Z. A. Handoo

Influence of cover crops and soil amendments on okra (Abelmoschus esculentus L.) production and soil nematodes

A pot experiment to determine the effects of summer cover crops and soil amendments on okra yields and population densities of various soil nematode taxa was conducted in two consecutive growing seasons in a subtropical region. Two cover crops, sunn hemp (Crotalaria juncea) and sorghum sudangrass (Sorghum bicolorrS. bicolor var. sudanense), were grown and returned to the soil with fallow as a control. As soon as these cover crops were harvested, they were soilincorporated together with one of several organic amendments. These organic amendments were biosolids, N-Viro soil (a 1 : 1 mixture of coal ash and biosolids), coal ash, co-compost (a 3 : 7 mixture of biosolids and yard wastes), and yard waste compost compared with a control (no additional amendment). Other treatments were fumigation with MC-33 (a mixture of 33% of methyl bromide and 67% of chloropicrin) and cover crop removal (harvested and removed cover crops and their residues from the soil). A nematode-susceptible vegetable crop, okra (Abelmoschus esculentus L.), was grown under these treatments. Among organic amendments, the application of biosolids produced the highest okra yield and biomass, and greatly suppressed root-knot nematodes, Meloidogyne incognita, in the soil. Between these two cover crops, sunn hemp was superior to sorghum sudangrass in improving okra production and in suppressing root-knot nematodes. The result indicates that growing sunn hemp as a cover crop and applying certain organic amendments can improve okra production and suppress root-knot nematodes, which are very damaging to okra plants. Such combined practices show a significant potential for application in organic farming and sustainable agriculture systems in a tropical or subtropical region.

Morphological and molecular characterisation of Hemicycliophora lutosa Loof & Heyns, 1969 and H. typica de Man,1921 from South Africa (Nematoda: Hemicycliophoridae)

Two Hemicycliophora species, H. lutosa and H. typica , found in samples from fallow soil and sugarcane soil in South Africa, were studied morphologically and, for the first time, molecularly. Diagnostic PCR-IT-rRNA-RFLP profiles generated by five restriction enzymes are provided. Study of phylogenetic relationships using D2-D3 expansion segment of 28S rRNA gene sequences revealed that H. lutosa was related to H. poranga . Hemicycliophora lutosa and H. poranga are compared morphologically. SEM photographs are given for H. typica and for H. lutosa for the first time. The male of H. typica represents a first report for South Africa.

First Report of the Stubby Root Nematode Paratrichodorus allius on Potato in North Dakota

6 Stubby root nematodes (Paratrichodorus and Trichodorus) are migratory ectoparasites that 7 feed on roots and vector tobraviruses (Riga et al. 2007). These nematodes are important to the 8 potato industry as they transmit Tobacco rattle virus (TRV) causing corky ringspot (CRS) disease 9 that has a direct economic impact on growers due to being abandoned or rejected by processing or 10 fresh markets (Charlton et al. 2010). TRV associated with CRS on potato in North Dakota was 11 reported but stubby root nematodes (SRN) were not investigated (David et al. 2010). In October 12 2014, three soil samples were collected from a potato field in Sargent County, ND to determine the 13 occurrence of SRN. Most of the field was harvested but a portion of the field was abandoned due 14 to 80 to 90% of the tubers (cv. Milva) exhibiting brown necrotic rings, arcs and spots, typical 15 symptoms of CRS. Diseased tubers from this field were tested and found to be infected with TRV. 16 Nematodes were extracted from soil using the sugar centrifugal flotation method and one of the 17 samples was found to contain SRN (44 per kg of soil). In April 2015, forty-nine soil samples were 18 collected from the same field and seven of the samples had SRN with population densities ranging 19 from 135 to 300 (mean = 175) per kg of soil. Nematodes were examined morphologically and 20 molecularly for species identification. Morphological measurements of adult females (n = 10) 21 included body length (range = 550.0 to 690.0 μm, mean = 606.8 μm), onchiostyle (40.0 to 47.5, 22 43.9), body width (35.0 to 58.0, 42.3), anterior end to basal bulb (90.0 to 150.0, 114.7), a (10.3 to 23 18.6, 14.7), b (4.0 to 6.7, 5.3), and V (50.0 to 60.0%, 53.8%). The anus and caudal pores were 24 subterminal. The nematode species was identified as Paratrichodorus allius (Jensen 1963) Siddiqi, 25 1974 according to morphological and morphometric characteristics (Decraemer 1980). DNA was 26 extracted from single nematodes (n = 7) isolated from three soil samples in 20 μl of extraction 27 buffer. The D2/D3 region of 28S rRNA, partial 18S rRNA, and ITS1 rDNA were amplified with 28 primer pairs D2A/D3B, SSUF07/SSUR26 and BL18/5818, respectively (Ye et al. 2015; Riga et al. 29 2007). PCR products were cloned using pGEM-T easy vector and sequenced. Since sequences 30 from all samples for each genomic region were identical, only one of the sequences from that 31 region was submitted to GenBank and thus represents a consensus sequence. The 18S rRNA 32 sequence (GenBank Accession No. KU094058, 919 bp) was 100% identical to one population of 33 P. allius (AJ439572) from Washington, 99% identical to P. teres, a closely related species of P. 34 allius, and less than 99% identical to other Paratrichodorus spp. The ITS1 rDNA sequence 35 (KU094059, 832 bp) was 99% homologous with two populations of P. allius from North Carolina 36 (KJ934124) and Washington (AM087124), but had no significant similarity with P. teres and other 37 Paratrichodorus spp. The 28S D2/D3 sequence (KU094057, 799 bp) was 91% or less homologous 38 with P. teres and other Paratrichodorus spp., but no P. allius sequence was available for 39 comparison. The molecular tests confirmed the identity as P. allius. P. allius is known to be the 40 most prevalent vector of TRV in Washington and Oregon (Riga et al. 2007). To our knowledge, 41 this is the first report of P. allius in North Dakota. 42

Hirschmanniella kwazuna sp. n. from South Africa with notes on a new record of H. spinicaudata (Schuurmans Stekhoven, 1944) Luc & Goodey, 1964 (Nematoda: Pratylenchidae) and on the molecular phylogeny of Hirschmanniella Luc & Goodey, 1964

A new species of the genus Hirschmanniella , H. kwazuna sp. n., is described from unidentified grass growing in undisturbed veldt from South Africa. Hirschmanniella kwazuna sp. n. is characterised by having a very irregular heat-relaxed body posture, body 1522-2049 μ m long, lip region low and rounded with four or five lip annuli, stylet 18-22.5 μ m long, lateral field areolated along entire body, spermatheca filled with sperm, tail with 62-81 ventral annuli narrowing to a tip bearing a ventral mucro, angular crystal-like inclusions within body cavity in most of the specimens and phasmid situated 12-24 annuli or 15-26 μ m anterior to tail tip. Males, like females, have crystal-like inclusions with the tail curved strongly dorsad in most specimens. Juveniles are similar to females. Molecular sequence analysis using the D2-D3 expansion segments of 28S, partial 18S and ITS rRNA sequences distinguished H. kwazuna sp. n. from H. loofi and other species of the genus. Hirschmanniella spinicaudata is reported from South Africa for the first time and described. Phylogenetic analyses based on analysis of the D2-D3, 18S and ITS rRNA genes are given for eight, ten and five valid and unidentified Hirschmanniella species, respectively.

Two new species of Paurodontella Husain & Khan, 1968 (Nematoda: Sphaerulariidae) associated with wheat and a diagnostic compendium to the genus.

An identification key to ten valid species of Paurodontella is given. A compendium of the most important diagnostic characters with illustrations of each species is included as a practical alternative and supplement to the key. The diagnosis of Paurodontella is emended and a list of all valid species of the genus is given. Two new species (Paurodontella myceliophaga n. sp. and P. balochistanica n. sp.) collected around the roots of wheat (Triticum aestivum L.) from North-West Frontier Province and Balochistan, Pakistan, are described and illustrated. Paurodontella myceliophaga n. sp. is characterised by having a short post-uterine sac, lateral field with four incisures, excretory pore at the base of the pharynx and fusiform median bulb, whereas P. balochistanica n. sp. has a longer and very slender body with posterior vulva, lateral field with four incisures and short mucronate tail. Because these species are limited in distribution, their importance is not known.

First Report of the Root-lesion Nematode Pratylenchus neglectus on Wheat (Triticum aestivum) in North Dakota

Root-lesion nematodes (Pratylenchus spp.) are important nematode pests that invade roots of plants and restrict productivity of wheat (Smiley et al. 2005). In August 2015, a soil sample was collected from a harvested wheat field in Walsh County, ND, and was found to contain 1,044 root-lesion nematodes per kg of soil using the sugar centrifugal flotation method. In October 2015, four soil samples were collected from the same field and had root-lesion nematodes ranging from 125 to 1,000/kg soil. One soil sample with 500 lesion nematodes/kg soil was used to inoculate hard red spring wheat cvs. Glenn and Faller. After 10 weeks of growth in a greenhouse room maintained at 22°C, wheat roots were harvested and washed, and light brown lesions were observed on lateral roots. The washed roots were cut into 1-cm segments for nematode extraction using the Whitehead tray method. After 48 h, lesion nematodes were recovered from the root tissues. Averages of 24 and 20 root-lesion nematodes per gram were found in the roots of Glenn and Faller, respectively. Nematodes from soil and wheat roots were examined morphologically and molecularly for species identification. Morphological measurements of adult females (n = 10) included body length (range = 402.0 to 495.0 μm, mean = 446.0 μm), stylet (15.0 to 17.5, 16.4), tail length (16.0 to 22.0, 18.8), body width (17.0 to 22.0, 19.6), anterior end to basal bulb (90.0 to 115.0, 101.6), a = (21.2 to 24.7, 23.1), b = (3.7 to 4.8, 4.4), c = (19.6 to 27.1, 23.8), and V (81.0 to 85.0%, 82.8%). The lip region had two annules, and was not set off, with anterior margins of apical lip annule convex, second annule was slightly wider than the first; lateral field had four lines with central zone of lateral field having oblique striae; tail terminus was smooth, rounded, or slightly oblique. The nematode species was identified as Pratylenchus neglectus (Rensch, 1924) Filipjev & Schuurmans Stekhoven, 1941 based on morphological and morphometric characteristics (Castillo and Vovlas 2007). DNA was extracted from single nematodes (n = 11) isolated from soil and wheat roots, and ITS region of rDNA was amplified (Tanha Maafi et al. 2003). PCR products from three nematodes were cloned using pGEM-T easy vector and sequenced, and the resulting ITS sequences were identical. The consensus sequence (GenBank Accession No. KU705392, 684 bp) was 99% homologous with one population of P. neglectus from China (JX046941) and 83% or less identical to other Pratylenchus spp. including P. thornei, a species closely related to P. neglectus. The specific primers from D3 28S rRNA and ITS rDNA were used to amplify DNA of eight nematodes and produced single bands specific for P. neglectus (Yan et al. 2008, 2013). The combination of the molecular tests confirmed the target species as P. neglectus. Two species of root-lesion nematodes, P. neglectus and P. thornei, were reported as damaging pathogens affecting wheat production in the Pacific Northwest (Smiley et al. 2005). To our knowledge, this is the first report of P. neglectus on wheat in North Dakota. The resistance levels of various wheat cultivars to this lesion nematode are being identified.

Suitability of southern pines, other selected crops, and nutsedge to a Longidorus sp. associated with stunting of loblolly pine seedlings

An undescribed needle nematode (Longidorus sp.) has been associated with severely stunted loblolly pine seedlings at a south Georgia nursery. Containers with selected crop and weed species were infested with 100 or 200 adults and juveniles of the Longidorus individuals to evaluate host suitability. Nematode populations increased in containers with slash, loblolly, and longleaf pine seedlings. The Longidorus sp. significantly reduced the dry root weights of slash (P = 0.008) and loblolly (P = 0.047) but not longleaf (P = 0.095) pine compared with controls. Populations of Longidorus decreased on nutsedge and small grains, including wheat, rye, oat, sorghum, and millet; and, in most experiments, populations decreased to levels found in fallow containers. Populations decreased on tomato and cabbage but increased slightly on red oak. The periodic removal of fields from pine production to grow cover crops consisting of small grains or to maintain fallow fields may be an important practice for management of this Longidorus sp.

Description of Loffienema dhanoriensis gen. n., sp. n. (Nematoda: Rhabditidae) from Jammu and Kashmir State, India

A new genus, Loffienema dhanoriensis gen. n., sp. n. is described and illustrated from soil mixed with mature compost of Biodiversity Park, Baba Ghulam Shah Badshah (BGSB) University, Rajouri, Jammu and Kashmir, India. It is characterized by medium-sized body, slightly offset labial region, weakly developed, isoglottoid stegostom, amphidelphic reproductive system, slender and separate spicules, spathulate gubernaculum and reduced bursa with eight pairs of bursal rays. Its relationship and distinguishing features with other closely related genera are discussed.

First Report of a New Stunt Nematode Tylenchorhynchus sp. From a Soybean Field in North Dakota

Stunt nematodes in the genus Tylenchorhynchus are common plant-parasitic nematodes, and several species have been reported to damage crops (Handoo et al. 2014). In 2015 and 2016, eleven soil samples were collected from a soybean (Glycine max) field in Richland County, ND. Nematodes were extracted from soil using sugar centrifugal flotation method (Jenkins 1964). Nine samples contained the stunt nematodes ranging from 125 to 900 per kg of soil. One soil sample with 600 stunt nematodes per kg was planted with a soybean cultivar Sheyenne in three replicates. After three months of growth at 22°C under greenhouse conditions, the stunt nematode population increased to a final density of 1,953 ± 674 individuals per kg of soil. The reproductive factor of this nematode was 3.26. Soybean roots were washed with tap water and brown lesions were observed on the roots. Morphological measurements of adult females (n = 14) included body length (mean = 744.3 μm, range = 622.0-830.0), stylet (21.3 μm, 20.0-22.5), body widt...

First Report of a New, Unnamed Lesion Nematode Pratylenchus sp. Infecting Soybean in North Dakota

First Report of a New, Unnamed Lesion Nematode Pratylenchus sp. Infecting Soybean in North Dakota | Plant Disease http://apsjournals.apsnet.org/doi/10.1094/PDIS-12-16-1749-PDN[7/13/2017 11:02:02 AM] 17.7 to 25.6), c’ (2.3, 2.2 to 2.4), spicule (17.5, 15.0 to 20.0), and gubernaculum (5.8, 4.5 to 7.5). DNA was extracted from single nematodes (n = 12) collected from soil and roots. D2-D3 of 28S rRNA (Subbotin et al. 2008) and ITS of rDNA (Yan and Smiley 2010) were amplified and sequenced. The ITS rDNA (KY200666, 981 bp) shared 95% sequence identity with P. alleni and low identity (≤87%) with other Pratylenchus spp. The D2-D3 (KY200665, 766 bp) had the highest identity of 96% with P. scribneri and 95% identity with P. hexincisus. No sequence of P. gibbicaudatus or P. flakkensis is available in GenBank. This species is very close to P. alleni but differs in having a slightly longer stylet, variations in tail shape, truncate to bluntly or broadly rounded tail with an annulated to occasionally smooth tail terminus, 4 to 6 lines in lateral field and 2 to 3 head annules. It is closely related to P. hexincisus, P. gibbicaudatus, and P. flakkensis but differs from them by one or more other characters: shape of head, number of head annules, tail shape, and V%. To our knowledge, this North Dakota Pratylenchus sp. population represents a new species of lesion nematode able to parasitize soybean.