Apple Tree Diseases: Powdery Mildew

Diseases play an important role in low productivity of any crop in the form of yield losses. Generally about 33% losses are due to diseases and insect pests. There are some diseases which not only impair with the yield losses but these also contribute towards poor quality of the produce. The question now arises that, What is Disease?: 

Disease is an impairment of health or a condition of abnormal functioning.

Diseases of Apple

Powdery Mildew
Collar rot
White Root Rot

Premature Leaf Fall
Sooty Blotch and Fly Speck
Apple Scab
Apple Mosaic Virus

In this post we are going to talk about the powdery mildew disease of apple. This disease is very common in Kinnaur district of Himachal Pradesh as dry weather plays an important role in the appearance of the disease.

Description: The disease infects leaves, blossoms, green shoot, and the fruit. On the leaves, the fungus can appear as felt-like patches or as a solid mat on the surface, particularly on the undersurface of the leaf. Initial infections on the underside of the leaf may cause chlorotic patches or spots to occur on the upper side of the leaf. This symptom, however, is not unique to powdery mildew so inspection of the underside of the leaf is necessary to confirm that powdery mildew is the cause of these symptoms. Under favorable environmental conditions, the disease spreads over the entirety of the leaf and progresses down the petiole on to young, green shoots. Infected leaves tend to crinkle, curl, or roll upwards along the edges giving them a narrow appearance. If the infection is severe, infected leaves will usually drop prematurely during the summer.

Shoot infections are the typical result of overwintering infections of the fungus in buds. When the terminals push in early spring, the fungus grows along with the new succulent growth and infects this tissue immediately. These shoots may be killed outright in the spring, or may survive throughout the season and die in late fall or winter. The initial growth of the fungus on newly infected twigs appears powdery white but eventually turns a darker brown. Small black fruiting bodies, called cleistothecia, can appear in the mycelial mat and function as the source for sexual reproduction and the eventual production of ascospores.

The blossoms, petals, sepals, receptacles, and peduncles may become infected and covered with the fungus. Blossom infections are less common but are important because infected blossoms will either fail to set fruit or produce small, stunted and/or russetted fruit. These fruit are unmarketable for fresh market consumption. 

In my next post I shall be talking about the 
Disease Cycle of Powdery Mildew, 
Management of Powdery Mildew

Apple Tree: Low Productivity in Apple: Strategies to Overcome

This post is in continuation to my previous post on Short term strategies to overcome the low productivity problems in apple

Following are the strategies that are needed to be adopted and farmers at field level are to be made aware of these strategies: There are two types of strategies viz. Short term strategies and Long term strategies Here I shall be discussing the Long Term Strategies to Overcome the Low Productivity in Apple

• Promoting high density plantation by using suitable rootstock and Spur type varieties for reducing the gestation period and increasing production per unit area
• Phasing out old plantations, which have completed their economic life, and replanting with new apple varieties on suitable rootstock.
• Introducing improved varieties of apple, which are regular bearers, heavy croppers, precocious, resistant to biotic and abiotic stresses and also useful for processing purpose
• Identification fruit trees of outstanding merit in existing apple plantations for use as mother trees when establishing future orchards
• Developing of infrastructure and facilities for multiplication of certified virus tested planting material of apple rootstock and scion varieties for use in future apple orchards
• Expansion of area under improved varieties of apple

In coming posts I shall be discussing about plant health management.

Low Productivity in Apple: Strategies to Overcome

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I am continuing after a long gap for some technical reasons especially pertaining to internet problems I am facing in the Tribal Area. This post is in continuation with the previous posts on the Low productivity in Apple. Now I shall be discussing on the strategies for improving the production, productivity and quality of apples .

Following are the strategies that are needed to be adopted and farmers at field level are to be made aware of these strategies:

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There are two types of strategies viz. Short term strategies and Long term strategies

Today I shall be discussing only the Short Term Strategies

• Improving orchard management techniques in particular the training and pruning of apple plants. This is the most important and crucial practice and extension workers as well as farmers must be trained in this technique

• Plantation of an adequate number of pollinizing varieties and the introduction of honey bees for effective pollination

• Water, being vital to apple fruit production, farmers should develop their own water harvesting facilities and install the drip irrigation system in the orchards on a large scale

• Adoption of modern plant tissue analysis technique for the diagnosis of nutrition problems in apple orchards, and the formulation of fertilizer schedules for each orchard based on this technique

• Promotion of scientific soil and water conservation techniques in apple orchards

• Undertaking timely measures for the control of pests and diseases of economic importance by adoption of integrated spray schedules. For this purpose IPM strategies are also required.

• Provision of antihail nets for protecting the crop against hail damage

• Rejuvenation of old apple orchards through pruning and judicious fertilizer application

• Promotion of the concept of fruit thinning in Delicious group of cultivars which has tendency of alternative bearing

In the next post I shall be discussing the the Long Term Strategies to Overcome Productivity Problems

Environmental Factors- Contributing Factor towards Low Productivity in Apple

This post is in continuation of our earlier post on Old and Senile Orchards - Contributing to low productivity in Apple part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh

Pest and Diseases

A number of pests and diseases have been found to affect the apple orchards. Besides apple scab, which first appeared in epidemic form during the year 1985-86, the emergence of some new pests and diseases like premature leaf fall and red spider mite, has been one of the most potent reasons for low productivity.

Adequate measures need to be taken to control these serious pests, in order to improve productivity and reduce losses.

Environmental Factors

The changing weather pattern seems to be the most important single factor responsible for the declining productivity of apple crops in the state. The reduction in annual snowfall and prolonged dry spells in the winter have become a regular feature, leading to a wide variation between day and night temperatures. Fluctuating temperatures during flowering period, particularly rains accompanied by low temperature, adversely affects the pollination due to restricted bee activity and retarded pollen tube growth. The occurrence of hail in many areas is a regular feature, and heavy losses are incurred due to these natural calamities thereby contributing to low productivity.

This post is part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh. Entire series is coverted through following topics

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

to be continued with the strategies to over come these bottlenecks..............................

Old and Senile Orchards - Contributing to low productivity in Apple

This post is in continuation of our earlier post on Moisture Stress- Contributing Factor to Low Productivity in Apple part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh

Old and Senile Orchards

The apple is the oldest cultivated fruit in Himachal Pradesh, and many orchards have outlived their economic bearing life. In addition there are many senile and unproductive trees even in the existing orchards, which need replacement. Such old and senile trees also contribute to low productivity of the existing plantations.

The available data also indicate that there are now 2400 ha of apple orchards which have crossed fifty years of the age, thus necessarily need to be replanted during the next ten years.

This post is part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh. Entire series is coverted through following topics

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

Keep following for the further posts.

Moisture Stress- Contributing Factor to Low Productivity in Apple

This post is in continuation of our earlier post on Canopy Management - Contributing factor to Low Productivity in Apple part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh

Moisture Stress

The apple farming in Himachal Pradesh has been developed under rainfed conditions, and serious moisture stress is commonly experienced at critical stages of plant growth and development, particularly between April and June and later on from September to November.
Though rainfall is sufficient, it is not well distributed. Because of steep hilly terrain, the rainwater generally flows down with high velocity resulting in low rate of absorption in the soil. There is a need to adopt technologies for in situ conservation of rainwater, harvesting of rainwater and its utilization during the critical periods through high efficiency irrigation systems.

This post is part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh. Entire series is coverted through following topics

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

Keep following for the further posts.

Canopy Management - Contributing factor to Low Productivity in Apple

This post is in continuation of our earlier post on Inadequate Nutrition - Contributing to Low Productivity in Apple part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh

Poor Canopy Management

The adoption of correct techniques for training and pruning of fruit trees is of vital importance for regulating fruit production. Only a few progressive orchardists are strictly following the scientific principles of pruning apples and are obtaining regular yields every year. It has been observed that in most orchards the training of the young trees is not done correctly, which results in an increased juvenile phase. Similarly the practice of spur thinning in the old trees is lacking. Another severely neglected aspect of pruning apples is the absence of summer pruning.

This post is part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh. Entire series is coverted through following topics

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

Keep following for the further posts.

Inadequate Nutrition - Contributing to Low Productivity in Apple

This post is in continuation of our earlier post on Pollination problems part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh

Inadequate Nutrition

Although the fertilizer recommendations for the apple fruit crops in the state as a whole have been standardized and made available to growers in the package and practices, yet such recommendations are not available on the regional basis. The fertilizer use efficiency is not optimum due to drought during the growth periods, leaching down and runoff of the nutrients during monsoon or unbalanced fertilizer use. The problems of nutrient management are further accentuated in areas where the land is sloping and with poor fertility, resulting in deficient root growth and thereby poor nutrient uptake by plants. Due to non-judicious use of fertilizers in many orchards, micronutrient deficiencies, particularly zinc, boron and manganese, have also been observed and need to be corrected by foliar application of the nutrients. Modern plant tissue analysis technology for the diagnosis of nutrient disorders, though available, has not been widely used.

Nutrient management in orchard is, therefore, required to be scientifically taken care, to overcome the problem of low productivity.

This post is part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh. Entire series is coverted through following topics

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

Keep following for the further posts.

Pollination problems

This post is in continuation of our earlier post on Management Practices part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh

Pollination Problems

Lack of Pollinizers: The low proportion of pollinizing varieties and non-synchronization of their flowering with the main Delicious varieties is yet another factor that has adversely affected fruit setting in major apple growing areas of the state. The horticulture census data (1989-90) reveal that in most of the orchards the pollinizing variety comprises only nine to ten percent against the 33 percent required for ensuring optimum pollination. Moreover in most of the orchards, Golden delicious has been planted as the major pollinizing variety, the flowering of which sometimes does not synchronize with the main Delicious varieties.

The orchardists must plant two or three varieties of pollinizers, properly spaced in entire orchard for ensuring adequate pollination. Varieties like Red Gold, Tydeman’s Early Worcester, Granny Smith, Cox’s Orange Pippin, Yellow Newton and Jonathan, besides carb apples like Golden Hornet, Snow Drift and Manchurian, can be planted as pollinizers for successful pollination.

Lack of pollinators: Pollination in apple is mainly done by the honey bees and other wild insect pollinators. It has been estimated that at least three beehives per hectare must be placed in orchard during flowering period to ensure pollination and fruit set.

This post is part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh. Entire series is coverted through following topics

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

Keep following for the further posts.

Management Practices

This post is in continuation of our earlier post on Genetic Potential of a Cultivator part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh

Management Practices

Planting density: The latest concept throughout the world is the optimum utilization of available space to achieve the maximum level of production per unit space by accommodating the maximum number of plants in a given area and harvesting maximum solar energy through photosynthesis. The apple orchards in HP, however, have been planted at a spacing of 20 to 25 ft accommodating 250 to 300 plants/ha. Such orchards have a long gestation period of fifteen to twenty years, resulting in low productivity.

The superiority of high density plantations in apples employing semi-dwarf rootstock have been demonstrated at the Regional Horticultural Research station, Mashobra, where the yield up to 70t/ha has been obtained in comparision to 4.5 to 6.5 mt/ha average yield in the state.

Therefore, it would be advisable to adopt high density plantation in suitable areas for improving apple productivity.

This post is part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh. Entire series is coverted through following topics

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

Keep following for the further posts.

Genetic Potential of a Cultivar

This is in continuation with the previous post on Low Productivity in Apple: Contributing factors in Himachal Pradesh

Genetic Potential of the Cultivar

In Himachal Pradesh, the Delicious group of apple varieties predominate. The horticulture census data (1989-90) have revealed that almost 90 per cent of the total apple plantation comprises the Delicious group of apples. These varieties are in general shy bearers, self-unfruitful and have strong tendency toward alternate bearing after a few years of commercial production. These varieties are also highly susceptible to temperature fluctuations during the flowering period resulting in low fruit set.

The majority of the apple plantations in HP have been developed on seedling rootstock, which do not have uniformity in production but produce vigorous plants with long gestation period. This is also one of the contributory factors for low productivity of apples per unit area.

This post is part of our series on Low Productivity in Apple: Contributing factors in Himachal Pradesh. Entire series is coverted through following topics

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

Keep following for the further posts.

Low Productivity in Apple: Contributing factors in Himachal Pradesh

The production data of apples in Himachal Pradesh reveal that there was considerable fluctuation in yield over years. The productivity of apples has been calculated on the basis of total production during a particular year divided by the estimated bearing area over ten years of age in the respective year.
The productivity has declined during the past thirty years has declined considerable from 6.5 mt/ha to nearly 4.5mt/ha thereby showing a decrease of thirty percent.

Causes of Low Production

Yield per hectare is the real indication of efficiency of the management in orchards. The decline in productivity of apple orchards in past few years has, therefore become a matter of concern to apple growers in Himachal Pradesh. The factors which affect the yield are the genetic potential of the varieties planted, the effect of climatic and environmental conditions and the management technology employed by the growers. The following major causes have been identified as responsible for low productivity in the apple orchards in Himachal Pradesh.

1. Genetic potential of the cultivar
2. Management Practices
3. Pollination Problems
4. Inadequate Nutrition
5. Poor Canopy Management
6. Moisture Stress
7. Old and Senile Orchards
8. Environmental factors

I shall continue with these factors in coming posts