Sigatoka disease in Banana Research

There are various methods for managing this disease that is a chemical method, the biological method, organic method, physical method, using resistant varieties and also use of integrated methods. Chemical method is a method that uses fungicides which are sprayed on the plant leaves this disease attacks. The biological method is the use of environment-friendly methods to control Sigatoka. Physical method is were affected leaves are removed from the plant to avoid spreading of the disease. Integrated methods involve combining many of this methods in order to control the disease. To increase the economic value of banana clones of high yielding banana species are being developed on a large scale. Banana is most important fruit crop for energy and nutrient for human, where banana has very low-fat content whereas, carbohydrates shared nearby 95% of total energy of banana food and the banana crop is the good source of vitamin A and protein (Noorulla, 2012).

There are a group of various fungal, bacterial and parasitic diseases which affect the yield of this crop. Sigatoka is a fungal disease which is caused by the pathogen Mycosphaerellafijiensisis one of the most widespread and economically damaging diseases. Currently for Australia black Sigatoka is not a major problem M. This disease does well in tropical weather with humid, hot and plenty of rainfall because it helps in the dispersal of spores of this fungus. the thethe optimal environment of the banana pathogen is similar to the condition that is required by the banana tree for its production. This pathogen normally infects young leaves and without any proper control, it will continue to cause more infection. A Lesion which is rusty brown start forming as of the early the signs of this diseases (Mobambo et al.

This lesions will appear like faint specks on this leaves and become visible underneath part of the leaf. • It forms single spots which is only found on lower side of the leaf. • It has thick scars of the spores. • It affects dessert bananas as well as cooking bananas • It has streak dark symptoms. • It is common in warm areas. This pathogen can produce through sexual and asexual reproduction. This disease can also be spread by water splash or wind from one plant to another. Sigatoka banana disease is common in major countries exporting banana in the world such as South Africa, China, India, West, and East Africa, Asia, USA, and South America. It normally begins spots on the lower surface of young leaves which can be third or fourth young one and this spread parrel to leaf veins.

Disease cycle and incidence Sigatoka disease undergoes several stages and it has two types of spores which begin with the red-brown sport. This sports later join together forming a band on side of the midrib. This germination depends so much on temperatures and moisture because they penetrate by germ tubes on leaf stomata that are a temperature above 20 degrees in the day and moisture of near 100%. Penetration of the host is the second stage of this cycle where after germination the species goes through an epiphytic period of growth that takes about 2-3 days to enable ascospore germ tubes to grow. The germ tube then produces a substance called an appressorium over stomatal pore and it is through this was the fungus direct the fine (Chilin et al.

The infection now moves from one stomatal opening to other which the results into Sigatoka lesions in the entire Leaf surface. Symptoms development is the third stage of the cycle where symptoms develop on the leaf forming forms of substomatal vesicles. These spores are dispersed by water where they are washed downwards so that they can infect underneath plants and leaves. Chemical management Chemical management is an important aspect in controlling diseases especially Sigatoka which affects banana. This involves using chemicals that hinder development, growth, and spread of this disease. Fungicides have to be the main chemicals which are used to control this disease but some pest causing the disease have developed resistance to it hence reducing the effectiveness of the fungicides (Brito et al.

Banana plants in many plantations can be exposed to the bad condition that will affect their production. The study showed that there were some isolated from commercial plantation especially from banana leaves and showed symptoms of Sigatoka disease. These plants were selected randomly from different fields some of which were under rustic management program while others were under the intensive programme. The analysis was done by comparing fungicides concentration between the isolated exposed to the different management program. The results showed that there was reduced sensitivity to fungicides where the intensive program was applied while those with a rustic method where it was applied. This analysis shows that there were high resistance strains in the intensive programme as opposed to the rustic group.

biological control has now become the alternate for the chemical method and this involves the use of resistant cultivars. This method, however, faces some challenges such as time spent to develop new cultivars with nature of banana cycles and the ability of the pathogen to rapidly adapt and develop new resistance. In biocontrol, fungi Trichoderma is mostly used method for many plants because it has many advantages such as low adverse impacts to human beings and the environment and it is affordable. In order to test the effectiveness of biocontrol, the Trichoderma 29 isolates were subjected to different conditions. This study concluded that out of 29 isolates, only 4 were able to reduce the severity of the disease to less than 20% of value. Yellow pulp can be caused by the high infestation of yellow Sigatoka.

Control of black Sigatoka has been managed through the use of fungicides which are applied depending on the weather forecast and use of systematic controls. Leaf pruning has to be the very crucial complementary method and this normally limits sources of ascospores (Mino et al. A study to determine whether leaf removal before harvest for about one month will deter premature ripening of banana was conducted. This study was also used to help evaluate how leaf removal culture can affect exportation of bananas especially one harvested in SD inspected plants. Modern Calaveras have moved from interspecific and intraspecific crosses (Pattison et al. Before 1981, Mainland Australia was a free nation from Sigatoka disease. Since 1981, there have been several occurrences of this disease.

Plant pathologist gave the ability to fast detect Sigatoka disease and distinguish it from other species that infect bananas and this has really helped to eradicate it. Before 1998, there were some conventional methods which were used to monitor bananas such as morphology and symptomology in Australia. This plan was successful until 1999 when new Black Sigatoka was discovered. Australia has come up with strategies to control Sigatoka diseases that is an integrated plan that incorporates both applications of fungicides and cultural practices. cultural practices include plant spacing that improves that improves air circulation, plot location away from water bodies, deleting and improved drainage. Application of fungicides varies from geographical location depending on which place is wetter than the other. In this case, protectant fungicides and systemic fungicides are used.

Organic management of Sigatoka Disease This is a management practice that helps to reduce fungicides use on a banana and it is based on local resources. Agro-ecological intensification is one of the approaches that rely on local resources, this practice is normally good for small banana production meaning that is only useful to small-scale farmer plantation (Pocasangre et al. It also helps to enhance environmental sustainability even though this approach doesn’t exclude the total use of external inputs, but more focus is on a biological mechanism so as to regulate disease and pests. Agric-ecological measures include crop rotation to improve soil biodiversity, use of cover crops that attributes to organic matter and improving soil structure, water storage, and infiltration. Changing paradigm of banana production is one organic method because there existed permanent banana plantation in tropical areas with high rainfall.

In Honduras, this varieties can only be used in local markets because they don’t meet exporting standards. In 2009, there was a selection platform to enable come up with high breed bananas. the aim of this was to come with dessert bananas that are resistant to disease. Resistant cultivars are a most practical method to control Sigatoka disease especially for small-scale farmers and subsistence farmer because the cost of fungicides is high. However, some of this resistant cultivars are not acceptable in the local taste and therefore is need to develop acceptable resistant variety (Freitas et al. Ascospores are since dispersed by wind and this can be for long distance, these measure in all banana plantation should be the same hence avoiding disruption.

Treatment works well where there is centralized decision such that decisions and action are performed by one technical person instead of having each banana grower to have their own strategy. • Eliminate all abandoned fields which have susceptible varieties. These fields need an application of fungicides until they become completely destroyed. • Effectively apply fungicide ensuring all leaves are covered with enough droplets so as not to give a chance to the Sigatoka diseases. Banana plants in soils deficient of potassium are prone to attack by Sigatoka diseases and other banana diseases. soils with deficiency of calcium have more symptoms of Sigatoka disease while those with deficient with nitrogen are even severe with Sigatoka disease symptoms. Sanitation is an important cultural practice that aims at controlling inoculums pressure in banana fields.

Sanitation can be done through leaf removal which needs to be incorporated with practices that can improve plant development. Systematic pruning has to be effective in controlling inoculums sources keeping it at a low level that can be controlled by chemical applications. There should be special care that needs to be taken when doing the spray of the banana plants this ensure that proper coverage and deposit of active ingredients on parrall leaves. Good spray should be carried out at the time when temperatures are the low and low speed of wind that lower than 2m/seg. Type of fungicides used in controlling BSD There are seven types of fungicides that can be used controlling Sigatoka disease but the main ones are protectants and systemic fungicides.

This fungicide is mixed with water emulsions or oil alone. Use of oil serves the important purpose such as ensuring small droplets which normally doesn't evaporate before getting to the destination, it improves uptake of fungicides by leaves, reduces the surface tension of leaves, it improves leaf absorption rate and prevents fungicides runoff due water solubility. This becomes the first incidence when Black Sigatoka disease was eradicated in commercial plantations. Successful eradication of this disease was through a combined effort by scientists, industry, regulatory bodies, growers, and crop monitors who had a good relationship and worked together. To achieve this, there was a key contributing factor that is the deployment of PCR molecular technology. This technology was developed by a research unit called cooperative center of research (Aman et al.

This assay was a compliment to the morphological identification and allowed samples to be diagonised and this was so crucial because it helped in having fast decision making in the campaign. Using resistant varieties has to be another alternative method, however, this method may lead to the production of unwanted products in exports and even in the local markets. Suggestions There is need to have more national policies on how to control Sigatoka disease by the governments in each region in order to enhance production of the banana product which is fourth food product after maize, rice, and wheat. There is a need to come up with the best resistant varieties which are acceptable in the global market. This will help to reduce the challenge of current varieties which cannot be exported but only used in the local market.

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