Use of potent fungicides is not the solution for microbial diseases. Misuse of fungicides often lead to the formation of fungicide resistant fungal pathogens. Investing money, time and energy in buying the potent fungicides that do not even solve the disease problems is simply ridiculous. We have other weapons to fight against the microbial pathogens. The rich and diverse microbial population have mighty warriors that can stand up to the rose pathogens, providing us several effective control measures.

In early 1930s, Scientists at Aberdeen, Scotland (Dr. Alan Paton and his associates) demonstrated the use of L phase bacteria for controlling bacterial diseases in crop plants. The L- phase bacteria are naked bacteria, bacteria without outer cell wall. When treated with the enzyme, lysozyme, the enzyme destroys the outer wall of the bacterium. Plants inoculated with the L-phase bacteria, Pseudomonas spp. do not develop microbial diseases.

Nearly after half a century, researchers are focusing their attention once again on Pseudomonas spp. for developing novel bacterial biocontrol agents for controlling pathogens on horticultural and agricultural crops. Several researchers have demonstrated unequivocally the effectiveness of the bacterial bio-control agent, Pseudomonas fluorescens in the control of a number of soil borne fungal diseases. Pseudomonas fluorescens can check a number of soil-borne lethal fungal diseases and leaf diseases of crops caused by pathogenic fungi and other bacteria. This microbe has the unique ability to control diseases and promote plant growth. It can enter the plant vascular system, reach the leaves, and act as a systemic bio-control agent against diseases. It produces antibiotics when sprayed onto a foliage inhibit the growth of fungal pathogens. In addition, the bacterial biocontrol agent produces chemicals, which make pathogen proliferation difficult. The chemical exudates of the bacterium interfere with the germination of fungal spores and their growth mechanism, thus preventing their establishment on the crops. An enzyme secreted by Pseudomonas fluorescens dissolves the cell walls of several fungal pathogens and thus annihilates them. The bacterial agent is compatible with the antagonistic fungus Trichoderma viride and other species as well. In combination with the fungal bio-control agent, Trichoderma viride, one can use Pseudomonas to control a wide variety of plant diseases.

The chemicals exuded by the pathogenic organisms attract Pseudomonas fluorescens which then moves fast towards the target pathogens using its flagella. Attracted by the plant root exudates, which serve as its major food, the bacterium grows over the root surface, and acts as a shield against the invading plant pathogens. It also reduces the root penetration by the pathogenic nematodes.

This bio-control agent is particularly effective against several rice diseases such as blast, brown leaf spot, sheath blight, sheath rot and bacterial leaf blight. It controls Panama wilt of banana, and damping off disease caused by Pythium in tomato, chilli, and tobacco. It effectively checks the root rot of soybean and other lentils and the stem rot of groundnut. It is worth trying these bacteria on roses.

Pseudomonas fluorescens secretes several plant growth substances, gibberellin-like (plant growth hormone) compounds that contribute to vigorous crop growth. The bacteria can also be applied with other biofertilizers such as Bacillus megatherium. Because of its compatibility with a wide range of bio-fertilizers and bio- control agents, Pseudomonas fluorescens is considered as an ideal candidate for integrated pest management programs.

Treating the seeds or the roots of seedlings prior to transplantation with Pseudomonas fluorescens to prevent microbial invasion. Spray the bacterial suspension on the leaves to contain the leaf diseases. When applied in the soil, the bacteria move towards the plant roots and grow profusely over the root surface. It then enters the vascular stream to act as a systemic agent. For seed treatment, mix a gram of the bacterial culture with a kg of seeds. Dip the seedlings in 0.5 per cent suspension for roughly two hours. For soil application, mix 2.5 kg of the culture with sand and spread it over a hectare. Use 0.5 per cent suspension as a plant protection spray. Rose breeders should use the seed, seedling, and foliar treatments as preventive measures against microbial diseases before releasing the roses for sale. Agricultural co-operative extensions should make this bacterial culture available to rose gardeners. Pseudomonas fluorescens is not a human pathogen, as such the gardeners do not have to worry about using this novel biocontrol agent.

Bacillus leptosporus, another soil borne bacterium is commercially available as ‘Rosa flora.' Soil and foliar applications of Rosa Flora seem to control black spot. Treating rose beds during dormant and growing seasons offer an excellent protection against black spot in a number of rose cultivars. A foliar application of Rosa Flora along with Wilt Pruf, an antitranspirant, appears to be more effective. Canadian researchers have demonstrated an effective control of powdery mildew in the green houses by a fungal antagonist, Stephanoascus flocculosa. The fungus, Ampelomyces quisqualis is a hyperparasite of powdery mildews. A. quisqualis infects the powdery mildew hyphae, forms its reproductive structures (the fruiting bodies known as pycnidia) within the hyphae, conidiophores, and fruiting bodies of the powdery mildew. A. quisqualis eventually reduces the growth of powdery mildew and kills it. Ecogen Corporation markets a formulated powder containing A. quisqualis under the trade name AQ 10.

In India, rose gardening is not as popular as it is in the USA. There are not many nurseries which cater for the needs of home gardeners. Even in a big city such as Chennai or Coimbatore, it is difficult to find nurseries where one can find rose cultivars for home gardening. One gets to see roses of all colors only in botanical gardens and in the homes of the rich and famous. Flower sellers mostly grow only one or two varieties of roses. In Northern India, roses are grown for perfume industry. However, horticultural departments in Agricultural Universities in India do excellent rose research and introduce a huge number of rose cultivars that are in no way inferior to the roses introduced by the hybridizers in The USA, Europe, New Zealand or Australia. . Indian rose gardeners can not spend huge amounts of money in maintaining a rose garden. Gardeners are not even aware of the health hazards that could result from the use of potent fungicides. Water is a precious commodity in India. Developing drought and disease resistant roses, making these roses available to home gardeners and educating them on rose culture using microbial biocontrol agents is the responsibility of rose societies and rosarians in India. In a country where neem tree is grown almost in every home, not many rose gardeners use neem oil based products for controlling rose pests and pathogens. It is the responsibility of department of agricultural departments all over India to send their officers to rose gardens to educate the commercial rose gardeners on the use of biocontrol agents and make the microbial biocontrol agents available to rose gardeners. Let roses bloom in all homes, big or small, all over India.