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Rust and Smut, both diseases of plants caused by pathogenic fungi in plants.

Rust and Smut, both diseases of plants caused by pathogenic fungi in plants. It is caused by the pathogenic fungi of the order Pucciniales or also known as Uredinales. Rust and Smut, both are the limiting factors for successful cultivation for forest crops and agriculture. Rusts are known to be the most dangerous pathogens to agriculture, forestry and horticulture. Some  of the examples of rust are wheat stem rust, white pine blister rust, soybean rust, coffee rust, etc.; these are economically important crops that are affected by rust. All of the rusts are parasites and they require a living host for completion of the life cycle and here, they can severely rescue the yield and growth of the host plant. On the other hand, smuts belong to the group of multicellular fungi that are characterised by the presence of numerous teliospores. Smut got their name from a Germanic word for dirt meaning dark, dust-like and thick-walled teliospores. Smut are usually Ustilaginomycetes belonging to the phylum Basidiomycota. Smuts mostly affect cereal and crop pathogens which are the members of the grass family (Poaceas) and sedges  (Cyperaceae). Some of the other host plants affected by Smut are Maize, Barley, Wheat, Oats, Forage Grasses and Sugarcane.

Learning the above mentioned points, students must have been much clearer about the rust and the smut and the differences between rust and smut. To explain further, we have put down a tabular chart that distinguishes rust and smut.

Ans: There are a number of economically important plants that are affected by smuts. It includes corn smut – Ustilago maydis, bunt and stinking smut of wheat – Tilletia spp. and loose smut of oats – Ustilago avenae.

Ans: Uredospores are produced by urediniomycetes and these are fungal spores formed during leaf rust. On the other hand, teliospores are fungal spores produced during leaf rust and smut  produced by Uredinomycetes and Ustilaginales fungi. The former has a thin cell wall and is oval shaped and the latter has a thick cell wall and is spindle shaped.

It is a group of fungal diseases affecting plants and the name is so because of their characteristic rusty appearance.

It is also a group of fungal diseases affecting plants like grasses, sugarcane and corn. It appears black due to the sooty look of the host or affected plants.

Uredospore stage shows the characteristic symptoms in case of rust.

Teliospore stage shows the characteristic symptoms appearing on plants due to smut.

Rust can be either heteroecious i.e. fungi requires two unrealed hosts for completing the life cycle, or it can also be autoecious.

Smuts are autoecious i.e. all the stages of the fungal life cycle occurring on the same host.

The nutrition intake for rust is intercellular using structures called haustoria.

The intake of nutrition for smuts can either be intercellular or intracellular.

Clamp connections are commonly observed in smuts.

Rust can produce up to 5 kinds of spores namely aeciospores, teliospores, basidiospores, pycniospores and uredospores.

Smuts produce only one kind of spore which is equivalent to its teliospores.

The terminal cells of the mycelium give rise to teliospore; this is the process of spore development in rust.

Here, intercalary cells give rise to spores.

Spores or teliospores are stalked, two-celled and each of them is binucleated.

Spores in smuts can be uninucleated or binucleated.

The hosts for rusts include gymnosperms, angiosperms and ferns.

The hosts for smuts are only angiosperms.