What was it all about?

This project investigated control and management options for growers to reduce postharvest decay of papaya caused by fungal diseases. This was critical research given the industry reports annual yield losses to postharvest decay of 20 to 40 per cent.

The project evaluated the effectiveness of pre-harvest applications of difenoconazole in spray programs with protectant fungicides; the impact of regularly removing senescent leaves and disease infected fruit; as well as postharvest hot water treatment.

The trials were conducted with growers in the Mareeba and Innisfail area, and researchers found that while current fungicide spray schedules for the control of foliar diseases during the warm and wet summer months provided a level of control of many of the postharvest rots of papaya, there was no benefit in including the curative fungicide difenoconazole in the spray program.

Removal of dead leaf proved an effective method of reducing disease inoculum levels in the crop and also had the benefit of providing clear access to the fruit column during spraying of fungicide.

In the postharvest trials, results from disease assessments showed that hot water temperature treatments between 50° and 52°C provided the optimal treatment for controlling disease.  Benefits included…

• Reduced need for postharvest chemical fungicides
  
  
• Increased profit through reduced spoilage in supply chains
  
  
• The potential for fruit to be valued more highly because it had been produced with less impact on the environment.

The researchers determined that growers can achieve adequate control of postharvest diseases of papaya by combining field sprays and postharvest hot water.