Blossom blight
Monilinia laxa
Blossom blight is a rot disease of stone fruit and hosts include apricots, cherries, nectarines, peaches, plums and almonds. Blossom blight is also a symptom of brown rot, which causes the death of flowers, fruit and occasionally shoots Blossom blight can result in significant losses as it can reduce fruit set and potential yield. Apples and pears can also be affected by blossom blight, although economic damage is rarely seen.
Description
Blossom blight-infected flowers turn brown and die, which can extend into the stem causing ringbarking and branch death. Fruit can also become infected closer to maturity, beginning as small brown spots, rotting within several days and often shrivelling up to form dry mummies.
Blossom blight survives over winter on mummified fruit on the ground, on trees and in twig cankers. Early in spring spores are released by rainfall and spread via wind, water or insects, infecting flowers and young shoots. Successful infection requires surface moisture and blossom blight thrives in warm, wet conditions. Secondary infections from blighted blossoms can be a source of inoculum affecting both immature and ripe fruit.
Control
Removal of fallen and infected fruit and shoots from trees will help reduce disease load. Pruning branches will increase air flow, allowing quicker drying times and better spray coverage. Additionally, insects such as carpophilus beetles and fruit fly can contribute to spread of the blossom blight and should be controlled, and overhead watering when trees are fruiting should be avoided.Monitor trees for symptoms and apply a preventative fungicide spray before the disease peaks. Luna® Sensation is registered for control of blossom blight in stone fruit and almonds and Luna® Experience for control of blossom blight in almonds.
References
Australian Stonefruit Grower (2012), ‘Blossom Blight Field Day Report’, No2/12 April/May pg 21-23, https://summerfruit.com.au/wp-content/uploads/2016/10/Australian-Stonefruit-Grower-April-May-2012-Summerfruit-Australia.pdfHerbiguide (Viewed Nov 2019), ‘Blossom Blight of Stone Fruit’, http://www.herbiguide.com.au/Descriptions/hg_Blossom_Blight_of_Stone_Fruit.htm
Villalta, O, Holmes, R and Kreidl, S (Viewed Nov 2019), ‘Best practices for Brown Rot Management – Booklet’, Biosciences Research, Department of Economic Development, Jobs Transport and Resources, Victoria State Government, http://www.hin.com.au/__data/assets/pdf_file/0006/19437/Brochure-Brown-Rot-Best-Practices-HIA-SF12004-Aug-2015.pdf
Brown Rot of stone fruits (Updated 25 June 2020)
https://agriculture.vic.gov.au/biosecurity/plant-diseases/fruit-and-nut-diseases/stone-fruits/brown-rot-of-stone-fruits