Sweet orange Physiological Disorders A Lecture By Allah Dad Khan To FFS Trainee
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Sweet Orange trees experience three main stages of fruit drop: post-set drop after fruitset, June drop during hot summer weather, and preharvest drop during ripening. Factors that can cause fruit drop include high or low soil moisture, nutrient deficiencies like zinc and phosphorus, and fungal diseases. Applying a combination of 2,4-D and aureofungin in early September helps prevent preharvest fruit drop. Granulation is a serious issue for citrus in North India, where the stem end of fruits hardens and dries out. Affected fruits are enlarged, gray in color, and have a granular texture. Factors associated with granulation include excessive growth, rootstock variety, frequent irrigation,
Sweet orange Physiological Disorders A Lecture By Allah Dad Khan To FFS Trainee
- 1. Sweet Orange Physiological Disorders A Lecture To ToT trainees ( FFS) By Mr. Allah DadKhan Provincial Coordinator IPM KPK MINFAL Pakistan
- 3. The most pronounced stages of fruit drop are, (i) immediately after fruitset at marble stage which lasts for a month after full bloom, referred as post-set drop, (ii) the second wave of intense fruit drop occurs at the onset of hot summer weather during May-June, known as June drop, and (iii) preharvest drop or premature drop occurring during ripening period, which lasts from August to December-January. Higher summer temperature, excess or deficiency of soil moisture, lack of nutrients like zinc, phosphorus and potash and attack of fungal diseases like anthracnose, styler-end rot and stem-end rot are some of the primary factors responsible for fruit drop. Application of 2,4-D 10ppm combined with aureofungin 20ppm in the first week of September provides excellent check against physiological and pathological pre-harvest fruit drop in citrus.
- 4. 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. This results in more quantity of rag and thus low pulp/rag ratio. The terms granulation, crystallization and dry end are used to describe this trouble. 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. 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
- 5. The deficiency causes yellowish translucent spots accompanied by leaf distortion or deformation. Mature and old leaves may show corky veins. They may be somewhat twisted or totted. Immature fruits become hard and somewhat misshaped. To control various leaf deficiencies, a combined spray of different microelements at a concentration of 25-50 ppm depending on the intensity of deficiency is generally applied. It is very likely that some of the components of such a spray would be a waste, if the trees are really not deficient in those elements. Copper and zinc are antagonistic when sprayed together. It is also observed that combined spray may cause tip burning of leaves in the absence of continuous stirring of spray fluid. It is, therefore, best to spray different micronutrients which are deficient individually rather than in combination based on leaf analysis.