here is some information on Mango
Flowers and small fruit can be killed if temperatures drop below 40° F, even for a short period. Young trees may be seriously damaged if the temperature drops below 30° F, but mature trees may withstand very short periods of temperatures as low as 25° F. The mango must have warm, dry weather to set fruit.
Abscission refers to the process by which fruits fall down for physiological reasons, as well as due to pests. Natural fruit abscission takes place up to about 60 days after flowering. Most fruits on a tree abscise as this is a natural thinning process, so only about 0.5% of the flowers actually set into fruits and only 0.1% is retained up to maturity. To manage fruit abscission, better nutrition should be given. There should also be adequate irrigation and pest control to minimize losses from pests.spraying 2% potassium nitrate at full bloom improves fruit set and fruit retention.
Why do some mango fruits crack? How are we going to manage it?
The fruits crack when the sun comes out after a downpour during the wet season. It is acknowledged that this is due to high internal pressure caused by the fruit or trees' inability to transpire during the humid days. Pressure builds up and as a result, the fruits crack. Some think that gibberellic acid can somehow be used to manage fruit cracking, but we actually have no definite management strategy for it. Some growers found that by harvesting the mangoes at 90 DAFI for the green market, they were able to avoid losses due to fruit cracking.
Low yield of mango (Mangifera indica L.) in the tropics is most often attributed to the failure of floral induction while in subtropical areas flowering is usually reliable but fruit set is often poor. Environmental stimuli are recognised as having a dominant effect on the yield potential of crops, particularly with respect to their determination of critical events such as the reproductive processes of the plant. The success of these stimuli is related to the sensitivity of the genotype which is ultimately reflected by yield in any given environment.
day/night temperatures below 20/15°C will result in floral induction.
Die back (Botryodiplodia theobromae Pat.) : Die back is one of the serious diseases of mango. The disease is prevalent in Rajasthan, Delhi, Tamil Nadu, Punjab, Haryana, Orissa, Gujrat, Maharashtra and Uttar Pradesh. The disease on the tree may be noticed at any time of the year but it is most conspicuous during Oct.-Nov. The disease is characterized by drying of twigs and branches followed by complete defoliation, which gives the tree an appearance of scorching by fire. The onset of die back becomes evident by discolouration and darkening of the bark. The dark area advances and young green twigs start withering first at the base and then extending outwards along the veins of leaf edges. The affected leaf turns brown and its margins roll upwards. At this stage, the twig or branch dies, shrivels and falls. This may be accompanied by exudation of gum. In old branches, brown streaking of vascular tissue is seen on splitting it longitudinally. The areas of cambium and phloem show brown discolouration and yellow gum like substance is found in some of the cells.
Bacterial canker (Xanthomonas campestris pv. mangiferaeindicae) : Canker disease of mango, caused by a bacterium, is prevalent in Andhra Pradesh, Maharashtra, Karnataka, Kerala, Tamil Nadu, U.P., Bihar, Delhi, Haryana, Madhya Pradesh and probably in several other mango growing areas. Besides being pathogenic on several varieties of mango, the organism is capable of infecting wild mango, cashew nut and weeds as well. The disease causes fruit drop (10-70%), yield loss (10-85%) and storage rot (5-100%). Many commercial cultivars of mango including Langra, Dashehari, Amrapali, Mallika, and Totapuri are susceptible to this disease.
The disease is found on leaves, petioles, twigs, branches and fruits, initially producing water-soaked lesions and later turning into typical cankers. The disease first appears as minute water-soaked irregular lesions on any part of leaf or leaf lamina. The lesions are light yellow in colour but with age, enlarge and turn dark brown to black. They become angular, cankerous and raised, and are surrounded by chlorotic halos. Several lesions coalesce to form irregular necrotic cankerous patches. In severe infections the leaves turn yellow and drop off. Cankerous lesions appear on petioles, twigs and young fruits. The water soaked lesions also develop on fruits which later turn dark brown to black. They often burst open, releasing a highly contagious gummy ooze containg bacterial cells. The fresh lesions on branches and twigs are water soaked which later become raised and dark brown in colour with longitudinal cracks but without any ooze.