Effect of wool-lined plastic caps impregnated with Bacillus licheniformis or copper oxychloride and sun-protector to prevent sunburn and control diseases in mango fruit

Summary

An innovative new strategy to apply copper fungicides, or the bacterial antagonist Bacillus licheniformis, to plastic caps with an added inner wool lining to protect mango fruit against both sunburn and disease was evaluated. Sun-protector sprayed onto trees alone, or as a carrier for the bacterial antagonist was also evaluated. Both capping and spraying treatments were evaluated over two growing seasons on two farms representative of different production regions in South Africa. Attachment and survival of the antagonist on the wool-lined caps were evaluated over 3 months using scanning electron microscopy. The use of wool-lined caps on mango fruit in the orchard led to a significant reduction in sunburn damage and provided an effective niche for B. licheniformis to attach and survive. However, wool-lined caps impregnated with copper fungicide or the bacterial antagonist had little added effect in controlling disease under field conditions when the disease pressure was low. Sun-protector, although intended to shield fruit from sunlight, proved ineffective against sunburn and did not further improve disease control when used as a carrier for biocontrol products. However, wool-lined caps alone have the potential to protect fruit against sunburn and infection over extended periods when farmers cannot gain access to their orchards.