Xanthomonas hortorum blight of Geranium

Xanthomonas hortorum Blight Infects Geranium

Geranium plants can become infected with the bacterial disease Xanthomonas hortorum blight,which seriously damages the plants' leaves and ultimately lowers both their aesthetic and monetary value. The bacteria Xanthomonas hortorum, which is responsible for this disease, can persist in soil and on plant debris for long periods of time, making it challenging to eradicate once it has infected a crop.

Symptoms of the disease:

 Small, water-soaked patches on the leaves of Geranium plants that gradually become yellow and eventually brown are signs of the Xanthomonas hortorum blight. The spots become larger as the illness worsens, and the leaves wilt and distort. The bacterium can potentially result in blossom and stem blight, which can kill the entire plant. 

 Spread: 

 The Xanthomonas hortorum blight is made more contagious by insects, splashing water, and mechanical damage to the plants. Therefore, areas with high humidity and rainfall as well as greenhouses and nurseries where plants are cultivated near to one another are more likely to experience the disease. 

 Control of disease: 

 The best method for controlling Xanthomonas hortorum blight is prevention. This can be accomplished by avoiding overhead watering, utilizing disease-free planting material, and maintaining proper hygiene. Additionally, it is advised to rotate crops with plants from other families to lessen the buildup of the bacteria in the soil and to stay away from planting geraniums in places where the disease has a history. It is crucial to confirm the diagnosis by sending samples to a diagnostic lab for testing if Xanthomonas hortorum blight is suspected. Once the illness has been identified, affected plants should be removed, destroyed, and the surrounding environment should be cleaned and sanitized.

 Natural control by herbs:

 Oregano: 

 Popular herb oregano (Origanum vulgare), which has antibacterial characteristics, has been proposed as a viable all-natural remedy for the Geranium Xanthomonas hortorum blight. There is limited study especially on the use of oregano as a control for blight on geraniums, despite some evidence suggesting that oregano oil or extracts may have antimicrobial activity against Xanthomonas hortorum. 

 Thyme: 

 Another herb with antibacterial capabilities, thyme (Thymus vulgaris), has been proposed as a potential all-natural remedy for the Xanthomonas hortorum blight on geraniums. Only a small amount of study has been done especially on the use of thyme to prevent the Geranium Xanthomonas hortorum blight. Some research, however, suggests that thyme oil or extracts may have antimicrobial benefits against Xanthomonas campestris, a similar bacterial disease that causes blight on cabbage plants. This implies that thyme might have some potential as a remedy for the geranium Xanthomonas hortorum blight. 

 Mugwort:

 A variety of plant illnesses have been linked to the usage of the herb mugwort (Artemisia vulgaris), which has a number of traditional therapeutic purposes. There is, however, little information on the use of mugwort to prevent the Geranium Xanthomonas hortorum blight. It's vital to remember that herbal treatments like mugwort shouldn't be used in place of tried-and-true illness management methods, just like oregano and thyme. It is best to speak with a plant disease specialist or extension agent if you are experiencing Xanthomonas hortorum blight on your geraniums for more detailed advice on how to effectively treat the disease in your particular circumstance. 

 Biological control using Bacillus subtilis: 

 Many bacterial species, such as Xanthomonas hortorum-caused bacterial blight, have been successfully controlled by using Bacillus subtilis as a biocontrol agent. Bacillus subtilis is a potential biocontrol agent for the Xanthomonas hortorum blight on Geraniums because it produces antibiotics and other substances that can prevent the pathogen from growing. Numerous studies have demonstrated that Bacillus subtilis can successfully manage the Xanthomonas hortorum blight on geraniums in greenhouse and outdoor settings. 

For instance, one study discovered that spraying Geranium plants with a suspension of Bacillus subtilis spores greatly reduced the severity of the disease and boosted plant development in comparison to untreated plants. The incidence of Xanthomonas hortorum blight on Geranium in a commercial nursery was dramatically decreased, according to another study, when Bacillus subtilis was applied to the soil. Numerous mechanisms are thought to be involved in how Bacillus subtilis fights Xanthomonas hortorum. First, Bacillus subtilis creates antibiotic substances, like bacitracin and surfactin, that can obliterate the infection or prevent its growth.  

The synthesis of phytohormones and enzymes that can break down the pathogen's cell wall are two additional ways that Bacillus subtilis can generate plant resistance to the disease. It is significant to note that a number of variables, including the strain of Bacillus subtilis employed, the application method, and the environmental circumstances, may affect how successful Bacillus subtilis is as a biocontrol agent against the Xanthomonas hortorum blight on Geraniums. Before using Bacillus subtilis on a wider scale, it is advised to carry out small-scale studies and improve the application methodology.

 In conclusion, numerous research have demonstrated the effectiveness of Bacillus subtilis as a biocontrol agent for the Xanthomonas hortorum blight on Geranium. Growers can obtain a more sustainable and ecologically friendly method of crop protection by adding Bacillus subtilis into an integrated disease management programme.

Author bio: Dr. Taha Arooj

Dr. Taha Arooj works as an Assistant Professor at GC University in Lahore, Pakistan.  Dr. Arooj teaches various botany courses including courses on physiology, phytopathology, and ethnobotany. She holds a Ph. D degree in Botany from GCU Lahore.