Mango trees are susceptible to various diseases, including red rust disease caused by the parasitic alga Cephaleuros virescens. The condition can cause a reduction in photosynthetic activity and defoliation of leaves, thereby lowering the vitality of the host plant. In this article, we will discuss how to control the red rust disease of mango trees.

Related Post, you can read it: Soil Preparation For Mango Farming: Optimize Your Farm Soil

Symptoms of Red Rust Disease

One may experience symptoms of red rust disease when they notice orange rusty spots on their leaves’ upper and lower surfaces. These spots may spread to the stem and fruit as well. The spots may also turn black and cause the leaves to fall off[4]. The disease can occur in all the world’s mango-growing tropical and subtropical regions, where temperature and humidity are favorable for the growth of the pathogen[2].

Mango Leaves

How Mango Red Rust Disease Spreads

The disease spreads through the deposition of either the sporangia or thallus filaments on the tissues of a susceptible plant host[1]. The pathogen is usually dispersed through water or wind. Under the proper environmental conditions, zoospores are released from the sporangia, and symptoms will develop[1]. The disease can occur in all the world’s mango-growing tropical and subtropical regions, where temperature and humidity are favorable for the growth of the pathogen.

The disease can also be spread through water splash from irrigation and rain, as well as through infected pruning tools or from infected plant debris[6]. The fungal spores (conidia) can be spread within and between trees on air currents, in dew droplets or rain splash, or on falling infected plant debris[5]. Reports of severe infection in nursery plants overseas may be associated with growing seedlings and young trees under the canopies of infected mango trees[3].

Control Measures

You can take measures to control the red rust disease of mango trees:

1. Prune and Fertilize: Proper pruning and fertilization of the tree can ensure proper aeration and reduce the risk of disease[2].
2. Bordeaux Mixture: Spraying Bordeaux mixture (6:6:100 or 0.6-1.25) can effectively control the disease[2]. The fungicide Bordeaux mixture consists of copper sulfate and hydrated lime.
3. Copper Oxychloride: The disease can also be controlled by spraying copper oxychloride (0.25%) [2].
4. Natural Algaecides: Citric acid, vinegar, and hydrogen peroxide (H2O2) are the most commonly used natural algaecides to control mango red rust disease[6].
5. Protective Algaecides: These chemicals will form a protective barrier on the mango leaves and stems, preventing the algal spores from colonizing the plant. Spray Dithiocarbamates, Captan, and Thiophanate-methyl[6].
6. Remove Diseased Leaves: Collect the diseased leaves from the orchard and burn them far away from the field to control the spread of the disease[6].
7. Planting Location: Plant the tree in the warmest area of your landscape, prune it so the mango has good air circulation, and keep the area underneath the tree free of plant debris, fallen fruit, and weeds[13].

People Also Ask (FAQs)

Q: What are the symptoms of red rust of mango on fruit?

Red rust from mango can cause fruit rot and premature drop on infected fruit. The fruit may develop brown to black lesions that penetrate deep into the flesh. The fruit may also show signs of tear staining, which is when spore-laden water droplets from infected twigs and panicles wash over and infect the fruit surface.

Q: How does the red rust of mango spread?

Red rust of mango spreads by spores produced by the alga on infected leaves and twigs. Wind, rain, insects, birds, animals, or human activities can disperse the spores. The spores can infect new leaves and twigs through natural openings or wounds. The disease can also spread through infected plant material such as cuttings or grafts.

Q: How can I prevent the red rust of mango from infecting my trees?

Please follow some preventive measures such as:

• • Choosing a suitable site for planting mango trees with good drainage, sunlight, and air circulation.
  • Select healthy and disease-free planting material from reliable sources.
  • Inspect your trees regularly for any signs of infection and remove any infected parts promptly.
  • Applying fungicides as recommended before or during flowering to protect your trees from infection.
  • Practicing good sanitation and hygiene around your orchard by removing fallen leaves, fruits, or branches that may harbor the alga.
  • Avoid wounding your trees by pruning, harvesting, or other activities that may create entry points for the alga.

Q: How can I treat the red rust of mangoes if my trees are already infected?

Please follow some curative measures such as:

• • Pruning and burning any infected branches and leaves to reduce the source of inoculum.
  • It is advisable to use fungicides for spraying, To manage the disease and stop it from spreading.
  • Apply fertilizers and irrigation as needed to improve the health and vigor of your trees.
  • Harvest and store your mature fruits in a cool, dry place to prevent decay.

Conclusion

Red rust disease can be a severe problem for mango trees, but it can adequately control you. Proper tree care and using preventive measures like sprays and algaecides can prevent disease. By following these control measures, you can ensure that your mango tree remains healthy and productive.

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Rebecca Vittetoe
I’m Rebecca Vittetoe, a field agronomist working with farmers through Iowa State University Extension.

Most of my time is not spent in an office—it’s spent in the field. I work directly with farmers, crop scouts, and ag professionals to solve real problems they face every season. From pest pressure to nutrient issues, I focus on what is actually happening in the field—not just what is written in books.

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