5 Brinjal diseases and their management
Transcript
Hello! Welcome to the last topic of this week that is important diseases of brinjal and their management. There are many diseases that are affected the brinjal crop but the most significant ones are Damping off, Phomopsis blight, Leaf spot, Fruit rot and Little leaf.
These are some of the diseases that are commonly seen in eggplants globally and let us take the example of Damping off at the beginning. So Damping off a brinjal is caused by a variety of fungal species that includes Pythium, Phytophthora and Rhizoctonia and we can see that this is a nursery bed disease and we can see that falling off the seedlings because of the infection at the collar or in the stem and within a short time we can see that the plants are affected in the nurseries. The pathogen is soil borne in nature all these pathogens are soil borne in nature and that is why we need IPM practices to manage this pathogen that includes Cultural, Chemical and Biological means. Cultural methods include use of healthy seed for sowing, this is the foremost criteria. So healthy seeds will not bring new inoculum to the nursery, avoid continuous raising of nursery in the same plot, because it has a possibility to bring new inoculum to the nursery beds so we changed the nursery beds from time to time. Soil solarization by spreading polythene sheet over the bed for 30 days before sowing. This is a very effective method of managing the damping of pathogens in nursery beds by covering the nurseries soil by spreading a polythene sheet at least 30 days prior to seed sowing. The chemicals that are found effective in management of the pathogen includes Thiram. The top soil should be treated with Thirom at a rate of 5 gram per meter square and that nurseries soil should be dressed with the same chemical at the rate of two gram per liter of water and it should be done at fortnightly interval. So these methods of application of chemical help us in reduction of the inoculum that is present in the nursery beds. So biological control has also proved effective and biocontrol agents such as Trichoderma viride can be applied at a rate of 1.2 kg per hectare is also proved healthy. And this is how we can manage the damping off of eggplant under nursery and field conditions.
Next one is Phomopsis Blight and it is caused by a fungal pathogen Phomopsis vexans. We can see the symptoms developing on the fruit as well as on leaf and the symptoms are very typical where the rotting areas are almost having some circular rings and the similar effect is also seen on the leaves and under infected portions either on the leaf or on the fruit we can see there are some black dotted spots which are raised and these are typical symptoms that help us identifying the pathogen that is causing the disease Phomopsis blight. The pathogen survives on eggplant crops and in crop debris as well as on seeds and soil so the pathogen has a wide range of survival mode so we need to look into these aspects while going for management of this pathogen.
So IPM practices are recommended that includes Cultural, Use of resistant cultivars and Chemical application. Cultural practices include use of clean seed which is again a very very important and foremost criterion to be considered. Then we should adopt good field sanitation practices. Crop debris should be properly burned and it should be cleaned and that is how we can achieve a good field sanitation. Then we should go for destruction of infected plant material this is again very important because the pathogen is harbored in infected plant materials and that is why this practice is very important. Then we can go for crop rotation for three to four years which nearly eliminates the disease from the infected fields. Then we can promote rapid leaf drying by timing of irrigations because the infected leaves Harbor pathogens so their rapid decomposition help us to eliminate the pathogen from the infected fields. Plant spacing is very important wider and larger gaps between the plants and rows help us to manage this pathogen because it does not favour growth of the pathogen when it is wide and apart. Then some of the resistant varieties are reported for this particular pathogen and one should go for using this resistant cultivars, chemicals which are recommended for anagement of disease include Thiram which can be applied as seed treatment at a rate of 2 gram per kg of seed then in the later stage one can go for spraying with Dithane Z-78 or Bordeaux mixture which effectively control the disease under field condition. So these are some of the effective control measures that help us to manage this Phomopsis Blight blight in brinjal.
The next important pathogen is Cercospora melongenae that cause Leaf spot in brinjal. This is again that having the symptoms are very typical where we can see that light centered and dark surrounding symptoms or spots that are developed on the plants later on the spots may quails and they give a larger necrotic areas on the leaf. Their whole leaf may be affected in a later stage. The pathogens survived in the volunteer plants, infected debris, and alternate host. So we need to look into this aspect of the survival for management of this particular pathogen. IPM practices are recommended for management of this particular disease which include mostly the cultural and chemical measures. Scouting feels frequently to catch any early infection is very important because in this way one few plants are affected we can easily rogue them out and we can reduce the inoculum from spreading to healthy plants at the same time. So their removal and destruction is recommended. Then fall tillage to bury the infected plant debris is another good practice that needs to be adopted for management of this particular disease. We can also go for crop rotation for at least two years, so these practices help us to minimize the inoculum load from the plant and it helps us to reduce the inoculum for passing over to the next season. Some of the chemicals that includes Carbendazim and Chlorothalonil can be used for spraying and they give good control of this disease. Carbendazim at the rate of 0.1 percent and Chlorothalonil at the rate of 2 gram per liter of water are recommended.
The next important disease is Fruit Rot of brinjal and is caused by Phytophthora nicotianae. The pathogen infect the fruits mostly from the bottom and you can see there is rotting of the fruit that takes place because of this pathogen infestation. The pathogen can survive in soil and that is why the IPM practices include cultural practices to remove the initial inoculum as well as chemical methods for suppression of the disease on infected plants. So proper water management is one important cultural aspect that needs to be considered and we should adopt practices that minimizes excess moisture on the plants, because excess moisture on the plants help rapid development of the pathogen and that is why we need to look into this particular aspect and manage the moisture content on the plant surface. Removal and destruction of affected fruits this is again a very important practice because once we remove and destroy the infected fruits that means we are also destroying the inoculum level for it’s spreading to new and fresh plants. Chemicals that has proved effective are Difolatan at the rate of 0.3% .We can apply it twice at an interval of 10 days and it gives very effective control over the disease i.e the fruit rot. Similarly, Ridomil and Bravo can also be applied for successful management of the disease under field conditions.
The next important disease is Little Leaf of Brinjal. It is caused by a virus the name itself suggests that that mostly the top new the developing leaves they become smaller in size and they remain small in size. In severe conditions the entire plant may be stunted and the leaves remain small throughout the plant. So this is a virus disease and that is why it is mostly survived in infected plants or related plant species. So IPM practices that includes cultural and chemical methods that is most widely recommended. Since the disease is transmitted by leaf hopper so we should think of lowering down the leaf hopper population by adopting appropriate measures. We should also adopt sanitary measures like eradication of susceptible volunteer crop plants from a previous planting, because volunteer plants harbor this virus for the next season. So volunteer plants should be traced and identified and they should be uprooted and they should be destroyed. Use of barriers of trap crops and early removal and destruction of infected plants also help us in minimizing the damage due to this particular pathogen.
The sowing time can be adjusted to avoid the main flights of the bear a beet leaf hopper. So, leaf hopper as I mentioned earlier is the vector that transmit the virus so we must have appropriate control measures that avoid the flights of beet leaf hopper that transmit this virus from infected plants to the healthy ones. Chemical sprays include Malathian at the rate of 2 ml per liter of water because it gives a good control over the leaf hoppers. So these are some of the important tactics that are useful for management of the brinjal diseases including a little leaf of brinjal and one must go for adopting these precise methods of management including the cultural and chemical that help us to reduce the inoculum level, spread of the pathogen and we can have good protection over these diseases in the fresh crop.
Thank you.
