Postharvest disease management for the control and anthracnose and stem and rot of mango fruits, commercial trial on the effectivity of heat treatment during controlled atmosphere transport/ storage

The inherently short shelf life of 'carabao' mango fruits limits its market to which it can be shipped in fresh form. Keeping fruits under low O2 and /or high CO2, called controlled atmosphere (CA), extended the storage life for almost one month. However, the major problems with the long term storage are quality deterioration and high incidence of disease. This study was conducted to develop a pre and post harvest management protocol that will maintain the quality and control diseases of mango during the 29-day stationary commercial CA storage upon exposure to air. An integrated cultural and disease management (IDM) program was implemented by Project 1 in an orchard in Pagasinan, [Philippines] consisting of pruning, sanitation, fertilization, growth regulation and need-based fungicide spray. Mangoes produced following the farmer's practice (FP) of calender-based spray program serves as control. Post harvest quality management activities include maturity check, field grading, use of rigid plastic crates for transport, timely application of heat treatment and precooling. Mangoes (5-5.8 tons) were packed in 5-kg cartons and stored in commercial CA van for 28-29 days at 12.5-13 deg C with O2 and CO2 maintained at 6% and 4%, respectively. Post-CA holding consisted of keeping fruits at different temperatures (25 deg, 20 deg, 17 deg and 14 deg C) simulating the conditions of importing countries. In the first trial wherein fruits were harvested during the early season (February), anthracnose and stem-end-rot were not adequately controlled during and after CA storage even with the combined pre-and post harvest disease management strategies employed. The post harvest heat treatment only reduced the incidence of disease. In the second trial where adjustment in the pre harvest fungicide spray program was employed and where fruits were produced during the hot month of May, both post harvest diseases were completely controlled during the 29-day CA storage. During ripening on air (post-CA), the desired disease level of 0-2% was attained up to the 5th day in fruits form IDM farm subjected to 7 min-dip at 53 deg C or 30-60 sec dip at 59 deg C. The control (nm-heat-treated) fruits had 18-20% disease incidence at the ripe stage. Storage under CA significantly retarded the ripening of the mango fruits for 28-29 days. The fruits attained the table ripe stage after 3 days exposure in air (post -CA) either at 25 deg, 20 deg, 17 deg or 14 deg C with shelf life extended for 3-4 days more after the attainment of the table ripe stage. Mangoes were of good quality and highly marketable after CA storage and even during holding in air at different temperature mainly due to the absence or very slight decay. Discoloration, shriveling, chilling injury and internal breakdown were absent. The pre- and post harvest management strategies employed did not affect the physico-chemical as well as the sensory attributes of the fruits at the ripe stage. The two commercial trials demonstrated that the success of CA storage relies on the integration of pre- and post harvest management strategies to maintain quality and control decay during and after CA holding. With this, the Philippines can now access through less costly sea shipment the potential but distant markets of Europe, North America and Middle East.