Tracking Gerbera Troubles: Surveying and Identifying Plant Diseases | InformativeBD

Sanzida Hoque, from the institute of Bangladesh. Mahbuba Khanam,  from the institute of Bangladesh and Nazmoon Naher Tonu, from the institute of Bangladesh. wrote a Research article about, Tracking Gerbera Troubles: Surveying and Identifying Plant Diseases. Entitled, Survey and Identification of Pathogenic Diseases Affecting Gerbera Plants. This research paper published by the International Journal of Biosciences | IJB. an open access scholarly research journal on Biosciences. under the affiliation of the International Network For Natural Sciences| INNSpub. an open access multidisciplinary research journal publisher.

Abstract

This comprehensive study aimed to investigate the causal organisms, disease incidence and pathogenicity of microorganisms affecting gerbera plants in the Dhaka zone of Bangladesh. Nine sites of Agargaon, Savar, Gazipur, and Narayanganj were surveyed to identify the diseases based on symptomological studies. Diseases caused by fungi including cercospora leaf spot (Cercospora sp.), alternaria leaf spot (Alternaria alternata), sclerotinia wilt (Sclerotinia sclerotiorum), anthracnose (Colletotrichum capsici), powdery mildew (Erysiphe sp.), blight (Curvulariageniculata), graymold (Botrytis sp.), stem rot (Fusarium oxysporum), and viral diseases such as leaf curl (Leaf curl virus) and mosaic (Mosaic virus) were identified. Among all the identified diseases, the highest disease incidence (66.67%, Gazipur) was exhibitedby alternaria leaf spot and the lowest disease incidence (5.56%, Narayanganj) was shown by graymold. The rate of reduction of plant height due to cercospora leaf spot, alternaria leaf spot, blight, anthracnose, graymold, sclerotinia wilt, stem rot, powdery mildew, mosaic, and leaf curl diseases was 28.1%, 28.42%, 12.47%, 12.69%, 28.36%, 30.67%, 19.14%, 28.08%, 12.89%, and 22.06%, respectively. The rate of reduction of other plant parts of gerbera was also recorded. To confirm pathogenicity, Curvulariageniculata, and Erysiphe sp. were tested on healthy gerbera plants following Koch’s postulates. The plants exhibited the disease symptoms of Curvulariageniculata and Erysiphe sp. after 9 and 6 days of inoculation, respectively, while the control plants remained symptom-free. Thus, the pathogenicity of Curvulariageniculata and Erysiphe sp. was confirmed.

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Introduction

Gerbera plants (Gerbera jamesonii) belong to the Asteraceae family andare highly valued for their vibrant and diverse range of colours, making them a beloved choice for floral displays and used as cut flowers or decorative garden flowers widely (Kanwar and Kumar, 2008). Some cultivars often have very attractive bicoloured flowers and the plant was named after Traugott Gerber, the German naturalist and botanist. Gerbera is also known as African Daisy, Barberton Daisy and Transvaal Daisy (Nagrale et al., 2013). Gerbera is one of the most charming and demanding cut flowers, which are cultivated under protective conditions in Bangladesh. It is ranked fifth among the top ten cut flowers and is considered one of the most valuable and promising cut flowers next to the rose (Saikia and Talukdar, 2017). Gerbera is used for the manufacturing of perfumes by extracting essential oils (Mohanty, 2014). Besides, these flowers are also used for flavoring food and for decoration. In Bangladesh, large-scale commercial cultivation of gerbera started in the mid-eighties in Jessore district when commercial floriculture flourished on account of its economic potential (Sultana, 2003). Dhaka, the capital city of Bangladesh, is a significant hub for Gerbera traders and users, where reportedly around 1600 retail flower shops are located. Bangladesh exports a large amount of ornamental and cut flowers to the world market without missing a year (Mou, 2012). Gerbera is very popular and has a great demand in markets, but they are prone to various pathogenic diseases such as leaf blight, leaf spot, gray mould, anthracnose, soft rot, root rot, bacterial leaf spot, powdery mildew, etc., which can significantly affect their growth and quality (Bose and Yadab, 1989).

Understanding the prevalence, identification of causal organisms, disease incidence, and confirmation of pathogenicity is crucial for effective disease management strategies for Gerbera cultivation. It aims to conduct a comprehensive survey to evaluate the range of diseases affecting gerbera plants, their respective incidence rates and pathogenicity confirmation. Accurate identification of causal organisms is vital for effective disease management strategies. The study employed symptomological observations and laboratory analysis to identify the pathogens responsible for the observed diseases. In addition to identifying the diseases and causal organisms, the study also aimed to determine the incidence rates of each disease. By quantifying the disease incidence, the researchers can assess the severity and impact of specific diseases on gerbera plants in the Dhaka region.

The findings of this study will contribute to a comprehensive understanding of the pathogenic diseases affecting gerbera plants in the Dhaka region. By identifying the causal organisms, determining disease incidence rates, and confirming pathogenicity, the research will provide valuable insights for developing effective disease management strategies, ensuring the health and productivity of gerbera crops. Consequently, the present work was focused on assessing the prevalence of pathogenic diseases and identifying the causal organisms associated with these diseases in the Dhaka region.

Reference

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Article source : Survey and Identification of Pathogenic Diseases Affecting Gerbera Plants 

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Cacao Phytophthora Pod Rot: Symptoms & Pathogenicity | InformativeBD

Angelina T. Gonzales, Diosa G. Alasaas, and  Macluven T. Gonzales from the different institute of the Philippines. wrote a research article about, Cacao Phytophthora Pod Rot: Symptoms & Pathogenicity, entitled,  "Symptomatology and pathogenicity of Phytophthora pod rot disease associated with Cacao plants in selected municipalities in the Province of Cagayan, Philippines". This research paper published by the Journal of Biodiversity and Environmental Sciences | JBES. an open access scholarly research journal on Biodiversity under the affiliation of the International Network For Natural Sciences | INNSpub. an open access multidisciplinary research journal publisher.

Abstract

The study aimed to describe the Phytophtora pod rot (PPR) symptoms disease associatedwith cacao plants and its pathogenicity to cacao. Specifically, it aimed to: (a) describe the PPR disease symptoms associated with cacao plants; (b) determine the pathogenicity of PPR disease to cacao seedlings, cacao flower and unripe and ripe pods; (c) document the reaction of cacao varieties to PPR disease. Samples isolated from infected cacao pods of five cacao farms revealed 14 isolates of Phythophthora spp. Pathogenicity test showed development of typical symptoms of Phythophthora of isolates from infected tissue of cacao pod. Incubation period was recorded between 4 days to 14 days after inoculation. The pathogen associated with Phythophthora pod rot belongs to Phythophthora palmivora. Cacao seedlings from 21-days old to 6 months manifested water-soaking leaves to leaf blighting symptoms, while infected flowers were found to have blighting and necrotic symptoms. Ripe variety could easily infected compared to unripe pod as shown by oily brown appearance and it changes from brown to black. White leathery structure or whitish appearance (sporangia) on the surface of the pods and mummified pods in advance stages.

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Introduction

Cagayan valley region contributes 4% of the national cacao production from the 10% shared of Luzon and Visayas region outside of Mindanao which is 80% of the total production of the country. In Cagayan province, there are more than 73 cacao farmers growing cacao with cacao production areas ranging from 1-15 has. Cacao nurseries are also operational in the region. Cacao Nurseries and farms are located in Santa Praxedes, Sanchez Mira, Gonzaga, Lal-lo, Lasam, Gatarran and Penablanca (Fig. 1.). Visits of these cacao-producing towns and nurseries, it has been observed that a number of the cacao plants of various stages of growth show various deviations from normal and symptoms: i.e., seedling blight that starts with vein clearing on the younger and defoliation in older leaves of up to to 4 months old in polybags; flowers turned brown; in fruits, chocolate brown necrotic lesions is commonly observed on infected pods which usually are accompanied by seed rot are common in cacao pods. 

Then pathogen appears on the surface of the pod as a whitish down on which masses of sporangia are produced. Diseased cacao fruits are commonly observed in the municipality of Lasam and Gattaran, Cagayan, Philippines. 

To date, there are four most common cacao pests and diseases in the Philippines, i.e., black pod rot, vascular streak dieback, cacao borer, Helopeltis and cacao stem borer (Department of Agriculture Bureau of Agricultural Research as cited by Tan et al., 2016). Phytophthora pod rot is a major disease of cacao and causes 20 to 30% pod losses, and kills up to 10% of trees annually through stem cankers (Bowers, J. H, et al 2001; Guest, 2007, and Adomako, 2007). The disease was first reported as cacao canker in Java in 1924 (Hartley and Rands, 1924).

Phytophthora pod rot is caused by four different species in the Stramenopile genus Phytophthora: P. capsici, P. citrophthora, P. megakarya, and P. palmivora which occur in almost all cacao growing region in the world (Guest, 2007). P. megakarya, which is restricted to Africa is the most aggressive species, causing 60-100% yield loss compared to the 15-30% losses attributed to P. palmivora (Nyassé et al., 2002; Tahi et al., 2006). Eight species of Phytophthora have been isolated from cacao: P. palmivora (Butler) Butler, P. megakarya (Brasier and Griffin), P. capsici (Leonian emend.) (P. tropicalis), P. katsurae (Ko and Chang), P. citrophthora (R.E. Smith and E.H. Smith), P. arecae (Coleman) Pethybridge, P. nicotianae (van Breda de Haan) and P. megasperma (Dreschler) (Erwin and Ribeiro 1996; Iwaro et al. 1997; Appiah et al. 2003). 

In the Philippines, cacao had been attacked by disease caused by Phythopthora faberi (Reinking, 1918; Tangonan (1999) host index listed Phythopthora pod rot disease in cacao. In addition, a review of Solpot (2001) enumerated the following diseases of cacao. Similar symptoms or disorders were reported by Panguntalan et al., (2022) on cacao plants of an orchard in Calauan, Laguna.

However, no report is available if the disease is occurring in the cacao nurseries and cacao farms in the province of Cagayan. Thus, this study was conducted to validate if Phytophthora spp. is involved and caused cacao pod rot disease in the cacao farms in Cagayan. This study is undertaken to: (a) collect asymptomatic and symptomatic cacao parts; and (b) isolate, characterize and identify pathogen associated with seedlings, flower, stems, and young and mature pods; (c) and observe and document if the tentative PRR isolates incite PRR disease in seedlings, flowers, and young and matured cacao pods.

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 Source : Symptomatology and pathogenicity of Phytophthora pod rot disease associated with Cacao plants inselected municipalities in the Province of Cagayan, Philippines

  

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