds were treated with partially purified acetone extract (3 ml): 100% clove bud oil cake (4 ml): 100% cow dung (3 ml)], T2 [seeds were treated with 100% alcoholic crude extract (2 ml): 100% clove bud oil cake (6 ml): 100% cow dung (2 ml)] and T1 [seeds were treated with 100% alcoholic crude extract (4 ml): 100% clove bud oil cake (4 ml): 100% cow dung (2 ml)] as compared to other bioformulation treatments and its PDI and PEDC were recorded 9.10%, 10.00%, 17.50%, 19.00% and 89.47%, 88.43%, 79.76%, 78.03%, respectively. Results showed that treatment with bioformulation treatment T3, notably increased plant height, number of leaves per plant, chlorophyll, carotenoids, and total soluble sugar content followed by formulations number T4, T2, and T1. However, total soluble protein content was observed to be less in T3 as compared to control. This study suggests that these bioformulations could be essential towards sustainable agricultural science deprived of harming the ecosystem. The synthesized bioformulations have enormous potential to be commercially explored for agriculture use.

A study on preventive effects of Lawsonia inermis L. bioformulations against leaf spot disease of maize

Three bioagents viz., Trichoderma harzianum Rifai, Trichoderma viride Pers. andTrichoderma virens (Miller et al) von Arx and five plant extracts viz., Artimesia absinthiumL., Datura stramonium L., Urtica dioica L., Juglans regia L. and Mentha arvensis L. were evaluated in vitro against Alternaria solani (Ellis and Martin) Jones and Grout causing early blight of potato through dual culture and poisoned food technique, respectively. Among bioagents, significantly higher mycelial growth inhibition of A. solani was recorded in the case of T. harzianum (71.85%), which was followed by T. viride (65.93%) and T. virens(58.65%) proved least effective in inhibiting the mycelial growth of A. solani. Among plant extracts, D. stramonium proved superior to all other botanicals, exhibiting (61.12%) mycelial growth inhibition of A. solani. This was followed by A. absinthium (58.54%).Urtica dioica (37.34%) proved least effective in inhibiting the mycelial growth of the test fungus.

	 

	Key words: Bioagents, plant extracts, potato, Alternaria solani, dual culture, early blight.

Bioefficacy of plant extracts and biocontrol agents against Alternaria solani

Alternaria leaf blight is one of the most important diseases of potato (Solanum tuberosum L.) worldwide. The disease was prevalent in all the potato growing areas of Kashmir valley surveyed during 2009 and 2010. The overall mean disease incidence and intensity ranged from 24.54 to 28.23% and 13.84 to 15.98%, respectively. The highest disease incidence (39.09%) and intensity (22.54%) was recorded in district Budgam. The lowest level of disease was in district Shopian (14.89 and 8.05%, respectively). The pathogen associated with the disease was identified as Alternaria solani (Ellis and Martin) Jones and Grout. In early stages of disease development, small irregular to circular dark brown spots on lower leaves appear, measuring 0.5 mm in size. Upto fourth week of June concentric  rings  form  as  a  result  of irregular growth patterns by the organism in the leaf tissue giving the lesion a characteristic ‘target spot’ or ‘bulls eye’ appearance. The maximum lesion size 7.4 mm was recorded in the second week of August.

	 

	Key words: Potato, Alternaria solani, survey, disease incidence, symtomatology.

https://www.academicjournals.org/article/article1382095621_Ganie et al.pdf

Status and symptomatology of early blight (Alternaria solani) of potato (Solanum tuberosum L.) in Kashmir valley

Five non-systemic fungitoxicants viz., chlorothalonil 50 WP, mancozeb 75 WP, captan 50 WP, propineb 70 WP and copper oxychloride 50 WP at six concentrations (1000, 1500, 2000, 2500, 3000 and 3500 ppm) each and five systemic fungitoxicants viz., thiophenate methyl 70 WP, carbendazim 50 WP, hexaconazole 5 EC, fenarimol 12 EC and difenconazole 25 EC at six concentrations (100, 150, 200, 250, 300 and 350 ppm) each were evaluated in vitro against Alternaria solani (Ellis and Martin) Jones and Grout causing early blight of potato through poisoned food technique. Among non-systemic fungitoxicants mancozeb 75 WP, irrespective of concentration was most effective and inhibited a maximum mean mycelial growth inhibition of 75.46% over check, followed by propineb 70 WP, captan 50 WP, chlorothalonil 75 WP, and copper oxychloride 50 WP with mycelial growth inhibition of 68.09, 66.07, 58.89, and 57.81% respectively. Among systemic fungitoxicants hexaconazole 5 EC was most effective and exhibited a maximum mean mycelial growth inhibition of 84.19% over check. Under in vivo conditions seed treatment with mancozeb 75WP (0.3 %) + foliar spray with hexaconazole 5 EC (0.1%) + foliar spray with datura (50%) + foliar spray with Trichoderma harzianum (1 × 107 spore/ml) were highly effective in controlling the disease severity as compared to control.

	 

	Key words: Fungitoxicants, Alternaria solani, poisoned food technique, Trichoderma harzianum, datura, early blight, potato.

https://africaneditors.org/journal/AJAR/full-text-pdf/32230-113024

Qazi Nissar

Papers

Bioefficacy of plant extracts and biocontrol agents against Alternaria solani

Status and symptomatology of early blight (Alternaria solani) of potato (Solanum tuberosum L.) in Kashmir valley

Integrated management of early blight of potato under Kashmir valley conditions