Volume 12 - 2022 -

1. The threat of transboundary plant pathogens to agricultural trade in Southern Africa: a perspective on Zimbabwe’s plant biosecurity – A review

Authors: Mudada N, Mapope N, Ngezimana W

Recieved: 19 October 2021, Accepted: 20 January 2022, Published: 08 February 2022

The high frequency of cargo, passengers and movement of goods across borders increases the chances of pest invasions and spread in a geographical area. This paper reviews the biosecurity concerns associated with cross border traffic in international trade, using Zimbabwe as a case study. It reviews the threats of transboundary plant pathogens due to cross border traffic and trade of agricultural products in Southern Africa. The importance of plant biosecurity in agriculture through institutions of plant quarantine measures in crop protection and plant biosecurity will be highlighted. The paper has related the importance of pathways of plant pathogens and their threats to agriculture systems through accidental introductions amongst other anthropogenic related pathways of pests’ introduction and spread. The review also addresses the relationship between pest risk analysis, human aided pests’ pathways, and bioterrorism threats. It explained how entry point quarantine officials must behave in so far as minimising the chances of new introductions, establishment and spread of exotic pests by employing modern conformity assessments test especially rapid testing techniques.  There are many pathogens threatening production of staple and strategic crops in Southern Africa if no extra care is given to cross border management of pathogen pathways. The list of pathogens threatening the block of countries in Southern Africa is long. Zimbabwe and other Southern African countries should have a critical watch and improve cross border quarantine inspections, constantly reviewing quarantine laws and procedures as well as exploiting the gains in the science of the use of rapid pest testing techniques for pest pathways in cross border to improve on easy of doing business and trade.

Keywords: accidental introductions – conformity assessments – pest risk analysis – rapid testing


2. Epidemiology and Management Strategies of Cocoa black pod (Phytophthora spp.)

Authors: Merga J

Recieved: 01 November 2021, Accepted: 20 January 2022, Published: 10 February 2022

Pathogens of the Straminipile genus Phytophthora cause widespread disease fatalities to worldwide cocoa productivity. Phytophthora megakarya sources substantial pod rot and losses due to canker in West Africa, although Phytophthora capsici and Phytophthora citrophthora cause pod decays in Central and South America. The universal and extremely destructive Phytophthora palmivora bouts entirely parts of the cocoa tree at all phases of the rising cycle in Ethiopia. This pathogen causes 20 to 30% pod damages through black pod rot, and kills up to 10% of trees annually through stem cankers. Phytophthora palmivora has a multipart disease cycle linking several causes of primary inoculum and numerous modes of distribution of subordinate inoculum. This consequences in explosive increases during suitable environmental conditions. The feast of local pathogens must be prohibited by effective quarantine fences. Opposition to all these Phytophthora species is characteristically low in commercial cocoa genotypes production. Disease losses can be abridged through combined management practices that comprise pruning and shade management, leaf covering, regular and complete picking, hygiene and pod case removal, suitable fertilizer application and targeted fungicide usage. Wrapping these options to convalesce uptake by smallholders presents a main challenge for the industry.

Keywords: Control – Disease – Epidemics – Production – Spices


3. Preliminary study on the effects of carbendazim on fungi isolated from crop soil samples obtained from Afe Babalola University and Ado-Ekiti farm

Authors: Ekundayo EA, Ogunmefun OT, Shobanjo TO, Anuoluwa IA, Oso AO, Oluwafemi YD, Akharaiyi FC

Recieved: 28 October 2021, Accepted: 04 March 2022, Published: 17 March 2022

Fungi were isolated from five different soil samples of 5 crops obtained from Afe Babalola University, Ado – Ekiti farm on Potato Dextrose Agar (PDA) and PDA supplemented with 1% chitin at 25 ± 2oC. Twenty-one (21) fungi were isolated and identified as Trichoderma viride, T. harzianium, Aspergillus niger, Penicillium digitatum and Epicoccum purpurascen. Four isolates were obtained from pawpaw (Carica papaya), five (5) from Moringa oleifera, five (5) from plantain (Musa parasidica), three (3) from garden egg (Solanum spp.) and four (4) from okra (Abelmoschus esculentus). The isolates were also screened qualitatively for chitinase on PDA amended with 2% chitin, 0.05% yeast extract and 0.01% congo red. None of the isolates showed any zone of clearance. The effect of a fungicide, carbendazim, at four different concentrations on the rate of growth of the isolates was determined. Trichoderma viride, T. harzianium, and Penicillium digitatum were able to grow on different concentration of carbendazim. However, A. niger, Epicoccum purpurascens were susceptible to carbendazim. This study shows that Trichoderma species were most resistant to the fungicide, and the lower the concentration, the higher the rate of growth. Therefore, T. viride and a lower concentration of carbendazim can be used in integrated pest management.

Keywords: Carbendazim – Chitinase – Integrated pest management – Susceptible – Trichoderma species


4. A comprehensive overview on fungal diseases of Aloe vera in India

Authors: Avasthi S, Gautam AK, Bhadauria R, Verma RK

Recieved: 15 February 2022, Accepted: 29 March 2022, Published: 22 April 2022

This study presented a comprehensive overview on fungal diseases of Aloe vera found commonly in India. The detailed analyses of the information obtained from the present study and previously published literature revealed that diseases of A. vera can be categorized into two main categories as spots and rots caused by various fungal pathogens. Total fifteen fungal species as Alternaria alternata, Cladosporium sphaerospermum, Colletotrichum gloeosporioides, Curvularia lunata, C. ovoidea, Fusarium fusaroides, F. proliferatum, F. solani, Helminthosporium sp., Penicillium purpurogenum, Phoma betae, P. eupyrena, Polyrostrata indica, and Pythium aphanidermatum were found associated with different disease of A. vera. Reduced leaf length, width, total number and colour & texture of mucilaginous gel were observed in infected plants. The detailed descriptions of the fungal diseases of A. vera viz. name of disease, causal organism, disease symptoms, cultural and microscopic characteristics along with systematic details are provided. This compendium will be a useful document for researchers working on various aspects of A. vera.

Keywords: Aloe vera – causal organisms – diversity – fungal diseases – India


5. Biology, disease development, distribution and control of rust pathogen Uromyces viciae-fabae

Authors: Gautam AK, Payal, Avasthi S, Verma RK

Recieved: 16 March 2022, Accepted: 29 March 2022, Published: 22 April 2022

Uromyces is an important plant pathogenic genus of rust fungi (Pucciniales, Basidiomycota). Uromyces fabae is one of the major species of this rust genus that affects the plant family Fabaceae. This rust fungus is autoecious in nature, produces aeciospores, urediospores and teliospores found on the surface of the host plant. This fungus has worldwide in distribution showed maximum distribution in various countries of Europe followed by Asia, Oceania and Australia. The majority of occurrences of this fungus was observed on Fabaceae whereas few cases on Asteraceae, Cucurbitaceae & Polygonaceae. Being a major pathogen on family Fabaceae, U. viciae-fabae diseases can be controlled by cultural and chemical methods. This study is focused on biology, disease development, distribution and control of rust pathogen Uromyces viciae-fabae. 

Keywords: macrocyclic – pathogens – Pucciniales – rust diseases


6. Documentation and statistical approach towards foliar fungi found in Western Ghats (Desh region of Maharashtra), India

Authors: Dubey R, Pandey AD

Recieved: 13 November 2021, Accepted: 26 April 2022, Published: 09 May 2022

This paper focuses on the systematics and statistical analyses of foliar fungi found in the protected forest areas of Western Ghats mounting in Desh region of Maharashtra, consisting of five districts viz., Ahmednagar, Pune, Satara, Sangli, and Kolhapur. During this study, 144 taxa of foliar fungi were taxonomically characterised from 192 fungal isolates obtained from 170 collections. With 12 species, Meliola was the dominant genus in terms of having the highest number of species. Among species, Corynespora cassicola was the dominant species in terms of having been isolated from the maximum number of collections (11). Besides taxonomic studies, the diversity of foliar fungi was also analyzed using statistical approaches aiming to analyze the difference in biodiversity across the districts, for which parametric and non-parametric approaches were adopted. Parametric ordinary least squares models were developed with species count as the regressand. There was statistically significant (p-value < 0.05 for F-test) difference in mean species count across the districts. Non-parametric Kruskal Wallis Test yielded similar results (p-value < 0.05) for the median species count. Jaccard Similarity Index was computed to analyze the similarity in species composition between any two districts, which was maximum (3.39%) between Satara and Kolhapur districts. No species was common in all districts; only one species (0.69% of total) was common in the maximum three districts, viz., Pune, Satara and Kolhapur. Desh region also showed high values of diversity indices viz., Gini-Simpson's (0.9918), Shannon’s (4.7425), and normalized Shannon’s (0.9543). The study thus provides the latest information on the foliar fungi occurring in the Desh region. Further, based on the statistical analyses, it can be concluded that Desh region exhibits rich diversity of foliar fungi.

Keywords: Foliicolous fungi – Maharashtra – Mycobiota – Statistical analysis


7. Identification and characterization of Colletotrichum gloeosporioides complex members from rubber plants in Sri Lanka

Authors: Atapattu KAMRP, Hunupolagama DM, Wijesundera RLC, Chandrasekharan NV, Wijesundera WSS, Kathriarachchi HS, Fernando THPS

Recieved: 13 November 2021, Accepted: 26 April 2022, Published: 17 May 2022

Colletotrichum leaf disease of rubber, caused by Colletotrichum species, can be considered one of the most severe diseases of Hevea brasiliensis in Southeast Asia. In Sri Lanka, both C. gloeosporioides and C. acutatum reported as causal agents of anthracnose on rubber trees. This paper presents a morphological, genetic, and pathogenic study conducted using Colletotrichum isolates belonging to the C. gloeosporioides species complex collected from different rubber cultivating areas of Sri Lanka. Here, except C. gloeosporioides, C. siamense has been recognized as the predominant species from C. gloeosporioides species complex causing rubber leaf disease in Sri Lanka. The identity has been confirmed using multilocus phylogeny analysis.

Keywords: Internal transcribed spacer region – Morphology – Phylogeny


8. Number of pustules of garlic rust under different temperatures and leaf wetness

Authors: Mallmann G, Monteiro FP, Fernandes JMC, Cardoso DA, Valmorbida J, Wamser AF, Lins Junior JC

Recieved: 13 April 2022, Accepted: 01 June 2022, Published: 09 June 2022

Puccinia porri is an etiological agent of garlic rust. The disease symptoms are characterized by leaf lesions that initially appear as whitish spots. With the disruption of the leaf cuticle, yellow-orange uredospores are exposed. These signs are commonly known as pustules. Bulb production is affected by the reduction of photosynthetically active leaf area. The decrease in production is most pronounced when the attack occurs before bulb formation. The objective of this work was to quantify the latency periods of garlic rust and the number of pustules formed under the influence of temperature (10, 15, 20 and 25ºC) and leaf wetness period (6, 12, 18 and 24h). The latent period for this pathosystem varied between 10 and 12 days when the plants were subjected to temperatures of 10, 15 and 20°C after inoculation. The number of rust pustules was higher in garlic plants subjected to a temperature of 15°C. However, there were also a significant number of lesions at temperatures of 10ºC, especially when the leaf wetness period was 24 hours. At temperatures above 20°C, the number of pustules was less expressive. The results are important to perform fungicide efficacy tests in optimal conditions for disease progression and epidemiological studies.

Keywords: epidemiology – Puccinia porri – uredospores


9. Varietal performance against blast and cercospora leaf spot of finger millet under different cultivation schemes

Authors: Sigdel B, Shrestha RK, Bohara BP

Recieved: 30 July 2022, Accepted: 26 September 2022, Published: 29 September 2022

Finger millet is the fourth-ranked cereal crop after rice, maize, and wheat in Nepal and ranks first among the mandate hill crops in terms of importance and priority. However, the blast disease caused by Pyricularia grisea and cercospora leaf spot caused by Cercospora eleusinis is reported to cause a significant reduction in the production of this crop. Therefore, the investigation was conducted at the research farm of the Institute of Agriculture and Animal Science, Sundarbazar, Lamjung, from June to November 2016 to compare varietal resistance and cultivation schemes against blast and cercospora leaf spot. The experiment was laid out in a split-plot design where four varieties of finger millet; Okhale 1, Kabre Kodo 1, Dalle Kodo 1, Kabre Kodo 2 were kept as the main plot factor while planting methods; System of Crop Intensification and Conventional transplanting were kept as subplot factor and replicated thrice. Scoring was done based on the recommended scale of (0-9) at 7-day intervals for leaf blast and cercospora leaf spot. In addition, the percentage of disease incidence was calculated for neck and finger blast. The area under the disease progress curve (AUDPC) and disease severities were not significantly different between tested varieties and planting methods for both diseases. Comparing neck blast incidence, Kabre Kodo1 showed the highest incidence of 1.85%. However, the finger blast was more on Dalle 1 with 1.81% incidence and the conventional transplanting method showed an incidence of 1.26%.

Keywords: AUDPC – Disease severity – Incidence – Pyricularia grisea


10. Characterization and pathogenicity of Diplodia seriata causing branch canker on Pinus pinea in Tunisia

Authors: Hlaiem S, Yangui I, Ezzine O, Della Rocca G, Barberini S, Danti R, Ben Jamâa ML

Recieved: 11 August 2022, Accepted: 26 September 2022, Published: 27 October 2022

Several species of Botryosphaeriaceae family are among the most aggressive pathogens associated with botryosphaeria dieback of agricultural and forestry trees. Particularly, Diplodia spp. having a cosmopolitan distribution, are well-known as virulent of woody plant hosts including Pinus spp. In recent years, symptoms of canopy wilt, branch dieback, necrosis, and trunk cankers have been noticed on Pinus pinea trees in Tunisian forests. However, this has been less well-documented in North Africa and especially in Tunisia. The aim of this study is to characterize the causal agent of P. pinea dieback in northeastern Tunisian forest. A collection of thirty-eight isolates obtained from symptomatic branches of P. pinea trees was identified as Diplodia seriata by means of morphological characteristics, and phylogenetic analysis of the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA. A pathogenicity test was conducted on 3-years-old P. pinea seedlings, confirmed the virulence of the fungus. To the best of our knowledge, this is the first record of D. seriata associated with branch canker on P. pinea in Tunisia.

Keywords: botryosphaeria dieback – forestry trees – phylogenetic analysis – virulence


11. Chemical control of bacteria Xanthomonas hortorum pv. gardneri and Xanthomonas euvesicatoria pv. perforans in vitro

Authors: Monteiro FP, Ogoshi C, Mallmann G

Recieved: 20 September 2022, Accepted: 27 October 2022, Published: 15 November 2022

Tomato bacterial leaf spot is a worldwide disease that causes high losses in processed and fresh tomatoes. This disease is caused by four species of bacteria (Xanthomonas hortorum pv. gardneri, Xanthomonas euvesicatoria pv. perforans, Xanthomonas euvesicatoria pv. euvesicatoria and Xanthomonas euvesicatoria pv. vesicatoria). Xanthomonas hortorum pv. gardneri and Xanthomonas euvesicatoria pv. perforans are the phytopathogenic bacteria most frequently found in tomato crops. The objectives of this work were to identify potential bactericides and to study the mancozeb and copper oxychloride in the management of bacterial spot caused by Xanthomonas hortorum pv. gardneri and Xanthomonas euvesicatoria pv. perforans. Forty-four active ingredients were tested at 1% of the commercial product (1000g c.p./100L H2O) as first screening. Posteriorly, those that inhibited bacterial multiplication were tested at their recommended doses. When used at a dose of 1000g c.p./100L H2O, the products that inhibited the multiplication of X. hortorum pv. gardneri and X. euvesicatoria pv. perforans were benzalkonium chloride, acetic acid, cuprous oxide, mancozeb, copper hydroxide, mancozeb + famoxadone, copper oxychloride, metiram + pyraclostrobin, Bordeaux mixture and Viçosa mixture. At the doses recommended in the package insert, the products that inhibited the multiplication of X. hortorum pv. gardneri and X. euvesicatoria pv. perforans were benzalkonium chloride, acetic acid, mancozeb, mancozeb + famoxadone and metiram + pyraclostrobin. Copper oxychloride at the recommended dose of 0.2% (200g c.p./100L H2O – 168g a.i./100L H2O) did not inhibit the multiplication of X. hortorum pv. gardneri. It has been estimated that 0.004% is resistant to the recommended dose of copper oxychloride. At doses higher than 0.4% (400g c.p./100L H2O – 336g a.i./100L H2O) there was no bacterial growth. However, once the bacteria grow in a culture medium containing 0.2% copper oxychloride of commercial product (200g c.p./100L H2O – 168g a.i./100L H2O), it can be multiplied in a culture media even at a dose of 1000g c.p./100L H2O (840g a.i./100L H2O), which would be equivalent to a dose of 10kg c.p./ha. Mancozeb inhibited bacterial growth from the dose of 0.1% (100g c.p./100L H2O – 80g a.i./100L H2O). However, when X. hortorum pv. gardneri resistant to copper oxychloride 1% (1000g c.p./100L H2O 840g a.i./100L H2O) is striated in a culture medium containing mancozeb, the bacteria multiply up to a dose of 0.5% mancozeb (500g c.p./100L H2O – 400g a.i./100L H2O). The in vitro results indicate that doses equal to or less than 0.2% copper oxychloride (200g c.p./100L H2O – 168g a.i./100L H2O) select colonies resistant to high doses of copper oxychloride and also decrease the efficiency of mancozeb.

Keywords: Bacterial spot – Benzalkonium chloride – Copper oxychloride – Mancozeb – Solanum lycopersicum


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Plant Pathology & Quarantine Online publishes reviews, research articles, methodology papers, and taxonomic works in the field of plant pathology. The official journal language is English.


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