Volume 13 - 2023
10. Characterization of infection patterns of common bean rust (Uromyces appendiculatus) under different management practices
Bhandari S, Srivastava A (2023)
8. Validation of a generic model for predicting garlic rust
Mallmann G et al. (2023)
6. First report of Pyrrhoderma noxium from rice in northern Thailand
Absalan S et al. (2023)
5. Biological characteristics of Diplodia sapinea f. sp. cupressi infecting Cupressus sempervirens L. in Tunisia
Hlaiem S, Ben Jamâa ML (2023)
4. Chemical control of Septoria lycopersici in vitro as first screening for fungicide efficacy studies
Monteiro FP et al. (2023)
3. Grain mould fungi of sorghum caryopses in Benishangul Gumuz, Ethiopia
Kebede M et al. (2023)
2. Distribution of foliicolous fungi in diverse forest types of Maharashtra State of India
Dubey R, Pandey AD (2023)
Volume 10 - 2020 -
Authors: Singh M, Mishra M, Srivastava DK, Singh PK
Recieved: 12 February 2020, Accepted: 10 March 2020, Published: 03 April 2020
A pot experiment was carried to study the impact of the intercropping system i.e. tomato/tomato, tomato/maize, tomato/chilli and tomato/eggplant on interaction with Fusarium oxysporum f. sp. lycopersici (Fol) and arbuscular mycorrhizal (AM) fungi. AM fungi root colonization of tomato was significantly affected by the intercropping system. AM fungi inoculated plants expressed increase biomass (26.72 g shoot fresh weight & 12.53 root fresh weight) of tomato compared to the untreated control (9.92 g root fresh weight & 3.64 g root fresh weight) treatment. The intercropping crops maize, chilli, eggplant, and tomato had no effect on disease incidence or disease severity; however, tomato significantly showed a negative effect on one plant/pot with regard to biomass and disease severity of Fol co-cultivated with tomato. The results of the bioprotection effects of AM fungi observed in the decrease of disease severity and/or damage of plant biomass does not depend on the AM fungi colonization but more on the intercropping crops.
Keywords: Bioprotection – Root Colonization – Mycorrhiza – Biotrophs – Soil-borne
Authors: Intaparn P, Noireung P, Maumoon R, Poti T, Wongwan T, McGovern RJ, Unartngam J, Tapingkae T, To-anun
Recieved: 07 January 2020, Accepted: 27 March 2020, Published: 09 April 2020
During August to October 2019, Catharanthus roseus plants with root and stem rot symptoms were collected from a greenhouse which belongs to farmers in Chiang Mai, Thailand. The causal agent was isolated from the roots and rhizosphere soil of C. roseus showing symptoms of root and stem rot disease in plantation areas in Chiang Mai, Thailand. The pathogen was studied by morphological characteristics and molecular analysis based on the internal transcribed spacer (ITS) region it was determined to be Phytopythuim sp. The pathogenicity of the isolate was tested by inoculating detached C. roseus leaves with an agar disc containing mycelium of the fungus compared with a sterile agar disc as the control. It was found that Phytopythium sp. isolate MCRC-Pp021 infected the C. roseus leaves causing a brown rot. Moreover, Phytopythium sp. MCRC-Pp021 infected and caused rot symptoms on plant crowns in 14 d after inoculation with a mycelial suspension. This research finding is the first record of Phytopythium sp. MCRC-Pp021 causing root and stem rot of C. roseus in Thailand. In addition, in a fungicide test, it was shown that dimethomorph and phosphorous acid were less effective against Phytopythium sp. MCRC-Pp021 at the recommended rate than mancozeb, propineb, thiram, fosetyl-aluminium, tridemorph and metalaxyl which exhibited high efficacy.
Keywords: morphological characters – pathogenicity – phylogeny – poison food assay – vinca
3. Efficacy of Ampelomyces spp. against powdery mildew disease of rose caused by Podosphaera pannosa
Authors: Wanasiri N, McGovern RJ, Cheewangkoon R, Kongtrakual P, To-Anun C
Recieved: 31 October 2019, Accepted: 07 February 2020, Published: 24 April 2020
The fungus Ampelomyces spp., a hyperparasite of powdery mildews, was isolated from flowering plants Zinnia elegans, Ageratum conyzoides, Hydrangea sp., and Dahlia spp. The morphological characteristics were observed using light and scanning electron microscopes. Pycnidia variable in shape (ovoid and ellipsoid) and conidia measuring 10.5 to 13.5 µm in length × 2.5 to 3.0 µm in width were detected. Four isolates of Ampelomyces spp. were obtained, AMP1-Ze, AMP2-Ac, AMP3-Hg and AMP4-Dl, to study their ability to inhibit conidial germination on onion cell tissue of the fungus Podosphaera pannosa which causes rose powdery mildew. The biocompounds produced by these mycoparasites had LC50 values between 91.20-190.55 ppm. The most effective biocompound was produced by the Ampelomyces–from Ageratum conyzoides (AMP2-Ac) and it was compared to a conventional fungicide (carbendazim 10cc/20L) and control (non-treated). This biocompound reduced the severity of powdery mildew disease by 45.33% in greenhouse experiments.
Keywords: Antagonistic fungi – biological control – hyperparasite – Podosphaera pannosa
4. Performance of Green Power and Shincheonggang tomato rootstocks in Ralstonia solanacearum contaminated area
Authors: Monteiro FP, Wamser AF, Ogoshi C, Valmorbida J, Cardoso DA, Perazolli V
Recieved: 05 December 2019, Accepted: 18 April 2020, Published: 22 May 2020
The bacterial vascular wilt caused by Ralstonia solanacearum is an important limiting factor to tomato production in contaminated areas. To overcome this problem the performance of Green Power and Shincheonggang tomato rootstocks in an R. solanacearum highly infested area was determined by measuring their productivities and the disease incidences. Both rootstocks had higher production compared to the tomato plants without rootstocks. The first symptom of the tomato bacterial wilt was observed 20 days after the seedlings transplant. More than 90% of the tomato plants without rootstocks have died at the 92º day after the transplant. At the end of the growing season was accounted for that 54% and 36% of Green Power and Shincheonggang rootstock plants died due to R. solanacearum infection, respectively. The area under the disease incidence progress curve for Green Power, Pay Pay, Shincheonggang and Compack were 3,643.50 ± 1,354.15; 11,959.50 ± 1,127.47; 1,638.00 ± 1,221.91 and 8,631.00 ± 728.98, respectively. The AUDIPC in both rootstocks were statistically different from the AUDIPC of plants without rootstocks. Despite the good performance of the rootstocks compared with plants without rootstocks, the R. solanacearum were found infecting them. Asymptomatic rootstocks plants of Green Power (74.91%) and Shincheonggang (98.44%) were infected by R. solanacearum confirmed through the vascular flow test. On average, the Green Power rootstock produced 115,925 fruits per hectare classified as extra AA and 160,333 fruits per hectare classified as extra A while Pay Pay plants without rootstocks produced 2,661 (extra AA) and 8,981 (extra A) fruits per hectare. The Shincheonggang rootstock produced 29,522 fruits per hectare classified as extra A fruits while Compack plants without rootstocks produced 416 fruits per hectare. The Compack plants without rootstock did not produce any extra AA fruits while the Shincheonggang rootstock produced 68,524 fruits per hectare. On the basis of the results, the rootstocks used herein are recommended as one component of a management program to control R. solanacearum.
Keywords: bacterial wilt – vascular disease – Solanum lycopersicum
5. Management of postharvest anthracnose of banana using inorganic salts alone and in combination with hot water
Authors: Sinthuja S, Prasannath K
Recieved: 30 March 2020, Accepted: 17 June 2020, Published: 22 June 2020
Experiments were conducted to evaluate selected inorganic salts alone and in combination with hot water for management of banana anthracnose disease. The efficacy of hot water treatment (HWT) and either sodium bicarbonate (SBC), sodium carbonate (SC) or sodium hypochlorite (SH) applied alone and in combination to suppress anthracnose disease was investigated in both naturally infected and artificially inoculated banana fruit cv. Kolikuttu during the storage. The in vitro efficacy of the selected salts on the inhibition of colony growth of the anthracnose fungal pathogen was also tested. Postharvest treatment involving fruit dipped for 30 min in 1% (w/v) SC following HWT (50°C, 3 min) reduced the severity of anthracnose, which was statistically similar (P > 0.05) with that of homai fungicide treatment. Among the tested salts, SC recorded the significantly highest (P < 0.05) in vitro inhibition of mycelial growth of anthracnose pathogen. Integration of SC with HWT could be a commercially acceptable and economically feasible non-fungicidal approach for the postharvest management of anthracnose during the storage of banana.
Keywords: Eco-friendly disease management – Fruit disease – Generally regarded as safe salts – Postharvest disease
Authors: Monteiro FP, Valmorbida J, Wamser AF, Ogoshi C, Cardoso DA, Perazolli V
Recieved: 10 October 2019, Accepted: 14 June 2020, Published: 16 July 2020
Strawberry cultivation is expanding in Brazil, but few tactics are employed to extent the shelf-life of the strawberries fruits, which are affected by postharvest fungi that cause rot. To clarify how this rot progress, the objective of this work was to study the relationship between fungi that colonize anthers and rot of strawberry fruits during postharvest. The incidence of fungi in the strawberry anthers, the disease progress in strawberry fruits with infested anthers and in vitro fungicides efficiency against Cladosporium sp. were performed. Cladosporium sp. was found in 100 % of the plants and in approximately 65% of the flowers during strawberry cultivation in a semi-hydroponic system. From 148 anthers without fungal signs placed into Petri dishes containing PDA, 94 were contaminated with Cladosporium and two of them had Penicillium sp. All 40 strawberry fruits which had Cladosporium sp. infesting their anthers were rotten by this fungus after nine days. As the most recurrent fungus was Cladosporium, the most efficient fungicides to control this fungus were azoxystrobin + diphenoconazole, boscalide + cresoxim-methyl, metconazole, methyl thiophanate, pyrimenthanil, tebuconazole and trifloxystrobin + tebuconazole at the recommended doses for Botrytis cinerea and Mycosphaerella fragariae. Anther colonization may serve as the nearest source of inoculum to incite postharvest disease, as anthers remain attached to the fruits.
Keywords: Blossom rot – Cladosporium – Fragaria x ananassa Duch. – Fusarium
7. First record of Erysiphe magnifica on the new host Magnolia × alba in Taiwan indicates high morphological plasticity of the anamorph under tropical conditions
Authors: Wang CT, Yeh YW, Lin LD, Kirschner R
Recieved: 29 May 2020, Accepted: 04 August 2020, Published: 07 August 2020
The identification of the first record of Erysiphe magnifica for Taiwan is based on anamorphic material on diseased leaves of Magnolia × alba. Internal Transcribed Spacer (ITS) sequence comparison shows 100% identity with other sequences from E. magnifica with a clear barcode gap to other species. The morphology, however, deviates considerably from that reported in the literature by up to over 100 μm long foot cells of the conidiophore, which in some cases is correlated with a shift of the basal septum at a distance above the supporting hypha. These deviations may be correlated with adaptability to tropical environment. The potential evolutionary and phytopathological implications of such morphological anamorph plasticity are discussed.
Keywords: Fungal biogeography – Erysiphales – Fungi – Magnoliaceae – tropical ecology
Authors: Madlao GMA, Gandalera EE, Waing KGD
Recieved: 07 May 2020, Accepted: 04 August 2020, Published: 20 August 2020
Daucus carota or commonly known as carrot is one of the most essential root crops worldwide that belongs to the family Apiaceae. Several studies show that different fungal pathogens like black root rot may infect the carrot resulting in great loss. Thus, this study was conducted mainly to isolate and identify different fungal species associated with black root rot of carrot. Identification of fungal isolates was done by observing its morphological and cultural characteristics, then, identified fungal species were molecularly identified using the Internal Transcribed Spacer region. A total of six species were subjected into Blast (Basic Local Alignment Search Tool) analysis which revealed that fungal species were identified as Aspergillus fumigatus, Aspergillus tamarii, Fusarium oxysporum, Fusarium solani, Mucor circinelloides and Rhizopus stolonifer. All fungal isolates revealed antagonistic interaction through in vitro interaction. Hyphal denaturation, branched hypha, lysed cells, hyphal penetration, and hyphal coiling were observed under the microscope. The two species of Fusarium, namely F. oxysporum and F. solani, make the study to conclude that the Fusarium species have potential for the development of biocontrol agents that would lessen the use of harmful chemicals.
Keywords: antagonism – black root rot – hyphal interaction
Authors: Avasthi S, Gautam AK, Bhadauria R, Verma RK
Recieved: 03 June 2020, Accepted: 19 August 2020, Published: 25 August 2020
Aloe vera (L.) Burm. f. is an important medicinal plant with long time tradition of use by variety of cultures. This plant is suffered with various fungal diseases caused by variety of fungal pathogens in different seasons which affects its morphological characters and diminishes the quality, quantity and production of gel. The present study was aimed to study the alteration in the morphological characteristics of Aloe vera artificially infested with Colletotrichum gloeosporioides and Fusarium proliferatum; the leaf spot disease causing fungi in this plant. Artificially infested leaves were examined in terms of plant height, leaf characteristics, colour and consistency of gel. Results of artificial infestation revealed that both the fungal pathogens have the ability to alter the morphological properties of A. vera plants. Therefore, control of the fungal diseases by applying appropriate management strategies is essential to protect this medicinal plant of massive commercial value.
Keywords: Aloe vera – fungal pathogens – gel texture – leaf spot – leaf length and width – plant height
10. First Record of Phytopythium vexans causing root rot on Mandarin (Citrus reticulate L. cv. Sainampueng) in Thailand
Authors: Noireung P, Intaparn P, Maumoon R, Wongwan T, To–Anun C
Recieved: 02 August 2020, Accepted: 22 September 2020, Published: 08 October 2020
A survey was conducted during 2017–2019 to identify the causal agents of citrus root rot in Thailand. The causal agent was isolated from the roots and rhizosphere soil of Citrus reticulata plants, which shows symptoms of root rot. The taxonomy and phylogeny of the pathogen was studied. The molecular phylogeny was studied based on Cytochrome c oxidase I (Cox1). The taxonomy and phylogeny revealed the pathogen to be Phytopythuim vexans. The pathogenicity of the isolate was tested by inoculating detached C. reticulata leaves with mycelial plug and zoospore suspension on root. It was found that Phytopythium vexans PS85 causes the brown rot on C. reticulata leaves and root rot. This is the first record of Phytopythium vexans causing root rot disease on Mandarin (Citrus reticulate) in Thailand.
Keywords: morphology – pathogenicity – phylogenetic – root rot
11. In vitro evaluation of Trichoderma species for antagonistic activity, fungicide tolerance and competitive saprophytic ability
Authors: Nair B, Abraham D, Mallikarjunaswamy GE
Recieved: 22 June 2020, Accepted: 09 October 2020, Published: 19 October 2020
Soil microbe interactions directly or indirectly affect plant health and soil quality. Plant growth-promoting and bio-control microorganisms have emerged as safe alternatives to chemical pesticides. Trichoderma species are known to exhibit antagonistic activity against a number of plant pathogenic organisms. The present study aims to understand antagonistic, pesticide tolerance and rhizosphere competence of three Trichoderma species namely Trichoderma harzianum, T. koningiiand T. pseudokoningiiin vitro. Trichoderma sp. were subjected against root wilt and rot causing pathogens namely Fusarium oxysporum and Sclerotiumrolfsiivia dual culture and exhibited effective antagonistic activity. Dithane M-45 75% W. P. fungicide at different concentrations viz. 50,100,150,200,250,300 ppm was tested by poison food method and Trichoderma harzianum and T. koningiiexhibited tolerance to fungicide at 300 ppm. Fungal cultures, 2 x 106spore suspensions were analysed for saprophytic ability. 40 ml of Trichoderma sp. conidial suspensions and colonization of paddy straw segments at 1cm apart from the bottom of the sterile plastic cup filled with 200 g of autoclaved potting medium up to 7-cm length was determined at 10 and 21 days of incubation. Trichoderma harzianum and T. koningiiexhibited good saprophytic and colonization ability. Both T.harzianum and T. koningii was isolated at 7cm depth with colonization frequency of 100% and 88% respectively whereas T. pseudokoningii colonized till 4cm depth with isolation frequency of 38% at 21 days of incubation. Most of the Trichoderma species show effective in vitro antagonistic ability but success in field depends on colonization efficiency. Thus present study details on applicability and necessary modifications for field triumphs of biological agents.
Keywords: Bio – control – Colonization – Fungicide – Saprophytic ability
12. Variation in susceptibility to Phyllosticta capitalensis-associated leaf disease among inter-specific hybrids, half-sibs and high-yielding clones of Para rubber tree (Hevea)
Authors: Narayanan C, Reju MJ
Recieved: 15 August 2020, Accepted: 18 September 2020, Published: 19 October 2020
High susceptibility of many commercial clones of Para rubber tree (Hevea brasiliensis) makes disease management very difficult warranting development and use of disease tolerant clones. Hence, hybridization was carried out using high-yielding and susceptible clones of H. brasiliensis viz. RRII 105, RRII 414 and RRII 430 and two disease tolerant species viz. H. spruceana and H. camargoana and two wild Rondônia germplasm accessions viz. RO 380 and RO 2871. The progenies from the breeding are under various stages of evaluation for their growth and rubber yield. During the course of evaluation, it was observed that many progenies were affected by a serious leaf disease in the form of spots which affected only mature leaves. In all leaf samples examined, conidiomata and ascomata were observed from the initial stages of leaf spot symptoms. Based on characteristic morphology of conidiomata and ascomata, the fungus which was consistently detected in the spots was identified as Phyllosticta capitalensis. Occurrence of P. capitalensis in both of its conidiomata and ascomata states with appendaged conidia and appendaged ascospores respectively, in association with the characteristic leaf spots in either H. brasiliensis or its inter-specific hybrids, is a novel report from India or elsewhere. In very few progenies, leaf blight associated with Pestalotiopsis sp., was also observed. In order to find variability in response to the leaf spot disease associated with P. capitalensis, all progenies were assessed for disease incidence and severity. Progenies of crosses viz. RRII 430 x RO 2871, RRII 414 x H. spruceana, RRII 414 x RO 380 and RRII 105 x H. spruceana had more than 80 percent disease incidences in their progenies. Progenies of cross RRII 430 x RO 380 showed minimum disease incidence (I = 61%). Half-sib progenies of a disease tolerant clone Fx 516 showed lesser disease incidences (I = 25-27%) and very low disease index (DI, 0.8-0.9) indicating better tolerance. In addition to the above, few other high-yielding commercial rubber clones were assessed for their susceptibility to P. capitalensis associated leaf spot. In an on-farm trial, two clones viz. RRII 430 and RRII 417 recorded maximum (I = 60%) disease incidence. Clone RRII 422 (I = 10%) followed by RRII 414 (I = 20%) showed minimum disease incidence. Two other clones viz. RRII 105 and RRII 429 showed moderate incidence (I = 50%). P. capitalensis was consistently detected and associated in all of the infected leaf samples from all the host species observed from early stages of disease development. However, more detailed studies are required to ascertain its specific role in disease development in order to develop suitable management strategies.
Keywords: Disease resistance breeding – Hevea brasiliensis – Hevea camargoana – Hevea pauciflora – Hevea spruceana – leaf spot – tolerance – Rondônia – wild germplasm
13. Development of integrated disease management program against Anthracnose-Twister (Colletotrichum gloeosporioides-Gibberella moniliformis) disease of onion (Allium cepa)
Authors: Alberto RT, Perez PM
Recieved: 20 June 2020, Accepted: 09 October 2020, Published: 22 October 2020
Anthracnose-Twister disease caused by Colletotrichum gloeosporioides and Gibberella moniliformis has always been the major problem of onion growers every onion season due to absence of efficient and cost effective management system, thus, this study was conceptualized by integrating all the available management approaches to put the disease at bay. The results showed that management program T3 (Benomyl-Propineb-Difenoconazole~Propiconazole (DP)-Difenoconazole-Carbendazim-Mancozeb-Trichoderma sp.) had the lowest % disease incidence and severity, where ideal size of the marketable bulbs, highest number and heaviest weight of the marketable bulbs were also obtained. It was also found out to be the most cost effective management program and had the highest net income. On the otherhand, highest % mortality was observed in T4 (Carbendazim---Mancozeb---Difenoconazole---Trichoderma sp.---Benomyl---Propineb---DP) and T9 (Untreated Control). It was also in this plots together with T8 (Farmer’s Practice) where the highest level of % incidence and % severity, lowest and lightest weight of the marketable bulbs were obtained. Furthermore, late transplanting date as well as using 15x15cm spacing between hills and rows and 5-day irrigation interval contributed against the occurrence of anthracnose-twister disease. The weather factors prevailing in the area were found to have an influence in the occurrence and progress of the disease in all the treated plots as well as in the control plots (T9) as it shows strong relationship between low temperature and small amount of rainfall which promotes low levels of incidence and severity. Moreover, results showed that application of protectant fungicide during the early part of the season followed by systemic fungicide application can bring down the disease incidence and severity as adequate protection to the plants were provided.
Keywords: Anthracnose – Twister – Disease – Integrated – Disease Management – (IDM) Management Programs
Authors: Dubey MK, Yadav M, Upadhyay RS
Recieved: 16 August 2020, Accepted: 09 October 2020, Published: 28 October 2020
Up-to-date information is presented based on an intensive search of literature records on the identity, occurrence, nomenclature, substratum, host ranges, geographical distribution and literature references of the genus Pythium from India. All Pythium species published until 2020 are included in this list. The survey result of all forms of analyses revealed that India has 55 species of Pythium belonging to the phylum Oomycota indicating the presence of rich mycoflora. Distribution of these Pythium species reported so far from freshwater and terrestrial habitats of various Indian states are listed alphabetically. The most frequently collected species are Pythium aphanidermatum, P. spinosum, and P. ultimum. The majority of these species were found as a parasite on a wide range of plants in both freshwater and terrestrial environment. Overall, this systematic checklist provides the total count of Pythium species, currently known to occur in India and it is also a valued addition for comparing Pythium diversity in India as well as the world. Besides, it represents the first comprehensive overview of Pythium since 1996 from India. The knowledge generated by this working checklist comprising accepted taxa in Pythium from India is hoped to be beneficial in the progress of the systematics, diversity, ecology, plant protection, aquaculture, ichthyopathology, quarantine and many other diverse arrays of applied scientific disciplines in the country.
Keywords: Disease – distribution – ecology – parasitic – soil-borne pathogen – saprobes – systematic taxonomy
15. Pyrenophora trichostoma (Pleosporaceae, Pleosporales): an overview of the species and first record on Bromopsis inermis from Russia
Authors: Goonasekara ID, Bulgakov TS, Jayawardena RS
Recieved: 25 September 2020, Accepted: 04 October 2020, Published: 28 October 2020
Pyrenophora consists of endophytes, pathogens and saprobes that are widely distributed on various cereal crops and grass hosts. Pyrenophora trichostoma was found on Bromopsis inermis in Russia (Rostov region) and it is described as the first record of this species from this host. The fungus, a sexual morph, was isolated using the single spore isolation technique. The morphology is illustrated and a description has been provided. Sequence data of the LSU and ITS gene regions were analysed to confirm the phylogenetic placement of the species. The history of P. trichostoma, its distribution and economic impact as a pathogen that causes leaf spots on cereals and wheat, has been discussed.
Keywords: grass fungi – pathogen – phylogeny – saprobe – taxonomy
Authors: Ogoshi C, Monteiro FP, Pinto FAMF, Perazzoli V, Cardoso DA
Recieved: 15 September 2020, Accepted: 26 October 2020, Published: 10 November 2020
Glomerella leaf spot (GLS) is an apple disease difficult to control, even with the use of chemical fungicides. In years of GLS high pressure, protective fungicides in the chemical group of dithiocarbamates, especially mancozeb, have been used frequently, and even so, the control has not been satisfactory. Because of this scenario, growers have been increasing the frequency of application and the dose recommended on the product label, a situation that will become unsustainable over the years, and resistance of some species belonging to Colletotrichum acutatum species complex to mancozeb has already been observed in Brazil. Our objective was to verify the efficiency of several chemicals’ fungicides in the control of GLS in field conditions in three consecutive crop seasons. The experiments were conducted at the Experimental Station of Caçador in 2017/2018, 2018/2019 and 2019/2020 crop seasons. The tested fungicides were: mancozeb, mancozeb + trifloxystrobin, mancozeb + trifloxystrobin + tebuconazole, fluxapyroxad + pyraclostrobin, chlorothalonil, dithianon, captan, metiram + pyraclostrobin, thiophanate-methyl + fluazinam, fluazinam, metiram, dodine, folpet, and propineb. We assessed the GLS incidence over time, and with these data, the Area Under the Disease Incidence Progress Curve (AUDIPC) and the control efficiency of each treatment were calculated. The experimental design was in randomized blocks with four replications. The fungicides mancozeb, mancozeb + trifloxystrobin, mancozeb + trifloxystrobin + tebuconazole, chlorothalonil, dithianon, captan, thiophanate-methyl + fluazinam, metiram, fluazinam, folpet and propineb showed an efficient control of GLS. The fungicide metiram + pyraclostrobin showed an intermediate control and the fungicides dodine, and fluxapyroxad + pyraclostrobin were not efficient in GLS control. In general, systemic fungicides were not efficient in GLS control. Protectant fungicides were the most efficient in GSL control, being excellent options to be rotated with the fungicide mancozeb, which is used as a standard in GLS control in Brazil.
Keywords: apple – Colletotrichum – non-systemic fungicides – protectant fungicides
17. Key transboundary plant pests of Coconut [Cocos nucifera] in the Pacific Island Countries – a biosecurity perspective
Authors: Datt N, Gosai RC, Ravuiwasa K, Timote V
Recieved: 04 November 2019, Accepted: 24 October 2020, Published: 13 November 2020
The movement of plant pests and diseases from one continent or country to another by-passing physical boundary is as ancient a menace as the drift of people themselves. Many of these species pose a direct threat to food security with progressive socio-economic perils affecting the livelihoods of people. The National Plant Protection Organisation of a country is vested with legislative powers to prevent the incursion of such species through the implementation of proactive measures such as risk assessments, monitoring, surveillance and controlling human-aided pathways. The unfortunate event of an unwanted incursion brings with it challenges of early detection and immediate implementation of eradication measures which are further compounded by capability gaps and funding constraints. The success of eradication is more than often determined by quick execution of appropriate emergency response measures and flexibility to scale operations when needed. Even with extensive and exhaustive eradication efforts applied, many-a-times the National Plant Protection Organizations face unfavourable results. Coconut is an extremely important subsistence as well as an economic plant for almost all island nations in the Pacific. In this view, existing transboundary pests of coconut in the Pacific Islands basin, namely Coconut Rhinoceros Beetle-Guam biotype, Coconut Lethal Yellowing phytoplasma and the Coconut Cadang-Cadang viroid pose more than a significant threat to countries free of these pests and which have put regional National Plant Protection Organizations on high alert.
Keywords: Cadang-cadang – Coconut Rhinoceros Beetle – Guam biotype – Lethal yellowing
18. Pathogenic Diaporthe from Italy, and the first report of D. foeniculina associated with Chenopodium sp.
Authors: Gajanayake AJ, Abeywickrama PD, Jayawardena RS, Camporesi E, Bundhun D
Recieved: 27 October 2020, Accepted: 10 November 2020, Published: 16 November 2020
Diaporthe is an important genus composed of pathogenic, saprobic and endophytic species. A Diaporthe species was collected from a dead aerial branch of Chenopodium sp. from Italy. Multi-locus phylogeny of ITS, CAL, HIS, TEF1–α and TUB2 sequence data showed that our strain clusters with Diaporthe foeniculina with good statistical support. A comprehensive description, photographs of micromorphological characteristics and phylogenetic trees to show the placement of the taxon are provided. This is the first report of D. foeniculina on Chenopodium sp. from Italy. Previously, Diaporthe foeniculina has been recorded from Italy as a pathogen on different plant species. Based on the previous findings, a list of known pathogenic Diaporthe species reported from Italy is provided.
Keywords: Coelomycetes – Diaportheceae – New record – Sordariomycetes – Taxonomy
19. Chemical Management of Anthracnose-Twister (Colletotrichum gloeosporioides and Fusarium fujikuroi) Disease of Onion (Allium cepa)
Authors: Perez PM, Alberto RT
Recieved: 17 July 2020, Accepted: 12 November 2020, Published: 26 November 2020
Among all other diseases of onion, anthracnose-twister caused by Colletotrichum gloeosporioides and Fusarium fujikuroi (formerly known as Gibberella moniliformis) remained the most destructive every cropping season. It destroys onion production, especially when left unmanaged. Studies showed that chemical management is still the best option in addressing this disease; thus, this study was conducted. It aimed to: (a) evaluate the different protectant fungicides available in the market in managing the disease; (b) test Paclobutrazol in suppressing the rapid production of gibberellic acid that triggers the development of the disease; and (c) compare the performance of Paclobutrazol and other fungicides in suppressing the disease when applied as preventative and curative. Results showed that onion plants treated with Captan and Paclobutrazol had the least incidence of disease under protective spray application. In contrast, onion plants applied with Carbendazim and Paclobutrazol had the least severity on both spray applications. Whereas, onion plants applied with Difenoconazole-Propiconazole and Auxin showed the highest disease incidence and severity in both spray applications. The shortest length of the neck was observed in onion plants treated with Benomyl+Paclobutrazol and Paclobutrazol alone, while the longest was observed in Difenoconazole-Propiconazole. The highest yield was obtained in onion plants treated with Carbendazim+Paclobutrazol and Captan, whereas the lowest yield was obtained in onions applied with Auxin and Difenoconazole-Propiconazole. Protective spray application obviously showed lower disease incidence and severity, shorter neck and higher yield compared to curative spray application.
Keywords: Anthracnose-Twister Disease – Disease Complex – Chemical Management
Authors: Pirnia M, Taheri A
Recieved: 07 August 2020, Accepted: 18 December 2020, Published: 28 December 2020
White powdery masses were observed on leaves of Lactuca tuberosa in southwestern Iran. Infected leaves were examined using a stereomicroscope and microscopic slides of fungal structures prepared in lactic acid 25%. Based on morphological characteristics of conidia, appressoria and foot cell of conidiophores, the fungus was identified as Golovinomyces bolayi. The fungus is an important pathogen causing powdery mildew disease and occurs on various Lactuca species. G. bolayi separated from G. orontii species complex and distinguished from other closely related species by having catenate conidia as well as nipple-shaped appressoria and sinuous-curved foot cell of conidiophores.
Keywords: Asteraceae – Erysiphales – Obligate parasite – Powdery mildew – Taxonomy
21. A new record of Lasiodiplodia pseudotheobromae causing leaf spot of Cynometra malaccensis in Thailand
Authors: Gomdola D, Jeewon R, Jayawardena RS, Pem D, Harishchandra DL
Recieved: 15 September 2020, Accepted: 29 December 2020, Published: 31 December 2020
Lasiodiplodia species are well-known plant pathogens, causing fruit rot, stem-end rot and die-back on a wide range of hosts. They are characterized by hyaline or pigmented, aseptate or septate, thick-walled conidia, usually with longitudinal striations. In this study, Lasiodiplodia pseudotheobromae was found to cause leaf spots of Cynometra malaccensis in Thailand. Based on morphology and phylogenetic analyses of internal transcribed spacer regions (ITS) and translation elongation factor 1-alpha gene (TEF1-α), we identify the taxon as L. pseudotheobromae; it is the first confirmed record on Cynometra malaccensis in the world.
Keywords: Botryosphaeriaceae – Fabaceae – Morphology – Multigene – Phylogeny – Taxonomy