ELUCIDATION OF THE FACTORS RESPONSIBLE FOR CRACKING AND SUNBURN IN LITCHI AND INTEGRATED MANAGEMENT TO MINIMIZE THE DISORDERS

Fruit cracking and sun-burning (lesion browning, pericarp necrosis) are the major issue in litchi production in India. The incidence of cracking varies significantly amongst cultivars, suggesting a strong genetic link. Experiments were conducted for consecutive five years (2003-2007) with an aim to elucidate the causes of the disorders and to develop an integrated management protocol to minimize/ control of both the disorders. We have examined the effect of different irrigation levels (0.20 to 0.60 DASM) during fruit growth and development period, use of organic mulch in tree basin, spraying of different nutrient elements (B and Zn) and Kaolin (aluminum silicate), placement of dessert cooler and overhead sprinkler irrigation system to influence the micro climates, bagging of fruit bunches and partial shading of trees by use of shade-nets (30%). Results revealed that all the treatments reduced both the disorders i.e., cracking and sunburn. The integrated approach, we suggest is mulching the tree basins with fallen litchi leaves, combined with irrigating the orchard during fruit growth and development at 40% depletion of available soil moisture and protecting the fruits with shade nets at 30 days before harvesting. The susceptible varieties for the disorders showed higher calcium content and slightly low fruit pressure than the less susceptible varieties. Higher temperature (>38°C) along with high humidity favours cracking disorders.