Journal of Phytopathology and Pest Management 7(1): 109-120, 2020
pISSN: 2356-8577 eISSN: 2356-6507
Journal homepage: http://ppmj.net/
∗Corresponding author: Abdallah A. M. Ali,
E-mail: abdallahali@agr.aswu.edu.eg
109
Copyright © 2020
Effect of certain essential oils and biocides on
controlling marjoram root rot and wilt diseases
Abdallah A. M. Ali1*, Yosra Z. Abo-Shosha2, Mahmoud M. H. Hassanin3
1Plant Pathology Department, Faculty of Agriculture and Natural Resources, Aswan University, Aswan, Egypt
2Central laboratory of Organic Agriculture, Agricultural Research Centre, Giza, Egypt
3Ornamental, Medicinal and Aromatic Plant Diseases Research Department, Plant Pathology Research Institute, Agricultural Research Centre, Giza, Egypt
Abstract
Keywords: Majorana hortensis, Fusarium oxysporum, Fusarium semitectum,
Rhizoctonia solani, Plant Guard, Actamyl 70% wp, thyme oil.
The aim of this study was to determine the impact of certain essential oils (eucalyptus and
thyme essential oils) and biocides (Plant Guard and Rhizo-N) as fungicidal alternatives for
the control of root rot and wilt diseases of marjoram (Majorana hortensis L.) caused by
several fungi. Marjoram plants with root rot and wilt symptoms were obtained from Giza,
Beni-Suief, and Minia governorates, Egypt. Pathogenicity tests showed that all isolated
fungi (Fusarium semitectum, F. solani, F. oxysporum, F. roseum, Rhizoctonia solani, and
Macrophomina phaseolina) had the ability to infect plants and seedlings. Fusarium
oxysporum, followed by R. solani, was the most pathogenic fungus on the marjoram
seedlings, resulting in pre- and post-emergence damping-off. Additionally, the most
significant disease incidence percentages on marjoram plants after transplanting were
caused by F. oxysporum and F. semitectum. In vitro investigations were performed utilizing
eucalyptus and thyme essential oils indicated that the growth of the investigated fungi (F.
oxysporum, F. semitectum, and R. solani) was significantly inhibited. However, thyme was
the most efficient treatment, especially at a concentration of 6000 ppm, which completely
inhibited mycelial growth of R. solani and F. oxysporum. The effectiveness of eucalyptus
and thyme essential oils, Plant Guard, Rhizo-N, and Actamyl 70% wp was determined for
the control of target diseases under greenhouse conditions. The results showed that all
tested treatments significantly reduced the disease incidence caused by the investigated
fungi. Actamyl was the most efficient treatment. Thyme oil was an effective treatment
against R. solani and F. oxysporum in the second order following Actamyl, whereas Plant
Guard was effective against F. semitectum and F. oxysporum. Generally, Plant Guard was
the most successful treatment for enhancing plant growth of marjoram plants. These findings
demonstrate the potential of applying Plant Guard as an alternate fungicide against wilt and
root rot diseases of marjoram plants.
Ali et al., 2020
110
1. Introduction
Marjoram, or sweet marjoram (Majorana
hortensis L.), serves as one of the most
valuable medicinal as well as aromatic crops in
Egypt. Plantations of marjoram have expanded
in recent years in Egypt. Marjoram is a
perennial plant, usually planted in a nursery,
and seedlings (60 days old) are transplanted in
the field. Ordinarily, plants are cut twice per
year for a period of three years. The dried
leaves are extensively used in the food
industry. Marjoram essential oil has various
applications in pharmaceutical preparations. It
is used as a stimulating and antibacterial
component in toothpaste, as well as in drugs
against whooping cough. Additionally, it is
used as a carminative in the case of
gastrointestinal disorders (Bellakkadar et al.,
1988). Wilt and root rot diseases were recorded
in Egyptian marjoram plantations, which had a
negative effect on vegetative growth and plant
standing (El-Gebaly, 1998; Hilal & Helmy,
1998; Hilal et al., 1990). The incidence of these
diseases often rises year after year. A lack of
suitable agricultural practices,