Stem rust (Puccinia graminis f.sp. tritici) - a most dangerous disease in wheat

 Stem rust (Puccinia graminis f.sp. tritici)

Stem rust, also known as black rust, is a devastating disease of wheat caused by the fungus Puccinia graminis f.sp. tritici. This fungus infects the stem, leaves and spikes of the wheat plant, leading to significant yield loss and even complete crop failure if left untreated. The disease is considered one of the most dangerous diseases of wheat and has the potential to cause food insecurity in affected regions.

Symptoms of stem rust include reddish-brown pustules on the stem and leaves of the wheat plant. The pustules can also appear on the spikes, which can reduce the number of grains and lower the overall quality of the wheat. As the fungus continues to spread, the infected plant will produce fewer spikes, resulting in a smaller yield. In severe cases, the fungus can cause the stem to break, leading to the collapse of the entire plant.

The fungus can spread rapidly under favorable conditions, such as high humidity and warm temperatures. The fungus spores are spread by wind and can infect wheat crops over large areas. The fungus can also survive in the form of resting spores on infected wheat stubble, which can infect new crops the following year.

Preventing stem rust is crucial in order to protect wheat crops from devastating losses. One of the most effective methods is the use of rust-resistant varieties of wheat. Wheat breeders have been able to develop varieties that are resistant to the most common strains of stem rust. In addition to this, crop rotation with non-host crops, and applying fungicides can also be effective in preventing the fungus from infecting the crop.

However, In recent years, a new virulent strain of stem rust has emerged called Ug99, which is particularly dangerous as it can infect wheat varieties that were previously considered resistant to stem rust. This strain emerged in eastern Africa in the late 1990s and has since spread to other parts of the continent and the Middle East, posing a significant threat to global wheat production. The fungus is able to infect the stem, leaf, and spike of the wheat plant, causing severe damage to the crop.

In response to this new strain, scientists and breeders have been working to develop new rust-resistant varieties of wheat. One approach is to use genetic engineering to introduce resistance genes from other plants into wheat. Another approach is to use traditional breeding methods to develop new varieties that are resistant to Ug99.

In order to control stem rust, farmers need to be aware of the disease and its symptoms, as well as the conditions that favor its development. Farmers should also take preventative measures such as using rust-resistant varieties, crop rotation and applying fungicides in order to keep the fungus from infecting the crop. Furthermore, farmers should also be aware of the new virulent strain of stem rust (Ug99) and take the necessary steps to protect their crops from this fungus.

In summary, stem rust is a serious disease of wheat that can cause significant yield loss and even complete crop failure. The fungus can spread rapidly under favorable conditions and can survive in the form of resting spores on infected wheat stubble. Preventing stem rust is crucial in order to protect wheat crops and new virulent strains such as Ug99 have increased the importance of this. The use of rust-resistant varieties of wheat, crop rotation, and applying fungicides are effective ways to prevent stem rust. It's also important for farmers to be aware of the new virulent strain of stem rust and take the necessary steps to protect their crops from this fungus.