Authors: Panchal Bhakti B., Dr. N. B. Patel, Dr. D. R. Bhanderi and Dr. R. V. Tank
ASPEE College of Horticulture and Forestry,
Navsari Agriculture University, Navsari- 396 450, Gujarat, India
E-mail: bhakti.b.panchal@gmail.com
Introduction
• Malady (physiological Disorder) refers to non parasitic or inanimate diseases of fruit crops.
• The major factors associated with these disorders are deficiency or excess of mineral elements, hormonal imbalance, improper pollination or fertilization or other abiotic stresses.
• Sometimes more than one factor may be responsible for the cause and hence seldom called as syndrome.
1) Mango
1) Alternate bearing
• The term biennial, alternate or irregular bearing generally signifies the tendency of mango trees to bear a heavy crop in one year (On year) and very little or no crop in the succeeding year (Off year).
• Most of the commercial varieties of north India, namely, Dashehari, Langra and Chausa are biennial bearers, while south Indian varieties like Totapuri, Red Small, Bangalora, and Neelum are known to be regular bearers.
• When a tree produces heavy crop in one season, it gets exhausted nutritionally and is unable to put forth new flush thereby failing to yield in the following season. The problem has been attributed to the causes like genetical, physiological, environmental and nutritional factors.
♦ Management :
• For overcoming biennial bearing, deblossoming is recommended to reduce the crop load in the 'On' year so that it is balanced in the 'Off ’year.
• Proper maintenance of orchard by way of effective control of pests and diseases and regular cultural operations may also result in better performance of the tree every year.
• Soil application of Paclobutrazol (PBZ) or Cultar @ 4 g/tree in the month of September resulted in early flowering with higher fruit set and yield.
• It may be applied every year for regular fruiting, particularly in young trees.
2) Malformation
• In India first time malformation in mango observed in Bihar, 1891.
• Mango malformation causes huge losses in Punjab, Delhi and Uttar Pradesh, and to some extant in Gujarat, Maharashtra, Bihar, West Bengal and Orissa.
• Vegetative malformation (bunchy top): it is common in nursery seedlings and young plants while floral malformation affects trees at the bearing stage. In this disorder the leaves become compact and a bunch is formed at the apex of shoot or in the leaf axil hence growth of shoot-let is arrested.
• Floral malformation: the incidence of disorder varies from variety to variety. It affects the productivity.
♦ Management:
• Affected terminals are to be removed along with 15-20 cm healthy portion.
• Spray NAA @ 200 ppm in Oct.-Nov. at fruit in bud stage.
- Use high volume sprayer for this.
- Repeat the same after 12-15 days.
• Black tip in mango first time observed by Woodhouse in 1909.
• Black tip is a serious disorder, particularly in the cultivar Dasheri. The affected fruits become unmarketable and reduce the yield to a considerable extent.
• The damage to the fruit gets initiated right at marble stage with a characteristic yellowing of tissues at distal end.
• Black tip disorder has generally been detected in orchards located in the vicinity of brick kilns. It has been reported that the gases like carbon monoxide, sulphur dioxide and ethylene constituting the fumes of brick kiln are known to damage growing tip of fruits and give rise to the symptoms of black tip.
♦ Management:
• Planting of mango orchards in North-South direction and 5-6 km away from the brick kilns may reduce incidence of black tip to a greater extent.
• The incidence of black tip can also be minimized by spraying Borax (1%) or other alkaline solutions like caustic soda (0.8%) or washing soda (0.5%).
• The first spray of Borax should be done positively at pea stage followed by two more sprays at 15 days interval.
4) Clustering
• The clustering (jhumka) at the tip of the panicle and appears as of bunch tip.
• These become dark green with green with a deeper curve in the sinus beak region.
• These fruit lets grow to marble size and growth ceases. Clustering develops due to adverse climate mainly low temperature in February-March.
• Most of the fruits ate aborted with shriveled embryos and do not develop further, signifying the role of normal embryo growth in the development of fruits.
5) Spongy tissue
• Fruits from outside look normal but from inside a patch of flesh becomes spongy, yellowish and sour this disorder.
• It is specific in Alphonso mango. This disorder reduces exports of this variety.
• The tissue become spongy due to inactivation of ripening enzyme induced by high temperature, convective heat and post harvest exposure to sunlight.
♦ Management:
• Use of sod culture and mulching can reduce this disorder. Varieties like Ratna and Arka Puneet which are hybrids of Alphonso do not suffer from this malady.
6) Fruit drop in mango
• Fruit drop in mango is a continuous process amounting to about 99%, at various stages of growth.
• Of the commercial varieties, Langra is more prone to the disorders, while Dashehari the least In mango, only about 0.1 % of tile perfect flowers develop fruits to maturity. The extent of fruit drop in mango varies from variety to variety and region to region.
• Fruit drop in mango can be classified into three distinct phases.
♦ Pin head drop
♦ Post setting drop
♦ May drop
• A good deal of fruit drop is attributed to disintegration of embryos and ovular abnormalities.
• Other factors like climatic conditions, disturbed water relations lack of nutrition, competition among fruits and pests and diseases, contribute to fruit drop, Further, hormones and their activities in the seeds play an important role in deciding the retention of fruits.
♦ Management:
• The extent of fruit drop in mango can be significantly reduced by regular irrigations during fruit development period.
• Orchards should be protected from desiccating winds by planting wind breaks.
• Timely and effective control measures against major pests and diseases should be adopted.
• Growth regulators like NAA and 2,4-D in varying concentration depending upon the variety and time of application can be sprayed. The optimum concentration lies between 10 and 15 ppm during the month of April-May.
2) Banana
1) Kotta vazai
- Kotta=seed. these malady affecting Poovan banana.
• Though few studies conducted earlier with sprays of 2,4-D 120 ppm enabled to obtain normal bunch, the cause of this malady is not known.
• It is suspected to be associated with incidence of banana streak virus.
2) Neer vazai
- Neer=water, and vazai=banana.
• Infested plants show poor plant growth, delayed shooting, lanky bunch with few hands and immature unfilled fingers.
• In infested plants, sever root damage is noted
♦ Management:
• Application of growth hormone NAA improves the finger filling.
- Use virus free planting material because it transmitted through suckers.
• It is due to low temperature affecting active growth of the plant. Leaves become yellow and in severe cases, the tissue gets killed.
• In case of normally flowering plants, the stalk carrying bunches elongates freely so that the entire inflorescence comes out of the pseudostem and hangs down.
• Bunch development is normal, but when the time of flowering synchronizes with low temperature, the bunch is unable to emerge from the pseudostem properly.
• The distal part of the inflorescence comes out and the basal part gets stuck up at the throat. Hence, it is called Choke throat.
• Maturity of the bunch is delayed by taking 5-6 months instead of 3.5-4 months for harvest.
♦ Management:
• Provision of shelter belts using Casuarina or Eucalyptus to prevent the effect of cold wind blowing into the orchard and planting low temperature tolerant varieties like Kullan check the disorder.
4) Finger drop
- Symptoms
♦ Management:
• Harvest physiologically matured green bunches
- Dehand bunches and cut into clusters
- Pack clusters in a carton
• Ventilate and allow the fruits at a temperature of 18°c
5) Skin abrasions
• Abrasions result from skin scuffing against other fruits or surfaces of handling equipment or shipping boxes. When exposed to low (<90%) relative humidity conditions, water loss from scuffed areas is accelerated and their color turns brown to black.
3) Citrus
1) Granulation
• Granulation is a serious problem of citrus, especially under North Indian conditions. This abnormality is initiated at the stem end of the fruit which gradually extends towards the stylar end.
• The affected juice sacs become hard and dry, fruits become grey in colour, enlarged in size, have flat and insipid taste and assume a granular texture. Granulated fruits contain less extractable juice as most of it turns into gelatinous mass.
• It is much more prevalent in larger sized fruits than in small fruit, in young than in old trees and in humid than in dry areas.
• Singh and Singh (1980) reported that in the areas with high incidence of granulation, the plant tissues contain high Ca and Mn, and low P and B.
• The incidence of granulation could be reduced to 50 per cent by applying two to three sprays of NAA (300 ppm) in the months of August, September and October. Spraying of GA 15 ppm followed by NAA 300 ppm in October and November also reduce granulation.
• This is mainly a physiological disorder and is largely attributed to high atmospheric humidity following heavy rains or heavy irrigation during hot weather.
• Two types of splitting, namely radial and transverse have been noticed.
- Radial cracking is more common than transverse one.
- Partial splitting is more prevalent while splitting down to inner core is rather rare.
♦ Management:
• The disease can be minimized by frequent and light irritations during the dry and hot periods and early picking of fruits soon after maturity.
2) Fruit Drop
• The causes attributed to fruit drop in citrus are lack of fertilization, mechanical shock, insects, disease, high temperature, rainfall, and defective irrational practices.
• The most pronounced stages of fruit drop occurs when the fruits are at marble stage. It lasts for a month after full bloom.
• On the onset of hot summer weather during May-June the second wave of intense fruit drop occurs while pre-harvest drop occurs during ripening period, which lasts from August-January.
♦ Management:
• The method of control depends upon the causes of the drop and the variety of the fruit. In order to reduce the pre-harvest drop, NAA (10 ppm) is sprayed from August till October at monthly interval.
3) Citrus Dieback/Decline
• Citrus dieback or orchard decline is a gradual deterioration process exhibiting loss of vigor, death of twigs and branches, reduction in yield and ultimate death.
• Many factors such as unsuitable soils, drought, lack of systematic manuring, general neglect, use of infected bud wood and field incidence of vector-bore virus disease contribute to this declining condition singly or in combination.
♦ Management:
• Adopting a package of practices such as selection of proper site and soil, raising of genuine and healthy plants from certified bud wood, use of proper rootstock, judicious irrigation and manuring.
• Scientific spray schedule against insect pests and diseases can successfully control the disease.
4) Oleocellosis
• It is caused by rind oil release when oil cells get ruptured during harvesting or during handling from the field to the pack house.
• It is more common in crop taken in 'Mrig' bahar and harvested during February- March.
• Careful harvesting and handling reduces incidence of oleocellosis. Rind oil from ruptured cells discolors the skin making the fruit unmarketable.
♦ Management:
Best way to reduce its incidence is to cure the fruit overnight at a temperature of 18-20°C for 12-24 hrs, before the fruit is moved from the field to the pack house.
References
1. Handbook of fruit production by S. Prasad & U. Kumar.
2. Post Harvest Handling and Processing of Fruits and Vegetables
About Author / Additional Info:
I am the student of 2nd semester Ph. D. -Horticulture (Agriculture). Main subject of my research work on vegetables and fruit crops.