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2 Apple diseases and their management


Hello! Welcome back to the second talk of this week. In the first talk we have come across the mango diseases and their management and today we are going to talk about important apple diseases and their management. Apple is also encountered is several different types of plant diseases among them some of them are most important like Powdery Mildew, Apple Scab, Fire Blight, and Black Rot which is also known as Frogeye Leaf Spot. These are the most highly rated diseases of apple that cause severe loss to the apple growers. We take up these diseases one by one.

First, we will take Powdery Mildew for it. Podosphaera leucotricha is the causal agent of powdery mildew of apple and the symptoms of these particular disease appears on the foliage particularly on the young leaves along with the inflorescence. So the entire plant get affected but plant gets suffer severe loss when the inflorescence of the plant get more infected because it ultimately affect flower development and fruit development. So infection on inflorescence has proved to be most vital for reduction in yield of the apple plant. The pathogen is airborne and it survives in infected trees. So infected trees from nearby orchards or in at a distant place may serve as a source of in a column for this particular pathogen.

So IPM practices has been recommended for this disease powdery mildew in apple and this includes Cultural, Use of resistant varieties along with Chemical applications. So cultural recommendations include the infected flowers or buds should be cut and they should be burnt. There are certain resistant varieties that are identified and these resistant cultivars of apples should be used for management of this particular disease where it is a problem. Then there are certain chemicals that has been identified for management of this particular disease. Some of the effective fungicides are Flint, Indar, Inspire, Super, Pristine, Rally, Procure, Merivon, Luna and Sovran. So these are some of the chemicals along in with Topsin M and Sulfur fungicides are also very very effective. Proper spraying at the proper time particularly at springtime sprays beginning at the tight cluster are proved to be very very essential and useful for managing this particular disease. So Apple and controls this problem of prowdery mildew but chemicals proved to be the best source for management of this particular disease.

Next important disease of apple is Apple Scab. It is caused by another fungus that is Venturia inaequalis. The symptoms of the pathogen include scabby appearance of the leaf surface and on the fruits. These are hard corky layers of cells and these are very easily manifested on fruits and on leaves. The pathogen mostly survived on detached leaves that are fallen on the soil. So management of pathogen needs to be focused on management of initial inoculum that is the fallen leaves in the soil. IPM practices are suggested for management of apple scab that includes cultural and chemical methods.

So cultural methods include since the fungus over winters on fallen leaves and fruits so raking up and destroying them is the most important practice for management of apple scab. Similarly, one can use or plant scab-immune varieties wherever it is available. Some of the genetic stock has been identified that are resistant to apple scab diseases and those should be used for plantation in apple scab infected areas. Chemicals are also proven effective for managing the pathogen that includes Captan, Flint,Pristine, Indar, Inspire, Super, Rally, Procure, Sovran, Fontelis, Merivon, Luna and Vanguard. These are some of the fungicides that help in managing the disease to lower down the severity significantly. Early season sprays are very important and that needs to be taken care of that the sprays should be given in the early stage of scab development.

Next is Fire blight of Apple that is caused by a bacterium Erwinia amylovora. We have seen that this bacterium has been causing tremendous problem in different parts of the world including European and American states. The Erwinia Fire blight is manifested through drying up off or blighted twigs of the plants slowly it affects the entire branch and it may lead to wilting of the entire plant. The pathogen is mostly survived in infected plants so the infected plants serve as the source of an initial inoculums of the pathogen.

IPM practices has been recommended for management of this bacterial pathogen that includes some cultural activities, some use of resistant varieties and application of certain chemicals. Cultural practices include avoidance of excessive nitrogen fertilizer application because it makes the plant more vulnerable or susceptible to the pathogen. So avoiding excessive nitrogen fertilizer is useful in manhandling the pathogenic problem. Then prune out the cankerous plants and blighted shoots before the growing season. It will significantly reduce the inoculum load in the orchard and there will be less disease progress in the orchard if these practices are done in a timely and effective manner. There are certain resistant varieties or resistant stalks have been identified and those should be used whenever it is available and that is recommended. Chemicals some of them are have proven effective in reducing the spread of the pathogen and those in chemicals include streptomycin sulphate and this should be applied during the bloom period only and every 3 to 5 days. So a frequent sprays of streptomycin sulphate during the bloom season can protect the new flush of by protecting them from getting infected by the fire blight pathogen. It should be alternate with Kasumin for best results. So an alternative application of streptomycin sulphate along with Kasumin it gives a good control of the pathogen. Streptomycin is not effective after the bloom period. So it’s application schedule should be properly adjusted to get good control over the pathogen. A late or dormant application of fixed copper in the form of spray or Bordeaux mixture is helpful. So these practices can or these chemicals can also be used for management of the bacterial pathogen. So fixed copper sprays during the growing season is helpful but Septomycin in application at the bloom period is considered to be the most effective control measure.

Next it is the Black rot or Frogeye Leaf Spot disease of apple and it is caused by a fungus Botryosphaeria obtusa. So this particular disease is very easy to detect by looking at the typical symptoms it produce. it produce two brown spots mostly almost together and it is very essential to identify these spots so that it can be detected at an early stage. That pathogen survives in the infected parts of the trees and that is why management of the pathogen applies with the management of the infected trees. There are IPM schedules that are recommended for management of this particular pathogen and that includes some cultural measures as well as some chemical measures. Though removing the mummies or dead wood and fire-blighted twigs is considered to be very important followed by their destruction because they serve as a hub for holding the in initial inoculum for infection in the new or fresh growing season. Some chemicals are also found effective among them Captan is found to be the most effective chemical. We can also Tank-mixing with Topsin M which also improves the effectiveness and summertime sprays are most important and here also timing of spray is considered to be the most important factor while managing the disease. So we have seen that these are some of the important diseases of apple and that causes severe loss to the apple production and we must take care of this apple diseases or that we have a good harvest at the end of the growing season.

Thank you.



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