Project Detail

Project Number

260007

Project Leader

F. Vries

Institution

ARC Infruitec-Nietvoorbij

Team Members

-

Student(s)

-

Date Started

April, 2003

Date Completed

March, 2006

Biological control of post-harvest decay of stone and pome fruit

Executive Summary

The objective of this study has been to evaluate the compatibility of selected antagonistic yeasts, separately or in combination to enhance their bio-control activity and plant extracts on stone and pome fruit in controlling Botrytis cinerea.

Mixtures of yeasts were tested for their ability to control Botrytis cinerea on Granny Smith apples. Applying the yeast individually was effective, but not as effective as expected. None of the mixtures showed a high degree (90-95%) of effectivity against B. cinerea.  Competition for space or for nutrients by yeasts could be the reason when they grew in the presence of the other.

Improved control of B. cinerea was obtained with the application of low levels (0.05%) of iprodione in combination with yeast mixtures on Granny Smith apples. This approach not only makes it possible to reduce fungicide concentration while maintaining adequate decay control, but also ensures a reduction of the chemical residue on the fruit. Increased concentration of Cryptococcus albidus of 2 x 109cells/ml and 1.1 x 109cells/ml of C. albidus plus Candida pelliculosa significantly reduced decay caused by B. cinerea.

The drench application (80%) showed higher decay compared with the wound-inoculated (55%) trial on apples and pears. Drench application is usually more thorough. Wound-inoculation is a pre-requisite for optimal decay control. It appears if Packham Triumph pears are more susceptible to infection compare to apple cultivars. Decay for 2004/05 season was generally higher for nectarines and peaches. No decay was found on plums during the 2004/05 season. Overall, plant extracts and yeasts were effective in reducing decay development on fruit, but fungicide treatment proved to be better.

For Final Report, please contact:

anita@hortgro.co.za