1 Mango diseases and their management
Transcript
Hello! I welcome you to the fifth week of this course and in this particular week we are going to talk about important fruit diseases and their management practices. So first of all we will be talking about mango and it’s the most important diseases that caused heavy losses in mango. So mango is mostly suffered by Anthracnose, Bacterial canker, Powdery mildew and Malformation. These are the most highly rated diseases of mango that cause severe loss to the crop every year.
Let us take Anthracnose at the beginning. It is a fungal disease caused by the pathogen Colletotrichum gloesporioides. The symptoms of the disease mostly manifested on the leaves and on the young twigs of mango plants followed by the symptoms under fruits. It is most evident when the young twigs mostly lost their leaves and they look burnt and this is the sign of Anthracnose infestation. The disease when it comes in the later stage it affects the fruits and it reduces the quality of the fruit and marketable quality is deteriorated because of this infestation. The pathogen survives in soil and infected debris in the orchard. So management of the pathogen should be in the soil and infected plants. There are IPM practices that are recommended for management of this particular disease and the practices include cultural and chemical. Disease leaves, flowers and twigs along with fruits that are lying on the orchard should be collected and they should be destroyed and pruned and burnt. This is a very very healthy practice because this reduces the inoculum level of the pathogen for occuring disease in the next season. Chemical sprays include carbendazim at 0.1% twice at 15 days interval during flowering and that controls the blossom infection. So this is very severe because once the blossom is infected we cannot expect fruit from the same tree that is why spraying at the blossom season is very very essential and carbendazim can take care of this particular pathogen. Then spray with copper fungicides at a rate of 0.3 percent for control of foliar infection proved effective. So since the pathogens survives in the fallen leaves or leaves on the plant itself that is why it is very essential that leaf should be sprayed with fungicides like copper fungicides. Post harvest management of anthracnose include dipping of fruits in carbendazim solution and in hot water at 52o C for 15 minutes. This saves the fruits from getting infected at post harvest days. So these are the practices that are recommended for management of anthracnose in mango and that is how we can save a huge loss by taking adequate control measures.
Next is Bacterial Canker and it is caused by Xanthomonas campestris pv. mangaiferaeindica. so this is another pathogen which is again very difficult to manage but we have developed techniques that are recommended for management of this particular bacterial pathogen. The symptoms of the disease appears on leaves mostly where one can see that brown spots surrounded by yellow halo is a common symptom. The spots are usually limited by the veins in the margins. The bacterial pathogen can also infect the fruits and we can see some exudations coming out from these infected regions. These symptoms once it is evident it can be sure that it is infected by the bacterial canker pathogen Xanthomonas campestris pv. mangaiferaeindica. The pathogen is an epiphytic and it survives on mango buds and immature fruits. So taking care of the intact plant is essential for management of this particular pathogen. The IPM practices recommends cultural and chemical measures that can lead to successful management of this particular pathogen. Cultural practices include regular inspection of the orchards, then adopting sanitation measures and seedling certification. These are preventive measures and once we adopt these measures we normally don’t allow the pathogens to be established in a new orchard. Chemical control includes spraying at least three sprays of streptocyclin or Agrimycin after first visual symptom at ten days interval. Although these chemicals are not very effective but at least they can reduce the severity of the disease to a great extent. Monthly sprays of carbendazim or copper oxychloride are also proved effective in controlling the disease. So along with the antibiotics carbendazim and copper fungicides can also be helpful in management of this particular pathogen. Spraying of copper-based fungicide has been found effective in controlling bacterial pathogen in large orchards. So these are the major recommendations that are suggested for adoption for management of bacterial canker in mango and by adopting these techniques we can successfully manage bacterial canker to a great extent.
Next one is Powdery Mildew that is caused by a Oidium mangiferae. So it is very easy to detect because whitish powdery like growth on the leaf surface of the plants it is very evident and it can be easily detected by looking into the powdery mass that is present on the leaf surface. the whole plant get affected as we can see that the young buds are also getting affected along with the fruits. So the entire foliage including the blossom get affected by this particular pathogen. The pathogen is mostly air borne and it arrives the orchard from already established disease in some other mango plants. So IPM practices are adopted and cultural and chemicals methods are recommended for management of this particular disease. Cultural methods includes pruning of diseased leaves. Since powdery mildew is a foliage pathogen so once the disease appears on few leaves those leaves should be pruned out immediately, followed by malformed panicles which are the primary source of inoculum. So pruning of the leaves infected leaves along with malformed panicles are the most recommended practices for management under cultural practices there are chemicals that are recommended for management of this particular disease and alternate spraying of wettable sulfur at the rate of 0.2% then Tridemorph at a rate of 0.1 percent and Carbendazim at a rate of 0.1 percent at 15 days interval are very very effective. So spraying of these chemicals can take care of the pathogen on the infected plants. The first place to be given at the panicles emergence stage. So this is timing is very important to reduce the loss caused by this particular pathogen. Three sprays of systemic fungicides during flowering season at 12 to 15 days interval is also recommended. Since it is airborne it can reoccur even in the later stage of the flowering season and that is why it is essential to have a second spray after at 12 to 15 days interval during the flowering season. The first place recommended where there is 25% of flowers are open so this is the right stage of application where 25% of the flowers have opened up.
The next disease is Mango Malformation. Although it is a disease which is caused by multiple factors there is a fungal agent that is found associated with this disease and that is Fusarium mangiferae. It is a very very difficult pathogen to control because its actual causal agents is rightly not worked out. Although association of Fusarium has been proved to be associated in most of the cases but other factors has not been properly established. Here the panicle it becomes shortened and the leaves become very small and you can see that all these newly developed stems are malformed and this can be in the whole plant if the plants are affected at an early stage. So Mango malformation is a serious disease to the mango growers because once it is established in an orchard it is very hard to eradicate it from the field. The pathogen Fusarium mangiferae basically in fact, it comes through infected seedlings and it can survive in soil. So management of this particular fungal pathogen that is associated with mango malformation is essential. For that certain IPM practices are recommended and cultural practices has proved to be the main reason for handling this particular problem. So cultural management include mango as we know that there is no definite control measures for this particular malformation of mango so control includes the following measures for mango malformation medicine. Avoiding scion stick from trees wearing malformed inflorescence for propagation is one of the most important cultural practice that need to be adopted. Then we can go for using certified saplings for propagation which ensures that there is no malformed seedlings are coming to the orchard and as soon as the disease symptoms are well expressed the affected terminals should be pruned along with a healthy portion of approximately 15 to 20 centimeter. So this is the most widely recommended and practiced cultural practice where the malformed tissues are cut out along with a portion of healthy tissues so that the inoculum or the causal agent that forms the mango malformation are completely wiped out from the existing plant. So these are some of the major diseases of mango and the pathogens associated with them and we have seen that how these pathogen can be successfully controlled by adopting mostly the cultural practices and in certain cases by application of certain chemicals.
Thank you.
