First Report of Catenaria anguillulae Infecting Rotylenchulus reniformis and Heterodera glycines in Alabama

A new fungal parasite of the reniform nematode has been observed parasitizing nematode populations that have increased on cotton in a sandy loam field soil in the greenhouse. When enumerated, 46% of the stock reniform nematode population was colonized by this fungus. Egg, vermiform, and adult stages of the reniform nematode were observed with light microscopy and scanning electron micrography (SEM). The nematophagous fungus, Catenaria auxiliaries, was identified morphologically. There are no sequences on the GenBank to achieve a molecular identification. This nematophagous fungus has been previously reported on the beet cyst nematode in Europe (1,2); however, to our knowledge there are no reports of this fungus parasitizing the reniform nematode. In vermiform life stages of the nematode, rhizomycelium is observed in the initial phase of infection and is characterized by ovoid cells, 9.5 to 13.5 × 17.0 to 24.5 μm in diameter, separated by septa. Usually 10 to 15 ovoid cells lacking intercellular hyphal filaments are produced within each vermiform body. Rhizoids 3.5 to 4.0 μm wide develop from the rhizomycelium. Mature swollen cells produce precursor sporangia that may mature into resting spores or zoosporangia. Resting spores are yellow-to-cream, 20 to 40 μm in diameter with a reticulate appearance, and are common in the vermiform nematode life stages. Zoosporangia are ovoid, 9.5 to 13.5 × 17.0 to 24.5 μm, and will erupt from the cuticle of the vermiform nematode releasing zoospores via papillae. Zoospores are 2.9 to 4.9 μm with visible globules in the anterior region and single flagella that are 9 to 11 μm long. The zoospores swim short distances, maneuvering in the direction of the flagellum. Adult reniform females observed through SEM exhibit zoospores encysted in the metacorpus region of the nematode. Parasitized eggs are internally colonized with zoosporangia that are 20 to 25 μm in diameter. In advanced stages of infection, the eggs darken in color and zoosporangia erupt through the cuticle of the egg. Reniform nematodes visibly colonized with zoosporangia and resting spores were placed on corn meal, water, and potato dextrose agars. None of these media supported growth of the fungus, supporting our theory that this organism appears to be an obligate parasite of the nematode. Koch's postulates was completed when eggs colonized with rhizomycelium and resting spores or zoosporangia were added to cotton plants in sterile soil previously inoculated with 2,000 healthy vermiform reniform life stages. Plants were allowed to grow for 30 days in the greenhouse after which the next generation of vermiform nematodes were extracted from the soil and examined under the microscope. Rhizomycelium, resting spores, and zoosporangia were present in 42% of the reniform vermiform life stages. Morphological comparisons of the rhizomycelium, resting spores or zoosporangia, and zoospores colonizing the reniform nematodes were similar to the initial observations. Thus to our knowledge, this is the first report of Catenaria auxiliaries parasitizing the reniform nematode. References: (1) B. Kerry. J. Nematol. 12:253, 1980. (2) H. T. Tribe. Trans. Br. Mycol. Soc. 69:367, 1977.

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Uso de esterco bovino e cobertura de solo no manejo de nematoides na cultura da soja

Revisão Anual de Patologia de Plantas ◽

10.31976/0104-038321v270002 ◽

2021 ◽

Vol 27 (1) ◽

pp. 32-50

Author(s):

Mauro Junior Natalino da Costa

Keyword(s):

Heterodera Glycines ◽

Meloidogyne Javanica ◽

Rotylenchulus Reniformis ◽

Pratylenchus Brachyurus

As doenças causadas por nematoides são consideradas importantes devido ao hábito polífago desses patógenos, estratégias de sobrevivência e aos prejuízos econômicos causados. No Brasil, as espécies que provocam os maiores danos na cultura da soja são: Meloidogyne javanica, M. incognita, Heterodera glycines, Pratylenchus brachyurus, Rotylenchulus reniformis e Aphelenchoides sp. Recentemente, surgiram relatos de incidência, em algumas regiões, de Tubixaba spp., Scutellonema brachyurus e Helicotylenchus dihystera. Dessa forma, é necessária a utilização de estratégias de manejo que auxiliem na redução dos níveis populacionais desses fitoparasitas. O uso de esterco bovino, associado a espécies vegetais para cobertura de solo, apresentase como uma alternativa para manejo de nematoides na cultura da soja, devido a um conjunto de propriedades nematostáticas e nematicidas, ao efeito benéfico às plantas e ao estímulo do desenvolvimento de inimigos naturais. São indicadas espécies de plantas que produzam resíduos que cubram melhor o solo, deixem mais palhada, distribuam seus sistemas radiculares pivotantes e/ou fasciculados, mantenham ou aumentem os teores de carbono, e incrementem a densidade/ riqueza macro e microbiológica. Esta revisão tem o objetivo de apresentar e discutir os principais efeitos do uso de matéria orgânica e alternativas de manejo e controle de nematoides na cultura da soja com o emprego de esterco bovino e cobertura de solo com diferentes espécies de plantas.

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First Report of Soybean Cyst Nematode (Heterodera glycines) on Soybean in North Dakota

Plant Disease ◽

10.1094/pdis.2004.88.11.1287a ◽

2004 ◽

Vol 88 (11) ◽

pp. 1287-1287 ◽

Cited By ~ 14

Author(s):

C. A. Bradley ◽

C. R. Biller ◽

B. D. Nelson

Keyword(s):

North Dakota ◽

Soybean Cyst Nematode ◽

Heterodera Glycines ◽

Plant Introduction ◽

Cyst Nematode ◽

Diagnostic Laboratory ◽

First Report ◽

Second Stage ◽

The North ◽

Pi 88788

During August 2003, soybean (Glycine max) plants from Richland County, North Dakota with white-to-yellow, lemon-shaped structures on the roots were brought to the North Dakota State University Plant Diagnostic Laboratory. To confirm that the structures were females of a cyst nematode, they were crushed and observed microscopically to determine if nematode eggs and second-stage juveniles were present. Morphology of the second-stage juveniles was consistent with Heterodera glycines, the soybean cyst nematode (SCN). A survey was conducted in soybean fields in 34 km2 around the field in which the samples originated. Ten of twenty fields surveyed had visible females on the roots of plants. Symptoms observed in those fields included patches of stunted, chlorotic, and dead plants. Soil samples were collected from selected areas within eight fields, eggs were extracted using standard soil sieving techniques, and egg numbers were determined. Egg numbers ranged from 550 to 20,000 eggs per 100 cm3 of soil. SCN collected from two different fields, designated as Dwight and LaMars, were used to determine their HG Type. Standardized procedures (1) were used in a growth chamber set at 27°C with 16-h days. Pots in the test were organized in a completely randomized design with three replicates; the test was repeated over time. After 30 days, females were extracted from roots and counted, and a female index (FI) was calculated for each indicator line (1). The mean number of females on susceptible standard cv. Lee 74, was 110. The Dwight SCN population had an FI of 5.3 on plant introduction (PI) 88788, 1.5 on PI 209332, 5.8 on PI 548316 (Cloud), and 0 on all other indicator lines. The LaMars population had an FI of 1.0 on PI 88788, 3.1 on PI 548316 (Cloud), and 0 on all other indicator lines. These results indicate that both SCN populations tested are HG Type 0. To our knowledge, this is the first report of SCN on soybean in North Dakota. Because other hosts of SCN, as well as soybean, are economically important in North Dakota, such as dry edible bean (Phaseolus vulgaris) and dry pea (Pisum sativum), this disease could adversely impact several commodities throughout the state. Reference: (1) T. L. Niblack et al. J. Nematol. 34:279, 2002.

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First Report of the Soybean Cyst Nematode, Heterodera glycines, on Soybean in Zhejiang, Eastern China

Plant Disease ◽

10.1094/pdis-93-3-0319b ◽

2009 ◽

Vol 93 (3) ◽

pp. 319-319 ◽

Cited By ~ 4

Author(s):

J. Zheng ◽

Y. Zhang ◽

X. Li ◽

L. Zhao ◽

S. Chen

Keyword(s):

Soybean Cyst Nematode ◽

Heterodera Glycines ◽

Eastern China ◽

Mainland China ◽

Its Region ◽

Cyst Nematode ◽

Northeastern China ◽

First Report ◽

Soybean Plants ◽

Two Populations

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is a destructive pest of soybean. Damage to soybean by SCN was first reported from northeastern China in 1899 (1). SCN has been documented in Anhui, Beijing, Hebei, Heilongjiang, Henan, Jiangsu, Jilin, Liaoning, Neimenggu, Shaanxi, Shandong, and Shanxi provinces in mainland China (1). These provinces are situated in the Heilongjiang and Songhuajing valleys in northeastern China and the eastern region of the Yangtze and Yellow rivers in northern China and have cold to temperate climates. In June of 2008, cyst-forming nematodes were detected in two soybean-growing areas of Hangzhou and Xiaoshan in Zhejiang Province, in subtropical eastern China. The soybean plants at the Hangzhou site showed symptoms of stunting and chlorosis, whereas no aboveground or root symptoms were observed on soybean plants at the Xiaoshan site, except for the presence of SCN females on the roots. The two populations had the same morphological and molecular characters. The cysts were lemon shaped with posterior protuberance, ambifenestrate, underbridge and bullae strongly developed, and lateral field of second-stage juveniles consisted of four incisures. The key morphometrics of cysts were fenestra length (41 to 52 μm) and width (33 to 48 μm), vulval silt (47 to 55 μm), and underbridge length (79 to 94 μm), all of which were coincident with that of SCN (2). Amplification of rDNA-internal transcribed spacer (ITS) region using primers TW81 (5′-GTT TCC GTA GGT GAA CCT GC-3′) and AB28 (5′-ATA TGC TTA AGT TCA GCG GGT-3′) yielded a PCR fragment of approximately 1,030 bp. The digestion patterns of the PCR fragments of the ITS region with AluI, AvaI, CfoI, MvaI, and RsaI showed identical restriction profiles to H. glycines (3), and the sequences exhibited 100% similarity with those of H. glycines isolates, Accession No. AY667456 from GenBank. Morphological and molecular identification confirmed that the two populations of cyst-forming nematodes from Zhejiang are SCN. To our knowledge, this is the first report of SCN in Zhejiang, now the most southern location in mainland China with confirmed infestation of SCN. References: (1) Z. X. Liu et al. Int. J. Nematol. 7:18, 1997. (2) R. H. Mulvey. Can. J. Zool. 50:1277, 1972. (3) J. Zheng et al. Russ. J. Nematol. 8:109, 2000.

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