Kirkuk University Journal for Agricultural Sciences (KUJAS)

In Vitro Evaluation of the Efficacy of Plant Extracts, Biological Agents, and Chemical Pesticides in Controlling Xanthomonas spp Bacteria Isolated from Tomato Plants in Erbil, Kurdistan Region, Iraq

https://doi.org/10.58928/ku26.17106
Volume 17, Issue 1
Winter 2026
Page 39-47
Kirkuk University Journal for Agricultural Sciences (KUJAS)

Document Type : Research Paper

Authors

Lina Musa Mahmod
Kamalaldeen M Fatah

Erbil/ Salahaddin University/ Collage of Agricultural Engineering Sciences

Abstract
Tomato (Solanum lycopersicum L.), coming in the second level in production and consumption over the entire world after cereals. It is an important source of essential vitamins, minerals and antioxidants Tomato provides an estimated 80% of daily intake of lycopene, folate, ascorbic acid, flavonoids, and potassium in the western diet. China, India, USA, Turkey, and Egypt are the major top producers of tomato over the entire world. According to the Ministry of Agriculture and Water Resources / Kurdistan Regional Government, total tomato production in 2021 was 248546 tons distributed over the four governorates. Xanthomonas spp. is the most significant tomato pathogen, causing losses ranging from 10% to 60% of the crop yield. Aqueous extracts of four medicinal plants, Maidenhair Fern, Turmeric, Clove, and Ginger alongside bioagents (Bacillus subtilis, Trichoderma harzianum) and commercial pesticides (Himex and Aryal Super) were evaluated for their antibacterial activity against Xanthomonas spp. isolated from infected tomato plants. Isolation, pathogenicity testing, and molecular identification confirmed the presence of X. euvesicatoria, and X. campestris. Clove extract shows strong antibacterial activity against both isolates, whereas, Ginger was moderately active against X. campestris. The bioagent, B. subtilis strongly active against the isolates, T. harzianum was ineffective. The commercial pesticide Himex was strongly effective, while Aryal Super was ineffective. Clove extract shows high inhibition rate on both X. euvesicatoria and X. campestris at 10 mg/mL. Ginger extract only moderately inhibits X. campestris at 100 mg/mL, while turmeric and maidenhair fern were not effective. B. subtilis strongly antagonistic against both bacterial species, whereas T. harzianum was ineffective. Among the chemical treatments, Himex demonstrated substantial antibacterial activity (47.37%–54.51%), while Aryal Super showed no inhibition.

The findings suggest that clove extract and Bacillus subtilis are promising eco-friendly alternatives to conventional pesticides for managing bacterial leaf spot in tomato cultivation.

Keywords

Xanthomonas campestris
Xanthomonas euvesicatoria
tomato
plant extract
antibacterial activity
biological control
clove
Subjects
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