Stomatal openings on boxwood leaves yield entry portals for leaf infection by Calonectria pseudonaviculata

Neck rot of onion caused by Botrytis spp., including B. allii, has previously been controlled in Australia with the fungicide Benlate (benomyl). Production of Benlate has recently ceased, therefore a field trial was conducted to examine the efficacy of alternative benzimidazoles fungicides. The trial compared 2 carbendazim fungicides (Marvel and Spin Flo) at 3 rates of application with Benlate applied at commercial rates and to non-treated plots in a randomised complete block design with 4 replicate plots per treatment. Fungicides were applied at 89, 96, 112 and 119 days after sowing. Plots were sprayed with inoculum consisting of a suspension of B. allii conidia 103 days after sowing. The incidence of B. allii infection in leaves was estimated 10 times during the season by collection and incubation of leaf samples. Fifty-six days after inoculum application the mean incidence of B. allii in leaves from fungicide treatments ranged from 0 to 10%, significantly lower (P<0.05) than that of non-treated plots (28.8%). The mean incidence of neck rot in bulb samples after 3 months of storage ranged from 1.0 to 9.9% in fungicide treatments, significantly (P<0.05) lower than that of non-treated plots (63.4%). The incidence of B. allii leaf infection in plots sampled at different times during the season and the incidence of neck rot in storage were all significantly correlated (r = 0.42–0.61, P<0.01), except prior to application of inoculum.

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Quantification of incubation, latent and infection periods of Phakopsora pachyrhizi in soybean, according to chronological time and degree-days

Summa Phytopathologica ◽

10.1590/0100-5405/1920 ◽

2016 ◽

Vol 42 (1) ◽

pp. 11-17 ◽

Cited By ~ 2

Author(s):

Anderson Luiz Durante Danelli ◽

Erlei Melo Reis

Keyword(s):

Infection Process ◽

Growth Chamber ◽

Phakopsora Pachyrhizi ◽

Degree Days ◽

Leaf Infection ◽

Chronological Time ◽

Accumulated Degree Days

ABSTRACT In experiments conducted in a growth chamber, the chronological time and the accumulated degree-days were determined for the duration of incubation, latent and infectious periods of Phakopsora pachyrhizi cultivars BRSGO 7560 and BRS 246 RR. Detached soybean leaflets were placed in gerbox-type acrylic boxes and inoculated with 20 x 103 uredospores/mL. The study was conducted at 12-h photoperiod and temperatures of 10ºC, 15ºC, 22ºC, 25ºC and 30°C for 30 days. Lesions and uredia/cm2were evaluated and the number of uredia per lesion was quantified after the beginning of sporulation. The sporulation potential was also quantified for cultivars BRSGO 7560 and BRS 246 RR. The steps of the infection process can be quantified based on both the chronological time and the accumulated heat. The cultivar BRSGO 7560 produced 4,012.8 spores/cm2 and BRS 246 RR, 7,348.4 uredospores/cm2. The largest number of uredia was produced at 25ºC in both cultivars; however, BRS 246 RR presented 372.7 uredia/cm2 and BRSGO 7560, 231.6 uredia/cm2. At 10ºC and 30°C, leaf infection did not occur in both cultivars.

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Management of Leaf Blight (Bipolaris sorokiniana) Disease of Wheat with Cultural Practices

Nepal Agriculture Research Journal ◽

10.3126/narj.v7i0.1870 ◽

2009 ◽

Vol 7 ◽

pp. 63-69

Author(s):

PCP Chaurasia ◽

E Duveiller

Keyword(s):

Grain Yield ◽

Plant Height ◽

Cultural Practices ◽

Flag Leaf ◽

Kernel Weight ◽

Leaf Blight ◽

Thousand Kernel Weight ◽

Leaf Infection ◽

Higher Doses ◽

Late Sowing

An experiment was conducted at agronomy farm of Agriculture research Station, Tarahara,Nepal for three consecutive years viz 2000/2001,2001/2002, and 2002/2003 to evaluate theeffects of different cultural practices on leaf blight diseases of wheat caused by Bipolarissorokiniana under terai conditions. The experiment was conducted in factorial RandomizedComplete Block Design with four replications. Four factors, two wheat verities RR-21 andNepal 297,two number of irrigations (two and three irrigations), two doses of Nitrogen fertilizerviz. 60kg N/ha and 120 kg N/ha and two dates of sowing of wheat were examined. Differentyield components, grain yield (kg/plot) and disease severity were recorded to judge the effects ofthese factors on severity of leaf blight of wheat. Nepal Line 297 had significantly less AUDPCbased on flag leaf infection and whole plan as compared to RR-21. Number of irrigations had nosignificant effect on AUDPC, as there was frequent rain during experimental period. Doses ofNitrogen fertilizer had significant effect on AUDPC based on flag leaf infection. It was higher incase of 60 kg N/ha. The third week of November sowing of wheat had lower value of AUDPCas compared to December sowing. Plant height, panicle lengths were highly significantly higherin case of RR-21 as compared to Nepal-297. Thousand kernel weight, and grain yield kg/ha weresignificantly higher in Nepal-297. All agronomic parameters except thousand kernel weight andnumber of tillers/plan were significantly higher in 120kg N/ha. The third week of Novembersowing of wheat had less plant height and panicle length, higher thousand kernel weight andmore grain yield. Leaf blight severity was highly significantly less in case of Nepal-297. Dosesof Nitrogen fertilizer had significant effect on plant height, panicle length, thousand kernelweight, percentage flag leaf infection and AUDPC based on flag leaf infection. Based on theresults of three years of experimentations, it can be concluded that Nepal-297 had less disease,number of irrigations had no effect on disease severity, higher doses of nitrogen fertilizer hadless flag infection and late sowing of wheat also had less disease. Numbers of irrigation's effectswere inconclusive as there were frequent rains during experimentation period. Based on aboveconclusion, it is recommended that growing wheat verity like Nepal-297, use of higher doses ofnitrogen fertilizer and sowing of wheat / first week of Dec help in minimizing the severity of leafblight. However late sowing had lowered grain yield.Key words: AUDPC; culture practices; disease management; leaf blightDOI: 10.3126/narj.v7i0.1870Nepal Agriculture Research Journal Vol.7 2006 pp.63-69

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Corynebacterium oortii. [Descriptions of Fungi and Bacteria].

IMI Descriptions of Fungi and Bacteria ◽

10.1079/dfb/20056400375 ◽

1973 ◽

Author(s):

J. F. Bradbury

Keyword(s):

Geographical Distribution ◽

Storage Period ◽

Vascular Bundles ◽

Lower Epidermis ◽

Tulipa Gesneriana ◽

White Spots ◽

Leaf Infection ◽

Tulip Bulbs ◽

Short Time ◽

White Scale

Abstract A description is provided for Corynebacterium oortii. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Tulipa gesneriana, the garden tulip. DISEASE: 'Geel-pok' (yellow pustule) of tulip bulbs and 'hels vuur' (hell-fire) of the leaves. Primary infection occurs on leaves, which show silver grey spots after a short time. These become up to about 5 mm diam. with brittle, easily cracked epidermis and disorganised-looking parenchyma within. Plants may also show leaves with areas in which the upper and lower epidermis is badly cracked, giving a characteristic rough look to the leaves. These plants show yellowish stem interiors that run down to the young growing bulbs. On bulbs the outermost white scale develops many tiny white spots which turn yellow and by the end of the storage period are yellow areas with raised tissue and ruptured outer skin. In section many vascular bundles are yellow. Less severely affected bulbs develop into stunted plants with leaves showing silvery streaks along veins. GEOGRAPHICAL DISTRIBUTION: Netherlands, England. TRANSMISSION: By planting out of infected bulbs, which may produce infected plants and in turn more infected bulbs; also from plant to plant in the field by leaf infection. The latter presumably in windy and wet conditions.

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On Analysis of Wheat Leaf Infection by Using Image Processing

Proceedings of the International Conference on Data Engineering and Communication Technology - Advances in Intelligent Systems and Computing ◽

10.1007/978-981-10-1675-2_56 ◽

2016 ◽

pp. 569-577 ◽

Cited By ~ 1

Author(s):

Rittika Raichaudhuri ◽

Rashmi Sharma

Keyword(s):

Image Processing ◽

Leaf Infection ◽

Wheat Leaf

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Impairment of leaf hydraulics in young plants of Citrus aurantium (sour orange) infected by Phoma tracheiphila

Functional Plant Biology ◽

10.1071/fp07065 ◽

2007 ◽

Vol 34 (8) ◽

pp. 720 ◽

Cited By ~ 7

Author(s):

Fabio Raimondo ◽

Francesco Raudino ◽

Santa Olga Cacciola ◽

Sebastiano Salleo ◽

Maria Assunta Lo Gullo

Keyword(s):

Conidial Suspension ◽

Sour Orange ◽

Citrus Aurantium ◽

Citrus Species ◽

Leaf Hydraulics ◽

Primary Mechanism ◽

Major Vein ◽

Leaf Infection ◽

Phoma Tracheiphila ◽

The Impact

Phoma trachephila (Petri) Kantschaveli et Gikachvili causes dieback of several Citrus species. The impact of this fungus on leaf hydraulics was studied in Citrus aurantium L. (sour orange) with the aim of identifying the primary mechanism of damage to leaves. Leaves inoculated with a conidial suspension were measured for conductance to water vapor (gL) and specific hydraulic conductance (Kleaf) every 3 days after inoculation. The earliest symptom of infection consisted of vein chlorosis. Functional vein density (FVD) was monitored and microscopic observations were made of major vein conduits. Impairment of vein hydraulics started 25 days after inoculation with a losses of Kleaf of 40% and gL of ~60%. Most minor veins within chlorotic areas were no longer functioning and some conduits of the major veins showed digested interconduit pits leading to vein cavitation. The close Kleaf–FVD relationship revealed that vein impairment caused drop of Kleaf and, consequently, of gL at chlorotic areas. Leaf infection was focused to veins that were first forced to embolise and then invaded by fungal hyphae. The vein embolism due to the Phoma amplifies the native dominant hydraulic resistance of leaf veins, and leads ultimately to early shedding of infected leaves.

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