Effects of wounding and relative humidity on the incidence of Phytophthora root and stem rot in soybean seedlings

2021 ◽  
pp. 101737
Author(s):  
Terufumi Tada ◽  
Chihiro Tanaka ◽  
Tomoyuki Katsube-Tanaka ◽  
Tatsuhiko Shiraiwa
Keyword(s):  
Relative Humidity ◽  
Stem Rot ◽  
Soybean Seedlings

scholarly journals A Crop Loss-Related Forecasting Model for Sclerotinia Stem Rot in Winter Oilseed Rape

2007 ◽  
Vol 97 (9) ◽  
pp. 1186-1194 ◽  
Author(s):  
S. Koch ◽  
S. Dunker ◽  
B. Kleinhenz ◽  
M. Röhrig ◽  
A. von Tiedemann
Keyword(s):  
Relative Humidity ◽  
Oilseed Rape ◽  
Disease Risk ◽  
Stem Rot ◽  
Forecasting Model ◽  
Crop Loss ◽  
Agricultural Practice ◽  
Sclerotinia Stem Rot ◽  
Winter Oilseed Rape ◽  
Stem Infection

Sclerotinia stem rot (SSR) is an increasing threat to winter oilseed rape (OSR) in Germany and other European countries due to the growing area of OSR cultivation. A forecasting model was developed to provide decision support for the fungicide spray against SSR at flowering. Four weather variables—air temperature, relative humidity, rainfall, and sunshine duration—were used to calculate the microclimate in the plant canopy. From data reinvestigated in a climate chamber study, 7 to 11°C and 80 to 86% relative humidity (RH) were established as minimum conditions for stem infection with ascospores and expressed as an index to discriminate infection hours (Inh). Disease incidence (DI) significantly correlated with Inh occurring post-growth stage (GS) 58 (late bud stage) (r2 = 0.42, P ≤ 0.001). Using the sum of Inh from continuous infection periods exceeding 23 h significantly improved correlation with DI (r2 = 0.82; P ≤ 0.001). A parallel GS model calculates the developmental stages of OSR based on temperature in the canopy and starts the model calculation at GS 58. The novel forecasting system, SkleroPro, consists of a two-tiered approach, the first providing a regional assessment of the disease risk, which is assumed when 23 Inh have accumulated after the crop has passed GS 58. The second tier provides a field-site-specific, economy-based recommendation. Based on costs of spray, expected yield, and price of rapeseed, the number of Inh corresponding to DI at the economic damage threshold (Inhi) is calculated. A decision to spray is proposed when Inh ≥ Inhi. Historical field data (1994 to 2004) were used to assess the impact of agronomic factors on SSR incidence. A 2-year crop rotation enhanced disease risk and, therefore, lowered the infection threshold in the model by a factor of 0.8, whereas in 4-year rotations, the threshold was elevated by a factor 1.3. Number of plants per square meter, nitrogen fertilization, and soil management did not have significant effects on DI. In an evaluation of SkleroPro with 76 historical (1994 to 2004) and 32 actual field experiments conducted in 2005, the percentage of economically correct decisions was 70 and 81%, respectively. Compared with the common practice of routine sprays, this corresponded to savings in fungicides of 39 and 81% and to increases in net return for the grower of 23 and 45 €/ha, respectively. This study demonstrates that, particularly in areas with abundant inoculum, the level of SSR in OSR can be predicted from conditions of stem infection during late bud or flowering with sufficient accuracy, and does not require simulation of apothecial development and ascospore dispersal. SkleroPro is the first crop-loss-related forecasting model for a Sclerotinia disease, with the potential of being widely used in agricultural practice, accessible through the Internet. Its concept, components, and implementation may be useful in developing forecasting systems for Sclerotinia diseases in other crops or climates.

scholarly journals Effects of Plant Spacing, Inoculation Date, and Peanut Cultivar on Epidemics of Peanut Stem Rot and Tomato Spotted Wilt

Plant Disease ◽  
2005 ◽  
Vol 89 (9) ◽  
pp. 969-974 ◽  
Author(s):  
L. E. Sconyers ◽  
T. B. Brenneman ◽  
K. L. Stevenson ◽  
B. G. Mullinix
Keyword(s):  
Relative Humidity ◽  
Sclerotium Rolfsii ◽  
Critical Factor ◽  
Stem Rot ◽  
Disease Development ◽  
Plant Spacing ◽  
Ambient Conditions ◽  
Tomato Spotted Wilt ◽  
Arachis Hypogaea L ◽  
Growth Habits

Two microplot studies were conducted with peanut (Arachis hypogaea L.) in 2000, 2001, and 2002 to determine the effects of plant spacing, inoculation date, and cultivar on stem rot development caused by Sclerotium rolfsii Sacc., tomato spotted wilt incidence, and microclimate (temperature and relative humidity). Stem rot severity and incidence decreased as plant spacings were increased in 5-cm increments from 5 to 30 cm. Two cultivars with similar susceptibility but different growth habits were compared. Perhaps due to heavy irrigation and extensive vegetative growth, stem rot was similar for ‘Florida MDR-98’ and ‘Georgia Browne’. Plants inoculated later in the year (90 days after planting [DAP]) had less disease at harvest, but often developed more severe symptoms within the first week of inoculation than plants inoculated at 50 or 70 DAP. Canopy microclimate was different than ambient conditions for all treatments; however, differences among treatments were inconsistent and did not explain differences in disease among spacings. Generally, as plant spacing decreased and plant population increased, stem rot increased and tomato spotted wilt was reduced. These data demonstrate that the physical spacing between plants is a critical factor in disease development.

scholarly journals First Report of Sclerotinia Stem Rot of Anemone Caused by Sclerotinia sclerotiorum in Korea

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 997-997 ◽  
Author(s):  
K. S. Han ◽  
J. Y. Kim ◽  
J. H. Park ◽  
H. D. Shin
Keyword(s):  
Relative Humidity ◽  
Sclerotinia Sclerotiorum ◽  
Crown Rot ◽  
Stem Rot ◽  
Economic Losses ◽  
High Humidity ◽  
Sclerotinia Stem Rot ◽  
First Report ◽  
Plant Pathol ◽  
Poor Ventilation

In Korea, anemones (Anemone coronaria L.) are mostly grown during winter, in polyethylene tunnels that may have high humidity and poor ventilation, to meet the high demand of cut flowers in February and March for school ceremonies. During the winter of 2011 to 2012, symptoms typical of Sclerotinia stem rot were observed in commercial crops of anemone (cv. Rosso Mistral Plus) in Hwaseong City, Korea. About 40% of anemones withered or died before harvest due to the disease, causing considerable economic losses. In one farmer's polyethylene tunnel with a good ventilation system in Icheon City, Korea, less than 1% of the anemones showed Sclerotinia stem rot during the same season. Symptoms included stem necrosis and withering of leaves, followed by crown rot and wilt a few days afterward. White cottony growth of the fungus was observed on dead plants and the nearby soil surface, especially under high relative humidity. Black sclerotia 2 to 7 mm in diameter developed in the mycelium. Isolations from surface-disinfested stem pieces onto potato dextrose agar (PDA) consistently yielded white, fluffy colonies. Two-week-old colonies produced plentiful numbers of sclerotia on PDA. The isolated fungus was morphologically identified as Sclerotinia sclerotiorum (Lib.) de Bary (1,3). Voucher specimens (n = 4) were deposited in the Korea University herbarium (KUS). Two isolates were deposited in the Korean Agricultural Culture Collection with accession numbers KACC46708 (ex KUS-F26433) and KACC46834 (ex KUS-F26437), respectively. Fungal DNA was extracted with a DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 (4) and sequenced using an ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequences of 501 bp were deposited in GenBank (Accession Nos. KC412065 and KC412066). A BLAST search revealed that sequences of the two Korean isolates showed 100% identity with those of S. sclerotiorum (e.g., GenBank Accession No. JN012606). A pathogenicity test was achieved by placing agar segments (9 mm2) from a 7-day-old culture grown on PDA on the stems of healthy anemones (cv. Rosso Mistral Plus) near the soil line. Three plants inoculated with agar blocks served as controls. Plants were maintained in a greenhouse at 16 to 20°C and relative humidity >90%. After 2 days, all inoculated stems became discolored, soft, watery, and covered with white mycelia, whereas control plants remained symptomless. S. sclerotiorum was consistently reisolated from the symptomatic tissue, fulfilling Koch's postulates. Sclerotinia stem rot of anemones caused by S. sclerotiorum has previously been recorded from the United States and New Zealand (2), and to our knowledge, this is the first report of S. sclerotiorum on anemone in Korea. According to our observations in damaged plots, low temperature, high humidity, poor ventilation, and continuous cultivation would accelerate the incidence of Sclerotinia stem rot in polyethylene tunnel cultivation systems in Korea. References: (1) M. D. Bolton et al. Mol. Plant Pathol. 7:1, 2006. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA. Retrieved December 3, 2012. (3) S. Umemoto et al. J. Gen. Plant Pathol. 73:290, 2007. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

scholarly journals First Report of Nectria haematococca Causing Stem Rot of Soybean in China

Plant Disease ◽  
2012 ◽  
Vol 96 (3) ◽  
pp. 457-457 ◽  
Author(s):  
Y. Gai ◽  
R. Pan ◽  
D. Xu ◽  
M. Deng ◽  
W. Chen ◽  
...  
Keyword(s):  
Elongation Factor ◽  
Morphological Characteristics ◽  
Its Region ◽  
Stem Rot ◽  
Universal Primers ◽  
Conidial Suspension ◽  
Fruiting Bodies ◽  
Nectria Haematococca ◽  
First Report ◽  
Soybean Seedlings

In October 2010, soybean (Glycine max) plants growing in commercial soybean fields in Zengcheng City, Guangdong Province developed symptoms consisting of stem and root rot, yellowing, and defoliation of leaves. Reddish, spherical fruiting bodies appeared in lesions that developed on stems. Plants with symptoms were sampled from fields. Fruiting bodies were excised from diseased tissues. Microscopic examination revealed that they were perithecia, globose to pyriform, and measured 197 to 260 μm in diameter and 226 to 358 μm long. When squeezed gently, cylindrical to clavate asci, 7.2 to 9.6 μm in diameter and 75.4 to 92.0 μm long, containing eight ascospores were exuded from the perithecia. Ascospores were ellipsoid to obovate, two celled, slightly constricted at the septum, had longitudinal striations, and measured 4.9 to 6.0 μm in diameter and 10.6 to 15.0 μm long. The fungus was isolated from the basal stem tissues of diseased soybean plants and cultured on potato dextrose agar (PDA) medium amended with streptomycin sulfate. On PDA, the culture developed into blue-pigmented colonies with whitish mycelium that produced oval to cylindrical microconidia. Microconidia had 0 to 1 septum, ranged from 2.5 to 5.2 × 7.6 to 29.4 μm, and were produced on monophialides. Macroconidia were cylindrical to falcate, thick walled, 2 to 5 septa, and 3.5 to 6.0 × 25.4 to 66.8 μm. Chlamydospores were present and ranged from 6.8 to 13.6 × 5.5 to 9.5 μm. Orange-to-reddish perithecia were readily formed in old culture. These morphological characteristics were consistent with descriptions of Nectria haematococca (anamorph Fusarium solani) (1). The rDNA internal transcribed spacer (ITS) region and the fragment of translation elongation factor 1-alpha (EF1-α) genes of the fungus were amplified, respectively, with universal primers ITS1/ITS4 and ef1/ef2 primers and sequenced. BLAST searches showed that the ITS sequences of three isolates (GenBank Accession Nos. JN015069, JN190942, and JN190943) had 99% similarity with those of N. haematococca(GenBank Accession Nos. DQ535186, DQ535185, and DQ535183) and the EF1-α sequences of three isolates (GenBank Accession Nos. JN874641, JN874642, and JN874643) had 100% similarity with those of F. solani (GenBank Accession Nos. DQ247265 and DQ247327). Completion of Koch's postulates confirmed the pathogenicity of the isolates in a replicated experiment. Thirty-day-old soybean seedlings of cultivar Huaxia No. 3 were inoculated by soaking their root systems in a conidial suspension (106 conidia per ml) for 30 min and then transplanted in plastic pots (20 cm in diameter) and incubated at 25 ± 2°C in a greenhouse. Control plants were treated with sterile water in the same way. There were four plants per pot and there were six replicates for each treatment. Within 3 weeks, more than 70% of the inoculated plants exhibited symptoms of leaf yellowing, stem rot, and root rots while control plants were symptomless. N. haematococca was reisolated from the diseased plants. To our knowledge, this is the first report of N. haematococca causing stem rot of soybean in China and the first description of sexual reproduction of F. solani causing soybean stem rot in nature. This pathogen may pose a serious threat to soybean production in China where soybean is a main crop. Reference: (1) C. Booth. The Genus Fusarium. CAB International, Wallingford, UK, 1971.

2012–2016 On-Farm Evaluation of Fungicide Programs for Peanut Disease Control in Hamilton County, Florida

EDIS ◽  
2017 ◽  
Vol 2017 (4) ◽  
Author(s):  
Keith W. Wynn ◽  
Nicholas S. Dufault ◽  
Rebecca L. Barocco
Keyword(s):  
Plant Pathology ◽  
Disease Control ◽  
Leaf Spot ◽  
Fungal Disease ◽  
White Mold ◽  
Stem Rot ◽  
Late Leaf Spot ◽  
Fact Sheet ◽  
On Farm ◽  
Hamilton County

This ten-page fact sheet includes a summary of various fungicide spray programs for fungal disease control of early leaf spot, late leaf spot, and white mold/stem rot of peanut in 2012-2016 on-farm trials in Hamilton County. Written by K.W. Wynn, N.S. Dufault, and R.L. Barocco and published by the Plant Pathology Department.http://edis.ifas.ufl.edu/pp334

EPIDEMIOLOGY, ECOLOGY AND PREVALENCE OF SOIL TRANSMITTED HELMINTHS FROM KOSHI REGION OF NORTH BIHAR.

2018 ◽  
Vol 24 (1) ◽  
Author(s):  
LAKSHMI CHOUDHARY ◽  
PRABHAWATI PRABHAWATI
Keyword(s):  
Relative Humidity ◽  
Ascaris Lumbricoides ◽  
Rainy Season ◽  
Climatic Factors ◽  
Trichuris Trichiura ◽  
Hookworm Infection ◽  
Soil Transmitted Helminths ◽  
High Incidence ◽  
Apparently Healthy

Prevalence of soil transmitted helminthes infections in apparently healthy school going children and other 528 people of different districts of Koshi regions of North Bihar were evaluated. Over all incidences of STHs infection was 39.39% during study. High incidence of STH was seen in the rainy season i.e., in the month of July and August, September, significantly higher (P<0.05) .The incidence of Ascaris lumbricoides was highest in the month of August (18.64%). The month of September was 15.25% followed by that of July (14.4%) and October with 10.16%. Also the incidence of hookworm registered the highest incidence in the month of June (19.27%) and lowest in the month of December (4.82%) during the study period. However prevalence of Trichuris trichiura was negligible and it was almost nil in the most of the months but was highest in month of September with 28.57% and lowest in October with 14.00% The climatic factors are responsible for soil transmitted helminthes which are temperature, rainfall and relative humidity. Ascariasis, Trichuriasis and Ancyclostomiasis (Hookworm infection) are found to be endemic in this region.

EL NINO RELATED CLIMATE AND DENGUE FEVER CASES IN JEDDAH, SAUDI ARABIA

2019 ◽  
Vol 25 (1) ◽  
Author(s):  
MASROOR ALI KHAN ◽  
KHALID AL GHAMDI ◽  
JAZEM A. MEHYOUB ◽  
RAKHSHAN KHAN
Keyword(s):  
Relative Humidity ◽  
Dengue Fever ◽  
El Niño ◽  
Significant Relationship ◽  
El Nino ◽  
Climate Data ◽  
Light Traps ◽  
Mosquito Abundance ◽  
Dengue Transmission ◽  
The Relationship

The focus of this study is to find the relationship between El Nino and dengue fever cases in the study area.Mosquito density was recorded with the help of light traps and through aspirators collection. Climate data were obtained from National Meteorology and Environment centre. (Year wise El Nino and La Nina data are according to NOAA & Golden Gate Weather Services). Statistical methods were used to establish the correlation coefficient between different factors. A high significant relationship was observed between Relative Humidity and Dengue fever cases, but Aedes abundance had no significant relationship with either Relative humidity and Temperature. Our conclusion is that the El Nino does not affect the dengue transmission and Aedes mosquito abundance in this region, which is supported by earlier works.

Sign in / Sign up

Export Citation Format

Share Document