Variability of Ascochyta fabae in South Australia

1999 ◽  
Vol 50 (8) ◽  
pp. 1475 ◽  
Author(s):  
F. L. Stoddard ◽  
S. Kohpina ◽  
R. Knight
Keyword(s):  
South Australia ◽  
Aerial Mycelium ◽  
Lesion Size ◽  
Strongly Correlated ◽  
Single Spore ◽  
Spore Size ◽  
Colony Diameter ◽  
Bean Plants ◽  
Stem Lesions ◽  
Ascochyta Fabae

Fifty-two isolates of Ascochyta fabae were established from 23 collections made in 3 States of Australia and were purified through 2 cycles of single-spore isolation. The isolates were evaluated for spore size, spore production, colony diameter, aerial mycelium, and pycnidia production. Variation in all of these traits among related single-spore cultures was comparable to that among unrelated ones and only colony diameter varied significantly among isolates. Spore size was 3–6 by 10–26 µm. Eight of these 52 isolates were chosen for further investigations of pathogenicity characteristics using 8 populations of faba bean. Plants were scored daily for rate of appearance of symptoms and then 15 and 21 days after inoculation for lesion size and number, production of pycnidia on the lesions and overall disease score. Leaves and stems reacted differently to the disease, with one isolate producing many leaf lesions but few stem lesions on one bean accession but many stem lesions on another. Lesion size was not strongly correlated with the other measures of disease. Resistant accessions had longer incubation periods, fewer total lesions and fewer pycnidia-producing lesions than susceptible accessions. The 8 isolates on the 8 bean accessions showed 7 distinct patterns of resistance. The results showed that in southern Australia, A. fabae exhibited great variability which was incompatible with classification into biologically meaningful pathotypes.

scholarly journals Occurrence of Dactylonectria torresensis Causing Root Rot on Astragalus membranaceus in northeastern China

Plant Disease ◽  
2020 ◽  
Author(s):  
Yi Ming Guan ◽  
Shu Na Zhang ◽  
Ying Ying Ma ◽  
Yue Zhang ◽  
Ya Yu Zhang
Keyword(s):  
Root Rot ◽  
Phylogenetic Trees ◽  
Aerial Mycelium ◽  
Northeastern China ◽  
Astragalus Membranaceus ◽  
Sterile Water ◽  
Water Control ◽  
Single Spore ◽  
Dry Rot ◽  
Dactylonectria Torresensis

Astragalus membranaceus Bunge (Fabaceae) is a perennial medicinal herb widely cultivated in China. In June 2018, root rot was observed on two-year-old A. membranaceus plants in Chaoyangshan town (northeastern China). In a 40-ha field, over 40% of the plants exhibited root rot and the infected area ranged from 10 to 70% of the roots. The roots first exhibited circular or irregular brown, sunken and necrotic lesions, and finally multiple lesions coalesced. The infected root surface was destroyed, showing rusty and dry rot (Fig. 1). Symptoms were concentrated in the main roots (Carlucci et al. 2017). The aboveground parts of infected plants did not initially show symptoms but gradually wilted; 7.6% of the plants died when root decay became severe. Infected roots were not used for processing and were not marketable. Ten infected roots were collected from May to October 2018 from the above location. The diseased root tissue was cut into 25 mm3 pieces, immersed in 1% NaOCl for 2 minutes, rinsed three times with sterile water and placed on water agar in Petri plates. After 15 days of incubation at 20°C, 11 single-spore isolates were obtained. Isolates HQ1 and HQ2 were randomly selected for morphological and molecular identification. Colonies grown for 10 days produced yellow, cottony to felty aerial mycelium on potato dextrose agar. Conidiophores originating laterally or terminally from the mycelium were solitary to loosely aggregated and unbranched or sparsely branched. Macroconidia predominated and were cylindrical, with a tendency to gradually widen towards the tip; 1- to 3-septate; and 20.2 to 31.0 × 3.0 to 6.7 µm (n=100). Microconidia had mostly 0¬- to 1-septate and 8.6 to 16.7 × 1.9 to 5.1 µm (n=100) (Fig. 1). Chlamydospores were rare, but occasional chlamydospore chains were observed. The isolates were tentatively identified as Dactylonectria torresensis (Cabral et al. 2012a). Further confirmation of the two isolates was conducted by DNA sequencing of the internal transcribed spacer (ITS, GenBank accession no. MN558983 and MN558984), β-tubulin (TUB, MN561692 and MN561693), histone 3 (HIS3, MN561694 and MN561695), and translation elongation factor (TEF, MN561696 and MN561697) genes (Cabral et al. 2012b). These sequences had 99 to 100% match with D. torresensis (JF735362 for ITS, JF735492 for TUB, JF735681 for HIS3 and JF735870 for TEF). Phylogenetic trees based on analyses of a concatenated alignment of all loci grouped these isolates into the D. torresensis clade (Fig. 2). The same two isolates were tested for pathogenicity. Healthy two-year-old plants were taken from the field, and their roots were disinfected with 75% alcohol for 3 minutes, rinsed with sterile water three times, immersed in a 1×105/ml spore suspension or sterile water (control) for 10 minutes, transferred to a tray filled with sterile sand and placed in a greenhouse (12 h photoperiod, 25°C). Twelve plants grown in three pots were used for each isolate, and the same number of plants were inoculated as a control. This experiment was repeated three times. After one month, inoculated plant roots showed the same symptoms as those observed in the field, while the controls remained symptomless and no pathogen was recovered. The same fungus was reisolated from all the infected plants and confirmed by sequencing all of the above genes. This is the first report of D. torresensis causing root rot in A. membranaceus in China. The occurrence of this disease poses a threat, and management strategies need to be developed.

scholarly journals First Report of Euphorbia larica Dieback Caused by Fusarium brachygibbosum in Oman

Plant Disease ◽  
2013 ◽  
Vol 97 (5) ◽  
pp. 687-687 ◽  
Author(s):  
I. H. Al-Mahmooli ◽  
Y. S. Al-Bahri ◽  
A. M. Al-Sadi ◽  
M. L. Deadman
Keyword(s):  
Elongation Factor ◽  
Aerial Mycelium ◽  
Its Region ◽  
Common Component ◽  
First Report ◽  
Ethnobotanical Uses ◽  
Artificial Inoculations ◽  
Stem Lesions ◽  
Desert Flora

Euphorbia larica Boiss. (Arabic = Isbaq) is a dominant and common component of the native desert flora of northern Oman. Traditional ethnobotanical uses have included use of the latex for treating camels with parasites. In February 2011, E. larica plants showing stem lesions up to several cm long and in many cases with stem dieback were collected from Al-Khoudh 50 km west of Muscat. The disease appeared widespread within the location where several dead specimens were also recorded, although the cause was unclear. Sections (5 mm) of five diseased branches taken from different plants and placed on potato dextrose agar (PDA) in all cases yielded Fusarium-like colonies. Colonies recovered were initially white becoming rose to medium red in color with abundant aerial mycelium. Macroconidia were scarce and scattered (mean of 20 spores: 26.83 × 4.73 μm) with three to four septa per spore; microconidia were slightly curved, ovoid, and fusiform (mean of 20 spores: 11.64 × 4.03 μm) with zero to two septa per spore. Spherical chlamydospores (mean of 20 spores: 11.05 μm) were terminal and intercalary, single, and in chains. In vitro characters and spores measurements conformed to previously described features of Fusarium brachygibbosum Padwick (1). Mycelial plugs (5 mm) were taken from 7-day-old cultures of the fungus grown on 2.5% PDA and applied to a small incision (3 mm) on the stems of healthy E. larica grown in situ and protected with wet cotton and Parafilm. The residual agar, mycelium, cotton, and Parafilm were removed after 7 days and symptoms were recorded. Control stems were inoculated using PDA (5 mm) plugs alone and inoculations were repeated twice. Artificial inoculations resulted in dieback of all stems within 11 days and fungal colonies identical to initial isolations were recovered from artificially infected surface-sterilized stem pieces. Identification of F. brachygibbosum was confirmed by comparing sequences generated from the internal transcribed spacer (ITS) region of the ribosomal DNA (ITS1 and ITS4 primers) and the intron region of translation elongation factor alpha (EF1-α) (EF-1-986 and EF-728 primers). The ITS and EF1-α sequences were found to share 100% and 99% nucleotide similarity to previously published sequences of the ITS (HQ443206) and EF1-α (JQ429370) regions of F. brachygibbosum in GenBank. The accession number of ITS sequence of one isolate assigned to EMBL-Bank was HF562936. The EF sequence was assigned to EMBL-Bank accession (submission number Hx2000027017; number will be sent later). This pathogen has previously been reported on date palm (2) in Oman but, to our knowledge, this is the first report of this pathogen on E. larica. References: (1) A. M. Al-Sadi et al. Crop Prot. 37:1, 2012. (2) G. W. Padwick. Mycol. Pap. 12:11, 1945.

scholarly journals First Report of Fusarium oxysporum f. sp. lactucae Race 1 Causing Fusarium Wilt of Lettuce in Norway

Plant Disease ◽  
2021 ◽  
Author(s):  
Maria Luz Herrero ◽  
Nina Elisabeth Nagy ◽  
Halvor Solheim
Keyword(s):  
Costa Rica ◽  
Fusarium Oxysporum ◽  
Vascular Tissue ◽  
Uv Light ◽  
Elongation Factor ◽  
Aerial Mycelium ◽  
Light Cycle ◽  
Single Spore ◽  
Fungal Isolates ◽  
Race 1

Lettuce (Lactuca sativa L.) is produced in Norway both in field and greenhouses. In Norway, greenhouse lettuce is one of the most important vegetables grown year-round. In winter 2018, wilting symptoms were observed on soil-grown lettuce of the cultivar Frillice in a greenhouse in south east Norway (Buskerud county). Affected plants showed stunted growth, wilting of outer leaves, and brownish discoloration of vascular tissues of taproots and crowns. According to the producer, the disease led to an estimated 10% of yield losses. Fungal isolates were obtained from crowns and roots of diseased plants collected from the greenhouse in 2018 and 2019. Two single spore isolates, 231274 from 2018 and 231725 from 2019, were used in further studies. The isolates were incubated on synthetic nutrient-poor agar (SNA) at 18-20 ⁰C, and a 12 hours dark, 12 hours UV light cycle. Isolate 231274 produced abundant macro- and microconidia characteristics of Fusarium oxysporum while macroconidia were never observed in isolate 231725. On potato dextrose agar (PDA), colonies of isolate 231274 were purple in color and colonies of isolate 231725 were pinkish with abundant aerial mycelium. For PCR-assay, DNA from mycelia was extracted using Easy-DNA kit (Invitrogen). A portion of the translation elongation factor 1-α (EF1-α) gene was amplified using primers F-728F (Carbone and Kohn. 1999) and EF2 (O'Donnell et al. 1998) as described by Aas et al. 2018. Blast analysis of both sequences (accession no. MW316853 for 231274 and MW316854 for 231275) obtained a 99% homology with the sequence of Fusarium oxysporum f.sp. lactucae (FOL) race 1 strain S1 (accession no. DQ837657)(Mbofung et al. 2007). Both isolates were identified as race 1 by using specific primers Hani3’ and Hanilatt3rev (Pasquali et al. 2007) as described by Cabral et al. 2014. To complete Koch’s postulate, lettuce plants of the cultivar Frillice were used. Race identity was confirmed using the differential lettuce cultivars Costa Rica No.4 (resistant to FOL race 1), Banchu Red Fire (resistant to FOL races 2 and 4) and Romana Romabella (resistant to FOL races 1 and 2) (Gilardi et al. 2017) provided by the breeding company Rijk Zwaan (De Lier, The Netherlands). For inoculation, roots of six 2-weeks old seedlings per cultivar were dipped in a spore suspension (1 x 106 CFU/ml) for 1 min, while controls were dipped in distilled water. Seedlings were planted in 250 ml pots containing fertilized potting substrate, and were placed in a greenhouse with temperature ranging from 15 to 35 ⁰C and an average of 23 ⁰C. After 10 days reduced growth was observed in cultivars Frillice and Banchu Red Fire for both fungal isolates. After 25 days wilting was observed in both cultivars. Affected plants presented discoloration of vascular tissue. No difference in growth was observed between cultivars Romana Romabella and Costa Rica No. 4 and their respective controls. FOL was re-isolated from all inoculated cultivars but not from controls. The colony patterns of the recovered isolates were the same than those of the isolates used for inoculation. These results confirm that the isolate belongs to race 1. Greenhouse lettuce in Norway is mainly produced in hydroponics. FOL is here reported to cause damages in soil- grown lettuce. Nevertheless FOL in hydroponic systems has been reported in Japan (Fujinaga et al. 2003) and Thailand (Thongkamngam and Jaenaksorn 2017). Thus, the possibility of infections in hydroponics remain a big concern for lettuce production in Norway.

scholarly journals First Report of Sclerotinia sclerotiorum on Common Ragweed (Ambrosia artemisiifolia) in Europe

Plant Disease ◽  
1999 ◽  
Vol 83 (3) ◽  
pp. 302-302 ◽  
Author(s):  
Gy. Bohár ◽  
L. Kiss
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Aerial Mycelium ◽  
The United States ◽  
Ambrosia Artemisiifolia ◽  
American Phytopathological Society ◽  
Common Ragweed ◽  
First Report ◽  
Sclerotinia Rot ◽  
Stem Lesions ◽  
Test Plants

Common ragweed (Ambrosia artemisiifolia L.) is reported as a host of Sclerotinia sclerotiorum (Lib.) de Bary in North America (2,4), but not in Europe. A Hungarian survey of fungal diseases of ragweed in 1994 did not find sclerotinia rot of common ragweed (A. artemisiifolia var. elatior (L.) Descourt.) (1). In autumn 1998, mature ragweed plants, 1 to 1.5 m tall, were collected from the borders of four sunflower (Helianthus annuus L.) fields in which sclerotinia rot of sunflower was frequently observed during the season, and also from six other roadside sites in Hungary. Ragweed plants exhibiting symptoms characteristic of sclerotinia rot, i.e., wilting foliage and light brown, dry lesions on the stems, were found only near two sunflower fields. Black, round to irregular or oblong sclerotia were also observed on the infected ragweed plants both externally on the stem lesions and internally, in the pith cavity. Sclerotia measured up to 5 mm in diameter and were 5 to 14 mm long. After isolation on potato dextrose agar, the pathogen produced abundant aerial mycelium and large sclerotia characteristic of S. sclerotiorum. To confirm pathogenicity, potted seedlings and mature plants of ragweed were inoculated in the greenhouse with autoclaved wheat grains colonized with mycelia of S. sclerotiorum placed 0.5 to 1 cm from the collar of the test plants. Seedlings were killed in 2 to 3 days while mature plants wilted after 5 to 6 days. In a field test, six mature plants were inoculated by attaching mycelial disks to their stems with Parafilm. These plants wilted 12 to 14 days after inoculation. The pathogen was reisolated from all diseased plants. This is the first report of S. sclerotiorum on common ragweed in Europe. Nonsclerotial mutants of the fungus (3) are being produced to be tested as potential biocontrol agents of common ragweed, which has become not only the most widespread, but also the most important allergenic plant species in Hungary since the early 1990s. References: (1) Gy. Bohár and L. Vajna. Nōvényvédelem 32:527, 1996. (2) G. J. Boland and R. Hall. Can. J. Plant Pathol. 16:93, 1994. (3) G. J. Boland and E. A. Smith. Phytopathology 81:766, 1991.(4) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.

scholarly journals First Record in Syria of Didymella fabae, the Teleomorph of Ascochyta fabae and Causal Organism of Faba Bean Blight

Plant Disease ◽  
2000 ◽  
Vol 84 (9) ◽  
pp. 1044-1044 ◽  
Author(s):  
B. Bayaa ◽  
S. Kabbabeh
Keyword(s):  
Faba Bean ◽  
Tap Water ◽  
Ascochyta Blight ◽  
First Record ◽  
Causal Organism ◽  
Plastic Bags ◽  
Bean Plants ◽  
Plant Pathol ◽  
Petri Dishes ◽  
Ascochyta Fabae

Ascochyta blight, caused by Ascochyta fabae Speg., is a common and destructive disease of faba bean (Vicia faba L.) in the Middle East, Europe, Canada, New Zealand (4), and Australia. The main sources of inoculum are debris and seeds from which spores are air- and splashborne. The teleomorph of A. fabae has been reported previously only from England (2). The presence of the teleomorph supports the variability reported in the fungus populations from Canada (3) and Poland (1). Stems of faba bean plants, severely infected with A. fabae, were collected in July 1999 from Tel Hadya, Syria. The plants previously had been inoculated with a mixture of isolates of the pathogen, collected from the main faba bean-growing regions in Syria between 1996 and 1998, and kept under shade. The infested stems were used to inoculate the ICARDA Faba Bean Ascochyta Nursery planted on 29 November 1999. During late January 2000, symptoms appeared on the susceptible faba bean genotype. Stem pieces from debris used for inoculations were collected from the field and examined microscopically for the presence of ascomata. The maximum, minimum, and mean temperatures and rainfall at Tel Hadya during December 1999 were 16.5, 5.8, and 8.7°C and 22.4 mm, respectively. There were 16 nights when temperatures dropped below 0°C, and 10 nights when temperatures were between 0 and 5°C. Ascomata of A. fabae ranged from 76 to 209 μm wide (average 158 ± 3.9 μm) and 101 to 285 μm in length (average 178 ± 4.1 μm). Asci were 10 to 15 μm wide (average 14 ± 0.3 μm) and 51 to 96 μm long (average 63 ± 1.1 μm). Ascospores were 5 to 8 μm wide (average 7 ± 0.2 μm) and 15 to 20 μm in length (average 17 ± 0.3 μm). These measurements are comparable to those reported from England. Individual ascomata were dissected from stem tissue and fixed to the lids of petri dishes containing 2% water agar. After 24 h, the petri dishes were examined microscopically to locate ascospores on the surface of the medium. Germinating ascospores and developing colonies were transferred from water agar to faba bean dextrose agar. Colonies characteristic of A. fabae developed on the latter medium within 7 days of incubation at 20 ± 2°C. Pathogenicity tests of developing colonies were carried out on 3-week-old faba bean plants (Giza 4) using a spore suspension (2.5 × 105 spores per ml) of each of the isolates. Both inoculated seedlings and control seedlings inoculated with sterile water were covered with plastic bags for 48 h in a plastic house maintained at 18 ± 2°C. After removal of the plastic bags, seedlings were wetted four times per day by spraying with tap water to runoff. Inoculated plants showed characteristic symptoms of Ascochyta blight 15 days after inoculation. The fungus was reisolated from lesions that developed on leaflets of all inoculated seedlings, but not from any of the control seedlings. This is the first report of the occurrence of A. fabae, the sexual stage of Didymella fabae Jellis & Punithalingam in Syria, and indicates that the fungus could develop population variants. These findings have implications for breeding for resistance to Ascochyta blight. References: (1) A. Filipowicz. Faba Bean Abstr. 4:47, 1983. (2) G. J. Jellis and E. Punithalingam. Plant Pathol. 40:150, 1991. (3) P. D. Kharbanda and C. C. Bernier. Can. J. Plant. Pathol. 2:139, 1980. (4) K. Y. Rachid et al. Plant Dis. 75:852, 1991.

scholarly journals First Report of Red-Fleshed Apple Anthracnose Caused by Colletotrichum siamense

Plant Disease ◽  
2021 ◽  
Author(s):  
Fengying Han ◽  
Yu-tong Zhang ◽  
Zaize Liu ◽  
Lei Ge ◽  
Lian-Dong Wang ◽  
...  
Keyword(s):  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Aerial Mycelium ◽  
Morphological Characters ◽  
Apple Fruit ◽  
Bootstrap Support ◽  
Single Spore ◽  
First Report ◽  
Crucial Information ◽  
Average Size

The red-fleshed apple (Malus niedzwetzkyana) produces a colored fruit and rich anthocyanins and it has become popular among consumers in Shandong (Yang et al 2020). In recent years, anthracnose diseases have been reported in red-fleshed apple orchards and nurseries in Shandong province, China. The incidence of anthracnose in the red-fleshed apple plantings ranges from 50-90%. Initially, anthracnose lesions on fruit begin as sub-circular shaped, sunken, pale brown. Over time black lesions enlarged and coalesced into large necrotic areas. The sunken centers of mature lesion became filled with slimy pink sporulation. In September 2015, fifteen fruit with anthracnose symptoms and sporulation were collected, and 11 single-spore isolates were obtained. Three representative isolates (JNTW11, JNTW2, JNTW33) were used for morphological and molecular characterization. On PDA, the colonies were initially white and turned into pale brown in three days. Orange-brown pigmentation was produced near the center on the reverse. Aerial mycelium was cottony, dense, pale white to pale gray. Acervuli developed visible orange-pink conidial masses. Conidiophores were colorless, septate, not branched or branched at the base. Conidia were 1-celled, hyaline, subcylindrical, oblong, attenuated with blunt ends, and the average size was 16.7 ± 1.5 × 6.1 ± 0.9 μm (n = 50). Appressoria were brown, obovoid or irregular, 9.2 ± 1.6 × 8.0 ± 1.8 μm (n = 20). The morphological characters matched the descriptions of Colletotrichum gloeosporioides sensu lato (Cannon et al. 2008). Isolates JNTW11, JNTW2, and JNTW33 were subject to bioinformatic characterization by partial sequencing of 6 genetic loci including the ribosomal internal transcribed spacer (ITS), actin (ACT), beta-tub2 (TUB2), calmodulin (CAL), chitin synthase (CHS-1), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (Weir et al, 2012). The ITS (MT577037, MT577040, MT577042), ACT (MT767712, MT767715, MT767717), TUB2 (MT767723, MT767726, MT767728), CAL (MT767689, MT767692, MT767694), CHS-1(MT767700, MT767703, MT767705), and GAPDH (MT767734, MT767737, MT767739) sequences were deposited in GenBank. The six sets of sequence data were concatenated “ITS-GAPDH-ACT-CHS-1-TUB2-CAL”, and the aligned sequences (2,007 bp) had 99.0% similarity to ex-type C. siamense ICMP18578. In a maximum likelihood phylogenetic tree, the highest log likelihood was -9148.55, and the isolates tested were in the C. siamense cluster with 96 % bootstrap support. Thus, the isolates were identified as C. siamense on the basis of multilocus phylogenetic analyses and morphological characters. To complete Koch’s postulates, several healthy red-fleshed apple fruit (‘Jiuhong’, 1 month prior to harvest) were inoculated using colonized and uncolonized hyphal plugs and a blank agar as a control. All inoculated fruit were placed in sterile tissue culture bottles containing 2 layers of wet paper towels at 28 °C under a 12 h light/dark cycle. All fruit developed anthracnose symptoms in 7 days while the controls did not develop any symptoms. The symptoms were similar to those collected from fruit in the field, and same fungus was re-isolated from the lesions. Presently it was known that C. acutatum, C. asianum, C. chrysophilum, C. cuscutae, C. fioriniae, C. fragariae, C. fructicola, C. gloeosporioides, C. godetiae, C. kahawae, C. karstii, C. limetticola, C. melonis, C. noveboracense, C. nymphaeae, C. paranaense, C. rhombiforme, C. salicis, and C. theobromicola could infect M. coronaria, M. domestica, M. prunifolia, M. pumila, and M. sylvestris worldwide. To our knowledge, this is the first report of C. siamense as a pathogen of M. niedzwetzkyana. This finding provides crucial information for the management of anthracnose disease in China.

scholarly journals First Report of White Leaf Spot Caused by Pseudocercosporella capsellae on Brassica juncea in Australia

Plant Disease ◽  
2005 ◽  
Vol 89 (10) ◽  
pp. 1131-1131 ◽  
Author(s):  
L. Eshraghi ◽  
M. P. You ◽  
M. J. Barbetti
Keyword(s):  
Brassica Juncea ◽  
Oilseed Rape ◽  
Western Australia ◽  
Leaf Spot ◽  
Oilseed Crop ◽  
Single Spore ◽  
First Report ◽  
White Leaf ◽  
Humidity Chamber ◽  
Stem Lesions

Brassica juncea (L.) Czern & Coss (mustard) has potential as a more drought-tolerant oilseed crop than the Brassica napus, and the first two canola-quality B. juncea cultivars will be sown as large strip trials across Australia in 2005. This will allow commercial evaluation of oil and meal quality and for seed multiplication for the commercial release Australia-wide in 2006. Inspection of experimental B. juncea field plantings at Beverley (32°6′30″S, 116°55′22″E), and Wongan Hills (30°50′32″S, 116°43′33″E), Western Australia in September 2004 indicated the occurrence of extensive leaf spotting during B. juncea flowering. Symptoms of this disease included as many as 15 or more grayish white-to-brownish spot lesions per leaf, often with a distinct brown margin. Some elongate grayish stem lesions were also observed as reported earlier for B. napus oilseed rape (1). When affected materials were incubated in moist chambers for 48 h, abundant conidia typical of Pseudocercosporella capsellae (Ellis & Everh.) Deighton were observed that matched the descriptions of conidia given by Deighton (2) and those on B. napus in Western Australia (1). Five single-spore cultures from lesions were grown on water agar (WA) where the colonies characteristically produced purple-pink pigment in the agar after 2 weeks growth in an incubator maintained at 20°C with a 12-h photoperiod (3). Since agar cultures of P. capsellae rarely produce conidia (3), this observation helped with the verification of the cultures. Mycelial inoculum from these cultures was used to inoculate cotyledons of 50 7-day-old plants of B. juncea to satisfy Koch's postulates. Small pieces of mycelia were teased out from the surface of the growing margin of potato dextrose agar (PDA) cultures and inoculated onto both lobes of each cotyledon and plants incubated in a 100% humidity chamber for 48 h within a controlled environment room maintained at 20/15°C (day/night) with a 12-h photoperiod. After 2 weeks, lesions 5 to 8 mm in diameter were observed on the cotyledons. There were no symptoms on control plants that were treated with water only. Lesions on infected cotyledons incubated on moist filter paper for 24 h produced abundant cylindrical conidia showing 2 to 3 septa measuring 42.9 to 71.4 μm long and 2.9 to 3.1 μm wide. Single-spore isolations from these conidia produced typical P. capsellae colonies showing purple-pink pigments in WA, and dark, compacted, and slow-growing colonies with a dentate margin on PDA. White leaf spot caused by P. capsellae is an important disease of crucifers worldwide, but to our knowledge, this is the first report of P. capsellae on B. juncea in Australia. In Western Australia, P. capsellae occurs on B. napus oilseed rape (1) and in 1956, 1984, and 1987, it was recorded on B. rapa, B. oleracea, and B. chinensis, respectively (4), and on the same range of Brassica hosts in other regions of Australia. References: (1) M. J. Barbetti and K. Sivasithamparam. Aust. Plant Pathol.10:43, 1981. (2) F. C. Deighton. Commonw. Mycol. Inst. Mycol. Pap. 133:42, 1973. (3) S. T. Koike. Plant Dis. 80:960, 1996. (4) R. G. Shivas. J. R. Soc. West. Aust. 72:1, 1989.

Variation in Australian and European collections of Trifolium glomeratum L. and the provisional distribution of the species in southern Australia

1974 ◽  
Vol 25 (1) ◽  
pp. 73 ◽  
Author(s):  
RG Woodward ◽  
FHW Morley
Keyword(s):  
Dry Matter ◽  
New South ◽  
South Australia ◽  
Growing Season ◽  
Strongly Correlated ◽  
Collection Site ◽  
South Wales ◽  
Matter Production ◽  
Wide Range ◽  
Flower Growth

Seventy-four lines of Trifolium glomeratum L. from a wide range of Australian and European environments were grown in a glasshouse at Canberra. Time to flower, growth habit, leaf markings, stipule colour, floret colour and dry matter production varied among collections, and within some lines. Numbers of flowers per plant, leaf: stem ratio, and dry matter yields were correlated with days to flower. The variation within the European collection was similar to that within the Australian collection. Time of flowering has probably been important in natural selection in this species, since the date of flowering at Canberra was strongly correlated with date of the end of the growing season (defined by effective rainfall) at the collection site of each ecotype. A survey during 1970 through New South Wales, Victoria and South Australia showed the western limit of spread of T. glomeratum to be through Garah, Burren Junction, Coonamble, Euabalong,Booligal, Moulamein, Beulah, Lake Hindmarsh, Mannum and Jamestown. Extrapolation of climatic restrictions to Western Australia indicated that the species could exist west of Lake Biddy, and possibly north and east to Geraldton and Esperance. The distribution appears to be controlled by the shortest length of growing season in which the species can germinate, grow, and set viable seed.

Tolerance of commercial cultivars and breeders' lines of wheat to Heterodera avenae Woll

1981 ◽  
Vol 32 (4) ◽  
pp. 545 ◽  
Author(s):  
JM Fisher ◽  
AJ Rathjen ◽  
AJ Dube
Keyword(s):  
Visual System ◽  
South Australia ◽  
Early Growth ◽  
Heterodera Avenae ◽  
Strongly Correlated ◽  
Average Yield ◽  
Commercial Cultivars ◽  
Final Yield ◽  
A Site

Many commercial cultivars and breeders' lines of wheat were ranked for tolerance to cereal eelworm by comparing their yield of grain on a site heavily infested with Heterodeva avenae with their average yield on five other areas of South Australia. Different methods for assessing tolerance were examined. A range from tolerance to intolerance was obtained, but most commercial cultivars were intolerant. Many breeders' lines were highly tolerant. A visual system for rating early growth was strongly correlated with final yield. Resistance and tolerance were not related.

scholarly journals First report of Fusarium falciforme (FSSC 3+4) causing root rot on chickpea in Mexico

Plant Disease ◽  
2021 ◽  
Author(s):  
Sixto Velarde Felix ◽  
Victor Valenzuela ◽  
Pedro Ortega ◽  
Gustavo Fierros ◽  
Pedro Rojas ◽  
...  
Keyword(s):  
Fusarium Solani ◽  
Root Rot ◽  
Species Complex ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Aerial Mycelium ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report

Chickpea (Cicer aretinium L.) is a legume crop of great importance worldwide. In January 2019, wilting symptoms on chickpea (stunted grow, withered leaves, root rot and wilted plants) were observed in three fields of Culiacan Sinaloa Mexico, with an incidence of 3 to 5%. To identify the cause, eighty symptomatic chickpea plants were sampled. Tissue from roots was plated on potato dextrose agar (PDA) medium. Typical Fusarium spp. colonies were obtained from all root samples. Ten pure cultures were obtained by single-spore culturing (Ff01 to Ff10). On PDA the colonies were abundant with white aerial mycelium, hyphae were branched and septae and light purple pigmentation was observed in the center of old cultures (Leslie and Summerell 2006). From 10-day-old cultures grown on carnation leaf agar medium, macroconidias were falciform, hyaline, with slightly curved apexes, three to five septate, with well-developed foot cells and blunt apical cells, and measured 26.6 to 45.8 × 2.2 to 7.0 μm (n = 40). The microconidia (n = 40) were hyaline, one to two celled, produced in false heads that measured 7.4 to 20.1 (average 13.7) μm × 2.4 to 8.9 (average 5.3) μm (n = 40) at the tips of long monophialides, and were oval or reniform, with apexes rounded, 8.3 to 12.1 × 1.6 to 4.7 μm; chlamydospores were not evident. These characteristics fit those of the Fusarium solani (Mart.) Sacc. species complex, FSSC (Summerell et al. 2003). The internal transcribed spacer and the translation elongation factor 1 alpha (EF1-α) genes (O’Donnell et al. 1998) were amplified by polymerase chain reaction and sequenced from the isolate Ff02 and Ff08 (GenBank accession nos. KJ501093 and MN082369). Maximum likelihood analysis was carried out using the EF1-α sequences (KJ501093 and MN082369) from the Ff02 and Ff08 isolates and other species from the Fusarium solani species complex (FSSC). Phylogenetic analysis revealed the isolate most closely related with F. falciforme (100% bootstrap). For pathogenicity testing, a conidial suspension (1x106 conidia/ml) was prepared by harvesting spores from 10-days-old cultures on PDA. Twenty 2-week-old chickpea seedlings from two cultivars (P-2245 and WR-315) were inoculated by dipping roots into the conidial suspension for 20 min. The inoculated plants were transplanted into a 50-hole plastic tray containing sterilized soil and maintained in a growth chamber at 25°C, with a relative humidity of >80% and a 12-h/12-h light/dark cycle. After 8 days, the first root rot symptoms were observed on inoculating seedlings and the infected plants eventually died within 3 to 4 weeks after inoculation. No symptoms were observed plants inoculated with sterilized distilled water. The fungus was reisolated from symptomatic tissues of inoculated plants and was identified by sequencing the partial EF1-α gene again and was identified as F. falciforme (FSSC 3 + 4) (O’Donnell et al. 2008) based on its morphological characteristics, genetic analysis, and pathogenicity test, fulfilling Koch’s postulates. The molecular identification was confirmed via BLAST on the FusariumID and Fusarium MLST databases. Although FSSC has been previously reported causing root rot in chickpea in USA, Chile, Spain, Cuba, Iran, Poland, Israel, Pakistan and Brazil, to our knowledge this is the first report of root rot in chickpea caused by F. falciforme in Mexico. This is important for chickpea producers and chickpea breeding programs.

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