Papaya, Carica papaya L., is a large perennial plant with rapid growth. It is an important fruit for Malaysian economy after durian and banana.The most popular cultivar in the local and export market is "Eksotika II", however postharvest pathogens cause significant losses.
Anthracnose by Colletotrichum gloeosporioides is one of the most serious pathogens during storage of papaya.
Malaysian scientists have studied the effect of pre-harvest applications of calcium chloride on anthracnose disease of papaya.
In vitro and in vivo tests were conducted to investigate the effect of calcium chloride application on fruit calcium content, spore germination, mycelial growth, and disease incidence.
For the study, pre-harvest foliar calcium sprays were applied biweekly to papaya trees in the experimental orchards at University Putra Malaysia. Solutions of 0.0, 0.5, 1.0, 1.5, and 2.0% (w/v) calcium chloride were tested. Then, fruits of uniform size and shape were harvested at index 2 (green with yellow trace), washed with water, dried, packaged in commercial boxes and stored at 12±2 °C and 85-90% RU for five weeks.
Results showed that pre-harvest calcium chloride sprays at 1.5-2.0% concentration increased significantly fruit calcium content, reduced significantly spore germination and the anthracnose incidence on fruits during five weeks of storage. After 35 days of storage, the anthracnose incidence was 100%, 62% and 46% in untreated (control), 1.5% calcium chloride treated, 2.0% calcium chloride treated fruit, respectively.
Scientists conclude that calcium is a safe and viable practice for postharvest disease control in papaya. Calcium salts may also have a significant role when fruit are subjected to long distance transportation. Moreover, the work will continue investigating pre-harvest calcium application at 1.5 or 2.0% concentrations combined with post-harvest dipping and infiltration of calcium to control anthracnose disease.
Source: Madani B., Tengku Muda Mohamed M., Biggs A.R., Kadir J., Awang Y., Tayebimeigooni A., RoodBar Shojaei T., "Effect of pre-harvest calcium chloride applications on fruit calcium level and post-harvest anthracnose disease of papaya", 2014, Crop Protection, Vol. 55, pagg. 66-60.
http://www.sciencedirect.com/science/article/pii/S0261219413002421