The Rose Rust Disease, caused by the fungal pathogen Phragmidum mucronatum, is one of the most common and destructive diseases affecting rose crops worldwide. The economic impact of Rose Rust Disease is significant, as it attacks the foliage and forms rusty-orange lesions, reduces flower yield, quality, and marketability, and can result in a substantial loss of yield. Effective disease management requires a combination of cultural, biological, and chemical control measures.
The disease’s prevention and control are critical for rose production’s sustainability and profitability. To effectively manage this disease, it is important to understand its disease cycle, the mode of disease spread, and the best methods for controlling it. This article will provide an overview and discussion of the Rose Rust Disease in Rose crops, including its symptoms, identification techniques, and control.
Rose Rust Disease Management
The Causal Organism of Rose Rust Disease
- Phragmidum mucronatum is an obligate biotrophic fungus that belongs to the Family Phragmidiaceae of Order Pucciniales of the Phylum Basidiomycota.
- Teliospores are thick-walled resting spores that are more resistant and are important for the pathogen’s survival and overwintering.
- Basidiospores are short-lived spores that can infect alternate hosts, such as brambles.
The Disease Cycle of Rose Rust Disease
- The lifecycle of Phragmidum mucronatum involves several stages, including urediniospores, teliospores, and basidiospores. The disease starts with the germination of basidiospores, produced in pustules on the infected rose plants. Basidiospores land on the rose plant’s surface and penetrate through the cuticle and epidermis.
- Over time, small, reddish-brown pustules develop on the lower surface of the rose leaves. These pustules contain masses of spores called urediniospores. The pustules rupture, releasing numerous urediniospores. In favorable environmental conditions, the cycle continues, with repeated cycles of spore release, dispersal, and infection throughout the growing season.
Occurrence of Rose Rust Disease in Rose Crop
- Location of Rose Rust Disease: This disease occurs in Rose crops in India, Africa, China, Bangladesh, Sri Lanka, Vietnam, Thailand, Indonesia, Malaysia, the Philippines, the United States, Mexico, Brazil, Colombia, Ecuador, Peru, and Australia.
- Host Range: The most common crops affected by Phragmidum mucronatum are Rose, Blackberry, Raspberry, Bramble, Quince, Hawthorn, and Firethorn.
Favorable Conditions for Rose Rust Disease Spread in the Field
- Temperature – The optimal temperature range for disease development is between 15-25°C.
- High Humidity – Urediniospores germination and fungal growth are favored by high humidity.
- Leaf Wetness – Wet leaves for extended periods provide a good medium for spore germination and infection.
- Alternative Hosts – The presence of alternate hosts like Brambles will act as a source of inoculum for the next season.
- Foliage Density – Dense foliage or crowded plantings that lack proper air circulation and sunlight penetration in dense canopies can create a microclimate conducive to the pathogen.
- Plant Stress – Plants under stress due to pruning cuts, wounds, injuries, and mechanical damage are more susceptible.
Damage Symptoms of Rose Rust Disease
- The rust disease is characterized by the development of distinctive rusty-orange lesions on infected plants’ leaves, stems, and petals.
- The pathogen primarily infects the leaves of rose plants, causing the characteristic symptoms.
- This disease can lead to defoliation, reduced flower production, and even plant death.
- The a