To study the important physiological disorder of fruit and plantation crops
- Mango malformation: It is a complex and serious malady in North India and not so common in South India. Some varieties like Chausa, Bombay green, and Fajri jafrani are more susceptible than others in India.
This malady has been distinguished into two groups i.e., vegetative malformation and Floral malformation.
The vegetative malformation is more pronounced in young plants. Affected mango seedlings or young plants develop excessive vegetative branches which have limited growth, swollen and with very short internodes, and develop abnormally compact rosette-like shoots presenting a bunchy top appearance.
Floral malformation: The affected inflorescence becomes clustered and round. Most of the flowers lack essential organs and don‘t set fruit and its inflorescence continuously hang on the tree for months, being more green and sturdy.
Causes: Various causes like nutritional disorders, physiological, viral, fungal and acarological are reported. The available literature doesn‘t appear to support the above causes except the fungal; the only positive evidence for the cause of this is fungal origin. i.e., Fusarium moniliforis.
- Destruct the infected small plant or plant parts
- Spraying a fungicide like Captan @ 3grams or Bavistin @ 1gram / litre of water
- Remove the affected parts by pruning 30cms below and paste with Bordeaux paste.
- Early deblossoming combined with NAA 20ppm spray during October also reduces this considerably.
- Bhardhan variety of U.P. is resistant and free from this infestation.
- Spongy tissue in mango: Non-edible sour patch develops in the mesocarp of mango fruit called spongy tissue.
- Normal and attractive fruits on cutting reveal spongy development in the flesh.
- This malady increase with increased nitrogen application
- Fruits with low calcium content are affected
- Heat arising from the soil inactivate the ripening enzymes
- The fruits have a bad odour and become unmarketable.
- Harvest fruits at the ¾th maturity stage.
- Apply calcium-containing fertilizers like calcium ammonium nitrate.
- Use of sod culture
- Varieties are susceptible: Alphanso. Olour, Totapuri
- Varieties resistant: Arka Puneet
- Sod culture and mulching are useful in reducing spongy tissue.
- Growing mango hybrids Ratna and Arka Puneet, which are free from this problem.
- Harvesting fruits when they are three-fourths matured rather than fully matured ones also reduces this malady.
- Irregular bearing or Alternate bearing or Biennial bearing in mango:
- Mango trees heavily bear fruits in one year (on year) and a much-reduced crop in the following year (off-year).
- Draining out of CHO and N reserves during „on year‟ is known to lead to a lean crop in the „off-year‟ as they are important for fruit bud initiation e. i. high C/N ratio helps for fruit bud initiation
- Varieties with axillary fruit-bearing habits possess less than terminal bearing
- Many commercial varieties are irregular bearers.
- Totapuri, Neelum, and hybrids in which Neelum is involved as one of the parents are regular bearers.
Measures to control alternate or biennial bearing
- Proper up keeping and maintenance of the orchard
- Girdling and ringing the bark
- Chemical regulation: Paclobutrazol (Cultar) @ 5ml a.i, dissolved in 10lit of water and drench along the basin 90cm apart from stem.
- Black tip of mango:
The distal end of the fruit first exhibits etiolated patches, later running black followed by discolorations and necrosis of the mesocarp.
- Gases like SO2, Ethylene, and CO affect the fruits.
- The distal end of the fruit turns black and gets hardened.
- Affected fruits become ripe pre-maturely and unmarketable.
- Exuding a brown gummy substance
- Brick kilns should be allowed to establish at least 2 km away from the mango orchard.
- Chimney height should be increased to at least 18 to 20 m.
- Spray borax (0.6%) + caustic soda (0.8%) thrice
(a) Before flowering.
(b) During flowering
(c) At fruit-set stage.
- Choke throat of banana
This disorder results from low temperature. Due to low-temperature yellowing of leaves occurs and under severe conditions the leaves become necrotic. The low temperature at the time of flowering affects the bunch formation. Under normal conditions, the bunch emerges from pseudostem but when the temperature is low it does not emerge properly from pseudostem.
The maturity time of the bunch is extended up to 5-6 months then 3.5-4 months. This order is called choke throat because in the inflorescence distal part comes out but the basal part becomes tapered at the throat.
- The management of choke throat includes the use of varieties that tolerate low temperatures and the use of eucalyptus as a shelterbelt to check the effect of cold wind.
- Kottai vazhai of banana
This disorder seriously affects the Pooran variety of bananas and results in 10-25% reduction in yield. This disorder is characterized by the presence of sharp, tapered and ill-filled fruits that have the seedy structure in their central core. That makes the fruits inedible. The symptoms of this disorder do not appear at the earlier stages.
- It can be managed by spraying 20ppm (1g in 50L of water) 2, 4-D. by applying this the seediness of the fruits can be completely controlled and make the fruits good in quality.
Granulation in Citrus:-
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 a 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. Several factors like luxuriant growth, rootstock and the variety, frequent irrigation, mineral constituents in plant tissue, time of harvest, exposure to sunlight, etc., are found to be associated with this malady. It is reported that in the areas with a high incidence of granulation, the plant tissues contain high Ca and Mn, and low P and B. The incidence is relatively high in the fruits of younger plants as compared to those in older plants. The vigorous rootstocks like rough lemon increase the incidence of granulation as compared to less vigorous rootstocks. Late maturity and persistent cold weather throughout the period of maturity have been found to increase the incidence of granulation.
- The incidence of granulation could be reduced to 50 percent 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.
Bronzing of Guava:-
Bronzing in guava is a complex nutritional disorder. When fruiting starts in a soil marginal in P and K, the nutrients are mobilized from older leaves to the fruits, causing bronze coloured leaves which results in reduced photosynthate transfer to the roots and reduced uptake.
- In mild symptoms, the mixture of 20 kg of FYM, 1 kg of SSP, 0.5kg MOP, and 100g ZnSO4 /tree should be applied to the soil.
- In severe cases, the dose may be doubled except FYM and foliar spraying of DAP 0.3% and SOP 0.5% is to be given 45 days after the emergence of leaves.
- Fruit cracking in Pomegranate
Fruit cracking is a serious problem with pomegranate. The malady is thought to be due to boron deficiency in young fruits while in developed fruits it may be caused due to variations in soil moisture content and atmospheric humidity. At the time of fruit ripening, if the soils become too dry and then irrigated heavily or there is some rain, cracking may occur.
- Some cultivars, like Guleshan, Khog, Kazaki are reported to be resistant to fruit cracking.
- Regular irrigation to maintain soil moisture at desired level
- spraying of calcium compounds or GA3 at 120 ppm on young fruits is reported to minimize the fruit cracking.
Shot Berries of Grape Hen and chicken
They are formed due to delay in pollination and fertilization of a few flowers or due to inadequate flow of carbohydrates into the set berries. Boron deficiency, incorrect stages of GA application, and girdling are the known reasons for shot-berry formation.
- Similarly, application of GA at the proper stage should be ensured. Boron or Zinc deficiencies should be corrected.
Pink Berry of Grape
As the bunch approaches maturity some berries in the bunch develop pink colour at random. The pink colour changes to dull red colour rendering the bunch unattractive.
- Indiscriminate use of Etherel for berry colouration can also cause this disorder.
- Bud and Flower Drop in Grape
The malady has been investigated and the association of a number of factors such as improper nitrogen application, improper fertilization, ambient temperature, heavy crop load, uneven ripening, and endogenous auxin deficiency at a particular stage of berry development is reported to cause the malady.
- Making 0.5 cm wide girdle from the trunk about 10 days before full bloom results in a better berry set.
- 500 ppm ethrel at veraison stage should be applied;
- dipping of bunches in NAA 100ppm 10 days before ripening reduces berry drop, heavy irrigation at bloom should be avoided.
- Commercial Fruits. By S. P. Singh
- A text book on Pomology, Vol,1. by T. K. Chattapadhya
- Tropical Horticulture, Vol.1, by T. K. Bose, S. K. Mitra, A. A. Farooqui and M. K. Sadhu